Study On Preparation And Properties Of Crystalline Polyurethane

PU (polyurethane) is a kind of polymer material that is used in national production with high consumption. Because the raw material source is rich, the preparation technology is simple, and the property is good (good oil and wear resistance, and strong cohesiveness), PU is widely used in various area in our life (such as traffic, sports and biomedicine). But the thermal resistance of PU is not good. Now there are some ways to promote the thermal property of PU, but there is many shortcomings. For example, adding inorganic particle could improve the thermal property of PU, but the mechanical property of PU reduced at the same time. In this paper, the raw materials were modified, By the way of changing the structure of molecular chain of Aliphatic dibasic alcohol, by introduce the aromatic structure in the main chain; On the other hand, there is crystalline texture in the aromatic segment, So both of the thermal resistance and mechanical property of the prepared PU were improved. The relationship between crystalline properties and the composition of aliphatic diol and the aliphatic aromatic copolyester diol was investigated by differential scanning calorimetry (DSC). The results showed that the crystalline properties of aliphatic polyester is good, but the melt point of it is not high; the melt point raised after aliphatic polyester copolymerizing aromatic monomer. The crystalline texture of copolyester was characterized by X-ray diffraction (XRD), and the spherulite morphology of the copolyester was observed by polarizing microscope (POM). It is found that the crystalline texture would be changed when the composition of copolyester changed. The influence of chain-extension on the crystallization property of diol was also studied, and after crosslinking, the chain-extension-diol was used to prepare PU. The PU was characterized by thermogravimetry (TG), tensile property The results showed that the heat resistance of PU was improved when the content of aromatic monomer increased; the strength of PU was improved because the presence of crystalline region. The work of modifying PU with diol have some reference value, Introducing aromatic segment into diol could improve heat resistance and mechanical property of PU.