Relationship between crystal hardness and melting temperature

4 Relationship between crystal hardness and melting temperature 

Equation (4.13) shows that the reciprocal value of the crystal hardness is related to the melting temperature of the crystals. 

342 K for PEO) in agreement with previous results (Balta Calleja Santa Cruz, 1996 Balta Calleja et al, 1994). The b/b ratio derived from the slope of the plots is around 2 for PET, 44 for PE and 95 for PEO. This result suggests that for flexible polymers the energy required for plastic deformation of the crystals is much lower than the melting enthalpy. As the chain stiffness increases, the b/b ratio seems to decrease as a consequence of a higher energy required for crystal deformation. 

Polymer surfaces is a field of increasing interest to both basic and applied research (Eisenriegler, 1993). The aim of this section is to show that microhardness is directly related to surface free energy and, therefore, to the degree of polymer perfection at polymer surfaces and interfaces. Studies have revealed that the morphology (crystal thickness and size of the interlamellar regions) of the polymer nanostructure are the main factors determining the microhardness (Balta Calleja et al., 1997). (See also Section 4.2.3.) The hardness-derived parameter 

It will be shown that changes in b in various polymers allow the estimation of changes in Oe which are related to the level of defects incorporated at the crystalline-amorphous interphase. 

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