Polyethersulfone PES

7/28/2019 Polyethersulfone PES

1/28

Polyethersulfone (PES)Technical Literature

Mitsui Chemicals, Inc.


2/28

Polyethersulfone (PES)

Contents

I Introduction 3

II Grades of PES 4

III General Physical Properties of PES 5

IV Physical Properties of PES 6

1 Heat Resistance 6

1-1 Short-term Heat Resistance 6

1-2 Long-term Heat Resistance 7

1-3-1 Dimensional Stability 9

1-3-2 Water Absorption and Dimensional Change 11

2 Mechanical Properties 12

2-1 Creep Resistance 12

2-2 Impact Resistance 13

2-3 Friction and Wear Properties 14

3 Electrical Properties 15

4 Environmental Properties 17

4-1 Flame Retardancy 17

4-2 Chemical Resistance 19

4-3 Hot Water Resistance 21

4-4 Weathering Resistance 21

V PES Molding Method 22

VI Fabrication of PES 24

VII PES Certification 25

VIII PES Molding Conditions 26

2


3/28

Polyethersulfone

1 Introduction

Polyethersulfone (PES) is a heat-resistant, transparent, amber, non-crystalline

engineering plastic having the molecular structure of .

PES is a tough and rigid resin similar to conventional engineering plastics, such

as polycarbonate, at room temperature.

The greatest characteristic of PES is that it has by far better high-temperature

properties than conventional engineering plastics. Specifically, PES remains in

satisfactory condition in long-term continuous use without causing any dimensional

change or physical deterioration at temperatures as high as 200C.

Properties of PES:

(1) Heat resistance:

Short-term heat resistance: HDT is 200 to 210C, and flexural modulus does

not decline at temperatures of up to nearly 200C.

(ASTM method)

Long-term heat resistance: UL temperature index is 180C, and the half life

period of tensile strength at 180C is 20 years.

(Heat aging properties)

(2) Dimensional stability:

The coefficient of linear expansion remains constant at temperatures of up to

nearly 200C.

(3) Creep resistance:

PES shows excellent creep resistance.

(4) Electrical properties:

PES shows excellent electrical properties, which are retained even in a

high-temperature range.

(5) Flame retardancy:

PES is certified for UL94-VO.

(6) Moldability:

Although PES is a high-temperature-resistant resin, it can be molded on

common injection-molding equipment.

3


4/28

Precautions in Using PES:

(1) Weathering resistance:

As the weathering resistance of the natural resin of PES is not very good, it is not

fit to be used outdoors.

(2) Chemical resistance:

PES is attacked by some polar solvents.

(3) Water absorption:

PES has satisfactory water absorption properties but has to be dried before

molding because it shows some water absorption.

(4) Notch dependence of impact strength:

Since PES moldings exhibit high notch dependence of impact strength, they

have to be so designed that they will have no sharp notch.

II Grades of PES

Description Grade Uses

Glass-fiber-reinforced gradepellets

SGN3030R Standard grade +30% GF: For injectionmolding. Improved mold release.

SGN2020R High-flowability grade +20% GF: For injectionmolding. Improved mold release.

SGN2030R High-flowability grade +30% GF: For injectionmolding. Improved mold release.

SGP2020R Super-high-flowability grade +20% GF: Forinjection molding. Improved mold release.

SGP2021R Improved-flowability grade of SGP2020R

Carbon-fiber-reinforced gradepellets

EXS-1 High strength and electric conductivity. Forinjection molding.

Sliding grade SGF2030 Low-friction/low-wear grade +20%. Withfluorocarbon resin added.

SGF2040 Low-friction/low-wear grade +30%. With

fluorocarbon resin added.FO-10D Low-friction/low-wear grade. No fiber

reinforcement. With fluorocarbon resin added.

* The above grades are Mitsui Chemicals proprietary compounds.

Packing: Pellets 25 kg, powder: 10 kg

4


5/28

III General Properties of PES (Representative Grades)

Item Testing Method Unit SGN2020R SGN3030R SGP2020R SGF2030

Physical

Light transmittance ASTM D-1003 %

properties Refractive index

Specific gravity ASTM D-792 1.51 1.60 1.51 1.57

Water absorption ASTM D-570 % 0.6 0.5

Molding shrinkage ASTM D-955 % 0.2/0.6 0.2/0.6 0.3/0.6 0.3/0.6

MechanicalTensile strength ASTM D-638 MPa 127 137 130 127

properties Tensile elongation ASTM D-638 % 3 3 3 3

Tensile modulus ASTM D-638 MPa 6800 9800

Flexural strength ASTM D-790 MPa 167 190 179 181

Flexural modulus ASTM D-790 MPa 6700 8800 7400 7400

Izod impact strength ASTM D-256 J /M 60 90 80 90

Rockwell hardness ASTM D-648 M98 M98

ThermalDeflection temperature under load ASTM D-648 C 214 217 215 216

properties Glass transition temperature C

Linear expansion coefficient, MD/TD ASTM D-696 X10-5/C 2.6/5.6 1.6/5.6 2.4/5.5 1.9/5.4

UL temperature index UL-746 C

ElectricalVolume resistivity ASTM D-257 cm 1016 1016 1016 1016

properties Dielectric constant 50 Hz ASTM D-150 3.7 3.7

1 MHz 3.7 3.7

Dielectric dissipation 50 Hz ASTM D-150 0.001 0.001

factor 1 MHz 0.006 0.006

Dielectric strength J IS C2110 kv/mm 26 26

OtherCoefficient of kinetic friction* 0.150.25

properties Flame retardancy 1.5 mm UL-94

0.4 mm V-0 V-0

Limiting oxygen index 1.6 mm ASTM D-2863 40 41

Note:

The above data show representative figures, not guaranteed figures.

Unit conversion: Tensile modulus, flexural strength and flexural modulus:

1 MPa = 10.2 kg/cm2

*: The other material = Al

Conditions: P = 1 MPa, V = 10 m/min, T = 30 min, no lubrication

5


6/28

IV Physical Properties of PES

1 Heat Resistance

1-1 Short-term Heat Resistance

Generally, the flexural modulus of thermoplastic resins, particularly crystalline

resins, falls sharply as temperature rises. However, PES retains a high flexural

modulus in a high-temperature range, with its physical properties declining only

slightly with a rise in temperature. Figs. 1 and 2 give actual examples with respect to

flexural modulus and tensile strength.

Figure 1

GFreinforced

Natural

Flex

uralmodulus(MPa)

Temperature (C)

6


7/28

Figure 2

Ten

silestrength(MPa)

GFreinforced

Natural

Temperature (C)

1-2 Long-term Heat Resistance (Heat Deterioration)

There is a method for evaluating the long-term heat resistance of resin in which

uses the half-life period of tensile strength. The half-life period of the tensile strengthof PES is 20 years at 180C as shown in Fig. 3. Further, PES is certified under UL

standards (UL746B) to be fit for continuous use at 180C. Fig. 4 makes a

comparison of temperature index of PES and other resins. Fig. 4 indicates that PES

has a higher temperature index than thermosetting resins as well as conventional

thermoplastic resins.

7


8/28

Figure 3 Temperature Dependence of Half-life Period of Tensile Strength

Figure 3 Temperature Dependence of Half-life Period of Tensile Strength

20 yr

10 yr

5 yr

1 yr

6 mon

1 mon

Temperature (C)

Figure 4 Comparison of UL Temperature of Various Resins

Natural

Increase in heat resistance by use of GFTem

eratur

e(C)

8


9/28

1-3-1 Dimensional Stability

The molding shrinkage of PES varies with gate shape and molding conditions.

But generally, the natural resin of PES shows molding shrinkage of 0.6% and is not

anisotropic. The GF-reinforced grade shows molding shrinkage of 0.2% but isanisotropic. The coefficient of linear expansion is low with that of the natural grade

being 5.6x10-5/C and that of the GF-reinforced grade being 2.3x10-5/C and remains

constant in a broad range of temperature. (Fig. 5)

PES stands adequately high temperature at the soldering step. (Fig. 6)

At 260C x 10 seconds, PES may cause a problem especially if the product has

not been dried properly. Furthermore, although PES shows some water absorption,

it exhibits only slight dimensional change due to water absorption even it is in

saturated condition.

Figure 5 Temperature Dependence of Linear Expansion Coefficient

Coefficientoflineare

xpansion(x10-5/C)

Temperature (C)

Natural

GFreinforced

9


10/28

Figure 6 Soldering Resistance

Immersion time (sec)Grade

10 30

SGN2020R {

SGN2030R {

SGN2040R {

SGN3020R {

SGN3030R {

SGF2030 {

SGF2040 {

SGP2020R {

{: No change

: Slight change

: Significant change

Testing method:

A test specimen 3 mm thick was hanged vertically and immersed in the soldering

bath.

Soldering temperature: 260C

Test specimen drying conditions: 150C x 5 hr

10


11/28

1-3-2 Water Absorption and Dimensional Stability

PES moldings absorb water in water or in the atmosphere. Water absorption

depends on humidity, time in which PES is allowed to stand, temperature,

moldings thickness and grades of PES. Fig. 7 shows water absorption curvesin water and under standard conditions.

Figure 7 Water Absorption Curves under Various Conditions Sample Thickness: 2 mm

Watera

bsorption(%)

Xxx(%)

Time (day) Time (day)

Table Dimensional Changes Due to Water Absorption: Specimens Immersed

in Water at 23C Until SaturationGrade Water absorption

(%)Change in cross

section(%)

Change in length(%)

PES E2010 2.1 +0.3 +0.3

PES SGN2020R(GF20%) 1.7 +0.3 +0.2

PES SGN3030R(GF30%) 1.5 +0.3 +0.1

11


12/28

2 Mechanical Properties

2-1 Creep Resistance

Fig. 8 shows changes with time in creep of PES at room temperature. Fig. 8indicates that PES is superior in creep resistance to other engineering plastics.

Further, Fig. 9 shows creep resistance of PES at high temperatures. PES has

excellent creep resistance even at high temperatures. Especially, the GF-reinforced

grade is suitable for uses requiring creep resistance.

Figure 8 Creep Curves of PES E2010 (DIN53444, 23C, equilibrium water absorption condition)

Distortion(%)

Time (hr)

Figure 9 High-temperature Creep (Tensile) Properties (Temp.: 150C, stress: 50 MPa)

Distortio

n(%)

Time (hr)

12


13/28

2-2 Impact Resistance

PES is a tough resin. Its toughness is retained adequately even at small

thickness of 0.5 mm or so, and PES allows a product to be designed to small wall

thickness. Furthermore, PES fails in a ductile way even at low temperature below0C and has satisfactory low-temperature impact resistance.

However, the impact resistance of PES is susceptible to notches, and the impact

resistance of a molded article declines if it has a sharp notch. Because of this, it is

necessary to design PES molded articles so that they will have no sharp notch.

Moreover, the impact resistance of PES is affected by water absorption, and the

impact resistance falls to some extent when PES is dry.

Figure 10 Temperature Dependence of Impact Resistance an and

Notched Impact Resistance ak (in Dry Condition)

Temperature (C)

ImpactResistanceanandNotchedImpact

Resistancea

J/m

13


14/28

2-3 Friction/Wear Properties

Friction and wear are properties inherent to any sliding part and involve many

factors. Specifically, friction and wear have to do with the opposite sliding part

material and its surface roughness, contour of the contact area, media such aslubricant, load, sliding speed and outside factors such as temperature.

The main factors affecting the friction coefficient and wear of PES are the

hardness and surface roughness of the opposite sliding part material, pressure that is

applied to the sliding part, temperature of the sliding surface and use/non-use of a

lubricant. Table 2 gives results of measurement of the friction coefficient and wear of

various grades of PES by using the same testing equipment.

Suzuki Friction/Wear Test

Test load (constant)

Oppositematerial(Fixed hallowtube)

Square testspecimen (fixe

Sliding surface

Table 2 Sliding Properties

Testing method: Suzuki friction/wear test (opposite material: board; test sample:

ring-shaped molded article)

Testing equipment: Friction/wear testing equipment of Tosoku Seimitsu Co.

Opposite material: SUS304(#800) with no lubricant, Al board

Testing conditions: P = 1 MPa (P = 0.5 MPa only for SNG2020R), V = 10 m/min,

T = 30 min

PES Sliding Grade PES

StandardGrade

Test Item Unit

FO-10D SGF2030 SGF2040 SGN2020R

PEI Sliding

Grade

Kinetic coefficient offriction

0.19 0.250.40 0.300.40 0.300.40 0.300.45

SUS

Wear mg 9 3 3 38 4

Kinetic coefficient offriction

0.17 0.150.25 0.150.35 0.300.50 0.350.50

AI

Wear mg 7 7 7 117 12

14


15/28

3 Electrical Properties

PES shows excellent properties in dielectric constant and dielectric dissipation

factor. These excellent properties are retained in a broad range of temperature from

low temperature to high temperature close to the glass transition point.The dielectric dissipation factor of PES is stable at a low value of 0.002 in a

temperature range from 20 to 225C. Further, frequency dependence is low at

approx. 0.003 to 0.004 at 105 Hz. (Fig. 11)

The dielectric constant of PES remains practically constant up to the vicinity of Tg.

(Fig. 12)

Thus, PES having these excellent electrical properties in the high-temperature

range and heat resistance is most suited for H-class applications.

Figure 11 Temperature Dependence of Dielectric Dissipation Factor

Dielectricdissipationfac

tor(tan

)

Temperature (C)

15


16/28

Figure 12 Temperature Dependence of Dielectric Constant

Dielectricconstant()

Temperature (C)

16


17/28

4 Environmental Properties

4-1 Flame Retardancy

PES is a self-extinguishing resin. PES with no flame retardant added has beengiven 94V-0 under the UL Standards.

Fig. 13 shows the limiting oxygen index to make a comparison of flame

retardancy. It is evident from the low limiting oxygen index that PES has excellent

flame retardancy.

Furthermore, the excellent flame retardancy of PES is also known from the fact

that PES emits very little smoke. Fig. 14 gives results of a smoke emission test of

the American National Bureau of Standard to make a comparison with other resins.

Figure 13 Comparison of Limiting Oxygen Index of Various Resins (ASTM D-2863)

Limitingoxygenindex(%)

Flameretardant

grade

* The resins show higher flame retardancy as the value increases.

17


18/28

Figure 14 Comparison of Smoke Emission (Smoke Chamber Test of NBS of USA,

Using Samples 1.6 mm Thick

Absorbance(correctedvalue)

* It becomes more difficult for resin to absorb light as smoke emission

increases.

18


19/28

4-2 Chemical Resistance

PES has excellent resistance to aqueous chemicals such as hot water, steam,

acid and alkali, oils, grease, gasoline, alcohols, aliphatic hydrocarbons, etc. (Table

3) However, like almost all other organic compounds, PES is attacked byconcentrated sulfuric acid and concentrated nitric acid.

On the other hand, PES being non-crystalline may be attacked by highly polar

solvents, such as ester, ketone and trichloroethylene. However, in almost all cases,

there is no problem because there are solvents available for substitution that do not

attack PES and perform the same function as such polar solvents. For example,

trichloroethane can be cited as a substitute for trichloroethylene.

The chemical resistance of PES varies to some extent, depending on the grades

of PES. E3010 is superior to E2010 in chemical resistance, and the GF-reinforced

grades are superior to the natural grade.

Table 3 Chemical Resistance of PES (under No Load)

Inorganic reagent Effect Inorganic reagent Effect

Ammonia A Benzene A

Ammonia water A Benzoic acid A

50% NaOH A Acetone C

50% KOH A Oxalic acid A

10% hydrochloric acid A Cyclohexane A

Concentrated hydrochloric acid A Cyclohexanol A

10% nitric acid A Cyclohexanon C

Concentrated sulfuric acid C Methanol A

Concentrated nitric acid C Glycerin A

Acetic acid A Trichloroethylene C

Boric acid A Trichloroethane A

Hydrogen peroxide solution A Xylene B

Hydrogen sulfide A Petroleum ether A

Iodine in potassium iodine B Ethylene glycol A

A: No effect. No absorption at 20C

B: Some effect. There will be some absorption and swelling. Depending on uses,the chemical is adequately usable.

C: Significant effect. Not usable for PES.

19


20/28

Table 4 Chemical Resistance of PES (under Stress of 9 MPa)

Resin

Chemicals

PESE2010

PESE3010

PESSGN3030R

PSu PC ModifiedPPO

Acetone R1S R4S R2S R1S

Methylethylketone R1S R2S R1S R1

Cyclohexane R1S R19S 20M+ D D D

Benzene C20S R1S R4M D

Toluene R1S R11M D

Xylene R4S R15M D

Trichloroethylene C20S C20S D D

1,1,1-Trichloroethane R8S R3M D

Carbon tetrachloride SLC2M R6S D

1,2-Dichloroethane R1S R1S 20M+ D D D

Perchloroethylene C20M R1S D

Chloroform R1S R1S 20M+ D D D

Trichlorotrifluoroethane D

Methanol

Ethanol

n-Butylalcohol

Ethylene glycol

2-Ethoxyethanol C20S C20S C20M R17M

Propane-1,2-diol

Heptan

Ethyl acetate R31S R20S R3S

Dimethylether C20M C20M C20M R1M

Carbon bisulfide R8S R1S D

Gasoline C20M

Diesel fuel

Symbols:

-: No change for 20 minutesC: Crazing

SLC: Slight crazing

R: Failure

D: Melting

S: Sand

M: Minute

+: Softening (deemed practically unusable)

*: For example, this indicates that R19S failed in 19 seconds.

20


21/28

4-3 Hot Water Resistance

There is no problem with the natural grade up to 100C, but microcracks will

occur at 120 in it. With the GF-reinforced grades, there is no problem with no

microcrack occurring even at 140C. (Table 5) Further, with respect to mechanicalproperties, tensile strength and elongation decline in the initial period but after that

remain unchanged at satisfactory levels, posing no practical problem.

Table 5 Changes with Time in Tensile Strength in Water (E3010)

Observation of the surface: After 10-day immersion in an autoclave

100C 120C 140C

Solid line E2010 No change Slightmicrocracking

Slightmicrocracking

Dotted line SGN2030R No change No change No change

Figure 15 Results of Immersion-in-water Test at 100C

Tensilestrength(MPa)

Elongation(%)


Figure 16 Results of Immersion-in-water Test

Tensilestreng

th(MPa)

Elongation(%)


4-4 Weathering Test

Molded articles of PES colored grades yellow and become brittle, like othergeneral moldings of aromatic resins.

21


22/28

V PES Molding Method

PES, which is a high-temperature-resistant resin, can be molded on common

molding equipment. PES can be processed by all types of processing, including

injection molding, extrusion, compression molding, solution casting and sintering.

An example of injection molding, the processing method used most commonly, is

explained in this section. Fig. 17 shows the flowability and viscosity of PES. As can

be seen clearly from Fig. 17, injection molding temperature has to be 350C or higher

for PES.

It is also necessary to keep the mold temperature at 150 to 180C to improve the

flowability of PES in the mold and reduce residual strain. The flow behavior of PES

under these conditions is similar to that of polycarbonate, and in fact PES can be

test-molded easily in a mold for polycarbonate. For detailed molding conditions and

operating procedure, refer to Section VIII PES Molding Conditions.

Precautions:

1. Since PES has water absorption properties, it has to be dried for more than 3

hours at 150C before molding.

2. A general hot air dryer is not suitable for drying PES. A vacuum dryer or a

dehumidifying dryer is fit for use for PES.

3. The heat stability of PES is satisfactory as shown in Fig. 18. But it is safe to

make sure that molding temperature will not exceed 380C.

Figure 17 Spiral Flow of PES

Flow length (Spiral flow: wall thickness 1 mm, mold temp. 150C,

injection pressure 150 MPa)

Flowlength(m

m)

Molding temperature (C)

22


23/28

Figure 18 Thermal Decomposition Curves of PES

W

eightloss(%)

Temperature (C)

In air

Temperature rise rate: 10C/min

23


24/28

VI Fabrication of PES

1 Adhesion

Many adhesives, such as epoxy-, urethane-, phenol- and silicone-based

adhesives, can be used for bonding PES/ PES and PES/other materials. PES

shows satisfactory adhesion. The use of these different adhesives is determined

depending on temperature, humidity and other use environmental conditions.

The bonding surfaces have to be degreased, roughened and treated otherwise

so that satisfactory adhesion will be achieved.

PES is also bonded by use of solvents such as N-methyl-2-pyroridon (NMP),

N,N-dimethylformaldehide and dichloromethane. However, these solvents may

cause stress cracking in those parts which will be subject to mechanical stress. The

viscosity of these solvents is increased by adding 3% to 15% PES. The bonded

materials have to be dried completely until all of the solvent is evaporated.

2 Other Bonding Method

Fastening with screws or bolts, snap-fitting and other joining methods can be

used for joining methods that will allow the PES product to be removed. J oining with

bolts is suitable for those products which are subject to high load and removed

frequently. Under this method, molded PES products are threaded for metal parts to

be inserted there. Such inserts may be fixed by force while the product is hot after

molding or by ultrasonic welding.

3 Hot Press Molding

PES sheets can be molded by use of a hot press using vacuum or compressed

air. The equipment for use requires a fixed frame that can be heated and a 2-step

heating means for providing a uniform temperature distribution to the surface and

cross section of the sheet. The heater has to be so designed that the temperature

will reach 270 to 280C within 40 to 50 seconds.

A metal mold is generally used, and an electric heater or a temperature controller

of the oil circulating type is attached to it. A wooden or resin mold is not suited forthis purpose. A vent should be provided in the mold to enable the air between the

mold and the sheet to be vented quickly. The vent should be provided at the end of

the molded product to be released from the mold. Generally, it is preferably that the

curved area of the mold should have a large radius and a large draft in contour and a

sharp edge should be avoided.

It may be said that the female mold is suited for hot-plate molding because the

molded product may shrink freely in the wall thickness direction. As the dimensions

of the molded product change significantly, the use of the male mold may cause

cracks at the time of shrinkage.

24


25/28

VII PES Cert ification

1 UL Standards

94V-0 Natural grade 1.5 mm

SGN (GF-reinforced grade) 0.4 mm

746B Natural grade 0.75 mm 180C

2 Food Sanitation Law

Requirements under standards for food, additives, etc. E2010

( 1959 Notification No. 370 of the Ministry of Health and Welfare)

3 Synthetic Resin Utensils and Packaging Containers Other Than Stipulated by

Individual Standards E2010

( 1982 Notification No. 20 of the Ministry of Health and Welfare)

25


26/28


27/28

melt flow index. This shall then be followed by setting the

cylinder temperature to 330C, purging the cylinder with PES

neat resin (E3010) adequately, and setting the cylinder

temperature to the PES molding conditions.

Stopping

procedures:

If PES is to be molded in the next molding operation, purge the

resin in the cylinder adequately with PES neat resin, lower the

cylinder temperature to 350C, discharge the PES remaining in

the cylinder adequately, and turn off the power supply.

If a resin other than PES is molded in the next molding

operation, purge the resin in the cylinder adequately with PES

neat resin, lower the cylinder temperature to 350C, and slowly

lower the cylinder temperature to 300C while purging the resin

with a polyethylene resin with a low melt flow index. After

confirming that the polyethylene alone is being discharged from

the cylinder and the cylinder temperature has lowered to 300C,

discharge the polyethylene completely from the screw and then

turn off the power supply.

If gel formation

has started:

If get formation should have started, do not raise the cylinder

temperature under any circumstance but immediately discharge

gelled materials. Then, purge the materials adequately from

the cylinder by slowing lowering the cylinder temperature to

300C while purging the resin with a polyethylene resin with a

low melt flow index. During the purging operation, never draw

near the nozzle of the injection molding equipment.

Cleaning of the

screw:

In cleaning the screw, slowing lower the cylinder temperature to

300C while purging the resin with a polyethylene resin with a

low melt flow index. After confirming that the polyethylene

alone is being discharged from the cylinder and the cylinder

temperature has lowered to 300C, pull the screw out of the

cylinder.

27


28/28

2 Example of Injection Molding Conditions

Given below is an example of injection molding conditions for PES.

Molded article

Gate shape

Fuse box

Pin 1 point

Burn-in outlet

Pin 4 points

Resin Grade

Composition, etc.

E2010Natural

SGN3030RGF-reinforced

Moldingconditions

(C) C1 340 360

C2 350 370

C3 360 370

NH 360 370

Mold temperature (C) 150 160Charging pressure (MPa) 100 200

Follow-up pressure(MPa) 30 50

Injection time (second) 5 10

Cooling time (second) 15 30

3 Mold Material

Since the mold temperature is raised to 150 to 180C for PES, it is recommended

that hardened steel be used. In the event of a small amount of production, the use ofNAC steel is also acceptable.

4 Annealing

Basically there is no need for annealing. But it has been found that the

annealing of molded articles with high residual strain (such as insert moldings and

thin-walled articles) improves their mechanical strength and stress crack resistance.

5 Mold Release

There is normally no need for using a mold release agent. However, if a mold

release agent has to be used unavoidably, fluorine-based ones or zinc stearate should

be used. No silicone-based mold release should be used because the use of such

mold release agent may cause stress cracks.

Documents

Polyethersulfone PES