A real‐time study on the evolution of the degradation of polypropylene during mixing process

Abstract

A real-time study to the evolution of the mechanisms of degradation of both PP powder and PP granular during the mixing process was achieved. A quantitative analysis of combination of the rheological torque-time curves obtained by a Haake rheometer with FTIR spectra was made. The construction of a series of the characteristic functions of the torque-time curve and the FTIR characteristic functions for polypropylene (PP) made the real time and quantitative analysis relatively profound. By means of these characteristic functions, the characters of the mechanisms of thermooxidative degradation, and the mechanism of mechanochemical degradation for PP were investigated. Two criterions for the mechanism of thermooxidative degradation and the mechanism of mechanochemical degradation were obtained. In the thermooxidative treatment process and the mixing process, the necessary condition for the significant occurrence of thermooxidative degradation of PP is Dh r (i) > 0.05, whereas the sufficient condition for the significant occurrence of mechanochemical degradation is Dh r (i) 0.05 (D l (i) < 0, and i > 1). A detailed description of the evolutions of the degradations for both the PP granules in which an antideterionant was added and the PP powder without any antideterionant was made. The roles and the evolutions of both the mechanism of thermooxidative degradation and the mechanism of mechanochemical degradation were discussed.

Effects of accelerated aging and compatibilizers on the mechanical and morphological properties of polypropylene and poly(acrylonitrile‐butadiene‐styrene) blends

“…Effects of aging on various materials such as PP, 23,24 ABS, 25 and a polystyrene and poly(lactic acid) blend 26 have been investigated. One appropriate investigation procedure for polymer materials is a simulated recycling method.…”

“…Accelerated thermo-oxidative aging is a common method for estimating the service lifetime of polymeric materials. Effects of aging on various materials such as PP, 23,24 ABS, 25 and a polystyrene and poly(lactic acid) blend 26 have been investigated.…”

A study of the controlled degradation of polypropylene containing pro-oxidant agents

“…Comparison of these absorbances can be used to normalize IR spectra since these peaks are insensitive to the oxidative degradation of pure polypropylene (Wang et al 2011). Figure 3 and Figure 4 show variation in the carbonyl (CI) and hydroxyl (HI) indices, respectively.…”

“…Absorbance in the region of 1725 cm -1 and 3500 cm -1 indicated the presence of carbonyl and hydroxyl groups (De Paoli 2008 ; Cáceres and Canevarolo 2009 ), respectively, and the absorbance peak at 2722 cm -1 was related to angular molecular vibrations in CH and axial molecular vibrations in CH 3 , as suggested elsewhere (Cáceres and Canevarolo 2009 ; Babetto and Canevarolo 2002 ; Rabello and White 1997 ; Garton et al 1978 ). Comparison of these absorbances can be used to normalize IR spectra since these peaks are insensitive to the oxidative degradation of pure polypropylene (Wang et al 2011 ). Figure 3 and Figure 4 show variation in the carbonyl (CI) and hydroxyl (HI) indices, respectively.…”

Influence of compatibilizer on blends degradation during processing

“…One of the methods used to evaluate the reduction or increase of the molar mass after thermomechanical degradation is measurement of the torque variation as a function of the processing time, in a torque rheometer coupled to an internal mixer [29][30][31][32][33][34][35] . Under constant conditions of temperature and rotation speed of the rotors, the variation of the torque is an indirect measure of the molar mass variation and, after loading of the polymers, there are three possibilities:…”