Thermal stability of modified poly(vinyl chloride) by TGA

Abstract

SynopsisThe stability of poly(viny1 chloride), as measured by thermogravimetric analysis, is significantly different from that of other thermoplastics. It is shown that the onset of weight loss can be correlated with the development of color in a processed resin. It is further shown that the ingredients within a rigid polyvinyl chloride compound drastically alter its thermal behavior. The effect of lubricant and stabilizer on the degradation of poly(viny1 chloride) is stressed.The processing of thermoplastic materials usually requires reasonably high temperature stability (up to 300°C.) of polymers. It is apparent that all resins do not behave similarly ( Fig. 1) and, since this is also true of single resins from different sources or of different batches of a resin from the same source, it is necessary to be able to distinguish or determine the differences in thermal stability. Thermogravimetric analysis (TGA) affords an excellent method by which this may be accomplished. Most of the common resins (e.g. , polyethylene and polystyrene) have a single weight-loss mechanism or reaction. This is not true, however, of resins such as polyvinyl chloride (PVC). PVC is especially vulnerable to changes in thermal conditions due to the chlorine groupings, and thus its weight-loss process is somewhat different (see Fig. 1).The thermal instability of PVC can be followed by a three-step weightloss thermogram on the TGA. This degradation procedure is identified as follows (Fig. 2): A is the region of dehydrochlorination (weight loss of 50-60y0), B is the evolution of simple hydrocarbons formed by cyclization and chain scission (weight loss of 15-3oyO), and C is a gradual evolution of the more complex degradation compounds.'r2The initial formation of conjugated bonds (caused by the evolution of HCl) imparts a coloring to the PVC compound that is quite unfavorable to the processer. Since PVC compounds are mixtures of PVC resin and additives such as lubricants, stabilizers, and modifiers, it is necessary to understand the influence of these additives 011 the stability of the material. It is the purpose of this paper to demonstrate the use of the TGA technique *

Phospholipid imprinted polymers as selective endotoxin scavengers

“…Nevertheless there was still a weak phosphorus signal which indicates that the removal was incomplete. The differences in decomposition profiles before and after Soxhlet extractions were used for elucidation of the degree of template removal 28 . The decomposition profile of PA ( Supplementary Figure S10 ) showed that the major decomposition of the template was the loss of fatty acids and glycerol by ~400 °C, whereas ~15% of the molecule corresponding to the inorganic NaPO 3 part remained up to 1000 °C.…”

An Untargeted Thermogravimetric Analysis-Fourier Transform Infrared-Gas Chromatography-Mass Spectrometry Approach for Plastic Polymer Identification

“…This would need further investigation as other additives (i.e., lubricants, stabilizers, and flame retardants) are also known to have an effect on the inflection point and mass loss. For example, Matlack and Metzger 23 found that lubricants decreased the initial inflection point, while stabilizers had the opposite effect. Given the low initial inflection point and the fact that there were two distinct pyrolysis events, PVC can be putatively identified by TGA.…”