Study On Toughening Modification Of Polypropylene Random Copolymer(PPR)

Random copolymer polypropylene(PPR)is a typical general plastic,and the application field of PPR is expanding year by year because of its green environmental protection,long life,good corrosion resistance and good processing performance,etc.However,due to the obvious brittleness of PPR,especially low impact strength at low temperature,high temperature creep property and so on,the application of PPR in the field of high toughness is limited.In this paper,the toughening modification of PPR was studied,and the PPR composites with excellent properties were prepared.PPR composite material was prepared by double screw extrusion granulation and injection molding.Three types of toughening agents are studied in this paper:different kinds of elastomers,different kinds of beta nucleating agents and nano-CaCO3 particles,through the design of orthogonal experiment to carry out the three compound system toughened PPR and to obtain the optimization performance of the PPR material.The results of experiments showed that compared with POE,the PPR that toughened by TPE was better.When the content of TPE was 15%,the performance of the composite was the best,and the blending system was the best.Compared with the impact strength at room temperature of pure PPR13.8KJ/m2,the impact strength was increased by 82.5%.The impact resistance of the blend system was improved by 9.25KJ/m2,9.13KJ/im2 and 8.53KJ/m2 at the temperature of 0?,-15?,-25?.The elongation rate of the system was increased by 304.91%,tensile strength decreased in varying degrees.The temperature resistance of PPR was improved by the increase of melting point of the system.In the process of melting and heating,PPR generates a new melting peak,which has no new crystal form;The results showed that the mechanical properties and crystalline properties of PPR materials were affected by different content of beta nucleating agents WBG-2 and TMB-5,WBG-2 can induce the PPR cooling crystallization process to produce more impact resistance of beta crystal form,and the effect is more obvious from the essence to improve the PPR macro impact performance.When the adding amount of WBG-2 was 0.1%,the impact strength of PPR was the best,and the impact strength increased by 64.86%compared with pure PPR.The low temperature toughness of the blend system was significantly improved and the tensile strength was decreased;The experimental results of the nano-CaCO3 inorganic particle toughened PPR were obtained when the nano-CaCO3 content was 3%,the impact strength of the system increased to a maximum value of 16.31 KJ/m2,the tensile strength value decreased by 2.52MPa,reaching 22.85MPa.Orthogonal experiment that designed by single factor experiment showed that taking the normal temperature and low temperature-15? as the evaluation index,the impact strength of the primary and secondary order was TPE>WBG-2>nano-CaCO3.the tensile strength of the primary and secondary order was WBG-2>nano-CaCO3>TPE.Considering all,the optimal combination of PPR composites was PPR 100 portion,TPE/WBG-2/nano-CaCO3-16:0.1:3.The impact strength of the system at room temperature was 27.23KJ/m2,the impact strength at low temperature-15? was 15.86KJ/m2,the tensile strength was 22.28MPa.The impact strength at room temperature increased by 64.86%and fracture elongation increased 1.11 times compared with pure PPR.