This thesis aims to investigate the effect of chemical compositions and moisture content on the rheology and properties of thermoplastic polyurethanes (TPUs). Specifically the effects of systematic changes in chemical structure on the rheological properties for two series of poly(hexamethylene oxide) (PHMO) based TPUs have been studied. Also the effect of moisture content on rheology of siloxane-macrodiol Elast-Eon 2 and the poly(tetramethylene oxide) (PTMO) based Pellethane were also investigated. The main conclusions drawn from the study are as follows:
• The chemical composition ratio and segment length of the model poly(hexamethylene oxide) (PHMO) based TPUs had a major effect on the linear and non linear rheology of the TPUs. This study involved the determination of the melting transitions, dynamic rheology, stress relaxation behaviour, time-temperature superposition behaviour and relaxation time characteristics.
• The molecular weight and molecular weight distribution had more of an effect than moisture content on the rheological properties of siloxane-macrodiol Elast-Eon 2 and the poly(tetramethylene oxide) (PTMO) based Pellethane. This was ascribed to the fact that the moisture content in the samples was quite low. This study involved the determination of the moisture content, molecular weight analyses, dynamic rheology and thermal effects on rheology.
These conclusions, based on understanding the relationship between chemistry, morphology and rheology, will aid in understanding the processibility of these materials, in order to develop optimal processing conditions.