Influence of annealing and additives on the crystallization behavior and properties of poly(vinyl chloride)

Abstract

Acetanilide (AC), adipic acid (AA) and potassium hydrogen phthalate (PHP) were chosen as additives to accelerate PVC crystallization and improve its mechanical properties. The influences of the additives and annealing on the crystallization behavior, micromorphology and the tensile properties were investigated by the thermal analysis, scanning electron microscopy (SEM) and the tensile test. Based on the analysis results, it was concluded that the melting peaks ranging from 110 to 200 °C and 200 to 240 °C were caused by the fusion of the fringed micelle crystals and chain-folded crystals respectively. AC advanced the fringed micelle crystal to develop, while AA and PHP promoted obviously the chain-folded crystal to grow. The addition of the foreign additives did not change the growth pattern of PVC crystallites, the growth of the micelle crystal was favorable at 110 °C, and the chain-folded crystal was developed at higher temperature. For PVC/AA and PVC/PHP, when annealed at 110 °C, a regular nest like network was formed, the crystallinity and the crystallite size were increased as well, and as a result, the tensile strength, Young’s modulus and the elongation at break point were improved simultaneously and greatly.

Keywords

poly(vinyl chloride) / additives / crystallization / networks / mechanical properties

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