Introduction of material properties and crystallization of commonly used plastics
Introduction of material properties and crystallization of commonly used plastics
The composition of plastics is made up of many linear, long and thin polymer aggregation, in accordance with the molecules into the degree of formal arrangement, known as the degree of crystallization (crystallinity), and the degree of crystallization available X-ray reflection to measure. Organic compound, the structure of the complex plastic structure more complicated, and the structure of the molecular chain (linear, wool ball, folding, spiral, etc.) change more, cause its structure also has changed a lot due to different forming conditions. The crystallinity of the plastic is crystalline plastic, and the intermolecular attraction is easy to interact with, and it becomes a strong plastic. In order to crystallize and the correct arrangement of the rules, the volume becomes smaller, the shrinkage rate and the thermal expansion rate increase. Therefore, the higher the crystallization, the worse the transparency, but the greater the intensity. Crystalline plastic has obvious melting point (Tm). When solid, the molecules are arranged in rules, strong in strength and strong in tension. When melting is bigger than volume change, more easily after curing shrinkage, internal stress is not easy to release, the finished product is not transparent, slow cooling in the forming, LengMo contraction after the date of production is bigger, hot mold shrinkage smaller after the date of production. Relative to crystalline plastics, another for an amorphous plastic, no obvious melting point, its solid molecules are arranged irregular, when melting than volume change is not big, not easy contraction after curing, product transparency, material temperature, the higher the yellow color, forming heat faster, in the following for both property comparison.
