Synthesis And Properties Of Polyurethane Cross-Linked By Diels-Alder Reaction

Polyurethane (PU), which has simple synthesis procedures and Excellent mechanical property that can be easily designed, has been used in many fields, such as elastomer, adhesive, leather and so on. Although this, TPU show us there is two big problems presented that TPU is weak at creep resistance and solvent resistance.These properties are belong to thermosetting PU.It is necessary to find a way that to discover a new kind of TPU which have cross-linked network and thermoplastic properties.In this thesis, the Diels-Alder thermally reversible bonds was been introduced as crosslinked bonds by a special design for PU structure. And then,we get a special TPU with thermally reversible crosslinked network.The specific works in this paper are listed as follows:1. A new diol structure with conjugated diene pendant group was been designed to introduce Diels-Alder reaction into PU. Propylene oxide and furfurylamine was used as the raw material to synthetic this new diol which named FDO in this paper. It is different from furfurylamine that furan pendant can be easily introduced into PU if FDO was used as chain extender, when furfurylamine can only used to terminated the PU polymer.2. A special polyurethane which is crosslinked with thermally reversible bomds is designed through the adjustment of structure. To achieve this, FDO was used as chain extender to synthetic a linear PU with furan pendant. BMI waht has two maleimide group was used as crosslinking agent, so that crosslinked network in PU could be all formed through Diels-Alder reaction.3. This PU polymer will own crosslinked network and show us its thermoplastic properties which is due to the Diels-Alder bonds. Repeated processing experiment result shows that the tensile strength of the DA PU after processing can reach about 90% of the processing before. There is a good stability in repeated process.