Self-vulcanizing blends of phenol hydroxy silicone rubber (PHSR) and fluoroelastomer (FPM) were prepared. Vulcanized rubbers with lower glass transition temperature (T(g)) were successfully obtained. The results of dy...Self-vulcanizing blends of phenol hydroxy silicone rubber (PHSR) and fluoroelastomer (FPM) were prepared. Vulcanized rubbers with lower glass transition temperature (T(g)) were successfully obtained. The results of dynamic mechanical analysis (DMA) show that the vulcanized FPM/PHSR (10 phr) blend has only one T(g) temperature, demonstrating the well compatibility between FPM and PHSR. The thermogravimetric analysis (TGA) demonstrates that the PHSR do little damage to the thermal stability of FPM. The vulcanization characteristics of the FPM/PHSR blends were analyzed by using oscillating disc rheometer (ODR). The results show that FPM/PHSR blends have smaller S(min) values and longer scorch time than that of FPM with the same level of bisphenol AF curing agent. It means that FPM/PHSR blends have better processability and curing security. Better mechanical properties can be gained for FPM/PHSR blends at appropriate level of PHSR.展开更多
3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formati...3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formation; the latter underwent in situ dimerization, cyclization, and rearrangement to give substituted indanols. The isopropenylphenol derived from 3,5-ditertbutyl-4-hydroxyacetophenone did not dimerize but condensed with its precursor to yield a substituted diphenylpropanone. 3-nitro-, 3,5-dinitro-, and 3,5-dibromo-4-hydroxyacetophenones on the other hand reacted normally to give ethylene ketals in good yields.展开更多
An intermolecular phenolic hydroxy methylation occurring between chiral N,N'-bis(2-hydroxyphenyl)-2,2-di- methyl-1,3-dioxolane-4,5-dicarbamide and co-crystallized methanol under electron impact ionization conditio...An intermolecular phenolic hydroxy methylation occurring between chiral N,N'-bis(2-hydroxyphenyl)-2,2-di- methyl-1,3-dioxolane-4,5-dicarbamide and co-crystallized methanol under electron impact ionization conditions was observed. The result was confirmed by X-ray diffraction structural ananlysis of a co-crystalline of (R,R)-enantiomer and methanol.展开更多
基金supported by the National Natural Science Foundation of China(No.50873036).
文摘Self-vulcanizing blends of phenol hydroxy silicone rubber (PHSR) and fluoroelastomer (FPM) were prepared. Vulcanized rubbers with lower glass transition temperature (T(g)) were successfully obtained. The results of dynamic mechanical analysis (DMA) show that the vulcanized FPM/PHSR (10 phr) blend has only one T(g) temperature, demonstrating the well compatibility between FPM and PHSR. The thermogravimetric analysis (TGA) demonstrates that the PHSR do little damage to the thermal stability of FPM. The vulcanization characteristics of the FPM/PHSR blends were analyzed by using oscillating disc rheometer (ODR). The results show that FPM/PHSR blends have smaller S(min) values and longer scorch time than that of FPM with the same level of bisphenol AF curing agent. It means that FPM/PHSR blends have better processability and curing security. Better mechanical properties can be gained for FPM/PHSR blends at appropriate level of PHSR.
文摘3-Methoxy-, 3, 5-dimethoxy-, and 3-phenyl-4-hydroxyacetophenones suffered alkyl carbonyl C-C bond scission to yield 4-hydroxybenzoate esters and 4-isopropenylphenols under standard conditions of ethylene ketal formation; the latter underwent in situ dimerization, cyclization, and rearrangement to give substituted indanols. The isopropenylphenol derived from 3,5-ditertbutyl-4-hydroxyacetophenone did not dimerize but condensed with its precursor to yield a substituted diphenylpropanone. 3-nitro-, 3,5-dinitro-, and 3,5-dibromo-4-hydroxyacetophenones on the other hand reacted normally to give ethylene ketals in good yields.
基金Project supported by the National Natural Science Foundation of China (No. 20272002) Ministry of Education of China (SRF for ROCS and EYTP) and Peking University (Present grant).
文摘An intermolecular phenolic hydroxy methylation occurring between chiral N,N'-bis(2-hydroxyphenyl)-2,2-di- methyl-1,3-dioxolane-4,5-dicarbamide and co-crystallized methanol under electron impact ionization conditions was observed. The result was confirmed by X-ray diffraction structural ananlysis of a co-crystalline of (R,R)-enantiomer and methanol.
