PBT/N100胶片的力学性能及交联网络的完整性

The mechanical properties,cross-linking network structures,physical cross-linking degree and tenacity of 3,3-diazidomethyloxetane (BAMO)-tetrahydrofuran (THF) random copolymer (PBT)/polyfunctional isocyanate (N100) binder films were tested and analyzed by means of the uniaxial tensile test,low field nuclear magnetic resonance(LF-NMR).A new physical parameter,Correction Factor,namely D,is defined to measure the integrity of each film.Results show that with the curing parameter R increasing from 0.8 to 1.7,the breaking strength increases slowly from 0.902 MPa to 1.365 MPa,and the elongation at breaking decreases from 220% to 110%.The cross-linking density increases progressively and the average molecular weight between the crosslink points decreases accordingly.The physical cross-linking degree of PBT/N100 binder films increase progressively.R=1.5 is a critical point for the network structure of these films.The network structures were improved before R reaches to 1.5,but after that they went worse gradually.The mechanical properties show a positive relationship with the cross-linking network structure integrity.When R=1.5,the PBT/N100 binder film shows the lowest D,the best network structure and the highest tenacity,thus the best mechanical properties.The unduly curing parameter will lead to the unfurl cure or over cure,which will result in the bad network structure,thus the poor mechanical properties.