REINFORCEMENT OF POLYURETHANE ELASTOMERS WITH MICROFIBERS HAVING VARYING ASPECT RATIOS

A mathematical model has been used to predict the effect of fibre aspe ct ratio on the mechanical properties of flexible polyurethane elastom ers reinforced with short, microscopic fibres. The study suggested tha t only a small fraction of the mechanical property improvement possibl e has been realized in previous attempts to reinforce polyurethane ela stomers using microfibres of modest aspect ratios. It was predicted th at the mechanical properties of flexible polyurethane elastomers could be improved significantly by reinforcement with small amounts of micr oscopic fibres having high aspect ratios. Samples were prepared and ch aracterized to test these predictions. Good agreement was seen between the theoretically predicted property trends and those actually observ ed. It was observed that only 2 phr of microscopic bacterial cellulose fibres having high aspect ratios nearly doubled the Young's modulus a nd tripled the strength of a flexible polyurethane elastomer. This rei nforcement far surpassed that observed for microfibres having more mod est aspect ratios.