Molecular basis tensile strength

Smith and Lemstra have shown a correlation between tensile strengths o.j. for a given level of Young s modulus E and polymer molecular weight for a series of gel spun and hot drawn fibres. The results are shown in Fig. 44 together with solid lines calculated on the basis of a linear dependence between log and log E, which can be written as... 

It has long been recognised that oriented polymers (i.e. fibres) are much less strong than would be predicted on the basis of elementary assumptions that fracture involves simultaneously breaking the bonds in the molecular chains across the section perpendicular to the applied stress. Calculations of this nature were originally undertaken by Mark [86] and rather more recently by Vincent [87] on polyethylene. It was found that in both cases the measured tensile strength was at least an order of magnitude less than that calculated. 

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