Degradation Of Polymer Blends

Polymers are seldom used in the pure state, variousadditives may be present of which one category includes asecond polymer. In the present study, the author reports theeffects on degradation properties of a polymer in the presenceof a second polymer in its environment. The effect ofdegradation of polystyrene (PS) and pbly (vinyl chloride) (WC)in the presence of various second polymers has been studied.Polymers are heterogeneous systems and in many cases the observeddegradation effects reflect the two phase character. It hasbeen found in the present study that interaction processesresult in some cases in destabilisation of the system while inother cases the thermal and weathering stabilities are improvedin the blend. The method of study involves the use of infraredspectrophotometecto follow chemical changes in the microstructurewhen films were exposed outdoor and when heated inan air oven at 100 oC The changes in the mechanical propertieswere followed by measurement of tensile strength using an instronmachine. Cast films have been used for the studies.In the system containing PS/ABS blend it was found that PShas a stabilising effect on ABS when exposed outdoors, theconverse is true when the blend was heated in air oven at lOO oCIt was also found that the weatherability of PVC and PBwere considerably improved in the presence of PS. The presenceof PS in PS/PB blend imparts rigidity to the blend. Similarlyfrom a measurement of carbonyl index it was found that PVC has astabilising effect on PB. In all cases the l:l blend gavethe best compromise of good mechanical properties, heatstability and outdoor weathering

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