Lamellar crystallization of pendant chains in radiation-crosslinked polyethylene fibres
Ultra-high molecular weight polyethylene fibres of the gel-spun/hot-drawn type were crosslinked by means of γ-radiation and several techniques were applied for the characterization of the molecular network. The crosslinked fibres showed a nonperiodic morphology both in scanning EM and in SAXS. After a heat treatment above 150° C, the temperature at which the chain-extended crystals melt or transform into the hexagonal phase, a well-defined lamellar morphology was observed. This is ascribed to fast relaxation of pendant chains from the chain-extended crystals into a more kinked state, and subsequent lamellar crystallization of these chains upon cooling. From a determination of the amount of lamellar crystals it is estimated that about 90% of the network consisted of pendant chains, as a result of chain-scission during irradiation.
Abstract The objective of this study was to evaluate the chemical and physical characteristics of fresh egg pasta samples obtained by using two different production methodologies: extrusion and lamination. The results of the study demonstrate that products have different characteristics in terms of colour and level of gelatinization, while they do not show significant differences with regard to the amount of absorbed water during the cooking stage. It was evaluated that it is possible to discriminate the two kinds of products by using FT-NIR spectroscopy. FT-NIR analysis results suggest the presence of a different matrix–water association, a diverse level of starch gelatinization and a distinct starch–gluten interaction in the two kinds of pasteurised samples.