High strength polyethylene fiber (Dyneema~R fiber: hereinafter abbreviated to DF) has a large negative thermal expansion coefficient(TEC) . Several kinds of fibers having differrent modulus from 15 to 134 GPa were prepared. The TEC of these fibers and fiber reinforced plastics (DFRPs) have been measured. TEC got more negative with increasing moduli of fibers, changed markedly between 15 and 51 GPa. The TEC of these FRPs shows positive values only at 15 GPa of fiber modulus and negative one above 51 GPa. Inter laminar sheare strength(ILSS) of these DFRPs increased with increasing in a fiber modulus and the difference of TEC between DFRPs and DFs also decreased. It was found that crack resistance increased with increasing in ILSS, and both ILSS and crack resistance of DFRP composed with corona discharged DF were higher than that with raw DF. UD-DFRP composed with corona discharged DF showed a more negative TEC. Corona treatment is a methode for providing with polar functional groupes on surfaces of organic fibers by passing through corona discharged chamber.
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