Research On The Improvement Of Low Temperature Mechanical Properties Of PPR Pipe

In terms of physical properties, mechanical properties and crystallization properties,etc. there are significant differences of random copolymerization polypropylene(PPR)resin and polypropylene(PP) resin. Especially under the condition of low temperature,PPR resin material is easy to brittle and the low temperature toughness is poor, which greatly affect the scope of use of PPR pipe. For research to improve the low temperature mechanical properties of PPR resin, this paper was prepared by melt blending modification of PPR composite material, By researching the different additives,preparation technology and the method of PPR composite matericals, it affects the performance of PPR composite material structure. The main results of this research are as follows:(1)When adding 20% POE to the PPR, the impact strength of composites reached maximum, but the tensile strength of the POE/PPR binary blend declined dramatically.From the micro angle analysis, the addition of POE elastomer would prompt out phase crystallization of PPR material, and it improved the PPR material melting temperature and crystallization temperature. From fracture morphology, low-temperature impact section of20%POE/PPR blend appear obvious stress pale clear. And make the change in fracture mode, by the brittle fracture to ductile fracture.( 2) Compare TMB-5 and WBG-2, the nucleating agent WBG-2 has better toughening effect on PPR, and the impact performance of PPR(0.1% WBG-2)is best. From the crystallization point of view, the nucleation efficiency of WBG-2 nucleating agent is higher.(3)Compare the impact strength and tensile strength of PPR-1 and PPR-2, PPR-1 is better than PPR-2. Compare the impact strength of PPR-1 and PPR-3, PPR-3 is better than the PPR-1, and the impact performance of PPR-3(0.1% WBG-2) is best. From fracturemorphology, due to add the POE elastomer and WBG-2 nucleating agent, PPR-3(0.1%WBG-2) section not only appear obvious fold phenomenon, but also forms a wide range of plastic sliding under the action of external force.(4)Adding 1% of nano-SiO2 in the PPR, the impact strength of composite reached its maxmum point. From fracture morphology, the low-temperature impact section of multivariate composite blend appear markedly different appearance characteristics. One is caused by coating structure which is occurred by POE elastomer and nano-Si O2. The other is the elastic POE and beta nucleating agent synergistic toughening of the matrix resulting in tearing and wrinkling phenomenon.