A novel thermosetting resin system for superabrasives based on novolak and bismaleimide （BMI） was developed. The novolak resin was allylated and then copolymerized with BMI. The structure of allyl novolak and reacti...A novel thermosetting resin system for superabrasives based on novolak and bismaleimide （BMI） was developed. The novolak resin was allylated and then copolymerized with BMI. The structure of allyl novolak and reaction mechanism were analyzed by FFIR. Thermal and mechanical properties were characterized by using com- prehensive thermal analyzer （DSC-TG） and strength tester, respectively. The results showed that high molecular weight of novolak was advantageous for heat-resistance, but was unfavorable for the bending strength. High allyl content improved the heat-resistance but lowered the bending strength. When the molecular weight of novolak was 450 and allyl content was 50%, the best resin system with good heat-resistance and bending strength was obtained. It was suitable for the manufacturing of superabrasive tools.展开更多
The rheological behavior of bismaleimide resin for resin transfer molding(RTM) was studied with DSC analysis and viscosity experiments A rheological model based on the dual Arrhenius equation was established and used ...The rheological behavior of bismaleimide resin for resin transfer molding(RTM) was studied with DSC analysis and viscosity experiments A rheological model based on the dual Arrhenius equation was established and used to simulate the rheological behavior of the resin The model predictions determined from the dual Arrhenius equation were in good agreement with experimental data The processing window of the resin system can be well determined based on the developed model The rheological model is importan...展开更多
A copolymer of bismaleimide-diallylbisphenol A-diphenylsilandiol was synthesized and the copolymerisation was studied by using N-phenylmaleimide, bisphenol A and diphenyl-silandiol as model compounds. The copolymer co...A copolymer of bismaleimide-diallylbisphenol A-diphenylsilandiol was synthesized and the copolymerisation was studied by using N-phenylmaleimide, bisphenol A and diphenyl-silandiol as model compounds. The copolymer could be well. cured around 200 degrees C, and the cured resins had good thermal stability. In the range of 170-210 degrees C, a higher curing temperature was favorable to obtain more thermal stable resin by reducing the content of diphenylsilandiol cyclo-homopolymer in resin which would spoil its-thermal stability.展开更多
目的研究胃超声结合身体质量指数(body mass index,BMI)用于指导行全麻剖宫产术术前禁食水时间的可行性。方法回顾性分析2012年1月—2022年12月在长春市妇幼保健院行全麻剖宫产术的450例孕产妇。根据孕产妇BMI增幅(△BMI)将其分为3组,A...目的研究胃超声结合身体质量指数(body mass index,BMI)用于指导行全麻剖宫产术术前禁食水时间的可行性。方法回顾性分析2012年1月—2022年12月在长春市妇幼保健院行全麻剖宫产术的450例孕产妇。根据孕产妇BMI增幅(△BMI)将其分为3组,A组△BMI<4 kg/m^(2),B组24 kg/m≤△BMI≤6 kg/m^(2),C组△BMI>6 kg/m^(2)。食用相同食物,比较3组胃排空能力及预后。结果A组禁食水时间为(6.85±1.53)h,B组禁食水时间为(7.49±1.46)h,C组禁食水时间为(7.84±1.24)h,3组禁食水时间比较,差异有统计学意义(P<0.05);3组Ⅱ、Ⅲ期及产前T1、T3、T4各时间点胃窦横截面积(cross-sectional area,CSA)比较,差异有统计学意义(P<0.05);3组妊娠结局[巨大儿、转入新生儿重症监护室(neonatal intensive care unit,NICU)、新生儿窒息]及口渴、饥饿感评分比较,差异有统计学意义(P<0.05);C组首次排气时间长于A组、B组,满意度评分低于A组与B组(P<0.05)。结论超声引导下胃窦部CSA可更精准地判定产妇的胃内容量,从而预判术前禁食水时间,改善妊娠结局。展开更多
The curing proces of chemical reactombetween flexible unsaturated polymer resin and diphenyl-methane bismaleimides which have been chain-prolonged by diaminodiphenylmethane is presented. also the kinetics parameter...The curing proces of chemical reactombetween flexible unsaturated polymer resin and diphenyl-methane bismaleimides which have been chain-prolonged by diaminodiphenylmethane is presented. also the kinetics parameters and curing technology are investigated.展开更多
PU/P(UBMI-BMI) IPNs with excellent thermal stability and mechanical properties were synthesized and characterized. The interpenetrating occurs in the hard segment domains of PU, which leads to enhancement of hydrogen ...PU/P(UBMI-BMI) IPNs with excellent thermal stability and mechanical properties were synthesized and characterized. The interpenetrating occurs in the hard segment domains of PU, which leads to enhancement of hydrogen bonding of N-H, and narrow-distributed small size of the dispersed phase.展开更多
文摘A novel thermosetting resin system for superabrasives based on novolak and bismaleimide （BMI） was developed. The novolak resin was allylated and then copolymerized with BMI. The structure of allyl novolak and reaction mechanism were analyzed by FFIR. Thermal and mechanical properties were characterized by using com- prehensive thermal analyzer （DSC-TG） and strength tester, respectively. The results showed that high molecular weight of novolak was advantageous for heat-resistance, but was unfavorable for the bending strength. High allyl content improved the heat-resistance but lowered the bending strength. When the molecular weight of novolak was 450 and allyl content was 50%, the best resin system with good heat-resistance and bending strength was obtained. It was suitable for the manufacturing of superabrasive tools.
基金National Natural Science F oundation of China(5 983 3 110 ) National Defence Foundation(0 0 j0 0 .5 .3 .hk0 14 4)
文摘The rheological behavior of bismaleimide resin for resin transfer molding(RTM) was studied with DSC analysis and viscosity experiments A rheological model based on the dual Arrhenius equation was established and used to simulate the rheological behavior of the resin The model predictions determined from the dual Arrhenius equation were in good agreement with experimental data The processing window of the resin system can be well determined based on the developed model The rheological model is importan...
文摘A copolymer of bismaleimide-diallylbisphenol A-diphenylsilandiol was synthesized and the copolymerisation was studied by using N-phenylmaleimide, bisphenol A and diphenyl-silandiol as model compounds. The copolymer could be well. cured around 200 degrees C, and the cured resins had good thermal stability. In the range of 170-210 degrees C, a higher curing temperature was favorable to obtain more thermal stable resin by reducing the content of diphenylsilandiol cyclo-homopolymer in resin which would spoil its-thermal stability.
文摘The curing proces of chemical reactombetween flexible unsaturated polymer resin and diphenyl-methane bismaleimides which have been chain-prolonged by diaminodiphenylmethane is presented. also the kinetics parameters and curing technology are investigated.
文摘PU/P(UBMI-BMI) IPNs with excellent thermal stability and mechanical properties were synthesized and characterized. The interpenetrating occurs in the hard segment domains of PU, which leads to enhancement of hydrogen bonding of N-H, and narrow-distributed small size of the dispersed phase.
