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Research ArticleEffect of Polymerization Conditions on Thermaland Mechanical Properties of Ethylene1-Butene CopolymerMade with Ziegler-Natta Catalysts

Mostafizur Rahaman1 M Anwar Parvez1 J B P Soares2 and I A Hussein1

1 Department of Chemical Engineering King Fahd University of Petroleum and Minerals Dhahran 31261 Saudi Arabia2Department of Chemical and Materials Engineering University of Alberta Edmonton AB Canada T6G 2V4

Correspondence should be addressed to I A Hussein ihusseinkfupmedusa

Received 20 February 2014 Accepted 22 May 2014 Published 11 June 2014

Academic Editor Giridhar Madras

Copyright copy 2014 Mostafizur Rahaman et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The effect of polymerization conditions on thermal and mechanical properties of ethylene1-butene copolymers synthesizedthrough titanium-magnesium-supported Ziegler-Natta catalysts was studiedThe increase in hydrogen pressure leads to a decreasein molecular weight (MW) storage modulus and melting temperature However it yields an increase in molecular weightdistribution (MWD) tan 120575 crystallinity tensile modulus yield stress and strain at break The effects of ethylene pressureand polymerization temperature on the copolymer MW MWD and thermal and mechanical properties have been investigatedHowever the impacts of ethylene pressure and polymerization temperature on copolymermodulus tensile strength crystallinitycrystallization peak temperature yield stress strain at break and yield strain are marginal The hydrogen pressure plays a majorrole in controlling the copolymer properties because it acts as an efficient chain transfer agent during polymerization reactionTheMW is the key parameter that influences flow activation energy However the other mechanical dynamic mechanical and thermalproperties not only depend on MW but are also influenced by other parameters

1 Introduction

The synthesis of ethylene-butene copolymers has been anattractive subject tomany authors because of their interestingproperties like low density high degree of branching and lowcost price per unit volume compared to ethylene-propylenecopolymer [1ndash3] One of the great advantages of thesecopolymers is that they can also be reused without decreasingtheir processing and physical properties Quan et al havesynthesized ethylene-butene copolymer through gas phasepolymerization technique where highly active catalysts likeTiCl4 SiO2or ZnCl

2alcoholAlR

3 and Ti(OBu)

4MgCl

2are

used [4] They have reported that the synthetic productshave the properties of both oligomer and copolymer andthe melting temperature crystallinity and crystallite sizedecrease with the increase in butene content in the copoly-mer The effect of polymerization conditions like hydrogenand comonomer concentration and polymerization time

on the properties of ethylene-butene copolymer synthesizedin two-step process has been reported elsewhere [1] Theinfluence of reaction time on ethylene1-butene copolymersynthesized over supported titanium-magnesium catalyst hasalso been studied [5 6] It has been shown that the increasein reaction time from 5 to 40min results in small increasein molecular weight (MW) narrowing of molecular weightdistribution (MWD) and decrease in 1-butene content in thecopolymer

Earlier the synthesis of homo- and copolymer of ethyleneusing Zeigler-Natta and other different catalysts has been car-ried outwhere discussions have beenmade on various aspectsof polymerization processes like the effect of catalyst typeon copolymer properties relationship of catalyst compositionwith molecular structure of homo- and copolymers and soforth [7ndash10] The advantages of using Zeigler-Natta catalystsare that they produce polymer products with high meltingpoint high MW and controllable morphology However

Hindawi Publishing CorporationInternational Journal of Polymer ScienceVolume 2014 Article ID 654260 10 pageshttpdxdoiorg1011552014654260

2 International Journal of Polymer Science

+30∘C hexane700 rpm

Ti(C8H17O)xCl4minusxCl3TiOTiCl3

HCl

Liquid solution Solid product Side product filtered-off

1 MgCl2 middot 3 C8H17OH + 5 TiCl4 MgCl2 middot C8H17O middot TiCl4

Scheme 1 Synthesis of the magnesium-supported Ziegler-Natta catalyst

there are some disadvantages associated with Ziegler-Nattacatalysts These catalysts have less control over the growingpolymer chain branching because there is the presenceof multiple metal sites on transition metal and also theremoval of catalyst from the final product is very difficult[11] Recently we have systematically discussed the effectof different polymerization conditions on dynamic mechan-ical thermal and mechanical properties of polyethylenehomopolymers made with Ziegler-Natta catalysts [12] More-over some correlations of homopolymers MWwith differentsolid state properties were also made in the same literature[12]

In the present section we have extended our previ-ous work where ethylene1-butene copolymers have beensynthesized over the same titanium-magnesium catalyst inlaboratory-scale reactor and investigated the effect of differ-ent polymerization conditions on copolymers MW MWDthermal and mechanical properties Similarly some corre-lations of copolymers MW with their solid state propertieslike dynamic mechanical thermal and tensile propertieshave been established and the fittings have been logicallydiscussed

2 Materials Methods andExperimental Techniques

21 Materials Ultrahigh purity nitrogen (99999) andpolymer grade ethylene (999) were supplied by PraxairCanada All the operations were performed under nitrogenusing standard Schlenk techniques or inside the glove boxEthylene and nitrogen were purified by passing throughcolumns These columns are packed with R3-11 coppercatalyst activated alumina and 3A4A mixed molecularsieves The materials such as titanium (IV) chloride (TiCl

4

99) and magnesium chloride (MgCl2 power-325 mesh)

were procured from Aldrich (Canada) and 2-ethyl-1-hexanol(99) was purchased from Alfa Aesar Germany Thesematerials were used for catalyst synthesis without furtherpurification Triethyl aluminum (TEA 1M in hexane) wasused as an activator and purchased from Aldrich CanadaThe reaction diluent hexane (HPLC grade 95 n-hexane)was purchased from J T Baker USA This was usedfor the synthesis of catalyst and copolymer It was puri-fied by passing through columns packed with activatedalumina and molecular sieves (Zeolum Type F-9 TosohCo Japan) The purified solvent was stored in Schlenkflasks (Sigma-Aldrich Canada) with 3A4Amixedmolecularsieves

22 Synthesis of Magnesium-Supported Ziegler-Natta CatalystThe solvent hexane (200mL) was taken to a 500mL roundbottled flask Magnesium chloride (762 g 008mol) and2-ethyl-1-hexanol (375mL 024mol) were added to it Aclear solution of the mixture was obtained after stirring andrefluxing for 24 hours Titanium (IV) chloride (05mol) wasslowly added dropwise to it at a stirring rate of 700 rpm andat a temperature of 30∘CThemixture was kept for 2 hours tocomplete the reaction The obtained precipitate was filteredand washed three times with hexane followed by dryingunder nitrogen flow Finally at the end of reaction a driedwhite powder was isolated Scheme 1 represents the syntheticroute for the synthesis of the catalyst

23 Synthesis of Ethylene1-Butene Copolymers The synthesisof ethylene1-butene copolymers is conducted under variousreaction conditions using magnesium-supported Ziegler-Natta catalyst A semibatch autoclave reactor (300mL) wasused for the polymerization reactions This reactor was com-posed of a mass flow meter and a temperature control unitThe temperature was controlled with a cooling coil and anelectric heater The tolerance of polymerization temperaturewas plusmn 02∘C of the set point The reactor was purged fivetimes with nitrogen before each reaction followed by heatingup to 140∘C under vacuum The reactor was purged againto the set point temperature under nitrogen flow Solvent(200mL) and triethyl aluminum activator (20mmol) weretaken in to the reactor followed by stirring for 5 minutesCatalyst slurry (30mg) mixed with hexane was injected intothe reactor and was stirred for 10 minutes In this typicalpolymerization process as for example the first run forsample 1 ethylene was continuously flowed to meet theethylene pressure of 5 bar inside the reactor under a stirringrate of 500 rpm Prior to ethylene 1-butene (713mmol) wasfed into the reactor Hydrogen gas was passed to the reactoruntil the pressure reached 1 bar The polymerizationreactiontemperature was adjusted to 60∘C and the polymerizationwas carried out for 30mins Ethylene flow to the reactorwas stopped at the end of the polymerization time andthe reactor was rapidly vented for reducing pressure andremoving reactantThe set temperature was reduced to roomtemperature The copolymer so obtained was precipitated in200mL ethanol followed by filtering and finally drying undervacuumThe detailed reaction condition and composition forall the copolymer samples are given in Table 1

24 Gel Permeation Chromatography (GPC) Gel perme-ation chromatography (GPC-IR Polymer Char Spain) was

International Journal of Polymer Science 3

Table 1 Ethylene1-butene copolymerization data (polymerization time 30min)

snumber 119875C2H4(bar) 1-Butene fraction (mmol) Poly

temp (∘C) 119875H2 (bar) MW (gmol) Mn (gmol) PDI (MWD)

1 5 713 60 1 162534 55472 2932 5 713 60 2 149653 45765 3273 5 713 60 3 123342 31871 3874 5 713 80 1 132669 42117 3155 5 713 80 2 119172 34442 3466 5 713 80 3 107637 26775 4027 5 1426 60 1 144653 42978 3538 5 1426 60 2 130350 33337 3919 5 1426 60 3 121622 26967 45110 5 1426 80 1 129823 34163 38011 5 1426 80 2 101153 23800 42512 5 1426 80 3 91842 19335 47513 10 713 60 1 176583 61254 28814 10 713 60 2 159136 51734 30815 10 713 60 3 131776 36043 36616 10 713 80 1 141970 46828 30317 10 713 80 2 123435 37772 32718 10 713 80 3 112062 29464 38019 10 1426 60 1 156754 45182 34720 10 1426 60 2 142238 36729 38721 10 1426 60 3 126835 29251 43422 10 1426 80 1 135454 37635 36023 10 1426 80 2 116068 28714 40424 10 1426 80 3 96752 21543 449

used to measure molecular weight and molecular weightdistribution of copolymers The samples were dissolved in124-trichlorobenzene at 160∘C followed by passing throughthree linear Polymer Laboratories columns These columnswere calibrated with polystyrene standards and operated ata flow rate of 1mLmin The detailed procedure of GPCcharacterizations has been mentioned elsewhere [13]

25 Differential Scanning Calorimetry (DSC) Differentialscanning calorimetry (DSC TA Instruments DSC Q1000series USA) was used to determine the melting temperatureof the polymers DSC test was carried out in nitrogenenvironment at a heating rate of 10∘Cmin where two scanswere performed The thermal properties of polymer dependon the previous historyTherefore it is a common practice inthermal analysis to heat the samples to remove the previoushistory and then perform the characterization under the samecontrolled history The second scan was used to characterizethe polymer samples

26 DynamicMechanical Analysis (DMA) DMA (TA instru-ment Q800 series USA) tests of the polymeric sampleswere performed in single cantilever (8mm length fixture)mode The sample specimens with a dimension of 8mm inlength and 101mm in width and thickness between 065 and

075mm were prepared using the fixed size mold in a carverpressThe temperature step sweepwas varied from 40 to 80∘Cwith a step of 10∘C per each frequency sweep For frequencysweep the range of frequency was 01ndash100Hz at the strain15 micron Temperature and frequency sweep test was runin strain controlled mode Time-temperature-superposition(TTS) mode was used to analyze the experimental data forgetting flow activation energy

27 Mechanical Testing Themechanical testing of polymericsamples was carried out at room temperature using Instron(model 5567 USA) tensile testing machine at a crossheadspeed of 50mmmin where gauge length was kept at 25mmThe samples were prepared according to ASTM D638 (TypeV) using a dog-bone mold in carver press

3 Results and Discussion

31 Effect of Polymerization Conditions on MW and MWDof Ethylene1-Butene Copolymers The variation of differentpolymerization conditions on MW and MWD of ethylene1-butene copolymers has been shown in Table 1 The effect ofhydrogen pressure on MW and MWD has been investigatedat 1 2 and 3 bar pressure It is seen from the table thatwith the increase in hydrogen pressure there is a decrease in


copolymer MW and broadening of MWD This decrease incopolymer MW and broadening of MWD can be explainedby considering the role of hydrogen pressure on the poly-merization reaction Actually the hydrogen present in thepolymerization reaction acts as a chain transfer agent forthe reaction [1 14] Thus the increase in hydrogen pressureresults in the termination of polymerization reaction Thisleads to the lowering of copolymer MW and broadening ofMWD Moballegh and Hakim have reported that an increasein hydrogen concentration by 026mol raised theMWD from8 to about 228 with considerable decrease in copolymerMW[1]This observation is consistent with our results mentionedherein This decrease in MW and broadening of MWD withrespect to hydrogen pressure are observed at both ethylenepressure values (5 and 10 bar) and both polymerizationtemperatures (60 and 80∘C)

The variation of MW and MWDwith respect to ethylenepressure (5 and 10 bar) has been shown in Table 1 Theincrease in ethylene pressure increases the copolymer MWand narrows the MWD MW is found to increase from119172 gmol to 123435 gmol (sample sets numbers 5 and17) when ethylene pressure was increased from 5 to 10 barwhile other polymerization conditions were kept the sameThis change represents an increase of 345 in MW andreduction in MWD from 346 to 327 (58 reduction inMWD) This decrementincrement level of percentage forMW and MWD varies with the sample sets The ethylenepresent in the polymerization reaction acts as an activator forthe catalyst in the reaction [14] At high ethylene pressure therole of ethylene as an activator is increased which results incopolymer with high MW and narrow MWD

Table 1 shows that MW and MWD of copolymer arealso affected by polymerization temperature An increasein polymerization temperature from 60 to 80∘C results inthe lowering of MW and broadening of MWD which canbe attributed to the strong chain transfer reaction duringcopolymerizationThe effect of comonomer concentration (1-butene) onMWandMWDhas been reported at two differentconcentrations in the table It is seen that the increase incomonomer concentration from 713 to 1426mmolL resultsin a decrease in MW and broadening of MWD due to thechain transfer reactionmechanism [1] In fact the increase incomonomer concentration leads to a decrease in the catalystactivity as reported in the literature [15ndash17]

32 Dynamic Mechanical Analysis (DMA) The effects of fre-quency and temperature on dynamic mechanical propertieslike storage modulus G1015840 and tan 120575 (damping factor) havebeen presented for the copolymer sample 2 (polymerizedat ethylene pressure = 5 bar hydrogen pressure = 2 barpolymerization temperature = 60∘C and polymerizationtime = 30min) The frequency has been varied from 01to 100Hz where the temperatures are 50∘C 60∘C 70∘Cand 80∘C The variation of G1015840 versus frequency measuredat different temperatures is presented in Figure 1 There isalmost a linear increase in G1015840 with the increase in frequencyOn the contrary G1015840 is found to decrease with the increase intemperature steps This is due to softening of copolymer at

100

200

300

400

500

600

700

Stor

age m

odul

us (M

Pa)

01 1 10 100Frequency (Hz)

Temp = 50∘C

Temp = 60∘C

Temp = 70∘C

Temp = 80∘C

T = 60∘C

t = 30min

PC2H4 =

PH2=

5 bar

2 bar

Figure 1 Dynamic temperature stepfrequency sweep for copoly-mer sample 2 synthesized at 119875C2H4 = 5 bar 119875H2 = 2 bar 119879polymerizationtemperature = 60∘C and 119905polymerization time = 30min

008

012

016

020

024

028


Temp = 50∘C

Temp = 60∘C

Temp = 70∘C

Temp = 80∘C

T = 60∘C

t = 30min

tan 120575

PC2H4 =

PH2=

5 bar

2 bar

Figure 2 Dynamic temperature stepfrequency sweep (tan 120575) forcopolymer sample 2 synthesized at 119875C2H4 = 5 bar 119875H2 = 2 bar119879polymerization temperature = 60∘C and 119905polymerization time = 30min

high temperature which leads to lowering of storage energyand thus G1015840 Figure 2 shows the effect of frequency on tan 120575at different temperatures It is observed that tan 120575 valuedecreases with the increase in frequency but increases withthe increase in temperature This increment in tan 120575 with theincrease in temperature is due to loss in storage energy athigher temperature

The effect of frequency on G1015840 at different hydrogenpressure namely 1 2 and 3 bar for the samples 1 2and 3 has been presented in Figure 3 The copolymeriza-tion conditions for these samples are the same (ethylenepressure = 5 bar polymerization temperature = 60∘C and


200

300

400

500

600

Stor

age

mod

ulus

(MPa

)


T = 60∘C

t = 30min

PH2=

PH2=

PH2=

PC2H4= 5 bar

Isothermally conditioned at 60∘C

1 bar2 bar3 bar

Figure 3 Storage modulus of copolymers synthesized at 119875C2H4 = 5bar 119879polymerization = 60∘C and 119905polymerization = 30min (samples 1 2 and3)

008

012

016

020

024

028


T = 60∘C

t = 30min

PC2H4 = 5bar

PH2=

PH2=

PH2=


tan 120575

1 bar2 bar3 bar

Figure 4 tan 120575 of copolymers synthesized at 119875C2H4 = 5 bar119879polymerization = 60∘C and 119905polymerization = 30min (samples 1 2 and 3)

polymerization time = 30min) The increase in hydrogenpressure results in reduction of G1015840 as is observed from thefigure Actually the hydrogen present in the reaction systemacts as an efficient chain transfer agent for the reaction ashas been mentioned earlier This leads to copolymer withshort chain length having lower MW In fact the degree ofchain entanglements in polymer decreases with the decreaseinMWand consequently results in lower value ofG1015840 Figure 4shows tan 120575 against frequency plots at different hydrogenpressure for the same set of samples It is observed from

320

360

400

016

020

024

175

210

245

(a)

(b)

(c)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 0964

R2= 0955

R2= 0992

G998400

(MPa

)ta

n 120575

ΔE

(kJm

ol)

Figure 5 Correlation plots ofMWwithG1015840 (a) tan 120575 (b) andΔE (c)

this figure that the increase in hydrogen pressure leads toincrease in tan 120575 value at any particular frequency In factthe polymer with lower MW (short chain length) will havehigher molecular movement compared to highMWpolymerof the same category This is because the polymer with lowMW will have low surface area per unit chain length whichresults in low physical attraction between the molecules [18]Thus the increase in molecular movement in copolymerresults in higher value of tan 120575 as tan 120575 is a measure ofstructural transformation (molecularmovement) in polymerThe higher the value of tan 120575 is the higher the structuraltransformation in polymer will be This is the reason forlow molecular weight polymer (short chain length polymer)having higher value of tan 120575 compared to long chain lengthpolymer The effects of ethylene pressure and polymerizationtemperature on both G1015840 and tan 120575 of the polymer are almostsimilar (not shown in picture) The differences exist only intheirmagnitudeThevariations ofG1015840 and tan 120575with respect tofrequencytemperature sweep ethylene and hydrogen pres-sure and polymerization temperature have been investigatedfor all samples but are not reported in this paper becausethe trend in variations is similar for all the samples Thecorrelation of G1015840 and tan 120575 with MW of polymers has beenestablished and the linear fit of the plots is shown in Figures5(a) and 5(b) The increase in MW leads to increase in G1015840which results in a reduction in tan 120575 values The coefficientsof correlation (R2) of the linear fit for G1015840 and tan 120575 are 0964and 0955 respectively Both R2 are almost close to unityindicating good linear correlation of G1015840 and tan 120575 with MW

The time temperature superposition (TTS) technique hasbeen applied to get the activation energy (ΔE) for all thesamples in solid state extracted from the DMA data Theresults of activation energy have been presented in Table 2The activation energy for all samples falls in the range of1839ndash2658 kJmol It is seen that the sample with higherMW exhibits higher ΔE The data of ΔE are plotted against


Table 2 Activation energy for copolymer samples (polymerization time 30min)


temp (∘C) 119875H2(bar) Activation energy (kJmol) MW (gmol)

1 5 713 60 1 2539 1625342 5 713 60 2 2437 1496533 5 713 60 3 2144 1233424 5 713 80 1 2251 1326695 5 713 80 2 2139 1191726 5 713 80 3 1984 1076377 5 1426 60 1 2354 1446538 5 1426 60 2 2234 1303509 5 1426 60 3 2141 12162210 5 1426 80 1 2205 12982311 5 1426 80 2 1941 10115312 5 1426 80 3 1839 9184213 10 713 60 1 2658 17658314 10 713 60 2 2486 15913615 10 713 60 3 2183 13177616 10 713 80 1 2326 14197017 10 713 80 2 2148 12343518 10 713 80 3 2047 11206219 10 1426 60 1 2436 15675420 10 1426 60 2 2334 14223821 10 1426 60 3 2174 12683522 10 1426 80 1 2278 13545423 10 1426 80 2 2061 11606824 10 1426 80 3 1886 96752

MW and are shown in Figure 5(c) which reveals a linearrelationship of ΔE with MW The value of R2 (0992) is veryclose to unity indicating that MW is the single parameterwhich influences ΔE

33 Differential Scanning Calorimeter (DSC) The thermalproperties of copolymer that is the crystallization temper-ature (Tc) melting temperature (Tm) and crystallinity(Xc) have been extracted from DSC and are shown inTable 3 The results show that Tc of copolymer remains inthe range of 11469ndash11789∘C This implies that the effects ofpolymerization parameters covered in this study on Tc aremarginal

The effect of hydrogen pressure can be correlated withcopolymer melting point as can be seen from the table It isobserved that Tm decreases with the increase in hydrogenpressure However this decrement in melting point is lesssignificantThis decrement inmelting point with the increasein hydrogen pressure can be explained by considering the roleof hydrogen as chain transfer agent during reaction whichalready has been mentioned earlier This role of hydrogenleads to lower MW copolymer that means lower surface areaof copolymer Thus there will be less physical attractionbetween low MW polymers chains for which less energy isrequired to overcome this force of attraction [18]This is why

with the increase in hydrogen pressure the melting pointof the copolymer decreases The ethylene pressure has lessimpact on melting point of copolymer It is seen from thetable that Tm at 5 bar of ethylene pressure is in the range of12399ndash13012∘C whereas at 10 bar of ethylene pressure is inthe range of 12591ndash13314∘C Thus a little bit positive shift oftemperature is observed when ethylene pressure is increasedThis positive shift may be due to narrow MWD of polymerssynthesized at high ethylene pressure Similarly the effect ofpolymerization temperature on copolymer melting point isless significant as is observed from the table

The effect of polymerization parameters on copolymercrystallinity has been reported in the same table as isobserved in the last column It is revealed from this tablethat the copolymer crystallinity increases with the increasein hydrogen pressure As the coordination polymerizationmethod is processed through successive polymerization andcrystallization [19] the increase in hydrogen pressure blocksthe active sites of polymerization resulting in decrease inpolymerization rate as a consequence the crystallization rateis increased This is why the increase in hydrogen pressureleads to increase in crystallinity [20] An almost similarobservation has been made for ethylene pressure that isthe increment in copolymer crystallinity is less significantwith the increase in ethylene pressure from 5 to 10 bar


Table 3 DSC analysis for copolymer samples (polymerization time 30min)


temp (∘C) 119875H2(bar) 119879

119888(∘C) 119879

119898(∘C) cryst (cooling)

1 5 713 60 1 11789 13012 46322 5 713 60 2 11686 12876 49543 5 713 60 3 11552 12592 53864 5 713 80 1 11691 12836 48135 5 713 80 2 11542 12737 52036 5 713 80 3 11437 12473 56577 5 1426 60 1 11683 12954 48608 5 1426 60 2 11552 12731 52449 5 1426 60 3 11463 12482 555810 5 1426 80 1 11534 12743 508311 5 1426 80 2 11445 12586 536112 5 1426 80 3 11392 12399 566313 10 713 60 1 11955 13314 517514 10 713 60 2 11856 13181 548615 10 713 60 3 11794 12977 570816 10 713 80 1 11834 13199 531917 10 713 80 2 11657 12968 568318 10 713 80 3 11529 12840 591219 10 1426 60 1 11867 13083 532120 10 1426 60 2 11679 12890 565021 10 1426 60 3 11580 12609 616322 10 1426 80 1 11677 12893 556623 10 1426 80 2 11512 12709 591024 10 1426 80 3 11469 12591 6362

as is observed from the table However the increment incrystallinity varies according to the condition of polymer-ization Shin et al have also reported similar results thatthe increase in ethylene pressure leads to marginal increasein crystallinity [21] The variation of copolymer crystallinitywith the increase in polymerization temperature is alsomarginal as is observed from the table

The influence of MW on polymer Tm Tc and Xc hasbeen investigated and the related plots are presented in Fig-ures 6(a)ndash6(c) It is observed from the figure that for all thethree cases though the data points are scattered randomlythere are the overall improvement in Tm (Figure 6(a)) andTc (Figure 6(b)) and reduction in Xc (Figure 6(c)) with theincrease in MW The R2 of the linear fits for Tm Tc andXc are 039 049 and 065 respectively far away from theunity Thus it can be said that the polymers Tm Tc and Xcare not only influenced by MW but also dependent on otherparameters

34 Mechanical Properties The results of mechanical prop-erties of copolymers like tensile modulus (TM) tensilestrength (TS) and strain at break (SB) are affected bythe polymerization parameters Table 4 shows themechanicaltesting results of copolymer for all the samples It is seenthat the increase in hydrogen pressure results in the increase

125

130

135

114

117

120

49

56

63

(a)

(b)

(c)

Tm

(∘C)

Tc

(∘C)

900 k 1200 k 1500 k 1800 kMw (gmol)

R2= 039

R2= 049

R2= 065

Xc

()

Figure 6 Correlation plots ofMWwith Tm (a) Tc (b) andXc (c)

in tensile modulus This type of result is obtained whenpolymerization is carried out at both 5 and 10 bar ethylene


Table 4 Mechanical properties of ethylene1-butene copolymer (polymerization time 30min)

snumber 119875C2H4(bar)

1-Butene fraction(mmolL)

Polytemp (∘C) 119875H2

(bar) Modulus(MPa)

Yield stress(MPa)

Yield strain()

Strain atbreak () TS (MPa)

1 5 713 60 1 419 plusmn 18 1363 plusmn 113 3 669 plusmn 23 4865 plusmn 4482 5 713 60 2 514 plusmn 21 1512 plusmn 125 3 756 plusmn 27 4555 plusmn 3563 5 713 60 3 591 plusmn 28 1708 plusmn 132 3 817 plusmn 35 4142 plusmn 3244 5 713 80 1 445 plusmn 15 1412 plusmn 121 4 686 plusmn 32 4791 plusmn 4255 5 713 80 2 544 plusmn 20 1522 plusmn 127 3 790 plusmn 28 4389 plusmn 3966 5 713 80 3 615 plusmn 31 1729 plusmn 131 3 845 plusmn 39 3989 plusmn 3477 5 1426 60 1 437 plusmn 17 1405 plusmn 112 4 678 plusmn 25 4732 plusmn 4148 5 1426 60 2 536 plusmn 22 1558 plusmn 118 4 771 plusmn 29 4345 plusmn 3829 5 1426 60 3 620 plusmn 29 1721 plusmn 124 4 823 plusmn 33 4024 plusmn 33210 5 1426 80 1 499 plusmn 20 1418 plusmn 114 4 698 plusmn 34 4655 plusmn 40611 5 1426 80 2 565 plusmn 27 1575 plusmn 119 4 785 plusmn 37 4261 plusmn 37512 5 1426 80 3 648 plusmn 33 1751 plusmn 125 3 842 plusmn 42 3864 plusmn 32613 10 713 60 1 458 plusmn 16 1381 plusmn 111 3 687 plusmn 26 5194 plusmn 45714 10 713 60 2 535 plusmn 23 1534 plusmn 122 3 784 plusmn 35 4665 plusmn 41215 10 713 60 3 634 plusmn 29 1723 plusmn 129 3 843 plusmn 39 4267 plusmn 33516 10 713 80 1 472 plusmn 19 1462 plusmn 113 3 702 plusmn 33 4943 plusmn 43617 10 713 80 2 575 plusmn 25 1558 plusmn 120 3 798 plusmn 37 4468 plusmn 39418 10 713 80 3 682 plusmn 34 1747 plusmn 126 3 856 plusmn 41 4153 plusmn 32819 10 1426 60 1 481 plusmn 23 1427 plusmn 115 3 698 plusmn 29 4984 plusmn 41920 10 1426 60 2 554 plusmn 27 1574 plusmn 123 4 812 plusmn 36 4466 plusmn 38621 10 1426 60 3 665 plusmn 34 1767 plusmn 131 3 876 plusmn 43 4183 plusmn 34222 10 1426 80 1 512 plusmn 29 1463 plusmn 117 3 718 plusmn 25 4745 plusmn 41423 10 1426 80 2 589 plusmn 36 1642 plusmn 128 3 828 plusmn 37 4336 plusmn 36824 10 1426 80 3 712 plusmn 39 1819 plusmn 133 3 896 plusmn 42 4035 plusmn 316

pressureWhenpolymerization is performed at 5 bar ethylenepressure the modulus is in the range of 419 plusmn 18ndash499 plusmn20MPa at 1 bar hydrogen pressure 514 plusmn 21ndash565 plusmn 27MPa at2 bar hydrogen pressure and 591 plusmn 28ndash648 plusmn 33MPa at 3 barhydrogen pressure Almost similar results are obtained whenpolymerization condition is maintained at 10 bar ethylenepressure where the tensile modulus is in the range of 458 plusmn16ndash512 plusmn 29MPa at 1 bar hydrogen pressure 535 plusmn 23ndash589plusmn 36MPa at 2 bar hydrogen pressure and 634 plusmn 29ndash712 plusmn39MPa at 3 bar hydrogen pressure Thus a careful look atthe results reveals that the tensile modulus value at 10 barethylene pressure is higher compared to tensile modulusvalue at 5 bar ethylene pressure Actually the tensile modulusis related to copolymer crystallinity as shown in Table 3 Itis seen that the copolymer with higher crystallinity is havinghigher modulus

The results of strain at break reported in the tableshow an increment in strain at break with the increase inhydrogen pressure The strain at break at 1 bar hydrogenpressure is in the range of 669 plusmn 23ndash698 plusmn 34 at 2 barhydrogen pressure is in the range 756 plusmn 27ndash785 plusmn 37 and at3 bar hydrogen pressure is in the range of 817 plusmn 35ndash842 plusmn 42when polymerization is conditioned at 5 bar ethylene pres-sure Similarly when polymerization is conditioned at 10 barethylene pressure the range of strain at break at 1 bar

hydrogen pressure is 687 plusmn 26ndash718 plusmn 25 at 2 bar hydrogenpressure is 784 plusmn 35ndash828 plusmn 37 and at 3 bar hydrogen pressureis 843 plusmn 39ndash896 plusmn 42 Thus the strain at break is somewhathigh for the copolymer synthesis at higher ethylene pressureIt is observed from the table that the yield strain remains inbetween 3 and 4 A careful look at Tables 4 and 3 revealsthat the copolymer with lowMW is having higher strain atbreak

Some variation of yield stress (YS) with the increase inhydrogen pressure is observed from the results shown in thesame table When polymerization is conditioned at 5 barethylene pressure the yield stress ranges at 1 bar 2 bar and3 bar hydrogen pressure are 1363 plusmn 113ndash1418 plusmn 114MPa1512plusmn 125ndash1575plusmn 119MPa and 1708plusmn 132ndash1751plusmn 125MParespectively This shows an increment in yield stress with theincrease in hydrogen pressure A similar type of incrementis observed when polymerization is conditioned at 10 barethylene pressure that is the yield stress ranges are 1381plusmn 111ndash1463 plusmn 117MPa 1534 plusmn 122ndash1642 plusmn 128MPa and1723 plusmn 129ndash1819plusmn 133MPa at 1 bar 2 bar and 3 bar hydrogenpressure respectively So from these results it comes true thatthe effect of ethylene pressure on yield stress is less significantcompared to the effect of hydrogen pressure It is also evidentfrom the table that the polymerization temperature has lowimpact on yield stress The tensile strength of copolymer


450

600

750

404550

700800900

141618

TM (M

Pa)

TS (M

Pa)

SB (

)YS

(MPa

)

(a)

(b)

(c)

(d)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 068

R2= 072

R2= 061

R2= 060

Figure 7 Correlation plots of MWwith TM (a) TS (b) SB (c) andYS (d)

improves with the increase in ethylene pressure but decreaseswith the increase in hydrogen pressure and polymerizationtemperature as is observed from the table

The data of tensile modulus (TM) tensile strength (TS) strain at break (SB) and yield stress (YS) are plottedagainstMWand are shown in Figures 7(a)ndash7(d) respectivelyAn effort to make linear fits of randomly scattered datapoints has been made for all four cases There is overalldecrement in TM SB and YS with the increase in MW Theimprovement happened only for TS The R2 of linear fitsfor TM (Figure 7(a)) TS (Figure 7(b)) SB (Figure 7(c)) andYS (Figure 7(d)) are 068 072 061 and 060 respectivelyThese R2 values are not close to unity indicating that thesemechanical properties not only depend on MW but arealso influenced by other parameters Actually rather thanMW these mechanical properties also depend on severalparameters like polymer crystallinity backbone chain lengthbranch (side) chain length chain entanglement branch chaincontent and so forth [4 12 22ndash25]Thus the establishment ofperfect correlation of MW with these mechanical propertiesis really difficult

4 Conclusions

The increase in both hydrogen pressure and polymeriza-tion temperature leads to decrease in copolymer MW andbroadening of MWD But the ethylene pressure plays theopposite role DMA results show an increase in storagemodulus but decrease in tan 120575 value with the increase in fre-quency On the contrary the storagemodulus value decreasesbut tan 120575 value increases with the increase in temperatureAn increase in hydrogen pressure results in reduction ofcopolymer storage modulus and melting point but increasein crystallinity tensile modulus strain at break and yieldstress It is seen that the copolymer with higher MW exhibitshigher activation energy It is revealed that the copolymer

with higher crystallinity is having higher tensile modulusHowever the impacts of other polymerization parameterslike ethylene pressure and polymerization temperature oncopolymer modulus tensile strength crystallinity Tc yieldstress strain at break and yield strain are marginalThe major role of hydrogen in controlling the copolymerproperties is due to its acting as an efficient chain transferagent during polymerization reactionThe correlation ofMWwith the thermal and mechanical properties of the polymeris given in this paper The MW is the key parameter thatinfluences ΔE whereas the other dynamic mechanical (G1015840and tan 120575) thermal (Tm Tc and Xc) andmechanical (TMTS SB and YS) properties not only depend on MW but arealso influenced by different parameters as mentioned earlierHowever almost good linear correlation of MW with G1015840 andtan 120575 is observed

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

Acknowledgments

The authors acknowledge the financial support provided byKing Abdul Aziz City for Science and Technology for thisresearch project under research Grant no AT-27-67 Theauthors also acknowledge the facilities and support providedby KFUPM

References

[1] L Moballegh and S Hakim ldquoMolecularweight bimodality ofethylene1-butene in a two-step polymerization process effectsof polymerization conditionsrdquo Iranian Polymer Journal vol 20no 6 pp 513ndash521 2011

[2] H S Mobarakeh M F Monfared and M Vakili ldquoGas phasecopolymerization of ethylene and 1-butene with prepolymer-ized MgCl

2supported Ziegler-Natta catalyst effect of AlTi

ratiordquo Iranian Polymer Journal vol 15 no 7 pp 569ndash575 2006[3] W Kaminsky ldquoNew polymers by metallocene catalysisrdquoMacro-

molecular Chemistry and Physics vol 197 no 12 pp 3907ndash39451996

[4] D-P Quan X-G Fan and H-H Wang ldquoStructure andmechanical properties of ethylene-butene copolymersrdquo Chem-ical Research in Chinese Universities vol 18 no 1 pp 52ndash552002

[5] Y V Kissin R I Mink T E Nowlin and A J BrandolinildquoKinetics and mechanism of ethylene homopolymerizationand copolymerization reactions with heterogeneous Ti-basedZiegler-Natta catalystsrdquo Topics in Catalysis vol 7 no 1ndash4 pp69ndash88 1999

[6] Y V Kissin F M Mirabella and C C Meverden ldquoMulti-center nature of heterogeneous Ziegler-Natta catalysts TREFconfirmationrdquo Journal of Polymer Science A Polymer Chemistryvol 43 no 19 pp 4351ndash4362 2005

[7] L G Echevskaya M A Matsko T B Mikenas V E Nikitinand V A Zakharov ldquoSupported titanium-magnesium catalystswith different titanium content kinetic peculiarities at ethy-lene homopolymerization and copolymerization andmolecular


weight characteristics of polyethylenerdquo Journal of Applied Poly-mer Science vol 102 no 6 pp 5436ndash5442 2006

[8] V Zakharov L Echevskaya T Mikenas et al ldquoSupportedziegler-natta catalysts for ethylene slurry polymerization andcontrol of molecular weight distribution of polyethylenerdquo Chi-nese Journal of Polymer Science vol 26 no 5 pp 553ndash559 2008

[9] M A Matsko L G Echevskaya V A Zakharov M I Niko-laeva T B Mikenas and M P Vanina ldquoStudy of multi-sitenature of supported Ziegler-Natta catalysts in ethylene-hexene-1 copolymerizationrdquo Macromolecular Symposia vol 282 no 1pp 157ndash166 2009

[10] Y V Kissin R I Mink and T E Nowlin ldquoEthylene poly-merization reactions with Ziegler-Natta catalysts I Ethylenepolymerization kinetics and kinetic mechanismrdquo Journal ofPolymer Science A Polymer Chemistry vol 37 pp 4255ndash42721999

[11] P Kaewarsa Polymerization of ethylene over the supportedZiegler-Natta andmetallocene catalysts onmagnesium hydroxideand magnesium hydroxychloride [Thesis in Chemistry Science]Graduate School Khonkaen University 2005

[12] M A Parvez M Rahaman M A Suleiman J B P Soaresand I A Hussein ldquoCorrelation of polymerization conditionswith thermal and mechanical properties of polyethylenes madewith Ziegler-Natta catalystsrdquo International Journal of PolymerScience vol 2014 Article ID 549031 10 pages 2014

[13] T Hameed and I A Hussein ldquoRheological study of theinfluence of M W and comonomer type on the miscibility ofm-LLDPE and LDPE blendsrdquo Polymer vol 43 no 25 pp 6911ndash6929 2002

[14] M I Nikolaeva T B Mikenas M A Matsko L G Echevskayaand V A Zakharov ldquoEthylene polymerization over supportedtitanium-magnesium catalysts effect of polymerization param-eters on the molecular weight distribution of polyethylenerdquoJournal of Applied Polymer Science vol 122 no 5 pp 3092ndash31012011

[15] J C W Chien and T Nozaki ldquoEthylene-hexene copolymeriza-tion by heterogeneous and homogeneous Ziegler-Natta cata-lysts and the ldquocomonomerrdquo effectrdquo Journal of Polymer ScienceA Polymer Chemistry vol 31 no 1 pp 227ndash237 1993

[16] P Kumkaew L Wu P Praserthdam and S E Wanke ldquoRatesand product properties of polyethylene produced by copoly-merization of 1-hexene and ethylene in the gas phase with (n-BuCp)

2ZrCl2on supports with different pore sizesrdquo Polymer

vol 44 no 17 pp 4791ndash4803 2003[17] K Heiland andW Kaminsky ldquoComparison of zirconocene and

hafnocene catalysts for the polymerization of ethylene and 1-butenerdquo Macromolecular Chemistry and Physics vol 193 pp601ndash610 1992

[18] L H Sperling Introduction to Physical Polymer Science Wiley-Interscience New York NY USA 4th edition 2006

[19] B Wunderlich ldquoCrystallization during polymerizationrdquoAdvances in Polymer Science vol 5 pp 568ndash619 1968

[20] A Munoz-Escalona and A Parada ldquoFactors affecting thenascent structure and morphology of polyethylene obtainedby heterogeneous Ziegler-Natta catalysts 2 Crystallinity andmelting behaviourrdquo Polymer vol 20 no 7 pp 859ndash866 1979

[21] Y-J ShinH-X Zhang K-B Yoon andD-H Lee ldquoPreparationof ultra high molecular weight polyethylene with MgCl

2TiCl4

catalysts effect of temperature and pressurerdquo MacromolecularResearch vol 18 no 10 pp 951ndash955 2010

[22] M F Talbott G S Springer and L A Berglund ldquoThe effects ofcrystallinity on themechanical properties of PEEKpolymer and

graphite fiber reinforced PEEKrdquo Journal of CompositeMaterialsvol 21 no 11 pp 1056ndash1081 1987

[23] J A Brydson Plastics Materials British Library Cataloguing inPublication Data 7th edition 1999

[24] G Wang B Guo and R Li ldquoSynthesis characterization andproperties of long-chain branched poly(butylene succinate)rdquoJournal of Applied Polymer Science vol 124 no 2 pp 1271ndash12802012

[25] U W Gedde Polymer Physics Library of Congress Cataloging-in-Publication Data Kluwer Academic Publishers 1st edition1995

Submit your manuscripts athttpwwwhindawicom

ScientificaHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CorrosionInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Polymer ScienceInternational Journal of



CeramicsJournal of


CompositesJournal of

NanoparticlesJournal of



International Journal of

Biomaterials


NanoscienceJournal of

TextilesHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Journal of

NanotechnologyHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

CrystallographyJournal of


The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014


CoatingsJournal of

Advances in

Materials Science and EngineeringHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Smart Materials Research



MetallurgyJournal of


BioMed Research International

MaterialsJournal of


Nano

materials


Journal ofNanomaterials


+30∘C hexane700 rpm

Ti(C8H17O)xCl4minusxCl3TiOTiCl3

HCl

Liquid solution Solid product Side product filtered-off

1 MgCl2 middot 3 C8H17OH + 5 TiCl4 MgCl2 middot C8H17O middot TiCl4

Scheme 1 Synthesis of the magnesium-supported Ziegler-Natta catalyst

there are some disadvantages associated with Ziegler-Nattacatalysts These catalysts have less control over the growingpolymer chain branching because there is the presenceof multiple metal sites on transition metal and also theremoval of catalyst from the final product is very difficult[11] Recently we have systematically discussed the effectof different polymerization conditions on dynamic mechan-ical thermal and mechanical properties of polyethylenehomopolymers made with Ziegler-Natta catalysts [12] More-over some correlations of homopolymers MWwith differentsolid state properties were also made in the same literature[12]

In the present section we have extended our previ-ous work where ethylene1-butene copolymers have beensynthesized over the same titanium-magnesium catalyst inlaboratory-scale reactor and investigated the effect of differ-ent polymerization conditions on copolymers MW MWDthermal and mechanical properties Similarly some corre-lations of copolymers MW with their solid state propertieslike dynamic mechanical thermal and tensile propertieshave been established and the fittings have been logicallydiscussed

2 Materials Methods andExperimental Techniques

21 Materials Ultrahigh purity nitrogen (99999) andpolymer grade ethylene (999) were supplied by PraxairCanada All the operations were performed under nitrogenusing standard Schlenk techniques or inside the glove boxEthylene and nitrogen were purified by passing throughcolumns These columns are packed with R3-11 coppercatalyst activated alumina and 3A4A mixed molecularsieves The materials such as titanium (IV) chloride (TiCl

4

99) and magnesium chloride (MgCl2 power-325 mesh)

were procured from Aldrich (Canada) and 2-ethyl-1-hexanol(99) was purchased from Alfa Aesar Germany Thesematerials were used for catalyst synthesis without furtherpurification Triethyl aluminum (TEA 1M in hexane) wasused as an activator and purchased from Aldrich CanadaThe reaction diluent hexane (HPLC grade 95 n-hexane)was purchased from J T Baker USA This was usedfor the synthesis of catalyst and copolymer It was puri-fied by passing through columns packed with activatedalumina and molecular sieves (Zeolum Type F-9 TosohCo Japan) The purified solvent was stored in Schlenkflasks (Sigma-Aldrich Canada) with 3A4Amixedmolecularsieves

22 Synthesis of Magnesium-Supported Ziegler-Natta CatalystThe solvent hexane (200mL) was taken to a 500mL roundbottled flask Magnesium chloride (762 g 008mol) and2-ethyl-1-hexanol (375mL 024mol) were added to it Aclear solution of the mixture was obtained after stirring andrefluxing for 24 hours Titanium (IV) chloride (05mol) wasslowly added dropwise to it at a stirring rate of 700 rpm andat a temperature of 30∘CThemixture was kept for 2 hours tocomplete the reaction The obtained precipitate was filteredand washed three times with hexane followed by dryingunder nitrogen flow Finally at the end of reaction a driedwhite powder was isolated Scheme 1 represents the syntheticroute for the synthesis of the catalyst

23 Synthesis of Ethylene1-Butene Copolymers The synthesisof ethylene1-butene copolymers is conducted under variousreaction conditions using magnesium-supported Ziegler-Natta catalyst A semibatch autoclave reactor (300mL) wasused for the polymerization reactions This reactor was com-posed of a mass flow meter and a temperature control unitThe temperature was controlled with a cooling coil and anelectric heater The tolerance of polymerization temperaturewas plusmn 02∘C of the set point The reactor was purged fivetimes with nitrogen before each reaction followed by heatingup to 140∘C under vacuum The reactor was purged againto the set point temperature under nitrogen flow Solvent(200mL) and triethyl aluminum activator (20mmol) weretaken in to the reactor followed by stirring for 5 minutesCatalyst slurry (30mg) mixed with hexane was injected intothe reactor and was stirred for 10 minutes In this typicalpolymerization process as for example the first run forsample 1 ethylene was continuously flowed to meet theethylene pressure of 5 bar inside the reactor under a stirringrate of 500 rpm Prior to ethylene 1-butene (713mmol) wasfed into the reactor Hydrogen gas was passed to the reactoruntil the pressure reached 1 bar The polymerizationreactiontemperature was adjusted to 60∘C and the polymerizationwas carried out for 30mins Ethylene flow to the reactorwas stopped at the end of the polymerization time andthe reactor was rapidly vented for reducing pressure andremoving reactantThe set temperature was reduced to roomtemperature The copolymer so obtained was precipitated in200mL ethanol followed by filtering and finally drying undervacuumThe detailed reaction condition and composition forall the copolymer samples are given in Table 1

24 Gel Permeation Chromatography (GPC) Gel perme-ation chromatography (GPC-IR Polymer Char Spain) was





1 5 713 60 1 162534 55472 2932 5 713 60 2 149653 45765 3273 5 713 60 3 123342 31871 3874 5 713 80 1 132669 42117 3155 5 713 80 2 119172 34442 3466 5 713 80 3 107637 26775 4027 5 1426 60 1 144653 42978 3538 5 1426 60 2 130350 33337 3919 5 1426 60 3 121622 26967 45110 5 1426 80 1 129823 34163 38011 5 1426 80 2 101153 23800 42512 5 1426 80 3 91842 19335 47513 10 713 60 1 176583 61254 28814 10 713 60 2 159136 51734 30815 10 713 60 3 131776 36043 36616 10 713 80 1 141970 46828 30317 10 713 80 2 123435 37772 32718 10 713 80 3 112062 29464 38019 10 1426 60 1 156754 45182 34720 10 1426 60 2 142238 36729 38721 10 1426 60 3 126835 29251 43422 10 1426 80 1 135454 37635 36023 10 1426 80 2 116068 28714 40424 10 1426 80 3 96752 21543 449













100

200

300

400

500

600

700

Stor

age m

odul

us (M

Pa)


Temp = 50∘C

Temp = 60∘C

Temp = 70∘C

Temp = 80∘C

T = 60∘C

t = 30min

PC2H4 =

PH2=

5 bar

2 bar


008

012

016

020

024

028


Temp = 50∘C

Temp = 60∘C

Temp = 70∘C

Temp = 80∘C

T = 60∘C

t = 30min

tan 120575

PC2H4 =

PH2=

5 bar

2 bar





200

300

400

500

600

Stor

age

mod

ulus

(MPa

)


T = 60∘C

t = 30min

PH2=

PH2=

PH2=

PC2H4= 5 bar


1 bar2 bar3 bar


008

012

016

020

024

028


T = 60∘C

t = 30min

PC2H4 = 5bar

PH2=

PH2=

PH2=


tan 120575

1 bar2 bar3 bar



320

360

400

016

020

024

175

210

245

(a)

(b)

(c)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 0964

R2= 0955

R2= 0992

G998400

(MPa

)ta

n 120575

ΔE

(kJm

ol)








1 5 713 60 1 2539 1625342 5 713 60 2 2437 1496533 5 713 60 3 2144 1233424 5 713 80 1 2251 1326695 5 713 80 2 2139 1191726 5 713 80 3 1984 1076377 5 1426 60 1 2354 1446538 5 1426 60 2 2234 1303509 5 1426 60 3 2141 12162210 5 1426 80 1 2205 12982311 5 1426 80 2 1941 10115312 5 1426 80 3 1839 9184213 10 713 60 1 2658 17658314 10 713 60 2 2486 15913615 10 713 60 3 2183 13177616 10 713 80 1 2326 14197017 10 713 80 2 2148 12343518 10 713 80 3 2047 11206219 10 1426 60 1 2436 15675420 10 1426 60 2 2334 14223821 10 1426 60 3 2174 12683522 10 1426 80 1 2278 13545423 10 1426 80 2 2061 11606824 10 1426 80 3 1886 96752









temp (∘C) 119875H2(bar) 119879

119888(∘C) 119879


1 5 713 60 1 11789 13012 46322 5 713 60 2 11686 12876 49543 5 713 60 3 11552 12592 53864 5 713 80 1 11691 12836 48135 5 713 80 2 11542 12737 52036 5 713 80 3 11437 12473 56577 5 1426 60 1 11683 12954 48608 5 1426 60 2 11552 12731 52449 5 1426 60 3 11463 12482 555810 5 1426 80 1 11534 12743 508311 5 1426 80 2 11445 12586 536112 5 1426 80 3 11392 12399 566313 10 713 60 1 11955 13314 517514 10 713 60 2 11856 13181 548615 10 713 60 3 11794 12977 570816 10 713 80 1 11834 13199 531917 10 713 80 2 11657 12968 568318 10 713 80 3 11529 12840 591219 10 1426 60 1 11867 13083 532120 10 1426 60 2 11679 12890 565021 10 1426 60 3 11580 12609 616322 10 1426 80 1 11677 12893 556623 10 1426 80 2 11512 12709 591024 10 1426 80 3 11469 12591 6362




125

130

135

114

117

120

49

56

63

(a)

(b)

(c)

Tm

(∘C)

Tc

(∘C)

900 k 1200 k 1500 k 1800 kMw (gmol)

R2= 039

R2= 049

R2= 065

Xc

()








(bar) Modulus(MPa)

Yield stress(MPa)

Yield strain()








450

600

750

404550

700800900

141618

TM (M

Pa)

TS (M

Pa)

SB (

)YS

(MPa

)

(a)

(b)

(c)

(d)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 068

R2= 072

R2= 061

R2= 060




4 Conclusions





Acknowledgments


References




























2TiCl4














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







1 5 713 60 1 162534 55472 2932 5 713 60 2 149653 45765 3273 5 713 60 3 123342 31871 3874 5 713 80 1 132669 42117 3155 5 713 80 2 119172 34442 3466 5 713 80 3 107637 26775 4027 5 1426 60 1 144653 42978 3538 5 1426 60 2 130350 33337 3919 5 1426 60 3 121622 26967 45110 5 1426 80 1 129823 34163 38011 5 1426 80 2 101153 23800 42512 5 1426 80 3 91842 19335 47513 10 713 60 1 176583 61254 28814 10 713 60 2 159136 51734 30815 10 713 60 3 131776 36043 36616 10 713 80 1 141970 46828 30317 10 713 80 2 123435 37772 32718 10 713 80 3 112062 29464 38019 10 1426 60 1 156754 45182 34720 10 1426 60 2 142238 36729 38721 10 1426 60 3 126835 29251 43422 10 1426 80 1 135454 37635 36023 10 1426 80 2 116068 28714 40424 10 1426 80 3 96752 21543 449













100

200

300

400

500

600

700

Stor

age m

odul

us (M

Pa)


Temp = 50∘C

Temp = 60∘C

Temp = 70∘C

Temp = 80∘C

T = 60∘C

t = 30min

PC2H4 =

PH2=

5 bar

2 bar


008

012

016

020

024

028


Temp = 50∘C

Temp = 60∘C

Temp = 70∘C

Temp = 80∘C

T = 60∘C

t = 30min

tan 120575

PC2H4 =

PH2=

5 bar

2 bar





200

300

400

500

600

Stor

age

mod

ulus

(MPa

)


T = 60∘C

t = 30min

PH2=

PH2=

PH2=

PC2H4= 5 bar


1 bar2 bar3 bar


008

012

016

020

024

028


T = 60∘C

t = 30min

PC2H4 = 5bar

PH2=

PH2=

PH2=


tan 120575

1 bar2 bar3 bar



320

360

400

016

020

024

175

210

245

(a)

(b)

(c)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 0964

R2= 0955

R2= 0992

G998400

(MPa

)ta

n 120575

ΔE

(kJm

ol)








1 5 713 60 1 2539 1625342 5 713 60 2 2437 1496533 5 713 60 3 2144 1233424 5 713 80 1 2251 1326695 5 713 80 2 2139 1191726 5 713 80 3 1984 1076377 5 1426 60 1 2354 1446538 5 1426 60 2 2234 1303509 5 1426 60 3 2141 12162210 5 1426 80 1 2205 12982311 5 1426 80 2 1941 10115312 5 1426 80 3 1839 9184213 10 713 60 1 2658 17658314 10 713 60 2 2486 15913615 10 713 60 3 2183 13177616 10 713 80 1 2326 14197017 10 713 80 2 2148 12343518 10 713 80 3 2047 11206219 10 1426 60 1 2436 15675420 10 1426 60 2 2334 14223821 10 1426 60 3 2174 12683522 10 1426 80 1 2278 13545423 10 1426 80 2 2061 11606824 10 1426 80 3 1886 96752









temp (∘C) 119875H2(bar) 119879

119888(∘C) 119879


1 5 713 60 1 11789 13012 46322 5 713 60 2 11686 12876 49543 5 713 60 3 11552 12592 53864 5 713 80 1 11691 12836 48135 5 713 80 2 11542 12737 52036 5 713 80 3 11437 12473 56577 5 1426 60 1 11683 12954 48608 5 1426 60 2 11552 12731 52449 5 1426 60 3 11463 12482 555810 5 1426 80 1 11534 12743 508311 5 1426 80 2 11445 12586 536112 5 1426 80 3 11392 12399 566313 10 713 60 1 11955 13314 517514 10 713 60 2 11856 13181 548615 10 713 60 3 11794 12977 570816 10 713 80 1 11834 13199 531917 10 713 80 2 11657 12968 568318 10 713 80 3 11529 12840 591219 10 1426 60 1 11867 13083 532120 10 1426 60 2 11679 12890 565021 10 1426 60 3 11580 12609 616322 10 1426 80 1 11677 12893 556623 10 1426 80 2 11512 12709 591024 10 1426 80 3 11469 12591 6362




125

130

135

114

117

120

49

56

63

(a)

(b)

(c)

Tm

(∘C)

Tc

(∘C)

900 k 1200 k 1500 k 1800 kMw (gmol)

R2= 039

R2= 049

R2= 065

Xc

()








(bar) Modulus(MPa)

Yield stress(MPa)

Yield strain()








450

600

750

404550

700800900

141618

TM (M

Pa)

TS (M

Pa)

SB (

)YS

(MPa

)

(a)

(b)

(c)

(d)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 068

R2= 072

R2= 061

R2= 060




4 Conclusions





Acknowledgments


References




























2TiCl4














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials








100

200

300

400

500

600

700

Stor

age m

odul

us (M

Pa)


Temp = 50∘C

Temp = 60∘C

Temp = 70∘C

Temp = 80∘C

T = 60∘C

t = 30min

PC2H4 =

PH2=

5 bar

2 bar


008

012

016

020

024

028


Temp = 50∘C

Temp = 60∘C

Temp = 70∘C

Temp = 80∘C

T = 60∘C

t = 30min

tan 120575

PC2H4 =

PH2=

5 bar

2 bar





200

300

400

500

600

Stor

age

mod

ulus

(MPa

)


T = 60∘C

t = 30min

PH2=

PH2=

PH2=

PC2H4= 5 bar


1 bar2 bar3 bar


008

012

016

020

024

028


T = 60∘C

t = 30min

PC2H4 = 5bar

PH2=

PH2=

PH2=


tan 120575

1 bar2 bar3 bar



320

360

400

016

020

024

175

210

245

(a)

(b)

(c)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 0964

R2= 0955

R2= 0992

G998400

(MPa

)ta

n 120575

ΔE

(kJm

ol)








1 5 713 60 1 2539 1625342 5 713 60 2 2437 1496533 5 713 60 3 2144 1233424 5 713 80 1 2251 1326695 5 713 80 2 2139 1191726 5 713 80 3 1984 1076377 5 1426 60 1 2354 1446538 5 1426 60 2 2234 1303509 5 1426 60 3 2141 12162210 5 1426 80 1 2205 12982311 5 1426 80 2 1941 10115312 5 1426 80 3 1839 9184213 10 713 60 1 2658 17658314 10 713 60 2 2486 15913615 10 713 60 3 2183 13177616 10 713 80 1 2326 14197017 10 713 80 2 2148 12343518 10 713 80 3 2047 11206219 10 1426 60 1 2436 15675420 10 1426 60 2 2334 14223821 10 1426 60 3 2174 12683522 10 1426 80 1 2278 13545423 10 1426 80 2 2061 11606824 10 1426 80 3 1886 96752









temp (∘C) 119875H2(bar) 119879

119888(∘C) 119879


1 5 713 60 1 11789 13012 46322 5 713 60 2 11686 12876 49543 5 713 60 3 11552 12592 53864 5 713 80 1 11691 12836 48135 5 713 80 2 11542 12737 52036 5 713 80 3 11437 12473 56577 5 1426 60 1 11683 12954 48608 5 1426 60 2 11552 12731 52449 5 1426 60 3 11463 12482 555810 5 1426 80 1 11534 12743 508311 5 1426 80 2 11445 12586 536112 5 1426 80 3 11392 12399 566313 10 713 60 1 11955 13314 517514 10 713 60 2 11856 13181 548615 10 713 60 3 11794 12977 570816 10 713 80 1 11834 13199 531917 10 713 80 2 11657 12968 568318 10 713 80 3 11529 12840 591219 10 1426 60 1 11867 13083 532120 10 1426 60 2 11679 12890 565021 10 1426 60 3 11580 12609 616322 10 1426 80 1 11677 12893 556623 10 1426 80 2 11512 12709 591024 10 1426 80 3 11469 12591 6362




125

130

135

114

117

120

49

56

63

(a)

(b)

(c)

Tm

(∘C)

Tc

(∘C)

900 k 1200 k 1500 k 1800 kMw (gmol)

R2= 039

R2= 049

R2= 065

Xc

()








(bar) Modulus(MPa)

Yield stress(MPa)

Yield strain()








450

600

750

404550

700800900

141618

TM (M

Pa)

TS (M

Pa)

SB (

)YS

(MPa

)

(a)

(b)

(c)

(d)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 068

R2= 072

R2= 061

R2= 060




4 Conclusions





Acknowledgments


References




























2TiCl4














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




200

300

400

500

600

Stor

age

mod

ulus

(MPa

)


T = 60∘C

t = 30min

PH2=

PH2=

PH2=

PC2H4= 5 bar


1 bar2 bar3 bar


008

012

016

020

024

028


T = 60∘C

t = 30min

PC2H4 = 5bar

PH2=

PH2=

PH2=


tan 120575

1 bar2 bar3 bar



320

360

400

016

020

024

175

210

245

(a)

(b)

(c)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 0964

R2= 0955

R2= 0992

G998400

(MPa

)ta

n 120575

ΔE

(kJm

ol)








1 5 713 60 1 2539 1625342 5 713 60 2 2437 1496533 5 713 60 3 2144 1233424 5 713 80 1 2251 1326695 5 713 80 2 2139 1191726 5 713 80 3 1984 1076377 5 1426 60 1 2354 1446538 5 1426 60 2 2234 1303509 5 1426 60 3 2141 12162210 5 1426 80 1 2205 12982311 5 1426 80 2 1941 10115312 5 1426 80 3 1839 9184213 10 713 60 1 2658 17658314 10 713 60 2 2486 15913615 10 713 60 3 2183 13177616 10 713 80 1 2326 14197017 10 713 80 2 2148 12343518 10 713 80 3 2047 11206219 10 1426 60 1 2436 15675420 10 1426 60 2 2334 14223821 10 1426 60 3 2174 12683522 10 1426 80 1 2278 13545423 10 1426 80 2 2061 11606824 10 1426 80 3 1886 96752









temp (∘C) 119875H2(bar) 119879

119888(∘C) 119879


1 5 713 60 1 11789 13012 46322 5 713 60 2 11686 12876 49543 5 713 60 3 11552 12592 53864 5 713 80 1 11691 12836 48135 5 713 80 2 11542 12737 52036 5 713 80 3 11437 12473 56577 5 1426 60 1 11683 12954 48608 5 1426 60 2 11552 12731 52449 5 1426 60 3 11463 12482 555810 5 1426 80 1 11534 12743 508311 5 1426 80 2 11445 12586 536112 5 1426 80 3 11392 12399 566313 10 713 60 1 11955 13314 517514 10 713 60 2 11856 13181 548615 10 713 60 3 11794 12977 570816 10 713 80 1 11834 13199 531917 10 713 80 2 11657 12968 568318 10 713 80 3 11529 12840 591219 10 1426 60 1 11867 13083 532120 10 1426 60 2 11679 12890 565021 10 1426 60 3 11580 12609 616322 10 1426 80 1 11677 12893 556623 10 1426 80 2 11512 12709 591024 10 1426 80 3 11469 12591 6362




125

130

135

114

117

120

49

56

63

(a)

(b)

(c)

Tm

(∘C)

Tc

(∘C)

900 k 1200 k 1500 k 1800 kMw (gmol)

R2= 039

R2= 049

R2= 065

Xc

()








(bar) Modulus(MPa)

Yield stress(MPa)

Yield strain()








450

600

750

404550

700800900

141618

TM (M

Pa)

TS (M

Pa)

SB (

)YS

(MPa

)

(a)

(b)

(c)

(d)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 068

R2= 072

R2= 061

R2= 060




4 Conclusions





Acknowledgments


References




























2TiCl4














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials







1 5 713 60 1 2539 1625342 5 713 60 2 2437 1496533 5 713 60 3 2144 1233424 5 713 80 1 2251 1326695 5 713 80 2 2139 1191726 5 713 80 3 1984 1076377 5 1426 60 1 2354 1446538 5 1426 60 2 2234 1303509 5 1426 60 3 2141 12162210 5 1426 80 1 2205 12982311 5 1426 80 2 1941 10115312 5 1426 80 3 1839 9184213 10 713 60 1 2658 17658314 10 713 60 2 2486 15913615 10 713 60 3 2183 13177616 10 713 80 1 2326 14197017 10 713 80 2 2148 12343518 10 713 80 3 2047 11206219 10 1426 60 1 2436 15675420 10 1426 60 2 2334 14223821 10 1426 60 3 2174 12683522 10 1426 80 1 2278 13545423 10 1426 80 2 2061 11606824 10 1426 80 3 1886 96752









temp (∘C) 119875H2(bar) 119879

119888(∘C) 119879


1 5 713 60 1 11789 13012 46322 5 713 60 2 11686 12876 49543 5 713 60 3 11552 12592 53864 5 713 80 1 11691 12836 48135 5 713 80 2 11542 12737 52036 5 713 80 3 11437 12473 56577 5 1426 60 1 11683 12954 48608 5 1426 60 2 11552 12731 52449 5 1426 60 3 11463 12482 555810 5 1426 80 1 11534 12743 508311 5 1426 80 2 11445 12586 536112 5 1426 80 3 11392 12399 566313 10 713 60 1 11955 13314 517514 10 713 60 2 11856 13181 548615 10 713 60 3 11794 12977 570816 10 713 80 1 11834 13199 531917 10 713 80 2 11657 12968 568318 10 713 80 3 11529 12840 591219 10 1426 60 1 11867 13083 532120 10 1426 60 2 11679 12890 565021 10 1426 60 3 11580 12609 616322 10 1426 80 1 11677 12893 556623 10 1426 80 2 11512 12709 591024 10 1426 80 3 11469 12591 6362




125

130

135

114

117

120

49

56

63

(a)

(b)

(c)

Tm

(∘C)

Tc

(∘C)

900 k 1200 k 1500 k 1800 kMw (gmol)

R2= 039

R2= 049

R2= 065

Xc

()








(bar) Modulus(MPa)

Yield stress(MPa)

Yield strain()








450

600

750

404550

700800900

141618

TM (M

Pa)

TS (M

Pa)

SB (

)YS

(MPa

)

(a)

(b)

(c)

(d)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 068

R2= 072

R2= 061

R2= 060




4 Conclusions





Acknowledgments


References




























2TiCl4














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials






temp (∘C) 119875H2(bar) 119879

119888(∘C) 119879


1 5 713 60 1 11789 13012 46322 5 713 60 2 11686 12876 49543 5 713 60 3 11552 12592 53864 5 713 80 1 11691 12836 48135 5 713 80 2 11542 12737 52036 5 713 80 3 11437 12473 56577 5 1426 60 1 11683 12954 48608 5 1426 60 2 11552 12731 52449 5 1426 60 3 11463 12482 555810 5 1426 80 1 11534 12743 508311 5 1426 80 2 11445 12586 536112 5 1426 80 3 11392 12399 566313 10 713 60 1 11955 13314 517514 10 713 60 2 11856 13181 548615 10 713 60 3 11794 12977 570816 10 713 80 1 11834 13199 531917 10 713 80 2 11657 12968 568318 10 713 80 3 11529 12840 591219 10 1426 60 1 11867 13083 532120 10 1426 60 2 11679 12890 565021 10 1426 60 3 11580 12609 616322 10 1426 80 1 11677 12893 556623 10 1426 80 2 11512 12709 591024 10 1426 80 3 11469 12591 6362




125

130

135

114

117

120

49

56

63

(a)

(b)

(c)

Tm

(∘C)

Tc

(∘C)

900 k 1200 k 1500 k 1800 kMw (gmol)

R2= 039

R2= 049

R2= 065

Xc

()








(bar) Modulus(MPa)

Yield stress(MPa)

Yield strain()








450

600

750

404550

700800900

141618

TM (M

Pa)

TS (M

Pa)

SB (

)YS

(MPa

)

(a)

(b)

(c)

(d)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 068

R2= 072

R2= 061

R2= 060




4 Conclusions





Acknowledgments


References




























2TiCl4














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials








(bar) Modulus(MPa)

Yield stress(MPa)

Yield strain()








450

600

750

404550

700800900

141618

TM (M

Pa)

TS (M

Pa)

SB (

)YS

(MPa

)

(a)

(b)

(c)

(d)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 068

R2= 072

R2= 061

R2= 060




4 Conclusions





Acknowledgments


References




























2TiCl4














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials




450

600

750

404550

700800900

141618

TM (M

Pa)

TS (M

Pa)

SB (

)YS

(MPa

)

(a)

(b)

(c)

(d)

900 k 1200 k 1500 k 1800 kMW (gmol)

R2= 068

R2= 072

R2= 061

R2= 060




4 Conclusions





Acknowledgments


References




























2TiCl4














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials





















2TiCl4














CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials










CeramicsJournal of







Biomaterials




Journal of


Journal of





CoatingsJournal of

Advances in








MaterialsJournal of


Nano

materials



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