Preparation And Application Study Of Cyclic Butylene Terephthalate Oligomers Resin With Alternative Melting Point

Cyclic butylene terephthalate(CBT)with different crystalline cyclic oligomers can be converted to poly(butylene terephthalate)(PBT)by adding appropriate catalysts.In the filed of polymer composites,CBT resin plays an important role for its low viscosity and thermoplastic character.In this thesis,a series of CBT with different melting point were prepared.Based on the exploration of the reaction mechanism,we create a new way named as two-step method to prepare CBT resins with the advantage of shoter reaction time and better thermal stability.Firstly the reaction intermediates was obtained to synthesize CBT resins under pseuo-high dilution conditions.CBT resin emulsion can convert to PBT resin film with good toughness and high transparency by casting and heating treatment.In the first part of this thesis,a series of CBT resins with different melting point were prepared.The effects of reaction time、two phase volume ratio and molar ratio were discussed.The molecular structure of CBT was charactered by infrared spectroscopy(IR)and hydrogen nuclear magnetic resonance(1HNMR).The reaction time was about 6 to 8 hours in the traditional method,because TPC is difficult to dissolve in methylene chloride which make it uneasy to control the titration speed and CBT will decompose when the polymerization was proceed.All of the above features limits the range of the application of the CBT resins.Therefore,we have developed a novel method named as two-step method to synthesis CBT resins by preparing reaction intermediates firstly to synthesis CBT resins with alternative melting point,and the products are of good thermal stability.The improved thermal stability of CBT can be tested by thermogravimetric analysis(TGA).This thesis explored the relationship between the polymerization 、 catalyst 、reaction time and cooling condition.To further explore the special property of CBT resins,PBT films and PBT fibers were prepared by casting and electrospinning.