The Advancement of Soy-based Polyols and Polyurethanes
Polyurethanes (PUs) are a class of polymers that have found many important applications such as thermoset and thermoplastic elastomers, adhesives, coatings, and both flexible as well as rigid foams.The general route to synthesize a thermoset network form of these polymers is by the reaction of a diisocyanate or one of higher functionality with a polyol that possesses an average functionality greater than 2. Polyols derived from soybean oil are interesting materials for polyisoeyanurate modification.These are raw materials from renewable resources and with isocyanates they produce polyurethanes (PUs) that can compete in many aspects with polyols derived from petrochemicals.Soybean oil is one of many vegetable oils that can be converted into a polyol by various methods, such as epoxidation, hydroformylation, and ozonolysis. Because of the high functionality, these polyols can also be crosslinked with diisocyanates to give rigid polyurethanes. The polymer properties are controlled by the crosslinking density as well as the structures of the polyols and isoeyanates.For example, the soy polyols were prepared from epoxidation of soybean oil followed by ring opening of oxirane and methanol was used as ring opener. Polyols of hydroxyl numbers range from 128 to 174 mgKOH/g were obtained by the variation of epoxidation time of soybean oil. A novel cast polyurethane resin has been synthesized by these polyols and TDI. Swelling of networks in toluene shows that sol fraction varies from 1.13 to 72.06％. The thermal and mechanical properties of cast resins were characterized by DSC and TG. The results show the glass transition temperature increases with the increasing of OH number and the thermal stability of the resins was slightly decreased with increasing OH number. This might be caused by the reduction of cross-linking density of the hydroxy network,which could be attributed to the incomplete reaction in the resin systems. The tensile strength at break increases with the increasing of OH number. Polyol with hydroxyl number 174 mgKOH/g gaves glassy polymer, whereas those below that value gave rubbers.
Liting Yang Chengshuang Wang Baolian Ni Linyun Wang
School of Chemistry and Environment,South China Normal University,Guangzhou P R China,510006
国际会议
5th International Symposium on High-Tech Polymer Materials(HTPM-V)(第五届国际高技术高分子材料学术会议)
北京
英文
143-144
2008-10-27（万方平台首次上网日期，不代表论文的发表时间）