Crystallinity and Molecular Ordering

Cooke, D., Gidley, M. J. (1992). Loss of crystalline and molecular order during starch gelatinisation origin of the enthalpic transition. Carbohydrate Research, 227, 103-112. 

Exploration of structural hierarchy (lamellar, crystalline and molecular order)... 

The counterion/cation effect choice of electrolyte The monomer Chemical polymerization The quest for extra functionality Molecular Structure and Microstructure of Polypyrrole Molecular Weight, Branching and Crosslinking Crystallinity and Molecular Order Surface Morphology and Film Density References... 

Phase Structure and Molecular Ordering.—Polyethylene remains the most popular subject for such studies, four papers dealing with solid polyethylene and two with molten polyethylene. Kitamaru e/ ah have studied the phase structure of bulk- and solution- crystallized polyethylene by broad-line n.m.r. Both types of samples show three components, a broad crystalline component, a narrow liquid-like component and an intermediate component... 

Before beginning the study of the structure of crystalline polymers, the subject of crystallography and molecular order in crystalline substances is reviewed. Long before X-ray analysis was available, scientists had already deduced a great deal about the atomic order within crystals. 

In the present study, the crystallinity and molecular weight measurement of the UHMWPE tibial insert were carried out in order to determine whether there was a change after the insert was implanted for 10 years. Fig. 8 shows the melting endotherm for the refrieved UHMWPE tibial insert. The heat of fusion for this sample was 164.85 J/g. It was obtained by integrating the area under the endothermic peak. The value of the average crystallinity obtained from DSC of the UHMWPE tibial insert was 56.6%. 

One may now ask whether natural systems have the necessary structural evolution needed to incorporate high-performance properties. An attempt is made here to compare the structure of some of the advanced polymers with a few natural polymers. Figure 1 gives the cross-sectional microstructure of a liquid crystalline (LC) copolyester, an advanced polymer with high-performance applications [33]. A hierarchically ordered arrangement of fibrils can be seen. This is compared with the microstructure of a tendon [5] (Fig. 2). The complexity and higher order of molecular arrangement of natural materi-... 

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