影响结晶的因素

no longer range order
dose not display constant distance between macromolecules or any regularity of the arrangement or orientation contain no pigment of fillers are transparent
growth
The growth of polymer crystal take place when nuclei growth by addition of further chain. It can be seen by the changing of spherulites radius. The spherulites become larger and touching to each other and then stop to growth.
Degree of polymer crystallinity
Factor affecting crystallinity
symmetry Intermolecular bonding tacticity branching Physical properties mechanical properties optical properties
a) X-ray diffraction
b) Crystallization and Melting Observation by Thermal Analysis
c) Observation by Density Analysis
spherulites
Semi-crystalline
Amorphous state
Order regular chain structure
Secondary forces holding the chains together in the
lattice must be strong
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nucleation
The creation of stable nucleus (the formation of small nuclei) randomly throughout the melt which id small ordered regions. Nuclei are active sites for the growing of crystal.
Crystalline state
homogeneous polymeric materials
Crystallization process
Highly crystalline Characteristic of plastic because
Highly amorphous
Requirement for crystallinity
Solution crystallization is a complex process being governed by various parameters. solubility which is a function of temperature and related saturation. For most materials solubility increases with temperature (Fig. 1). Supersaturation is critical because it is the driving force for crystal nucleation – either spontaneously (primary nucleation) or in the presence of existing crystals (secondary nucleation - growth).
They combine the strength of crystalline
polymers with the flexibility of amorphous
Semi-crystalline polymers can be tough with an ability
to bend without breaking