Processability characteristics of chlorinated poly(vinyl chloride)

Abstract

Chlorinated poly(vinyl chloride) (CPVC) is known to have a higher softening temperature than conventional poly(vinyl chloride) (PVC). Its processability characteristics are, however, different; it has been reported that CPVC is more difficult to process. However, only limited information on the processability characteristics is available. This paper describes some studies of the flow behavior of CPVC melts in a capillary rheometer. The true melt viscosity and activation energy were determined between 190° and 210°C for a number of samples, and they appear to be related to the cohesive energy density of the samples. It was observed that melt fracture, i.e., gross distortion of the extrudate, occurs even at low shear rates in samples having a high chlorine content. This has been attributed to the relatively high pressures that have to be used, the pronounced non‐Newtonian nature of the melt, and melt elasticity. It is postulated that melt elasticity could result from crosslinking at the site of the double bond which is known to be formed by dehydrochlorination.

Effect of segment structure on the thermal stability ofCPVCin theGas–Solid PVCchlorination process

“…However, most of the previous studies are focused on the relationship between the molecular chain structure and its properties: Cao et al [7] demonstrated that the substituents of free radicals are stereo selectively located due to the spatial hindrance of macromolecular chains that complicates the molecular structure of CPVC; Marvin et al [21] discussed the relationship between the thermal properties and structure of CPVC and found that the replacement of chlorine atoms made the molecular chain rigider. Krishnan [22] found that there are more CHCl structures in the molecular chain that reduce the flexibility and entanglement of the molecular chain and deteriorate the processability. Research on the effect of segment structure on thermal stability and rheological properties of CPVC is still a blank area (Figure 2).…”

Toughening of chlorinated polyvinylchloride with acrylonitrile-butadiene-styrene graft copolymers

“…It is well known to have a higher softening temperature, higher heat deflection temperature, lower flammability, lower smoke properties, and chemical inertness than conventional polyvinylchloride (PVC). However, in the literature , it has been reported that CPVC is more difficult to process. Moreover, it has poor impact strength, which limits the application of CPVC.…”