Partially crystalline structure

Tliis funding is of practical relevance for liquid-phase strategy because the partially crystalline structure of peptide-PEG esters permits ea handling of the precipitated product. Furthermore, the danger of inclusions of low molecular weight components as observed in amorphous precipitates is considerably reduced ... 

Polysaccharides are good candidates for renewable nanofillers because they have partially crystalline structures conferring interesting properties. Two important types of nanofillers have been developed from cellulose, namely whiskers and nanocrystals. Whiskers have also been developed from chitin while starch has been used for preparation of nanocrystals. 

Partially crystalline structures in polymer systems form as a result of the kinetics of the crystallization process, and an understanding therefore requires an analysis of the prevalent mechanisms. One meets different conditions, and we begin with briefly addressing them. 

The physical properties of polymers are governed mainly by morphology, ie, their amorphous or partially crystalline structures anisotropy of binding forces, ie, strong covalent binding within the molecular chains (intrachain force) and weak van der Waals or H-bond forces between molecules (interchain force) and relaxation processes, where changes of place of molecular groups are activated by external mechanical or electrical load. 

The temperature dependence of the ultrasonic velocity (Figure 15), normalized to the glass transition temperature, indicates that both polycarbonate and poly(ether sulfone) possess similiar molecular relaxation characteristics. In contrast, polysulfone either has a much higher sound velocity (modulus) in the rubbery state or (as is more likely) undergoes another relaxation (with associated decrement in the sound velocity) between 363 K and the glass transition. This is probably a consequence of partially crystalline structure existing in the solid at room temperature. 

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