Morphology and crystallization kinetics of poly(ethylene brassylate)

Poly (ethylene tridecanedioate), also known as poly(ethylene brassylate) (PEB), is a long-spaced aliphatic polyester obtained from a renewable source. PEB in a range of molar mass between 27,000 and 188,000 Dalton crystallize rapidly as single peaks at 55 C and display two major melting peaks (60 -70 C). The two melting peaks are associated with crystallites that differ in the packing of the crystalline ester layer. Although the WAXD patterns are undistinguishable, differences in the ester layer packing lead to the effect of self-poisoning at the growth front, and hence to a deep depression of the growth rate at temperatures approaching the transition between both forms, from above. This minimum of the rate, first described for n-alkanes, is also observed in the overall crystallization kinetics obtained by DSC, and follows a general behavior of precision polyethylenes that develop different crystalline polymorphs by changing undercooling.