ABSTRACT
It has been generally accepted that melt elasticity plays an important role in the foaming process.1,2 It is well known that elastic properties in the molten state are enhanced by broadening the molecular weight distribution and incorporation of long-chain branches. This is the reason why low-density polyethylene (LDPE) produced by radical polymerization method, rather than linear low-density polyethylene (LLDPE), is employed for foaming. Furthermore, various properties are required for foams these days, such as high rigidity, high heat distortion temperature, and biodegradability. However, in the case of engineering plastics, the incorporation of long-chain branches is difficult on an industrial scale and often loses cost performance. Moreover, typical biomass-based polyesters such as poly(lactic acid) (PLA) and poly(3-hydroxybutyrate) show narrow molecular weight distribution
CONTENTS
4.1 Introduction ..................................................................................................83 4.2 Melt Elasticity ...............................................................................................84
