RESEARCH FOR FORMING POROUS STRUCTURES BASED ON PVC

Abstract

In this work, we report on phase equilibrium in systems «plasticizer mix - blowing agent». Dioctiphthalate, butylbenzylphthalate and dicresyl phosphate were used as plasticizer, and simple oligoesters (ethylene glycol, diethylene glycol, triethylene glycol) served as a blowing agent. We conducted an experiment and built triple phase diagrams. Diphenylcresylphosphate proved to be fully compatible with diethylene and triethylene glycol, but not to the ethylene one. Triple systems «Butyl benzyl phthalate - Diphenylcresylphosphate - Simple oligoesters» turned out to be homogeneous for several created compounds. To achieve this for a triple system, the minimal quantity threshold is either 20% of triethylene glycol or 30% of diethylene. As for the case of dioctyl phthalate for second plasticizer, the minimal threshold for blowing agents is 70%. We constructed a device that allows to detect phase equilibrium for liquid systems. We devised several compounds and a technological proccess for creating porous PVC-based membranes using thermal molding. We selected such molding due to several advantages when compared to other methods for producing porous membranes, such as: required density, elasticity, open pores, and narrow pore size distribution. We managed to create several samples based on emulsion type PVC, butyl benzyl phthalate, diphenylcresyl phosphate, diethylene and triethylene glycol. During the phase inversion thermal process temperature should be around 180 degrees of celsium. Porous materials have the following properties: open porosity 38-44%, breaking strength 1.0 – 1.2 MРa, relative extension 43-63%, maximal pore size (2.3 – 2.8)·10-6 m, average pore size (0.5 – 1.1)·10-6 m.