Research Of The Preparation And Properties For Continuous Fibre Reinforced Thermoplastic PCBT Based Composites

Cyclic butylene terephthalate(CBT)is a new kind of functional resin which has large ring polyester structure,when it reaches its melting point,the viscosity will be as low as water;ring-opening polymerization will happen when the resin melt combined with catalyst,we can get the thermoplastic engineering plastics poly(cyclic butylene terephthalate)(PCBT)when the polymerization finishes.Because of the low melt viscosity,we can use the traditional thermoset composites moulding process to manufacture thermoplastic composites,besides,because of the excellent performance like high strength,high impact resistance and recyclability,the PCBT based composites have great application potential in thermoplastic composites.In this dissertation,we got PCBT via in-situ polymerization of CBT,then continuous fiber reinforced PCBT based thermoplastic composites were prepared via liquid moulding process.From the comparison of different process parameters,we got the best manufacturing parameters.The reaction devices were improved and a new manufacture method called catalyst-loading was also developed,the resin injection time window was enlarged vastly by using this new method.Secondly,the properties of PCBT were studied.Finally,we studied the mechanical properties of continuous glass fiber and carbon fiber reinforced PCBT composites.This paper gives the performance parameters theoretical basis and theoretical direction of the engineering applications of PCBT based thermoplastic composites,it has great significance for the prolongation of thermoplastic composites.First continuous fiber reinforced PCBT based thermoplastic composites were manufactured via liquid moulding process,the best catalyst mass fraction is 0.5%,polymerization temperature is 180?,catalyst mixing time is 15s and vacuum pressure is-0.095MPa.The reaction devices were improved and a new manufacture method called catalyst-loading was also developed,the principle for this new method was combined catalyst with fiber,when the CBT melt contact with the catalyst polymerization happened.This new method enlarged the resin injection time window from 200s to 500s.The improved process made it possible to moulding big size components which have complex construction.Then the properties of polymer were studied.The results showed that:The catalyst mass fraction would influence the molecular weight and crystallization of PCBT.When the catalyst mass fraction was 0.3%,the molecular weight of PCBT was 5238,crystallization was 34%.With the raise of catalyst,the amount of active centers in the reaction system increased,the chain growth reaction rate raised,as a result the molecular weight increased.When the catalyst mass fraction reached 0.5%,the molecular weight was 18744,crystallization was 53%.The molecular weight and crystallization would not have obvious change with continue increasing of catalyst.When the polymerization temperature increased from 160? to 210?,the molecular weight and crystallization increased first and then decreased.When the polymerization temperature was 160?,the molecular weight was 8765,the crystallization was 37%.When the polymerization temperature was 180? to 190?,the molecular weight was 19146,the crystallization was 55%.When the polymerization temperature was up to 210?,the molecular weight decreased to 12746,the crystallization decreased to 47%.The IFSS between PCBT and glass fiber was about 34.31 MPa,the IFSS between PCBT and carbon fiber was about 56.96MPa.In the end the mechanical performances of GF/PCBT and CF/PCBT composites were studied.The results showed that:The tensile strength of GF/PCBT was 520MPa,tensile modulus was 27GPa,flexural strength was 475MPa,flexural modulus was 24.8GPa,interlaminar shear strength(ILSS)was 42.5MPa.The tensile strength of CF/PCBT was 771 MPa,tensile modulus was 63GPa,flexural strength was 545MPa,flexural modulus was 62GPa,ILSS was 45.6MPa.