Mechanical Properties of Polymeric Solids

Publisher Website
Google Scholar
Abstract
A short survey is given of the correlation between mechanical properties and molecular model of homopolymer solids in rubbery, glassy and crystalline state. Particular emphasis is given to the plastic deformation of crystalline solids and the mechanical properties of the fibrous structure obtained by such deformation. The main difference between the spherulitic and the fibrous morphology, which explains the enormous difference in elastic modulus and strength, is not the crystallinity, crystal structure and orientation, but the fact that the basic element of the former structure is the extremely thin and easily deformable crystal lamella and, in the latter case, the very long and strong microfibril. The deformation of the fibrous structure is only possible by the sliding motion of microfibrils which is opposed by the autoadhesion forces between adjacent microfibrils over their full length or by fracture of microfibrils; which demands the rupture of the intrafibrillar tie molecules constituting a much larger fraction of the total number of chains of the crystal lattice than in the case of spherulitic morphology.