Analysis of UV induced dehydrochlorinated PVC (With hydroquinone) using direct pyrolysis mass spectrometry (DPMS), TGA, UV/VIS-NIR and FTIR techniques
Author
Avcı, Ercan
Advisor
Süzer, Şefik
Date
2003Publisher
Bilkent University
Language
English
Type
ThesisItem Usage Stats
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Abstract
Poly(vinyl chloride) (PVC) degrades easily upon heat and light exposure via loss of HCl.
The mechanism of this process is well understood, known as the zip mechanism and the
dehydrochlorination results in conjugated segments, polyenes. It is also possible to utilize
PVC polymer as an in-situ acid donor since the main degradation product is HCl.
Addition of hydroquinone (HQ) into PVC matrix sensitizes the photodehydrochlorination
of PVC at 312 nm.
In this study the effects of photodehydrochlorination on thermal and material properties
of PVC were investigated using DPMS and TGA as well as UV-Vis-NIR and FTIR
techniques. In addition, the photodegradation of PVC/PVAc blend, copolymer (PVC-coPVAc)
and PVAc were similarly investigated. Dehydrochlorination of the polymers
resulting from UV-exposure were also investigated for doping of PANI in blends.
HCl evolution behavior of the UV dehydrochlorinated PVC exhibits a characteristic
property which is different from the unirradiated ones. Both DPMS and TGA results
confirms the sensitization of PVC photodehydrochlorination at 312 nm by hydroquinone
(HQ) resulting in a temperature onset that is the lowest (140
oC). HQ assistance upon 312
nm UV exposure is not significantly observed in the copolymer. The low temperature onset of UV-induced copolymer is a promising result to produce longer polyene chains,
since polymer backbone starts to decompose after ca. 220
oC, using copolymer might be
an alternative to PVC.
Keywords
Poly(vinyl chloride)(PVC)FTIR
UV-Vis-NIR
TGA
DPMS
photodegradation
polyaniline
hydroquinone
PVC-co-PVAc
Poly(vinyl acetate)(PVAc)