Antonietta Genovese

Simulation of the specific interactions between polyamide-6 and a thermoplastic polyurethane

Abstract Polyamides have many desirable properties such as high melting temperatures, chemical resistance and superior mechanical properties. However, its crystalline morphology can limit its applications. It is the specific interaction, hydrogen bonding that gives rise to the crystalline structure of polyamides. This interaction is strong and important when blending on the final morphology and mechanical properties. Polyurethane contains polar functionality that can also interact with the polar component of polyamide. Hence, it is important to study the interaction between such a blend as polyurethane can enhance the toughness of polyamide due to its elastic properties. This study is an insight into the specific interaction between two polar polymers in a simulation whereby the interaction is maximised. Hydrogen bonding has been observed between molecules of either polyamide–polyurethane and polyamide–polyamide, and it is sufficiently strong to cause the polymer chains to distort rather than disrupt the hydrogen bonds. When groups of like polarity, such as carbonyl groups, come into proximity, the polymer chains again distort from their regular conformation because of mutual repulsion.

New Ceramifying Polymer Materials for Passive Fire Protection Applications

A new class of polymer composites has been developed for flame retardancy and passive fire protection. The key feature is a controlled transition from a degrading polymer composite to a ceramic residue in a fire situation. The polymer can be thermoplastic, thermoset or elastomeric. The composites are processable using conventional equipment to form extruded profiles, sheet, moldings, each of which may be foamed. The composites can retain flexibility and durability within the required filler content range. Fire protection is afforded by formation of a ceramic by fusion and reaction of the fillers over a defined temperature range. Ceramic formation commences at relatively low temperature coincident with polymer pyrolysis to maintain structural integrity of the material and minimizes shrinkage. The ceramic is able to develop adequate strength to maintain a fire barrier. One form of the material has been implemented in fire resistant cable sheathing. The composites discussed were prepared from poly(siloxiane) elastomer to demonstrate the concept.