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Characterising the toughness of impact modified PVC: the use of linear elastic fracture approach

Hassan, Azman and Haworth, Barry (2003) Characterising the toughness of impact modified PVC: the use of linear elastic fracture approach. In: Conference on Advanced Materials 2003, 20 - 21 May, 2003, Putrajaya Marriot Hotel, IOI Resort, Putrajaya. (Unpublished)

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Abstract

The occurrence of unexpected brittle failure in plastics parts poses a serious and ongoing problem to the plastics industry and therefore a better understanding of the mechanisms of fracture in these materials is needed. Extensive research has been carried out and has led to the evolution of fracture mechanics as a means to evaluate and analyse the brittle failure of materials. The use of linear elastic fracture mechanics (LEFM) parameters such as critical stress intensity factor (Kc) to characterize the toughness of polymers is now quite widespread. However, the application to thermoplastics, particularly rubber-modified materials, is less well developed. Kc corresponds to a critical level of stress intensity at the tip of a crack-like defect and there are criteria to be met for the fracture mechanics parameter to be valid. PVC-U is a relatively tough polymer but has a disadvantage of being prone to occasional brittleness. Articles made from PVC-U sometimes fail prematurely through brittle fracture during service when the applied stress is concentrated due to the presence crack or other discrete imperfections. To overcome the disadvantage and to increase toughness, multiphase systems consisting of PVC and a rubber component, known as impact modifiers were developed and being used in construction applications. A fracture mechanics approach has been used previously in the evaluation of the toughness of PVC-U pipe materials. Using instrumented falling weight impact tests in the flexural mode, a technique was developed enabling fracture mechanics principles to study impact modified PVC. The main objective of this study is to examine the effect of strain rate on the fracture mechanics data. The other objective was to determine the Kc1 validity criterion for the high impact PVC under these conditions.

Item Type:Conference or Workshop Item (Paper)
Uncontrolled Keywords:Critical stress intensity factor, linear elastic fracture mechanics, modified PVC, thermoplastics
Subjects:T Technology > T Technology (General)
Divisions:Chemical and Natural Resources Engineering (Formerly known)
ID Code:5090
Deposited By: Norhani Jusoh
Deposited On:14 Feb 2008 01:21
Last Modified:01 Jun 2010 03:23

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