Structure-Morphology-Rheology Relationships in Thermally Stable TPU Having Side-Chain Liquid Crystals

University Of Akron, Akron OH

Investigators

Abstract

Abstract - Han - 9981972 Thermoplastic polyurethane (TPU) consists of hard segments composed of diisocynate and short-chain diols (as chain extender) which form a crystalline phase at service temperatures, and soft segments composed of long-chain diols which control low temperature properties. The most undesirable feature of the many TPUs currently available commercially is thermal instability at processing temperatures, approximately 190-220oC, i.e., they undergo thermal degradation and/or crosslink reactions. This is primarily due to the thermal instability of aromatic diisocyanates often used in commercial TPUs. The PI plans to investigate structure-morphology-rheology relationships in thermally stable TPUs having side-chain liquid crystals. The rheological behavior of TPUs is intimately related to the morphological state of the polymer. A better understanding of structure-morphology-rheology relationships in TPU with or without side-chain liquid crystals, can be used to determine consistent and optimum processing conditions. The PI plans to investigate how hydrogen bonding might affect the morphology and thus the rheology of TPU with and without side-chain liquid crystals using in situ infrared spectroscopy at elevated temperatures (170-250oC). Oscillatory, transient, and steady-state shear flow behaviors of the TPUs synthesized with and without side-chain liquid crystals will be investigated. The research, when completed, may lead to the possibility of creating special supramolecular structures by means of small changes in the architecture of the macromolecules.