INDUSTRIAL TRANING PROGRAMME

FOR

PST 309 . 3 : INDUSTRIAL PROJECT / SEMINARS

K . G . N . P . SOMARATHNAAS / 2007457

B . Sc POLIMER GROUP 2006 / 2007UNIVERSITY OF SRI JAYAWARDENAPURA

NUGEGODA

SELECTING THE BEST SULPHUR TO ACCELERATOR RATIO TO GET THE PRODUCT GIVING BEST PERFORMER.

Contents Page No:Preface ………………………………………………………….. 1Acknowledgement …………………………………………. 2Chapter 01

Introduction of Dry Rubber Industry ……………………. 3Rubber Industry in Sri Lanka ……………………………. 5About AMW ……………………………………………….. 7Tyre Retreading Manufacturing …………………………. 8Process line to Manufacture of procured tyre tread …... 9Tyre Structure …………………………………………….. 10Properties of tread …………………………………………11

Chapter 02What is R4 …………………………………………………. 12Processing Condition & Mixing Sequence ……………… 13Properties of R4 …………………………………………… 13

Chapter 03About Experiment …………………………………………. 14Method ……………………………………………………… 15Results of Experiment 01 …………………………………. 17Conclusion of Experiment 01 …………………………….. 21Experiment 02 ……………………………………………… 22Results of Experiment 02 …………………………………. 22Conclusion of Experiment 02 ……………………………… 27

Chapter 04Discussion, conclusion & References …………………….. 28

Preface

The principle objective of this report is to introduce about tyre retarding and to select the best vulcanizing system to obtain best quality retread for tyres.In this project, dry rubber products, vulcanizing systems, tyre retreading, selecting the best Sulpher to accelerator ratio to obtain best quality product in compounds have been discussed.

K.G.N.P. SomarathnaAS/2007457/2006/2007

Acknowledgement

First I would like to express my sincere gratitude to Dr. L.M.K. Thilakarathne, project supervisor and course coordinator of Polymer Science and Technology at department of Chemistry, Faculty of applied science, university of Sri Jayewardenepura for assigning me to AMW group of factories, Nagoda, Sri Lanka and his valuable guidance extended constructive criticism throughout my study and also spending his valuable time in bringing my study to successful completion.

I wish to express my sincere thanks to the Prof. Sudantha Liyanage, Dean of the faculty of applied science, senior lecturer at department of Chemistry faculty of applied science, university of Sri Jayewardenepura. I also thanks full to Dr. Laleen Karunanayaka and all of the staff members of the department of chemistry for their interest and valuable advice during my studies.

My special thanks to Mr. Yugantha Piyadasa, senior Quality Assurance and Development Manager, and all the staff of AMW group of factories for making me aware on Dry Rubber technology.

I shall be thankfull to all the friends supported me for giving help to success of my training and project.

K.G.N.P. SomarathnaAS 2007457/2006/2007

DRY RUBBER INDUSTRYIntroduction

Among thousands of industries dry rubber industry has become a major industry in today’s world. Not only in the world, even in Sri Lanka has dry rubber industry played a vital role among other industries. It provides dry rubber products for domestic use and also to the export market. Therefore dry rubber industry contributes largely in our economic growth. With the growth of the

industry world, dry rubber consumption has increased. Also in Sri Lanka there was a rapid growth in dry rubber industries. Following figures show growth of the dry rubber industry in last two

decade.

Year Dry rubber Consumption(Mt)

Year Dry rubberConsumption(Mt)

1981 10789 1992 19960

1982 11980 1993 23670

1983 12856 1994 24780

1984 13783 1995 34690

1985 11344 1996 35520

1986 22764 1997 35440

1987 10563 1998 50200

1988 19720 1999 36830

1989 20128 2000 40250

1990 22500 2001 35550

1991 21040 2002 35600

Figure 1.Locally produced dry NR consumption in Mt

The dry rubber based industries in Sri Lanka started during the war years as tube vulcanizing and tyre retreading industries and they were completely based on locally produced dry NR. In 1967 Sri Lanka commenced production of cross ply tyres, has consumed about 5% of domestic NR production. It was started as the Kelani Tyre manufacturing corporation.Today Sri Lanka is the world’s fifth largest exporter of natural rubber, generating over 100,000 tons annually. More than 60 percent is exported in an unprocessed form.On the manufacturing front, Sri Lanka is the world’s leading supplier of solid rubber tyres for off-road vehicles. Major investments have also been made by producers of healthcare and surgical rubber products, where high quality raw material is of primary importance. Globally, there is a good demand for rubber tiles and floor coverings. In addition, shoe producers obtain rubber heels and sole from Sri Lanka.Opportunities investment includes the manufacture of tyres, tubes and automotive rubber products, especially by relocating these facilities from high cost industrialized or industrializing countries.

Sri Lanka’s Competitive Advantages in the Rubber Industry• Availability of high quality raw rubber at competitive prices.• Recognition as a high quality Natural Rubber (Latex Crape) Producer.• Access to a pool of technical and professional manpower at competitive wage rates.• Attractive incentives.• Good infrastructure.• Competencies built over 124 years of experience in the industry.• Availability of supporting services (research and development facilities, testing and certification services).

The Rubber Industry in Sri LankaSri Lanka is the world’s 9th largest producer of NR. It is also the major supplier of high quality latex crepe to the world market and the world’s largest manufacturer and exporter of solid tyres for off-road vehicles. Nearly 60% of the NR production in Sri Lanka is used for value added rubber products. The bulk of these value-added products are for the export market. Foreign investors from 2o countries have set up lucrative and long sending world class ventures under BOI approval. The 59 BOI approved rubber industry projects consume nearly 75% of Sri Lanka’s total domestic NR production.Today in Sri Lanka there are several companies which produce branded dry rubber products. Their production contributes to both domestic and export market. Among these factories,Associate Motorways Ltd. Richard P. Exports Ltd.Loadstar (Pvt) Ltd.Ceat-Kelani Intern. Tyres (Pvt) Ltd.

Rubber Product Manufacturing in Sri Lanka

Product TypeNo of projects Investment

(Rs. Millions)Employment(No’s)

Tyre Retreading 3 5% 558 4% 235 1%

Pneumatic types & Tubes

3 5% 4825 31% 4077 25%

Solid Tyres 4 7% 896 6% 667 4%

Footwear 2 4% 855 5% 306 2%

Flooring 2 4% 928 6% 253 2%

Other dry 8 14% 390 2% 942 6%

Latex dipped 26 46% 6652 43% 9244 56%

Latex form 8 14% 547 3% 676 4%

Total 56 100% 15651 100% 16400 100%

Dry rubber Industries

Motor car components

Household’s appliances (Flooring)

Other products

Dry rubber industry can be divided in to three parts.

Among various kinds of dry rubber industries, Tyre manufacturing has become a major and essential industry in today’s world. Large percentage of the total dry rubber consumption goes to

the tyre industry. This industry becomes more popular with the retreading of tyres.In Sri Lanka, Ceat-Kelani International Tyres (Pvt) Ltd, Associated Motorways Ltd, Richard

P. Exports Ltd, etc are the main companies that involving in the tyre manufacturing and treading.Due to environmental issues and very high consumption of dry rubber, treading industry

came into scene. Today it provides large amount of job opportunities while helping to develop the economy in the country. Also dry rubber industry is a very challenging field. With the economic

growth, competition has increased largely within last few years.

About AMW

Associated Motor Ways (AMW) is the pioneer privately owned group of companies located in main rubber growing area in Kaluthara district in Sri Lanka. The

company has been established in 1949. The present assets of the company worth were US$22 million in 2002-2003. AMW is one of the leading rubber products factories

in Sri Lanka producing motor cycle & three-wheel tyres & retreading small to large scale tyres using hot cure, pre cure (cold), Dir Hard & vaculug processes.

Associated Auto Ways Associated universal (Pvt) Ltd, Associated CEAT (Pvt) Ltd are associated companies and their external customers are mainly global

rubber industries, Arpitalian compact soles (Pvt) Ltd, and Oman Vacu-Lng Company. The company has captured the export market too and is producing Trap straps, Mud Flaps, Carpets, two and three-wheeler tyres and rubber compounds to be exported to

USA, Canada, and India and Middle East countries.

About AMW RetreadingAMW rebuilds all size ranging from small passenger car tyres to large off

the road earthmover tyres. The tyre retreading process enjoy ISO 9002 certification and the organization is the market leader in Sri Lanka in this field apart from

rebuilding customer tyres, avarity of tyre retreading material available for sale.

Tyre Retreading ManufacturingAs the presences of imported pneumatic tyres are rising sharply, most of

the people are used particular bus and lorry owner used retreaded tyres in their vehicles. Among 30 tyre trading companies, AMW Company is the oldest tyre

retreading company set up in Sri Lanka as further as late 1949.At the early stage retreading of tyre was done by the molded process

where green tyre build on a completely buff old tyre & it vulcanized by placing inside the mould at high temperature and pressure.

The main drawback of this process is that the output is very low and only one tyre can be retreaded in a mould in about 45 minutes Further ;

Mould is specific. One specific tyre size can be compression cured in a particular mould and even a

different quality tyre of the same dimension can’t be cured in this mould. Hence in order to overcome this incomesinning process, the new pre cured tread system has

been introduced. In this method instead of molding a green tyre inside a mould, fully prevulcanized tread is pasted on the clean buffed bold surface of the old tyre by

means of rubber cement. Then several of these tread pasted tyres are finally cured inside an auto clave. Hence large no of tyres of different brands can be cured at once

in this process.

Mixing of rubber and Chemicals

Sulphuring

Mystification in two roll mill

Extrusion of moulds

Testing the samples

Getting camel back

Place in trunk for further cooling

Applied camel back to mould

Tread

Process line to manufacturer of pre cured tyre trades.

2 min

(After 4 hours

From mixing) (In bambery)

After 8 hours

Cooling (By passing in water)

(Curing)

Tyre structure

Serial No Element Functions01 Tread Tread is the part which comes into contact with road

surface. It protects the carcass & provide high grip, longer life, maneuverability and durability.

02 Steel Belts This provides stiffness to the tread & protect the carcass.

03 Spiral Layer This provides high durability & maneuverability.

04 Shoulder Shoulder is the thickest part of the tyre. It protects carcass from external shocks & damages.

05 Sidewall Sidewall is the most flexible part of the tyre. It protects carcass & provides comfortable ride

06 Ply cord Ply cord is the main body of a tyre. It sustains the inflation pressure and endures load and road shocks.

07 Bead Filler This provides high durability & maneuverability.

08 Bead Wires It holds the tyre on rim.

09 Chafer Chafer protects ply cord at the bead area from the heat generation developed due to the abrasion of bead and rim flange.

Properties of a Tyre TreadTread is the most important part of the tyre which is getting in contact with the road surface during rubbing of the vehicle. Hence wearing resistance of the thread should be very high & it should not be too hard to discomfort passenger inside vehicle. It should not be too soft or slip ring as well for

the safety of the vehicle.

What is R4R-4 is the tread compound to make a procured rubber tread for three wheel tyres.

Chemical composition of R-4Master compound

MaterialQty(kg)

Sc 3x 94.000

Br 01 23.500

Accimel 0.188

Z no 5.875

Stearic acid 2.350

CBN-375 70.500

Processing oil 17.000

Permanex TQ 0.880

Batch weight 214.293

R-4 is a sulfuring process.

Material Qty(kg)

2nd stage master 190.000

Santo cure(TBBS)(Accelerator)

1.256

Sulphur(Vulcanizing agent)

1.345

6 PPD (activator) 1.020

PVI (Pre vulcanizing inhibitor) 0.110

Processing conditions & mixing sequence1st Stage Time (min)NR+BR+ (black+ Accimel + chem. B-)(2 no 95 + stearic Acid)…………………………………………………………………. 0.00Process oil……………………………………………………………………………...... 2:00Sweep……………………………………………………………………………............. 3:30Dump……………………………………………………………………………………… 5:00

2nd stage (After 4 hours from mixing)Re-pass (in Banbarry) ………………………………………………………………….. 2:00

Sulphuring (After 4 hours from 2nd stage mixing) Weight (Kg)Master compound ……………………………………………………………………190.000 kgNS (TBBS)……………………………………………………………………………..1.256 kgSulphur…………………………………………………………………………………1.345 kg6 PPD…………………………………………………………………………………..1.020 kgPVI ……………………………………………………………………………………..0.110 kg

Properties of R-4

Property ValueTensile strength (TS) kgcm-2 ………………………………………………….. 190-200Elongation at break (%)………………………………………………………… 500-550Moduless at 300% (kgcm-2) …………………………………………………… 85 -107Hardness (shore A) (IR)………………………………………………………... 60-62Specific gravity (gcm-3) ………………………………………………………… 1.135 +/- 0.01Abrasion loss (mm-3) …………………………………………………………… 60-67

Rheometer properties

T Minimum T s2 / s T Max T90% /s

1.15-1.80 45-60 9.5-12.8 84-115

ExperimentImproving properties in the R-4 compound by changing the Sulphur to accelerator ratio

Objective: - Selecting the best Sulphur to accelerator ratio to get the product giving best performance.

Vulcanizing SystemThere are three vulcanizing systems available for curing. Those are conventional

vulcanizing system, semi-efficient vulcanizing system (Semi EV),efficient vulcanizing system(EV).

Vulcanizing System Amount-ratio of Sulphur to accelerator

Conventional vulcanizing system Greater than 1(Sulphur =2 to 4 per)(Accelerator = 1 to 0.5 per)

Efficient vulcanizing system (EV) Less than 1(Sulpher =0.4 to 0.8 per)(Accelerator = 3 to 0.5 per)

Semi-efficient vulcanizing system (semi-EV)

Approaches 1Sulpher =1 to 1.5 per)(Accelerator = 1.5 to 1.0 per)

AMW use only conventional vulcanizing system for R-4 sulfuring. Because it gives better cross linking

MethodHere we have sulfur zing process. Following procedure was carried out;Master compound was obtainedIt was masticated by using two roll millAfter 2 minutes, immediately it was added TBBS, Sulfur, PVI, 6 PPD to two roll millThen the sulfured compound was obtained from the two roll mill in sheet of 1cm in thickness.After an hour one piece of compound was cut and it was subjected to curing characteristic test using a Rheometer.Then after 24 hours two samples were obtained from the sulfur compound and one vulcanized sample was subjected to the tensile strength, of using thetensometer and the other vulcanized sample was subjected to test obresion loss by means of a abrasion tester. Note: - 1. Before testing tensile strength the sample should be cut to the shape of bumble using dumbel cutter.

Usually thickness =2mmCut

width=0.41 m 0.4 cm2. Also before testing abrasion loss of the sample, sample was

obtained as in the following shape by using a mould.

Properties obtained from RheometerScotch time (TS2)T90

Modulus (T max)T Min

Properties obtained from tensile meterTensile strength = Breaking load (kg) Area (cm2)Modulus at 300% = Load at 300% (kg) Area (cm2)Properties obtained from Abrasion testerAbrasion = Weight Lost(w1-w2) Specific gravity (Sp)

Above procedures were done for following trials. Here in these trails only varying sulfur & accelerators, master compound and other chemicals are same for all the trails.Experiment 01In lab scale testing we had to convert amount of ingredients as follows,

WeightMaster batch…………………………………………… 250 gNS…………………………………………………………… 1.652 gSulfur ………………………………………………....... 1.769 gPVI ………………………………………………….........1.144 g6 PPD ………………………………………………….... 1.02 g

In experiment 1, amount of sulfur was kept constant an amount of accelerator was varied as follows. WeightSulfur amount = 1.769 g

Accelerator amount; A 1.550 g

B 1.600 g

C 1.700 g

D 1.650 g

E 1.750 g

Results:-Rheograph for composition type A

Rheograph for composition type B

Reograph for composition type C

Reograph for composition type D

Rheograph for composition type E

Rheograph for composition type all together

( 1=A, 2=B, 3=C, 4=D, 5=E)

Tensile Strength Results

Composition type

Thickness /cm

Cut width /cm

Area /cm2

Lord at300% /Kg

Elongation at break%

Breaking load/Kg

Modules at300%/Kgcm-2

Tensile strength /Kgcm-2

  0.253 0.39 0.0986 9.2 500 20.8 93.3 210.9

  0.264 0.41 0.1082 10.8 500 21.8 99.8 210.5

(A) 0.212 0.4 0.0848 9.9 490 17.5 114.4 206.4

  0.24 0.38 0.0912 9.8 500 18.7 107.5 205

  0.251 0.39 0.0999 10.8 510 21 110.3 214.5

          500     209.5

                 

  0.242 0.41 0.0992 9.8 490 18.5 98.8 186.5

  0.28 0.41 0.1148 13 470 20.8 113.2 181.2

(B) 0.21 0.41 0.0861 10.1 450 16.5 117.3 191.6

  0.266 0.4 0.1064 13.8 450 21.4 129.9 201.1

0.242 0.41 0.0992 12.5 460 18.8 126 189.5

          464     189.9

                 

  0.215 0.4 0.085 10.2 480 17.8 118.6 206.9

  0.208 0.42 0.0873 10.8 470 17.2 123.7 197

(C) 0.198 0.39 0.0772 9.8 480 16.8 126.9 217.6

  0.232 0.38 0.0882 10.2 470 18.5 115.6 209.7

  0.18 0.4 0.072 8.8 500 15 122.2 208.3

          480     207.9

                 

  0.252 0.4 0.1008 12.8 500 21 126.9 208

  0.22 0.4 0.088 9.5 500 19.8 107.9 225

(D) 0.22 0.4 0.088 10.5 500 17.8 119.3 202.3

  0.21 0.38 0.0798 10 510 18.2 125.3 228

  0.232 0.38 0.0881 10 520 19.2 113.5 217.9

          506     216.2

                 

  0.263 0.4 0.1052 11.4 500 20.2 108.4 192

  0.24 0.37 0.0888 11.2 480   126.1  

(E) 0.253 0.41 0.1037 13.5 450 20.4 130.2 196.9

  0.22 0.42 0.0924 11.8 470 18 127.7 194.8

  0.255 0.4 0.102 11.2 450 16 109.8 156.8

          470     185.4

Abrasion testing Results

Composition (A) (B) (C) (D) (E)

type          

Hardness 63 59 63 59 59

(IRHD)          

Specific 1.124 1.138 1.122 1.136 1.127

gravity (g/cm3)          

Weight loss (g) 1.61 1.62 1.63 1.96 1.59

  1.53 1.56 1.56 1.6 1.5

  0.08 0.05 0.07 0.07 0.09

           

Abrasion(mm3) 71.1 52.7 62.3 61.6 79.8

71.161.6 62.3

52.7

79.8

0

10

20

30

40

50

60

70

80

90

A B C D E

Composite Type

Abr

asio

n lo

ss (m

m3 )

Tensile strength with composition type

Abrasion loss with composition Type

Conclusion:According to that experiment,Recipe containing sulfur amount = 1.769 gAnd accelerator amount = 1.6505 g (Composition Type D) was the best. Hence the sample containing 1.650 g of accelerator, keeping sulfur constant was the best.

Experiment 2 In experiment 2 following trails were done as the procedure mentioned in experiment 1. For all the trails accelerator amount was kept as 1.650 g (conclusion of experiment 1) and sulfur amount was varied. WeightAccelerator amount = 1.650 gSulfur amount; F1.770 g G1.870 g H1.820 g

I1.720 g J1.670 g

Results:-Rheograph for composition type F

Rheograph for composition type G

Rheograph for composition type H

Rheograph for composition type I

Rheograph for composition type J

Rheograph for composition type all together

(1=F, 2=G, 3=H,4=I, 5=J )

Tensile strength Results

Compositiontype

Thickness/cm

Cut width/cm

Area/cm2

Lord at300% /Kg

Elongationat break%

Breakingload/Kg

Modules at300%/Kgcm-2

Tensile strength/Kgcm-2

  0.2165 0.41 0.1086 11.5 480 20 105.9 184.2

  0.275 0.41 0.11 12.6 470   114.5  

(F) 0.248 0.41 0.1017 12.8 480 19.8 125.8 194.7

  0.18 0.41 0.0738 9.4 470 15.4 127.4 208.9

  0.216 0.4 0.0864 10.2 470 16.8 118 194.4

          474     195.5

                 

  0.252 0.42 0.1058 12.8 480 22.6 120.9 213.6

  0.23 0.4 0.092 11.5 470 19.8 125 215.2

(G) 0.238 0.41 0.0975 11.8 470 19.8 121 203.1

  0.21 0.4 0.084 10 500 17.2 119 204.9

  0.22 0.4 0.088 10.8 500 18.8 122.7 213.6

          484     210

                 

  0.228 0.4 0.0912 11.8 480 19.6 129.4 214.9

(H) 0.235 0.38 0.0893 13.3 490 21.4 148.9 239.6

  0.23 0.38 0.0874 12.8 480 21.1 146.4 241.4

  0.252 0.4 0.1008 11 490 20.6 109.1 204.3

          485     225

                 

  0.267 0.41 0.1093 11.1 500 19.8 101.3 180.8

  0.232 0.42 0.0974          

(I) 0.3 0.41 0.123 13.2 500 22.8 107.3 185.3

  0.245 0.4 0.098 11.2 500 19.4 114.3 197.9

  0.185 0.42 0.0777 7.6 520 13.4 97.8 198.2

          505     190.5

                 

  0.272 0.4 0.1088 12.5 470 19.2 114.8 176.5

  0.253 0.39 0.0986 11.2 470 19.8 113.6 200.8

(J) 0.252 0.39 0.0983 8.8 480 19 89.5 193.3

  0.224 0.4 0.0896 10.6 470 17.8 118.3 198.6

  0.295 0.38 0.1121 13.8 470 23 133.1 205.2

          472     194.8

Abrasion testing results

Composition type

(F) (G) (H) (I) (J)

Hardness(IRHD)

60 61 60 60 60

Specific gravity(g/cm3)

1.139 1.134 1.139 1.127 1.126

Weight loss(g) 1.631.55

1.631.57

1.611.55

1.631.56

1.631.56

0.08 0.06 0.06 0.07 0.07

Abrasion(mm3)

70.2 52.9 52.6 62.1 62.1

T en sil

e St re ng th

K gc m-

2

210

225

190.5

194.8

170

180

190

200

210

220

230

F G H I J

195.5

Composition Type

Tensile strength with composite type

Abrasion lost with composition type

Conclusion:-According to the experiment 2 composition type H was found is the best. So the sulfur amount should be 1.82 g to get optimum physical properties.

Discussion:-According to the results, the best level of sulfur and accelerator to obtain

best technological properties were 1.820 g and 1.650 g respectively But according to AMW, they were using sulfur and accelerators in quantities 1.769 g and 1.650 g respectively . But according to the results discussed above sulfur amount should be 1.820 g. But AMW does not use that amount, because of the cost. However based on my observations AMW agreed to change sulfur and accelerator contents recommended by me above.

Conclusion:-In order to obtain best properties for the retreading, best sulfur

to accelerator ratio to the need is 1.820 g to 1.650 g respectively.

References:-• Handbook for rubber of Dr. Subramanian, senior lecturer of university of Moratuwa• AMW company case study• www.wikipedia.com