The nature of poly (vinyl chloride) crystallinity—the microdomain structure

Abstract

The microstructure of polyvinyl chloride (PVC) controls much of its processing and property behavior. A model put together from X-ray diffraction and small-angle scattering data, swelling data, and processing data shows that PVC crystallites, of a wide melting range and spaced at 0.01 micron, act as crosslinks in a three-dimensional network. Tie molecules limit swelling by plasticizer. The network prevents strong primary particle interaction at low melt temperatures. At higher temperatures, partial melting and then recrystallization leads to strong ties between particles and a tough product.

Nanoscopic characterization of a plastisol gelation and fusion process utilizing scanning electron microscopy and atomic force microscopy

“…Marcilla and Garcia [1] theorized that PVC particles swell with plasticizer during the gelation stage and that partial dissolution of microcrystallites leads to increased viscosity. Summers [5] used X-ray diffraction and smallangle scattering data to show that tie molecules limit the swelling of PVC particles during plastisol solubilization. Examinations of AFM phase images support this idea.…”

A scientific approach to rigid poly(vinyl chloride) extrusion

“…These primary particles persist in the melt to quite high melt temperatures of 215 to 22OOC (5 to 7). Each primary particle maintains its independence as a unit of melt flow because it is held together by a three dimensional network of crystallites and tie molecules (8). Fusion (gelation) takes place by partial melting of crystallites which liberates PVC molecules for greater particleto-particle interaction followed by recrystallization upon cooling (8).…”

“…Each primary particle maintains its independence as a unit of melt flow because it is held together by a three dimensional network of crystallites and tie molecules (8). Fusion (gelation) takes place by partial melting of crystallites which liberates PVC molecules for greater particleto-particle interaction followed by recrystallization upon cooling (8). The crystallinity, measured by infrared, shows widely varying crystallite perfection, which results in a very broad melting range (9).…”

Morphology and Sound Velocity of Plasticized Polyvinylchloride Studied Using Scanning Acoustic Microscope

“…On the other hand, the PVC particles are broken to the size of PVC primary particles in the well-dispersed domains. The physical properties of the well-dispersed domains have been investigated by several methods, [4][5][6] but no information about the physical properties of the pseudonetwork domains has been reported, since it is difficult to measure the physical properties of the local domain. To design a highly functional polymer, it is desirable to investigate the mechanical properties of the local domains.…”