Optimization and development of processing aids for PVC foam applications

Abstract

Kaneka Belgium develops and produces additives for PVC to improve its properties. Processing aids are added to improve fusion of the PVC resulting in better processability. PVC has poor processability characteristics other than slow fusion such as melt fracture, poor melt strength and extensibility. Processing aids improve melt rheology thanks to their high molecular weight chains. This master's thesis aims to improve the production process of a processing aid as well as develop a new processing aid. Properties of former processing aid should remain the same whilst production efficiency increases. Development of a processing aid resulting in a low-density PVC foam product with good surface finish is a desired outcome.

Processing aids are produced via free radical emulsion polymerization. Changes in recipe such as solid content, emulgator type, reaction time and post-initiation methods aim to improve the production process. To ensure properties remain within range, evaluation of parameters such as molecular weight, particle size distribution and shear viscosity are performed. In attempt to develop a new processing aid, parameters such as chain transfer agent, monomer composition and functional groups are changed along with blending of processing aids. Die swell and Brabender tests are performed to evaluate melt rheology of the new processing aid.

Alterations to the former processing aid resulted in an improved production efficiency. First developments towards the new processing aid were conducted.