Study On Crystallization, Rheological Properties And Mechanical Properties Of Polyester Materials

Cyclic butylenes terephthalate (CBT) is a new kind of resin. When CBT heated to a considerable temperature, its viscosity will be very low. If CBT is heated to 160-240℃, it will be melted just like water. So CBT is very useful in the impregnation of inorganic filler and fortifying fibre. In suitable temperature and through catalyst function, it will be polymerized to the thermoplastic poly(butylene terephthalate) (PBT) with high molecular weight, which means it will has low manufacturing viscosity and high performance of the final products.PBT is one of the most important thermoplastic engineering plastics. But it also has some flaws such as the low thermal deformation temperature, the large gap impact sensitivity, the size instability under the high temperature and flammability etc, so these have limited its application. Many methods have been used in order to improve the capability of PBT. Usually, PBT filled with particles and blended with modification are the two main methods. In this study, the experiment aims at overcoming the shortcomings of PBT by taking CBT into PBT to improve the mechanical property and the molding of PBT has been tried.Poly(trimethylene terephthalate) (PTT) is a new promising polyester material, which possesses good elasticity and low modulus. It has been widely used in the fields of fiber such as carpet and sportswear etc. Poly (ethylene terephthalate) (PET) is one of the important industrialized aromatic polyester materials which applied in the fields of fiber, film and engineering components etc. In this study, after blending PTT with PET, the fibre intensity and heat distortion temperature of PTT are improved in the foundation of PTT excellent properties.Also, the mechanical properties, impact intensity, DSC and the rheological experiments of CBT/PBT were tested. The DSC result shows that the CBT/PBT blends have a good compatibility in amorphous phase. The melting point of pure PBT is about 224.2℃, which is almost the same with the CBT adding to PBT. However the melting point of CBT is increased. The result of rheological experiment indicates that the viscosity decreases with the adding of CBT, which is propitious to the molding of the material. The result of the mechanical property indicates that CBT/PBT is improved with the increase of the content of CBT and reduced the brittleness.In the study, the mechanical properties and DSC of PET/PTT blends are performed. The DSC result shows that the PET/PTT blends have an excellent compatibility in amorphous phase. The chain segments of PET and PTT tend to crystallize respectively in the crystal phase of their blends. Tensile strength and tensile modulus of PET/PTT blends are increasing with the ascending of PTT content. However tensile strength and tensile modulus of PET/PTT blends decrease with the blend ratio tending to 5/5.Overall, the study on the structure and properties of polyester blend in this work affords the foundation for the development and theory direction in the molding and manufacturing process.