The rheology of PVC - An overview

Abstract

-Three aspects of the rheological behavior of PVC are considered. These are (a) particulate flow which occurs below the true crystalline melting point, (b) true melting flow which occurs at or above the melting point and (c) the flow of PVC compounds. The effect of structural differences, resulting from different polymerization temperatures employed in preparing different molecular weight polymere, on the melt viscosity and flow activation energy is reexamined and new data presented to unconfound the effect of syndiotacticity and molecular weight. The three flow behaviors of PVC is shown to be presented by three distinct flow regions. Because of thermal instability, the true melt flow region is only achieved with difficulty. However, in commercial operations this latter state is seldom, if ever, achieved in rigid formulations. The effect of compounding additives, especially lubricants and plasticizers and the importance of thermal and mastication history on the flow behavior is discussed with reference to the flow mechanism.

Dynamic rheological behavior and microcrystalline structure of dioctyl phthalate plasticized poly(vinyl chloride)

“…It is well known that there is a hierarchical morphology for poly(vinyl chloride) (PVC) grains obtained from suspension polymerization,1 which results in a complex flow behavior during the processing. It is well agreed that PVC grains containing primary and subprimary particles are hard to plasticize into homogeneous melts at their processing temperature and shearing stress; therefore, PVC shows particulate flowing characteristics during its melt processing 2, 3…”

“…It is well agreed that PVC grains containing primary and subprimary particles are hard to plasticize into homogeneous melts at their processing temperature and shearing stress; therefore, PVC shows particulate flowing characteristics during its melt processing. 2,3 Plasticized PVC is widely used in medical applications and automobile parts because of its excellent physical properties and low cost. [4][5][6][7][8][9] A lot of studies have been done on the mechanism of the plasticization and improvement of PVC products.…”

Thermorheological analysis of PVC blends

“…Actually molten PVC blends are complex systems, because the peculiar rheological behavior observed in PVC at processing temperatures (170 -190°C), is due to the presence of ordered domains or microcrystallites. [23][24][25][26] The thermorheological complexity of pure PVC, which has been probed by dynamic viscoelastic results, 27,28 constitutes a difficulty in addition to the analysis of molten blends. However, in this article we show that temperature dependence analysis of dynamic viscoelastic functions in the molten state represents a useful technique to investigate structural and morphological aspects, related to final properties, of miscible and immiscible PVC-based blends.…”

The effect of crystallites on the rheological properties of microphase‐separated PVC‐PBA‐PVC triblock copolymers obtained by single electron transfer‐degenerative chain transfer living radical polymerization

“…4 and Table 2, which allows us to find resemblances between the rheological response of our triblock copolymers and the well-studied extrusion rheology of PVC samples. It is known [34][35][36][37][38][39] that PVC behaves rather like a filled polymer, owed to the systematic presence of crystallites at the test temperatures. A significant difference, in favor of the copolymers, is that, owing to the viscosity reduction associated with the copolymerization with PBA, temperatures considerably lower than with PVC can be used in capillary extrusion experiments.…”