Study of the rheology and foaming processes of poly(vinyl chloride) plastisols with different foaming agents

摘要

Poly(vinyl chloride) (PVC) plastisols are widely used in the production of flexible PVC foams. In this study, we investigated the evolution of the complex viscosity of PVC plastisol by dynamic oscillatory tests, the storage modulus of the PVC compound by dynamic mechanical analysis, and the thermal behavior including the decomposition of three chemical blowing agents (CBAs), namely, azodicarbonamide, 4,4'-oxybis(benzenesulfonyl hydrazide), and sodium bicarbonate, by differential scanning calorimetry. Furthermore, the morphology and quality of the foams obtained from the corresponding plastisols were characterized by scanning electron microscopy. The results indicated that the onset decomposition temperature T2(5%) of a CBA in plastisol is the most critical indicator of the foam quality. The temperature difference corresponding to [T2(5%) - T eta(max)] was also proved to be another important parameter. When T2(5%) is within the optimum temperature range of a PVC plastisol, the bigger the [T2(5%) - T eta(max)] difference, the better the quality of the foams.