The morphology, rheology and processing properties of polyvinyl chloride
The critical observations of Berens and Folt (1) and Collins and Krfer (2) have focused research on the particulate nature of PVC. It has been shown by many working in the field that this particulate nature is the controlling feature in both the fusion and flow behavior of PVC compounds. The morphological nature of the suspension resin can be related to the ease of processing of PVC compounds. Resin particles with interior particulate material loosely packed break apart easily and are more readily processed than tightly packed systems. Resin particle uniformity is also important in the fusion process. A model for the fusion process of PVC is proposed based upon these findings. The effects of additives used in compounds is discussed. The factors the author views as being important for the future development of PVC processing is presented. Polyvinyl chloride is the world's second largest commercial polymer and one of the oldest. Surprisingly, the work that has been done characterizing its rheological, morphological and physical properties has only taken place in the last two decades. The other major polymers such as polystyrenes and polyolef ins, technical history goes back at least three or four decades. The reasons for this delay in the technical investigations of PVC was most likely due to the unique and complex properties of this polymer. In addition to the complex properties of PVC, a second major drawback to its study is its thermal degradation