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Jul 07, 2023 461 likes •635 views

Solvent Resistance and Mechanical Properties in Thermoplastic Elastomer Blends Prepared by Dynamic Vulcanization J.D. (Jack) Van Dyke Trinity Western University, Langley, B.C., Canada Marek Gnatowski Polymer Engineering Co. Ltd, Burnaby,

SLIDE 1

Solvent Resistance and Mechanical Properties in Thermoplastic Elastomer Blends Prepared by Dynamic Vulcanization

J.D. (Jack) Van Dyke

Trinity Western University, Langley, B.C., Canada

Marek Gnatowski

Polymer Engineering Co. Ltd, Burnaby, B.C., Canada

Andrew Burczyk

Defence R&D Canada-Suffield, Canada

SLIDE 2

Mixing Methods

High shear melt mixing



Without curing agents  non-vulcanized blends

 Continuous phase dependent on proportions in the

blend

With curing agents  dynamic vulcanization
Non-vulcanized component becomes continuous

phase, almost independent of proportion in blend

SLIDE 3

Non-Vulcanization vs. Dynamic Vulcanization

SLIDE 4

Objective of Present Work

 Dynamic Vulcanization on a Variety of

Thermoplastic / Rubber Combinations

 Thermoplastics (PA, PP, and PBT)  Rubber (CIIR, NBR)

 Measure

 Mechanical properties  Exposure to solvents (hexane and CHCl3)



% insolubility, swelling index

 DSC and SEM

SLIDE 5

Effect of % Thermoplastic on Properties

PP-CIIR Blends

0.0 5.0 10.0 15.0 20.0 25.0 30.0 35.0 18 20 25 30 35 40 50 60 100 % Polypropylene Tensile Strength (MPa)

Tensile Strength (MPa)

PP-CIIR Blends

10 20 30 40 50 60 70 80 18 20 25 30 35 40 50 100 % Polypropylene Hardness (Shore D)

Hardness (Shore D)

60-90 50-90

SLIDE 6

Tensile Strength Comparison in Blends

PA- CIIR PP- CIIR PA- NBR PP- NBR PBT- NBR 15 20 25 30 35 40 50 0.0 2.0 4.0 6.0 8.0 10.0 12.0 14.0 16.0 18.0 20.0

Tensile Strength Blend Type % Plastic

SLIDE 7

DSC Results – Thermoplastic Phase

Tm (°C) ΔHf (J/g

plastic)

PA 178.7 60.6 PA/CIIR 175.6 58.1 PA/NBR 176.5 58.5 PP 163.3 80.9 PP/CIIR 161.6 83.1 PP/NBR 161.5 80.6 PBT 223.0 38.1 PBT/NBR 222.6 46.0



Phase separation



Dynamic vulcanization effects

 rubber phase

(curing, particle formation)

 thermoplastic phase

(MW reduction, graft formation, crystallization effects)

SLIDE 8

SEM OF PA/NBR BLEND

PA-NBR Blend PP-NBR Blend

SLIDE 9

1 2 3 4 5 6 8 16 24 32 40 48 56 64 72 80 88 96 Time (hrs) Swelling Index

100 NBR 40 PA /60 NBR

Solvent Uptake – Kinetic Studies

Rate of solvent

uptake determined on rubber and blend samples

Blends achieve

equilibrium relatively quickly

Example of

100 NBR and 40 PA/60 NBR

SLIDE 10

Swelling Index: PA – CIIR Blend at Different Compositions

 S.I. Values

consistently below theoretical line (physical mixture)

 Continuous

thermoplastic phase prevents solvent expansion

f cured rubber

phase

PA-CIIR Blends

1 2 3 4 5 6 7 10 20 30 40 50 60 70 80 90 100

% Polyamide Swelling Index

Swelling Index

SLIDE 11

Swelling Index Values for Other Blends

PP-CIIR Blends

1 2 3 4 5 6 7 10 20 30 40 50 60 70 80 90 100 % Polypropylene Swelling Index

Swelling Index PA-NBR Blends

1 2 3 4 5 6 10 20 30 40 50 60 70 80 90 100

% Polyamide

Swelling Index

SLIDE 12

Swelling Index Values for Other Blends

PP-NBR Blends

5 10 15 20 25 30 10 20 30 40 50 60 70 80 90 100

% Polypropylene Swelling Index

Swelling Index

PBT-NBR Blends

5 10 15 20 25 30 10 20 30 40 50 60 70 80 90 100 % PBT Swelling Index

Swelling Index

SLIDE 13

Relationship Between Swelling Index and % Elongation

 Minimum

elongation reached at similar composition as change in S.I. Curve

 Phase inversion

 Similar results for

all blends studied.

PBT-NBR Blends

5 10 15 20 25 30 10 20 30 40 50 60 70 80 90 100 % PBT Swelling Index 100 200 300 400 500 600 Elongation (%)

Swelling Index Elongation (%)

SLIDE 14

Conclusions

1. Dynamic vulcanization – variety of rubber plastic blends, many with elastomeric properties.

Elastomeric properties seen between 20-40%

thermoplastic

2. Both rubber and plastic phases affected during the dynamic vulcanization process. 3. Solvent exposure – rapid swelling upon exposure to solvent (tested on hexane and CHCl3). Similar performance expected with

ther solvents.

SLIDE 15

Conclusions (continued)

4. S.I. values of blends are significantly less than expected “theoretical” values.

“caging effect” at higher thermoplastic

compositions.

5. Minimum elongation values reached at phase inversion. 6. Increased compatibility in blends

reduced particle size (discrete phase)
frequently produces less caging effect on the

rubber phase

SLIDE 16

Acknowledgements

 Defence R&D Canada – Suffield  Laboratory staff at PEC

Dave Lesewick, Christine Mah, Beverley Start
Laboratory staff at TWU

 Leanne Edwards, Simon Moore, Kim Klassen

 DRDC – Esquimalt (SEM results)

 Bruce Kaye

Website: www.polymer-engineering-co.com/