In this paper, four kinds of polymethacrylates(PMAs) used as multifunctional additives were synthesized from quaternary C1—C14 methacrylate, among which sample 4 exhibited relatively better performance. According to ...In this paper, four kinds of polymethacrylates(PMAs) used as multifunctional additives were synthesized from quaternary C1—C14 methacrylate, among which sample 4 exhibited relatively better performance. According to the methacrylate ratio of sample 4, the optimized reaction conditions of PMA were explored by orthogonal experiments comprising 4 factors and 3 levels, and the optimized reaction conditions covered an initiator dosage of 0.8 %, a molecular weight regulator dosage of 0.4%, a reaction temperature of 95 ℃ and a reaction time of 8.5 h. When the optimized PMA samples were used to formulate the 75W/90 automotive gear base oil, they exhibited improved shear stability and good low temperature property. In comparison with foreign commercial polymethacrylate GP, the optimized PMA samples exhibited better thickening ability, similar shear stability and slightly weak low temperature property, with their performance being the same as GP's on the whole. The slight difference in the performance between the optimized PMA and GP was attributed to the difference of chain length of copolymers and the distribution of relative molecular mass between them.展开更多
Euphemism, as the linguistic and cultural phenomenon, is a lubricant in linguistic communication used in different aspects of social lives. With the rapid development of science and progress of human civilization, eup...Euphemism, as the linguistic and cultural phenomenon, is a lubricant in linguistic communication used in different aspects of social lives. With the rapid development of science and progress of human civilization, euphemism, as one of the most important components in English language, has the tendency of multiplying. This paper, based on the development of euphemism in modem American English, sums up the basic features of euphemism in modem American English and analyzes its formation and application in modem American society and culture with the objective of improving learners＇ communication ability in the context of cross cultural communication.展开更多
文摘In this paper, four kinds of polymethacrylates(PMAs) used as multifunctional additives were synthesized from quaternary C1—C14 methacrylate, among which sample 4 exhibited relatively better performance. According to the methacrylate ratio of sample 4, the optimized reaction conditions of PMA were explored by orthogonal experiments comprising 4 factors and 3 levels, and the optimized reaction conditions covered an initiator dosage of 0.8 %, a molecular weight regulator dosage of 0.4%, a reaction temperature of 95 ℃ and a reaction time of 8.5 h. When the optimized PMA samples were used to formulate the 75W/90 automotive gear base oil, they exhibited improved shear stability and good low temperature property. In comparison with foreign commercial polymethacrylate GP, the optimized PMA samples exhibited better thickening ability, similar shear stability and slightly weak low temperature property, with their performance being the same as GP's on the whole. The slight difference in the performance between the optimized PMA and GP was attributed to the difference of chain length of copolymers and the distribution of relative molecular mass between them.
文摘Euphemism, as the linguistic and cultural phenomenon, is a lubricant in linguistic communication used in different aspects of social lives. With the rapid development of science and progress of human civilization, euphemism, as one of the most important components in English language, has the tendency of multiplying. This paper, based on the development of euphemism in modem American English, sums up the basic features of euphemism in modem American English and analyzes its formation and application in modem American society and culture with the objective of improving learners＇ communication ability in the context of cross cultural communication.
