Naslov
Effect of PVC/CPE blend composition on thermooxidative degradation

Autori
Stipanelov Vrandečić, Nataša ; Klarić, Ivka

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
Proceedings of the European Polymer Federation Congress / Lemstra, P. - Eindhoven : European Polymer Federation, 2001

Skup
European Polymer Federation Congress

Mjesto i datum
Eindhoven, Nizozemska, 15.07.2001. - 20.07.2001

Vrsta sudjelovanja
Poster

Vrsta recenzije
Nije recenziran

Ključne riječi
PVC/CPE blends; thermooxidative degradation

Sažetak
Poly(vinyl chloride) (PVC) is often mixed with other polymers to modify its physical properties in a desired manner. Chlorinated polyethylene (CPE) is a commonly used impact modifier of PVC but its compatibility with PVC depends upon the chlorine content and the distribution of the chlorine atoms along the polyethylene backbone. The optimal improvement of PVC processing characteristics is achieved by adding 15 to 20 % of CPE with 36 % chlorine content. PVC/CPE blends are used for the production of geosynthetics, marine and hydroisolation foils and the like. Since these blends are in contact with air during their processing and their application as well, a good knowledge of their thermooxidative stability is important. Generally, it is well known that thermal stability of each polymer in the blend (in any atmosphere) can be significantly changed due to possible interaction of the polymer blend components and their degradation products. To investigate the behaviour of PVC/CPE blends in the oxidative atmosphere, accelerated thermooxidative degradation of PVC/CPE blends of different composition (100/0, 90/10, 80/20, 70/30, 50/50, 30/70, 0/100) was investigated by means of dynamic thermogravimetric analysis in the flowing atmosphere of air. From the thermogravimetric curves (TG) it is evident that the thermooxidative degradation of PVC/CPE blends occurs through two basic degradation steps. To estimate the thermal stability of the blends, the following characteristics of TG curves for the first basic degradation steps were used: the onset temperatures (T1o), the temperatures at the maximal rate of degradation (T1m), the degrees of conversion at the corresponding maximal rates (ƒŃ1m), and the mass losses at the end of the first (ƒ´m1) degradation step. In the range of conversions from 2.5 to 40 % the basic degradative reactions were the dehydrochlorination of PVC and CPE. Kinetic parameters (the apparent activation energy E, and preexponential factor Z) were calculated after isoconversional Flynn-Wall-Ozawa method. The compensation dependence between these parameters was found for all the investigated compositions of the blends. The values of compensation ratios (E / ln Z) as well as the characteristics of TG curves confirm the stabilising effect of CPE on PVC dehydrochlorination in the blends with more than 50 % of CPE. The dependence of activation energy on conversion indicates complexity of thermooxidative degradation process of these blends. The superior thermal stability of CPE to the stability of chemically similar PVC could be explained by difference in microregularity of the corresponding polymer chains.

Izvorni jezik
Engleski

Znanstvena područja
Kemijsko inženjerstvo

POVEZANOST RADA