Tensile force at break of gel-spun/hot-drawn ultrahigh molecular weight polyethylene fibres

Fibres obtained by gel spinning of ultrahigh molecular weight polyethylene (UHMWPE) were drawn to various ratios, and the improvement of the tensile strength of the hot-drawn filaments with increasing draw ratio has been studied. The tensile force at break of gel-spun/hot-drawn UHMWPE fibres appeared to be constant for draw ratios exceeding lambda = 30. From scaling arguments, full chain extension is expected at this draw ratio. On the basis of development of the physical properties during drawing, it is concluded that little disentangling occurs up to lambda = 30. Beyond this point, slippage of chains through entanglement hooks becomes predominant. The observed constant tensile force at break can be explained by this drawing mechanism.