Study On The Synthesis And Properties Of Cross-Linkable Poly(Propylene Carbonate)

Poly(propylene carbonate)(PPC),a kind of high-molecule-weight polymer derived from the alternating copolymerization of carbon dioxide and propylene oxide under catalyst,exhibits a series of excellent properties including biodegradability,transparency and gas barrier,and has promising application in the field of medical materials and packaging materials.Nevertheless,PPC has low glass transition temperature,poor thermal stability and poor mechanical property,which severely limit its large-scale application.Cross-linking reaction,an effective method to improve the performance of high-molecule materials,can improve the thermal and mechanical properties of matetials efficiently.In this paper,the modified PPC,derived from the terpolymerization of carbon dioxide,propylene oxide and the third monomer,was synthesized in order to improve the thermal stabilities and mechanical properties of PPC.What is more,the structure and properties of modified PPC were determined by Fourier-transform infrared spectroscopy(FT-IR),~1H nuclear magnetic resonance(~1H NMR),gel permeation chromatography(GPC),thermal gravimetric analysis(TGA),and differential scanning calorimeter(DSC)measurements and so on.The main results are listed as follow:The modified PPC-BTCDA,derived from the terpolymerization of carbon dioxide,propylene oxide and the third monomer bicyclo[2.2.2]oct-7-ene-2,3,5,6-tetracarboxylic dianhydrid(BTCDA),is a kind of cross-linkable polymer which can significantly improve the thermal stability and mechanical properties of PPC.And the measurements indicate that,when the addition of third monomer BTCDA increases to 4%,the 5%weight-loss degradation temperature and the maximum weight-loss degradation temperature of PPC-BTCDA-4,compared with pure PPC,increase 58.6?and 55.1?,respectively.Meanwhile,the glass transition temperature also increases 4.6?.What is more,the tensile strength of PPC-BTCDA-4 increases 24.5 MPa compared with the pure PPC.And the modified PPC-BTCDA still has good rheological property,which means the modified PPC-BTCDA still has good hot-workability.The modified PPC-MF,derived from the terpolymerization of carbon dioxide,propylene oxide and furfuryl glycidyl ether(FGE)/maleic anhydride(MA),is a kind of cross-linkable polymer which can improve,to some extent,the thermal property of PPC.The modified PPC-MF has better hot-set elongation and permanent deformation than pure PPC,and it indicates that the modified PPC-MF has stronger resistance to strain and deformation at higher temperature compared with pure PPC.And the measurements indicate that,when the addition of monomer FGE/MA increases to 4%,the maximum weight-loss degradation temperature of PPC-MF-4 is 45?higher than that of pure PPC.Nevertheless,the 5%weight-loss degradation temperature and the glass transition temperature of PPC-MF are31.8?and 6.8?lower than those of pure PPC,respectively.Meanwhile,the tensile strength of PPC-MF-4 is 4.6 Mpa lower compared with pure PPC,which means the addition of monomer FGE/MA did not improve the mechanical property of PPC,but decline the mechanical property of PPC.