Charakterisierung der stabilität von modifizierten polypropylen‐glasfaser‐verbunden nach thermo‐ und photooxidation

Abstract

ZUSAMMENFASSUNG:Homopolymerisat und verschieden chemisch modifiziertes Polypropylen wurden fur die Compoundierung mit Glasfasern unter Anwendung verschiedener Stabilisierungsvarianten im Hinblick auf ihre thermo-und photooxidative Bestiindigkeit charakterisiert. Zur Untersuchung der thermooxidativen Stabilitat der Polymer-Compounds wurde die direkte Messung der Sauerstoffabsorption angewendet. Die durch die thermischen Oxidationsprozesse hervorgerufenen Veriinderungen in der Ziihigkeit und im Dehnungsverhalten wurden durch den Schlagbiege-und den Zugversuch charakterisiert. Die durch die Photoalterung hervorgerufenen Veranderungen wurden IR-spektroskopisch verfolgt. Die Untersuchungsergebnisse werden hinsichtlich des Einflusses von Stabilisatorsystem, Modifikator und Glasfasern diskutiert.Demnach weisen die mit 0,lOVo BHT, 0,30% DSTP, 0,05% Irganox 1010 und 0,25% SUMMARYFor the purpose of being compounded with glass fibres, homopolymers and polypropylene chemically functionalized in different ways were characterized with regard to their thermooxidative and photooxidative stabilities, after having been subject of different manners of stabilization. Consequently, in the basic state and after short ageing times, the compounds stabilized with 0.10% BHT, 0.30% DSTP, 0.05% Irganox 1010, and 0.25% Tinuvin 770 exhibit the best thermooxidative and mechanical stabilities. This effect is lost with increasing periods of ageing. Concerning the modifier it can be said that the samples functionalized with a mixture of acrylic acid and maleic anhydride in 5 : 1 ratio show the best thermooxidative and mechanical behaviour; on the other hand, the photooxidative behaviour is the worst. Pure maleic anhydride modifier leads to a significant worsening of the thermooxidative and mechanical properties, the UV stability is not changed against the unmodified samples. Glass fibres cause a significant improvement of the compound properties -particularly when applying a modifier -, a considerable retardation of the thermooxidation period as well as a decrease of the photostability. The latter influence is, however, not completely clear.

Effect of iron carboxylates on the photodegradability of polypropylene. II. Artificial weathering studies

“…The maximum absorbance region for some groups which were related to degradation products are listed in Table II. In literature, the absorbance bands occur at 840, 974, 1166, 1455, and 2720 cm −1 were considered as reference peaks for polypropylene 21–25. In this work, the peak at 974 cm −1 (CH 3 rocking band) was chosen as reference peak, which remains unchanged during degradation.…”

Effect of iron carboxylates on the photodegradability of polypropylene. I. Natural weathering studies

“…The maximum absorbance regions for some groups, which were related to degradation products, are listed in Table II. Several peaks at 840, 974, 1166, 1455, and 2720 cm À1 were found in the literature [24][25][26][27][28] as reference peaks for PP. In this study, the band at 974 cm À1 (CH 3 A rocking band) was chosen as a reference peak because it remained unchanged during the degradation process.…”

Fotodegradação do polipropileno: Um processo essencialmente heterogêneo

“…O índice de carbonila foi obtido como a razão entre as áreas sob o pico de grupos carbonila (situado na faixa 1700-1800cm -1 ) e um pico de referência para o polipropileno (situado em 2720cm -1 ). O pico de referência foi escolhido seguindo-se outros estudos da literatura 15,16 e deve representar vibrações moleculares não afetadas pelo envelhecimento. As determinações de peso moleculares médios por GPC foram realizadas em Rapra Technology Ltd. (Shawbury, UK) cujos procedimentos aplicados para polímeros degradados foram discutidos anteriormente 17 .…”