Effect of Photo-Oxidative Degradation on Environment Stress Cracking Behavior of

Polycarbonate Injection Molded Parts

Hanjian,Zhao Yaqiong, Wang Yanxiao, Yan Chenguang, Wang Yimai, Liu Chuntai

National Engineering Research Center for Advance Polymer Processing Technology,Zhengzhou University, 97 Wenhua Road, Zhengzhou, Henan, P. R. China

The photo-oxidative degradation and environmental stress cracking of plastic tend to occur simultaneously due to the complexity of the actual service environ-ment.This paper discusses the effect of photo-oxidative degradation on the ESC behavior of PC injection molded products, depending on the failure behavior and performance changes of undegraded and degraded plastics under the action of chemical solvents.

Introduction

Experimental

By the ESC tests and morphology observation,

The results indicate that there is a synergistic

effect between photo-oxidative degradation and

environmental stress cracking for PC injection

molded parts. And reveal that stress relaxation

test is a better way to evaluate this effect.

Abstract

Sample Preparation

Photo-Oxidative Degradation Testing

Half of the specimens were irradiated for 168 hours

continuously at 50±2°C in an ultraviolet(UV) weathera

ble chamber.

ESC Testing

The stress relaxation test and tensile stress-strain

test were carried out in the ethanol environment.

Photodegradation of Polycarbonate

Results and Discussion

The significant yellowing after a 168 hours UV irradiation

Tg of undegraded and degraded specimens

Tensile Stress-strain Behavior

ESC behavior of PC specimens

Stress Relaxation Behavior

Stress relaxation curves of PC specimens under different test conditions

(a) (b)

(c) (d)

The surface cracking of PC specimens after stress relaxation in the ethanol environment (a,b)Undegraded

specimens and(c,d)degraded specimens

Tensile stress-strain curves of PC specimens under different test

conditions

The surface cracking of PC specimens after tensile stress-strain in the ethanol environment (a)Undegraded specimens

and(b)degraded specimens

(a) (b)

The results indicate that there indeed exists

a synergistic effect between photo-oxidative

degradation and the ESC behavior for PC sp

ecimens.

The stress relaxation test is a better way to

evaluate the synergistic effect between phot

o-oxidative degradation and the ESC behavi

or of PC injection molded parts.

Conclusions

Sudesh S Fernando, Paul A, Polym Degrad Sta

b 94, 87 (2009).

Nagai N, Okumura H, Imai T,Polym Degrad Sta

b, 81,495(2003).

Jennifer M Hoffman, Angele Sjong, SPE ANTE

C PROCEDINGS, 1412 (2006).

A R Sousa, Polym Degrad Stab, 92, 1475 (200

7).

References

Photo-oxidative degradation of plastics ESC of PC injection molded parts