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YY/T 1599-2018 牙科学 聚合物基修复材料聚合收缩测试方法 激光测距法 Dentistry-Test method for polymerization shrinkage of polymer-based restorative materials-Laser ranging method
本标准规定了测量牙科聚合物基修复材料聚合收缩性能的激光测距法的试验装置和试验方法。<br />本标准主要适用于光固化聚合物基修复材料以及由光引发聚合的充填修复材料。<br />本标准不适用于化学固化和双重固化（Ⅰ类和Ⅲ类）聚合物基修复材料。...
2023-10-17 23:12:01浏览：28
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KS M ISO 11668-2017 Binders for paints and varnishes. Chlorinated polymerization resins. General methods of test
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2023-10-01 03:24:01浏览：22
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HG/T 5403-2018 镁钛系乙烯聚合催化剂化学成分分析方法 Analytical method of chemical composition for Mg-Ti based ethylene polymerization catalyst
本标准规定了镁钛系乙烯聚合催化剂化学成分分析方法。<br />本标准适用于镁VC系乙烯聚合催化剂中镁（Mg)、钛(Ti)、铝（Al)、(Cl)、四氢呋喃(THF)、钒（V）和固含量质量分数的测定。...
2023-08-11 08:48:01浏览：31
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Preparation of microsized crosslinked microspheres by dispersion copolymerization of polystyrene/pol
Dispersion copolymerization of styrene with polyethylene glycol 200-dimethacrylae as the cross-linking agent was completed by using poly(N-vinyl pyrrolidone) and 2,2-azo-bisisobutyronitrile as the steric stabilizer and initiator, respectively.Crosslinked copolymeric microspheres were prepared directly by the one-step method of dispersion copolymerization. The effects of the content of polyethylene glycol 200-dimethacrylae on the particle morphology and the copolymerization rate were investigated. It shows that the crosslinking agent plays an important role in the particle morphology and the system stability. When the content of crosslinking reached 2.5wt%, the floriated particles were obtained....
2020-12-22 21:24:13浏览：78
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Structure Analysis of Polyacrylonitrile Polymerized in Ionic Liquids
Polyacrylonitriles (PANs) were synthesizid both by atom transfer radical polymerization (ATRP) and free radical polymenzation in ionic liquid 1-buty-3-methylimidazolium chloride ([bmim]Cl).[bmim]Cl demonstrates to be a preferable solvent for ATRP of acrylonitrile (AN).The polymerization maintains the usual advantages of ATRP with molecular weight agrees well withtheoretical value and low polydispersity (PDI=1.15).It is also shown the higher conversion and lower molecular weight dispersion in ionic liquid than in dimethylformamide (DMF).From FTIR and NMR analysis,it is confirmed that the chemical structures of PANs synthesized in [bmlm]Cl were identical with that obtained in DMF.In atom transfer radical polymerization,the methine and cyan carbon atoms in isotactic configuration for PAN preduced in [bmim] Cl have a configuration consisting of about 55.5% isotactic diads.It is higher than that obtained in DMF which is 52.2%,So,ionic liquid has effect on the stereostmcture of PANs.Further analysis of 13C NMR spectra indicated that the isotacticity of PAN synthesized by free radical polymerization was lower than that of PAN prepared by ATRP,although both of them were random in stereoregularity.Besides the pentad tacticities of PANs also suggested that the sequence distributions of them all obey Bernoulli statistics....
2020-12-06 21:11:24浏览：78
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丙烯酸钠-丙烯酰胺高吸水树脂的合成与性能
以过硫酸钾为引发剂、N,N-亚甲基双丙烯酰胺（NNMBA）为交联剂，采用水溶液聚合法制备聚丙烯酸钠-丙烯酰胺高吸水性树脂，研究了丙烯酸与丙烯酰胺比例、单体浓度、引发剂用量、交联剂用量以及聚合温度对树脂吸水性能的影响。制备的高吸水性树脂吸蒸馏水为593g·g-1，吸自来水为260g·g-1，吸0.9%NaCl溶液为66.7g·g-1。...
2020-10-26 22:14:25浏览：61
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用13C-NMR表征高乙烯含量乙烯-丙烯无规共聚物的结构与性能
采用淤浆聚合法，使用3种聚丙烯催化剂制备了高乙烯含量乙烯-丙烯无规共聚物，并采用核磁共振碳谱对共聚物结构和性能进行了表征。结果表明：在相同聚合条件下，使用二醇酯化合物作为内给电子体的ND催化剂同已商业化的两种Ziegler-Natta催化剂CAT1和CAT2聚合得到的乙烯-丙烯无规共聚物中的乙烯摩尔分数接近，为75%~78%；使用ND催化剂聚合得到的乙烯-丙烯无规共聚物链段中乙烯-丙烯单元序列分布更均匀；使用ND催化剂聚合得到的乙烯-丙烯无规共聚物中橡胶相相对含量高于采用CAT1和CAT2催化剂。...
2020-09-28 16:47:12浏览：64
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Kinetic model of gas phase polymerization of 1,3-butadiene catalyzed by supported rare earth coordin
Gas phase polymerization of 1,3-butadiene (Bd) catalyzed by supported rare earth coordination system is studied and a new kinetic model is proposed. Four elementary reactions or processes: the process of exposure and activation of potential active catalytic center, propagation, deactivation and chain transfer reaction to alkyl aluminum, are considered in this model. Some important parameters, such as monomer-consuming rate, are well expressed as the functions of macroscopic polymerization conditions such as pressure, temperature, and duration. The model can simulate the whole polymerization procedure satisfactorily....
2020-09-15 12:28:59浏览：87
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功能化聚烯烃接枝共聚物的制备和应用研究新进展
介绍了制备功能化聚烯烃接枝共聚物的意义及近年来功能化聚烯烃接枝共聚物的设计与合成中的应用研究新进展，重点评述了制备功能化聚烯烃接枝共聚物时所采用的3种方法，I偶合接枝法；II引发接枝法：①阴离子聚合；②硼氧自由基存在下的控制自由基聚合；③原子转移自由基聚合（ATRP）；④氮氧自由基存在下的控制自由基聚合（NMRP）；⑤可逆加成-裂解链转移活性自由基聚合（RAFT）；III直接接枝法，并对上述方法进行了简单的优缺点对比。随后介绍了功能化聚烯烃接枝共聚物的应用。最后对功能化聚烯烃接枝共聚物的未来发展趋势进行了展望，认为对新型、高效、实用的制备方法的探索以及实际应用将是功能化聚烯烃接枝共聚物领域的主要研究方向。...
2020-07-13 09:55:48浏览：205
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Improvement of Taihu water quality by the technology of immobilized nitrogen cycle bacteria
Experimental studies were carried out on the purification of eutrophicTaihu Lake water by dynamic experiment using immobilized nitrogen cycle bacteria(INCB). The results showed that the eutrophic water of Taihu Lake can be purifiedeffectively as it passes through the experimental reactor into which some immobilizednitrogen cycle bacteria were put. The removal efficiencies for Total N (TN), NH4+-Nwith immobilized nitrogen cycle bacteria were 72.4% and 85.6%, respectively. It wasfound that the immobilized nitrogen cycle bacteria also have purificatory effect oneutrophic water of Taihu Lake at winter temperature (7°C), and that the removalmefficiencies for Total N (TN), NH4+-N were 55.6%, and 58.9%, respectively. Theremoval efficiencies for TN and NH4+-N depend on the time the water stays in theexperimental reactor.``...
2020-07-08 21:52:19浏览：61
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α-烯烃减阻剂特性粘度的研究
通过本体聚合在催化剂TiCl4/Al(Et)3作用下合成α烯烃减阻剂，通过红外光谱(IR)和X射线衍射(XRD)对聚合物进行结构分析，研究了合成聚合物影响因素对减阻聚合物特性粘度的影响．结果表明当粘度达到8.8 dl/g时减阻率可达到43.1%,即在一定范围内减阻率与粘度成正比．此时合成减阻剂的最优条件为3?C，主催化剂(TiCl4/MgCl2)、助催化剂(Al(Et)3)和二苯基二甲氧基硅烷(DDS)用量分别是0.085克，0.14毫升和0.04毫升．...
2020-06-12 16:09:36浏览：1420
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乙二醇葡糖苷产物组成的工艺调控
在酸性催化剂存在下,由葡萄糖和乙二醇经缩醛化制备了乙二醇葡糖苷,运用气相色谱法研究了反应压力、反应温度、催化剂用量及醇糖摩尔比对乙二醇糖苷组成或葡萄糖平均聚合度（DP）的影响。结果表明,在保证产物质量和合成过程的技术经济合理性的前提下,适当改变反应压力和反应温度对产品组成的影响不大,而调整催化剂用量和醇糖摩尔比可以达到调控产物组成的目的,且用于表征产物组成的DP值随催化剂用量和醇糖摩尔比增大而减小,催化剂用量在0.2%～0.5%变化时,DP由1.39降低到1.14;醇糖摩尔比在4～1∶1变化时,DP值由1.31上升到1.95。...
2020-06-12 15:04:45浏览：1428
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乙二醇葡糖苷产物组成的工艺调控
在酸性催化剂存在下,由葡萄糖和乙二醇经缩醛化制备了乙二醇葡糖苷,运用气相色谱法研究了反应压力、反应温度、催化剂用量及醇糖摩尔比对乙二醇糖苷组成或葡萄糖平均聚合度（DP）的影响。结果表明,在保证产物质量和合成过程的技术经济合理性的前提下,适当改变反应压力和反应温度对产品组成的影响不大,而调整催化剂用量和醇糖摩尔比可以达到调控产物组成的目的,且用于表征产物组成的DP值随催化剂用量和醇糖摩尔比增大而减小,催化剂用量在0.2%～0.5%变化时,DP由1.39降低到1.14;醇糖摩尔比在4～1∶1变化时,DP值由1.31上升到1.95。...
2020-03-23 18:33:28浏览：1441
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带路径约束的聚烯烃牌号切换操作优化方法
产品多样化需求使得聚烯烃生产过程中经常需要进行牌号切换操作.以往关于牌号切换优化的研究大多只关心切换过程结束后聚合物质量指标是否达到目标牌号值,对过渡过程中质量指标及状态变量的波动情况缺少关注,而过程的波动会影响到最终产物的质量性质和操作平稳性.为此,本文以聚乙烯气相流化床反应器为对象,通过在牌号切换优化命题中加入关于熔融指数等的路径约束,防止过渡过程中的状态变量剧烈波动影响聚合物树脂质量.为求解此类带路径约束的动态优化问题,对常规的控制变量参数化方法进行了改进,通过求解微分代数方程(DAE方程)将路径约束转化为控制变量约束.仿真结果表明,加入路径约束可以有效避免牌号切换中变量的剧烈波动,增强过程平稳性....
2020-03-23 17:46:42浏览：1438
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茂金属催化剂及烯烃齐聚物研究进展
21世纪是全新的科学技术时代，茂金属聚合物是化学工业中新型树脂产品，其产品开发进展很快。本文综述了近些年茂金属催化剂的发展状况，系统的介绍了茂金属催化剂的主要特征和优势，并对茂金属烯烃聚合物的加工和应用情况进行了阐述。...
2020-03-23 17:45:46浏览：1453
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