Research On Synthesis And Properties Of TPU

Thermoplastic polyurethane elastomer,referred to as TPU.It is a new type of synthetic materialyesl between rubber and plastic,which combines the advantages of rubber and plastic.It is formed by polymerization reaction of diisocyanate,macromolecular polyether or poter diol and small molecule diol chain extender.so its structure is relatively special.Its special structure determines that it has the following advantages:(1)The physical and mechanical properties are very excellent,the main performances are high mechanical strength,wide adjustable range of hardness,good hydrolysis resistance.(2)The low temperature performance is excellent.the main performance is that the glass transition temperature is low,even at low temperature,it still has good flexibility and elasticity.(3)There are various processing methods,and the selection of processing methods is mainly determined by the structure of its molecular chain,and its molecular chain structure is the same as that of ordinary thermoplastic,so the processing method and processing equipment of ordinary thermoplastic are applicable to it.Such as extrusion and injection.At present,thermoplastic polyurethane elastomer has been widely used in all aspects of people’s daily life because of its excellent processing performance and excellent mechanical properties.In this paper,thermoplastic polyurethane elastomer was prepared by one-step method.The effects of isocyanate index,hard segment content,the type of soft segment oligomer diol,the proportion of soft segment oligomer diol,the type of hard segment diisocyanate,the proportion of hard segment diisocyanate,the type of hard segment chain extender and the proportion of hard segment chain extender on the properties of thermoplastic polyurethane elastomer were studied.We founded that:(1)By changing the isocyanate index(0.98~1.02),it can be found that: The mechanical strength of the material increased with the increase of isocyanate index;With the increase of isocyanate index,the elongation at break of the material decreased;The hardness of the material did not change with the change of isocyanate index,and the value of isocyanate index had little effect on the hardness;With the increase of isocyanate index,the processability and low temperature performance of the material became worse.(2)By changing the hard segment content(27%~38%),it can be found that: When the isocyanate index value was fixed.With the increase of hard segment content,the mechanical strength and hardness of the material increased;The elongation at break decreased with the increase of hard segment content;The processability and low temperature performance of the material became worse with the increase of hard segment content.(3)By changing the type of polyols and the blending ratio,it can be found that: The comprehensive properties of CAPA7201 A elastomer were the best;PTMG2000 elastomer had the best processability and low temperature performance;When PTMG1000 and PCDL1000 were used together,with the decrease of PTMG1000 content,the processability and low-temperature performance of elastomer materials became worse;When the ratio of PTMG1000/PCDL1000 was 80/20,the composite performance was the best.(4)By changing the type of diisocyanate and its blending ratio,it can be found that: MDI type elastomer had the best comprehensive properties,it has the highest tensile strength and the largest elongation at break;The machinability of TODI type elastomer was the worst among several materials,but its low temperature performance was the best;When MDI and TDI were used together,with the increase of MDI content,the low temperature performance of the material was better,but the processing performance was gradually worse;When the ratio of MDI/TDI was 80/20,the composite performance of elastomer was the best.(5)By changing the type of chain extender and its blending ratio,it can be found that: BDO type elastomer had the best comprehensive properties;HQEE elastomer had the worst processability and the best low temperature performance;When BDO and HDO were used together,with the increase of BDO content,the mechanical strength and hardness of the elastomer materials increased,the processability and low temperature properties also improved,while the elongation at break decreased;When the ratio of BDO/HDO was 60/40,the comprehensive properties of elastomer were the best.