© 2019 W. R. Grace & Co.

Study of the effect of ASTM and ISO testing

conditions on mechanical properties of

polypropylene

Jing Zhong, Amaia

Montoya

W. R. Grace

© 2019 W. R. Grace & Co.

Outline

Introduction to W. R. GRACE

Overview of ISO and ASTM Standards

Specimen Preparation Comparison

• Specimen Dimension

• Injection Molding Condition

Mechanical Properties Comparison

▪ Flexural Modulus

▪ Tensile Property

▪ Notched Izod Impact Strength

Summary

© 2019 W. R. Grace & Co.

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Grace is a leading global supplier of specialty

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Strong Market Positions and Financial Performance

A $2 Billion Technology Leader

~$5BMarket Cap1

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75%Business Outside

the US

80%#1 or #2

Business Positions

#1▪ FCC Catalysts

▪ Hydroprocessing

▪ Hydrocracking

▪ Polyolefin catalysts

▪ Independent polypropylene process

technology licensing

▪ Specialty silica gel

Refining Technologies Specialty Catalysts Materials Technologies

2 Based on FY20173 Catalysts Technologies includes unconsolidated ART joint venture; FCC = Fluid Catalytic Cracking, SC = Specialty Catalysts, ART = Advanced Refining Technologies;

FCC and ART together constitute the Refining Technologies operating segment

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GRACE Licensing Innovation Strategy

Innovation strategy: Drive improvements in

PP product through catalyst and donor.

UNIPOL® PP Process Licensing

Grace’s PP

Catalyst

AdvancedPP

Products

Enabling technologies

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Overview of ASTM and ISO Standard

▪ ASTM and ISO are accepted globally

▪ Preference in different regions and countries

45%

55%

HPP

ASTM ISO

47%53%

RCP

ASTM ISO

54%46%

ICP

ASTM ISO

UL Prospector Statistics

The ASTM and ISO are equivalently applied in the Data Sheet

© 2019 W. R. Grace & Co.

Overview of ASTM and ISO Standard

ASTM method ISO method

Injection Molding D4101,D3641 1873, 294

Flexural Properties D790 178

Tensile Properties D638 527

Notched Izod Impact Resistance D256 180

© 2019 W. R. Grace & Co.

Specimen Preparation Comparison: Dimensions

• ISO specimen is narrower but thicker than ASTM specimen

• Similar cross section for ISO and ASTM specimen

ASTM ISO

Narrow Section: 57 x 12.7 x 3.2 mm Narrow Section: 80 x 10 x 4 mm

Cross Section: 40.6 mm2 vs. 40 mm2

127 x 12.7 x 3.2 mm80 x 10 x 4 mm

63.5 x 12.7 x 3.2 mm80 x 10 x 4 mm

Tensile

Flex

IZOD

© 2019 W. R. Grace & Co.

Specimen Preparation Comparison: IM Conditions

1 1.5 2.5 4 6.5 10.5 17.5 30

250

240

230

220

210

200

190

255

7

▪ Melt temperature are the same only for MFR 2.5-4 and 10.5-17.5

▪ Injection molding ISO conditions use lower mold temperature and longer cycle

time

Injection molding ASTM ISO

Cycle Time 45 s 60 s

Holding Time 15 s 40 s

Mold Temperature 60°C 40°C

Injection Speed 200 mm/s 200 mm/s

MFR

Meltin

g T

em

pera

ture

, °C

ASTM

ISO

© 2019 W. R. Grace & Co.

Part Morphology

Molding conditions affect part morphology

▪ Morphological structure of injection molding part:

1. Non-spherulitic skin

2. Intermediate zone

3. Spherulitic core

▪ Skin layer and intermediate zone morphology

dominate the properties

Woodward, A. E. Understanding Polymer Morphology; Hanser Publishers; Munich, 1995

1

2

3

© 2019 W. R. Grace & Co.

Injection Molding using Moldex 3D

ASTM ISO

Melt Temperature 230C 230

Mold Temperature 60 40

Max. Inj. Pressure, MPa 50 MPa 50 MPa

Packing Time 15 40

Cooling Time 20 13

Mold Opening Time 5 5

Injection Speed, cm3/s 40 40

Material Parameters

MFR, g/10min @230°C 2.5

Thermal Conductivity 1.5E-3 J/sec.com.°C

Heat Capacity 3.1 J/g. °C

Viscoelasticity White-Metzner Model

Crystallization Appendix I

Modulus relaxation Appendix II

PVT Appendix III

Viscosity Appendix IV

© 2019 W. R. Grace & Co.

Temperature Distribution

Different temperature distribution in ASTM and ISO bars

▪ ISO bar has lower surface temperature

▪ Core of ISO bar takes longer time to cool

ASTM ISO

0

20

40

60

80

100

120

140

160

0 0.2 0.4 0.6 0.8 1

Te

mp

era

ture

, °C

Normalized Thickness

ASTM ISO

t=20s

© 2019 W. R. Grace & Co.

Shear Stress Distribution

▪ Shear stress is higher for ASTM

ASTM ISO

0.04

0.05

0.06

0.07

0.08

0.09

0.1

0.11

0.12

0.13

0.14

0 0.2 0.4 0.6 0.8 1 1.2

She

ar

Str

ess,

Mpa

Normalized Thickness

ASTM ISO

© 2019 W. R. Grace & Co.

Predictions Based on First Principles

From the simulation,

▪ ASTM specimen should show higher flex modulus and yield stress, because of

larger thickness of skin layer and shear zone. This is caused by higher shear

rate and cooling rate in ASTM specimen.

▪ ASTM specimen should show higher IZOD especially for ICP. ASTM specimen

have more oriented rubber phase and smaller rubber size due to less

coalescence.

© 2019 W. R. Grace & Co.

Design of Experiments

▪ HPP with MFR 0.1 to 50, ICP with MFR 5-75

HPP Resins MFR

HPP1 3.5

HPP2 1.6

HPP3 8

HPP4 47

HPP5 17

HPP6 3

HPP7 0.3

HPP8 0.1

ICP Resins MFR

ICP1 6

ICP2 20

ICP3 12

ICP5 75

ICP6 55

ICP7 16

ICP8 20

ICP9 6

ICP10 6

ICP11 5

© 2019 W. R. Grace & Co.

Results and Discussion: Flexural Modulus

▪ Numerical values of flexural modulus equivalent under ISO and

ASTM standards

500

1000

1500

2000

2500

500 700 900 1100 1300 1500 1700 1900 2100 2300 2500

Fle

x.

Modulu

s (

ISO

Chord

), M

Pa

Flex. Modulus (ASTM 1 % Secant), MPa

HPP ICP

© 2019 W. R. Grace & Co.

Results and Discussion: Yield Stress

▪ Numerical values of yield stress equivalent for ICP

▪ Discrepancy in HPP

15

20

25

30

35

40

45

15 20 25 30 35 40 45

Yie

ld S

tre

ng

th (

ISO

), M

Pa

Yield Strength (ASTM), MPa

HPP ICP

© 2019 W. R. Grace & Co.

Factors Affecting Yield Stress

▪ Variation based on MFR and XS observed.

▪ Multivariate evaluation showed that only XS is relevant variable

▪ When the isotacticity is high, the crystallization rate is faster. Yield

strength is less affected by the injection molding conditions.

0.99

1

1.01

1.02

1.03

1.04

1.05

1.06

0.1 1 10 100

Yie

ld S

tress (

AS

TM

)/Y

ield

Str

ess (

ISO

)

MFR, g/10min

0.99

1

1.01

1.02

1.03

1.04

1.05

1.06

Yie

ld S

tre

ss (

AS

TM

)/Y

ield

Str

ess

(IS

O)

XS

© 2019 W. R. Grace & Co.

Results and Discussion: Notched IZOD

ASTM D256

▪ Impact strength is given in J/m

▪ Impact strength = Ec/h

• Ec = corrected energy (J)

[reading from equipment]

• h = thickness (m) = 0.0032m

▪ J/m / 10.2 kJ/m2

ISO 180

▪ Impact strength is given in kJ/m2

▪ Impact strength = Ec/(h*bN)

▪ Ec = corrected energy (kJ) [reading

from equipment]

▪ h = thickness (m) =0.004m

▪ bN = length under notch (m)

▪ kJ/m2 *8.0 J/m

There is no calculation to translate from ASTM to ISO

a

h

bN

Specimen ASTM (mm) ISO (mm)

thickness h 3.2 4.0

Total width a 12.7 10

Width under notch bN 10.2 8

© 2019 W. R. Grace & Co.

N. Izod Impact Resistance Comparison

• ISO bars show different impact resistance compared to ASTM bars

HPP

0

2

4

6

8

10

12

14

16

18

0 2 4 6 8 10 12 14 16 18

ISO

N. IZ

OD

(IS

O),

kJ/m

2

N. IZOD (ASTM), kJ/m2

© 2019 W. R. Grace & Co.

N. Izod Impact Resistance Comparison

▪ ASTM is lower than ISO when MFR is in low range

▪ The difference is possibly due to the orientation and crystal

structure in the injection molding

-6

-5

-4

-3

-2

-1

0

1

2

0.1 1 10 100

IZO

D(A

ST

M)-

IZO

D(I

SO

), k

J/m

2

MFR, g/10min

HPP

© 2019 W. R. Grace & Co.

N. Izod Impact Resistance ICP

• Higher ASTM N. Izod impact than ISO

• The trend is more obvious with higher impact strength

0

10

20

30

40

50

60

70

0 10 20 30 40 50 60 70

IZO

D (

ISO

), k

J/m

^2

IZOD (ASTM), kJ/m^2

© 2019 W. R. Grace & Co.

0.5

0.6

0.7

0.8

0.9

1

1.1

1.2

1.3

1.4

0.1 1 10 100

Fle

x (A

ST

M)

/ F

lex

(IS

O)

MFR, g/10min

Comparison with Technical Data Sheet Data

▪ Flex(ASTM)/Flex(ISO) between 0.8 and 1.3

▪ >95% of grades are between 0.9 and 1.3

Data from producers that report both tests

© 2019 W. R. Grace & Co.

Comparison with Technical Data Sheets

▪ Most grade in the range IZOD(ASTM) / IZOD(ISO) 0.7 to 1.7 – Also

aligned with findings reported here

▪ Differences increase with IZOD values

Data from producers that report both tests

0.5

0.7

0.9

1.1

1.3

1.5

1.7

1.9

2.1

2.3

0.1 1 10 100

IZO

D (

AS

TM

)/ I

ZO

D (

ISO

)

MFR

-10

-5

0

5

10

15

20

25

30

0 20 40 60 80

IZO

D (

AS

TM

)-IZ

OD

(IS

O),

kJ/m

2IZOD (ASTM), kJ/m2

© 2019 W. R. Grace & Co.

Summary

Critical to understand ASTM and ISO standards to correctly

evaluate materials performance… and help our customers

develop advanced products…

HPP ICP

Flex. Modulus ASTM (1% Secant) ≈ISO

( Chord )

ASTM (1% Secant) ≈ISO

( Chord )

Yield Stress Medium/High XS, ASTM

> ISO;

Low XS, ASTM ≈ ISO

Overall, ASTM/ISO = 1-

1.1

ASTM ≈ ISO

N. IZOD (23°C, kJ/m2) Fractional MFR, ASTM <

ISO; Medium/High MFR,

ASTM ≈ ISO

Low IZOD, ASTM/ISO=1-

1.2

High IZOD, ASTM/ISO >

1.2

© 2019 W. R. Grace & Co.

The End! Thank You.

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