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Effect of the modification of the polymer-rich phase composition on the formation of structural defects in radical suspension PVC

(2007) Purmová, Jindra

Poly(vinyl chloride) (PVC) is one of the most successful modern synthetic materials., but its serious disadvantage is its low thermal stability. This obstacle has been overcome for a long time by the addition of stabilizing agents mostly containing heavy metals. Nowadays, the use of these materials is subject to a range of regulations. For some applications, no suitable heavy metal-free alternatives are yet available. Many studies on the degradation and stability of PVC showed that the reason for such poor thermal properties originates from the polymerization process. The chlorine atoms contained in some structural defects are prone to elimination, thereby converting them into initiation sites of the degradation process. An improvement in this aspect, i.e. suppressing of the above-mentioned side reactions, could therefore lead to PVC with better inherent thermal stability and this would complement and enhance any positive results achieved in the research on heavy metal free stabilizers.
Study of the distribution of defect structures in fractions of PVC of different molecular weight showed that in suspension polymerization process, short PVC chains with high content of defect structures are formed on the surface of the particles. The number of such chains increases with monomer conversion. Also addition of an compound containing functional groups able to interact with PVC chains led to a decrease in the number of defects. It can be concluded that the improvement in the PVC quality by modification of the processes at the waterpolymer interface have potential to lead to more intrinsically stable PVC. A complementary way to this goal is the protection of PVC chains from hydrogen abstraction by complexation with different compounds. Compounds from the family of additives used in PVC compounding are especially interesting alternatives from not only a scientific, but also an economic point of view.

	Title and contents
	Chapter 1
	Chapter 2
	Appendix I
	Chapter 3
	Appendix II
	Chapter 4
	Chapter 5
	Chapter 6
	Chapter 7
	Chapter 8
	Summary
	Samenvatting
	Acknowledgments
	Curriculum vitae
	Stellingen
	Complete thesis