Segmented Polyurethane Reinforced with Nano Sized Cellulose Fibers

V. S. CONTOS; M. L. AUAD; S. NUTT; N. E. MARCOVICH; M. I. ARANGUREN

Ventura, California, USA

Conferencia; Gordon Conference, Composites; 2006

Gordon Conferences

The effects of the hard-segment content on the thermal and mechanical properties of shape memory polymers (SMP) reinforced with micro sized cellulose fibers were investigated. The SMP selected for this work was a thermoplastic polyurethane (TPU) prepared from 4,4-diphenylmethane diisocyante (MDI), 1,4-butanediol (BD) and poly(ethylene glycol) (PEG). Four sets of TPU were synthesized containing a constant soft-segment molecular weight of 2000 and a variable MDI/BD-based hard-segment content ranging 23-45 wt%. X-ray measurements revealed that the crystallinity of the TPU decreases as the hard segment content increases. On the other hand, mechanical testing reveals that the shape fixity capacity increases and the shape recovery ability decreases with hard segment concentration. For each set, TPUs were reinforced with 0.1wt%, 0.5wt% and 1wt% of cellulose. The study on thermal and mechanical properties was performed using DSC, DMA and tensile testing. The results show that hard-segment crystalline melting temperature was in the range of 175-200 ºC and soft-segment melting temperature was in the range of 10-25 ºC. With increasing cellulose content, tensile and dynamic storage modulus as well as glass transition temperature increased in all the series.