- 學位論文
利用擴鏈劑及固態聚合法改質對熱塑性聚酯彈性體分子量與流變性質的影響
Effects of Chain Extenders and Solid-State Polymerization on the Molecular Weight and Rheological Properties of Thermoplastic Polyester Elastomer
摘要
熱塑性聚酯彈性體（Thermoplastic Polyester Elastomer, TPEE）是由聚酯硬鏈段與聚醚軟鏈段連接成的嵌段共聚物，結合了熱固性橡膠的彈性特質及熱塑性高分子在高溫下易加工的特性。然而，商用TPEE因為其分子量較低的線性結構及較窄的分子量分佈，造成熔融強度低或彈性不足的問題，不利於紡絲、吹塑、發泡製程。 本研究中以混煉法混摻異氰尿酸三縮水甘油酯（Tris(2,3-epoxypropyl) isocyanurate, TGIC）、Joncryl®ADR擴鏈劑（ADR）或均苯四甲酸二酐（pyromellitic dianhydride, PMDA），以提高TPEE的分子量及支化程度，藉此提升TPEE的流變性質，為了避免高溫下長時間改質發生副反應或熱降解，後續將固態聚合法作為混煉的附加製程，讓尚具有反應活性的末端基與添加劑能夠在相對低溫與真空的環境下繼續反應。 實驗數據顯示，添加ADR 1 phr為提高TPEE流變性質的最佳改質條件，熔融態流變分析表明，改質後的TPEE流變儲存模數及剪切黏度分別較原料提高1.1倍及1.8倍，並發現有支化結構的剪切致稀現象，經過固態聚合後，流變儲存模數及剪切黏度更是提高至母粒的2.4倍及49.4倍，也有更加明顯的剪切致稀現象。此外，較寬的分子量分佈及較低的本質黏度可以證實添加ADR擴鏈劑能形成一些分子量較高的支化結構，再透過固態聚合讓樣品進一步發生反應使分支結構含量上升，因而提高流變性質。後續進行了TPEE經過改質後的結晶性質、微結構與機械性質分析，同時探討了二次加工可行性。
並列摘要
Thermoplastic Polyester Elastomer (TPEE) is a copolymer comprised of polyester as hard segments and polyether as soft segments. TPEEs combine the elastic characteristics of thermosetting rubber with the processability of thermoplastic polymers at elevated temperatures. However, commercial TPEE faces challenges such as low melt strength and insufficient elasticity due to its linear structure with low molecular weight and relatively narrow molecular weight distribution, which hinders its suitability for processes like spinning, blow molding, or foaming. In this study, compounding was employed to blend TPEE with chain extender, namely Tris(2,3-epoxypropyl) isocyanurate (TGIC), Joncryl® ADR (ADR), and pyromellitic dianhydride (PMDA). The aim was to enhance the molecular weight and branching structure of TPEE, thereby improving its rheology properties. To avoid the possibility of side reactions or thermal degradation during high-temperature reactions, subsequent solid-state polymerization (SSP) was utilized as an additional processing step. SSP enables reactive end groups and additives to continue reacting under relatively low-temperature and vacuum conditions. The experimental results revealed that the addition of 1 phr ADR was the optimal modification condition for enhancing the rheology properties of TPEE. Rheological analysis in the melt state indicated that the modified TPEE exhibited a 1.1 times increase in rheological storage modulus and a 1.8 times increase in shear viscosity compared to the pristine material. Moreover, shear-thinning indicative of a branching structure was observed. After solid-state polymerization, the rheological storage modulus and shear viscosity further increased to 2.4 times and 49.4 times that of the pristine material, respectively, accompanied by more pronounced shear-thinning behavior. Besides, the higher value of polydispersity index (PDI) and the lower intrinsic viscosity also prove that the addition of ADR chain extender facilitates the formation of higher molecular weight branched structures. Furthermore, through solid-state polymerization, the sample undergoes additional reactions leading to an increased content of branched structures, thereby enhancing its rheological properties.Subsequent analyses included the crystalline properties, microstructure, mechanical properties of modified TPEE, and its feasibility for secondary processing were also investgated.