Mechanical properties direct relationship between Young

In the literature it has been shown conclusively that there is a direct relationship between the degree of orientation of molecular chains and the mechanical properties, such as Young s modulus. 

Does the weak interchain coupling imply poor mechanical properties The answer is No for films with = 15, Young s modulus reaches 50 GPa and the tensile strength approaches 1 GPa, mechanical properties which are characteristic of high performance materials. More importantly, the data in Fig. VI-2 demonstrates a direct correlation between the electrical conductivity and the mechanical properties. The linear relationship implies that the increase in both the conductivity and the modulus (or tensile strength) with draw ratio result from increased uniaxial orientation, improved lateral packing and enhanced interchain interaction. 

The majority of research concerned with the relationship between physical structure and mechanical properties of fibres is concerned with the Young s modulus. Theoretical calculations showed that at absolute zero the modulus of polyethylene crystals in the chain direction is between 260 and 320 GPa the value obtained by X-ray measurements assuming homogeneous stress was 240 GPa. The moduli in other directions obtained both by calculation and by the X-ray method are considerably lower. The moduli in the chain direction for other polymers, with essentially extended-chain conformations, are somewhat lower e.g. 110GPa for PET ). For polymer crystals with helical chain conformations, the chain modulus is further reduced e.g. 42 GPa for isotactic polypropyleneThe average transverse moduli obtained by various experimental methods are typically between 2 and 4GPa. ... 

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