| Cyclic butylene terephthalate(CBT), has a low processing viscosity which canbe as lowas0.1Pa s (water-like), can betransformed into linear high molecularweight thermoplastics via entropically-driven ring-opening polymerization ina shorttime scale (<tens of minutes). It overcomes the high melt viscosity of mostlythermoplastic, making it possible that the molding equipment of fabricatingthermosetting resin matrix composites can be applied toprepare the thermoplasticresin matrix composites. This paper adopts the moulding process to prepare highperformance basalt fabric reinforced CBT composites.The polymerization mechanism of CBT resinimpacted by differenttemperatures and catalysts and the method of the composites preparation wereinvestigated. The aromatic hyperbranched polyestertoughenedPBT and itscomposites was also prepared and optimized. The viscosity-average molecularweightand the mechanical properties of the pCBT were measured by the ubbelohdeviscometer and the universal testing machine. The HAKKE rheometer andRotational rheometer were adopted to measure the rheological properties. Scanningelectron microscopy (SEM) is employed to analyse the fracture surfaces of thesamples.The results showed that when the optimal dosage of F4105catalyst andtemperature were0.3wt%and220℃. The viscosity-average molecular weight,viscosity and tensile strength of this samplewere2×104，5000Pa.sand42.1MPa,respectively. However, when the F4105catalystwas substituted by the two lauricacid tin produced by china, the optimal dosage was0.9wt%.The viscosity-averagemolecular weight and viscosity were1.75×104and1300Pa.s. Compared with thePBT purchased by market, pCBT which prepared by two types of catalyticpolymerizationhad a greater brittleness. Therefore, this paper adopted the aromatichyperbranched polyesterto enhance the toughness of pCBT.When the aromatichyperbranched polyester was added3%and4%, the tensile and impact properties ofPBT can be improved by53.6%and46.3%respectively. The fracture mode seenfrom the SEM analysis showed that the typical brittle fracture changed intotheplastic deformation.In addition，to solve this problem, a non-isothermal production process forfabricating composites withCBT as matrix was developed, and a novel approach ofpreparing interphase interfaces in situ polymerization to manufacture basaltfiber/CBT composites was also presented, including pretreatment of fiber reinforcement by catalyst and polymerization of the matrices after fullyimpregnation of fibrous reinforcement to gain the desired basalt fiber/PBTcomposites. The basalt fiber/PBT composites did not suffer mechanical propertyloss as compared with the composites manufactured by traditional method. Theamount of catalysts used preparing composites was more than the preparation ofCBT casting. For F4105catalytic system, the optimal dosage is0.5wt%, and theshear strength, bending strength andmaximum impact of the composite materialwere34.7MPa,541.1MPa and4100N, respectively.For two lauric acid tin catalyticsystem,the optimal dosage was1.3wt%.The shear strength, bending strength andmaximum impact were31.6MPa,430.25MPa and4800N. Compared withcommercial PBT resin,PBT which generated by CBT in-situ polymerizations wasbrittle.As the matrix of compositesPBT resin would limitthe further improvement inthe mechanical properties of composite materials.For this, the hyperbranchedpolyester wasaddedto improve the properties of composites,but the resulting had alittle increase in the mechanical properties and bad interfacial adhesion. Althoughthe toughness of PBT apparent increase, its contribution to the improvement of thestrength was small... |
