离子液体功能化salen Mn催化苯乙烯与CO2一锅合成碳酸苯乙烯酯

合成了咪唑离子液体功能化salen Mn配合物(IL-salen Mn),并作为催化剂应用于苯乙烯与CO2一锅合成碳酸苯乙烯酯反应中.以尿素过氧化氢(UHP)为氧化剂、吡啶氮氧化物(PyNO)为助剂,催化苯乙烯高效制备环氧苯乙烷,继而催化环氧苯乙烷与CO2发生环加成反应合成碳酸苯乙烯酯.考察了催化剂种类和用量、助剂用量、氧化剂种类和用量、反应时间、反应温度及CO2压力对上述反应的影响.结果表明,当催化剂IL-salen Mn用量为苯乙烯物质的量的8％、n(苯乙烯):n(UHP):n(PyNO)=1.0:3.0:0.2、环氧化反应温度和时间分别为30℃和5 h、环加成反应温度和时间分别为80℃和12 h、CO2压力为1.0 MPa时,苯乙烯的转化率为90％,碳酸苯乙烯酯收率达到32％.结合前期研究与反应时间动力学结果,推测了该一锅反应的可能机理.     

离子液体功能化salen Mn催化苯乙烯与CO2一锅合成碳酸苯乙烯酯

合成了咪唑离子液体功能化salen Mn配合物(IL-salen Mn),并作为催化剂应用于苯乙烯与CO2一锅合成碳酸苯乙烯酯反应中.以尿素过氧化氢(UHP)为氧化剂、吡啶氮氧化物(PyNO)为助剂,催化苯乙烯高效制备环氧苯乙烷,继而催化环氧苯乙烷与CO2发生环加成反应合成碳酸苯乙烯酯.考察了催化剂种类和用量、助剂用量、氧化剂种类和用量、反应时间、反应温度及CO2压力对上述反应的影响.结果表明,当催化剂IL-salen Mn用量为苯乙烯物质的量的8％、n(苯乙烯):n(UHP):n(PyNO)=1.0:3.0:0.2、环氧化反应温度和时间分别为30℃和5 h、环加成反应温度和时间分别为80℃和12 h、CO2压力为1.0 MPa时,苯乙烯的转化率为90％,碳酸苯乙烯酯收率达到32％.结合前期研究与反应时间动力学结果,推测了该一锅反应的可能机理.     

离子液体功能化salen Mn催化苯乙烯与CO2一锅合成碳酸苯乙烯酯

合成了咪唑离子液体功能化salen Mn配合物（IL-salen Mn）,并作为唯一催化剂成功应用于苯乙烯与二氧化碳一锅合成碳酸苯乙烯酯反应中。首先,以尿素过氧化氢（UHP）为氧化剂、吡啶氮氧化物（PyNO）为助剂,催化苯乙烯高效制备环氧苯乙烷,继而催化环氧苯乙烷与二氧化碳发生环加成反应合成碳酸苯乙烯酯。分别考察了催化剂的种类和用量、助剂用量、氧化剂种类和用量、反应时间以及反应温度等因素对上述反应的影响。当催化剂用量为8 mol%（以反应物总的物质的量记）,n(苯乙烯)∶n(UHP)∶n(PyNO)=1.0∶3.0∶0.2,环氧化反应温度和时间分别为30 ℃和5 h,环加成反应温度和时间分别为80 ℃和12 h,二氧化碳压力为1 MPa时,苯乙烯的转化率为90%,碳酸苯乙烯酯收率达到32%。结合前期研究与反应时间动力学结果,推测了该串联反应可能的机理。     

无溶剂法制环氧苯乙烷的工艺研究

无溶剂条件下,以苯乙烯为原料、双氧水为氧化剂、自制的负载型磷钨杂多酸季铵盐为催化剂制备环氧苯乙烷。通过单因素实验和正交实验探讨了反应时间、反应温度、物料比、催化剂用量、助剂用量等因素对合成反应的影响,得到了较佳的环氧苯乙烷合成条件:反应时间为6.5 h,反应温度为55℃,n(苯乙烯)∶n(过氧化氢)=1.5∶1.0,催化剂16 g,助剂2.5 g,苯乙烯100 mL(91 g)。苯乙烯转化率可达78%,环氧苯乙烷选择性可达89%。     

温和条件下DMF催化苯乙烯空气环氧化的研究

不加任何其他催化剂,N,N-二甲基甲酰胺(DMF)既为溶剂又为催化剂,在温和条件下催化苯乙烯的空气环氧化反应.探讨了反应温度、反应时间、反应介质及不同的氧化剂对苯乙烯的环氧化效果的影响.结果表明,反应温度对选择性生成环氧苯乙烷的影响较大,低温不利于反应的进行,但是温度过高,有部分的苯乙烯会发生聚合;随着反应时间的延长,转化率缓慢增加,环氧苯乙烷的选择性变化不大;同时对比了其他氧化剂如过氧化氢、次氯酸钠、叔丁基过氧化氢和纯氧等氧化苯乙烯的实验结果,发现空气明显优于另外几种氧化剂.以空气为氧源,DMF为溶剂,控制110℃反应4 h,苯乙烯的转化率和选择性分别达到了12.6%和72.6%.     

一种环氧苯乙烷合成新工艺

提出以MgCO3在700℃焙烧制得的MgO为催化剂,双氧水为氧化剂催化氧化苯乙烯合成环氧苯乙烷的新工艺。优化得到较佳工艺条件为:苯乙烯为0.47 mL(4.0 mmol),n(H2O2)∶n(苯乙烯)=6∶1,V(乙腈)∶V(苯乙烯)=10∶1,MgO为50mg,NaOH为10 mg,反应温度为60℃,反应时间为10 h。在此条件下,苯乙烯转化率达95.0%,环氧苯乙烷选择性达92.0%。     

钴卟啉-四丁基溴化铵串联催化苯乙烯在氧气和二氧化碳中合成碳酸苯乙烯酯

通过仿生催化，将苯乙烯、氧气（O₂）和二氧化碳（CO₂）直接合成环状碳酸酯在现代化学中极具学术研究意义和工业应用价值。采用钴卟啉-四丁基溴化铵为双组分催化剂，以2-氧代环戊烷羧酸甲酯为助剂，在O₂和CO₂条件下，直接将苯乙烯转化为碳酸苯乙烯酯。系统考察了催化剂用量等因素对催化性能的影响。在最佳反应条件下，苯乙烯的转化率高达99%，环状碳酸酯的收率可达35%。利用在线紫外与在线红外探讨了该串联反应可能的机理。结果表明，钴中心与2-氧代环戊烷羧酸甲酯的环内氧原子配位后活化氧气形成过氧活性物种，进而形成高价钴-氧中间体，其通过传递氧原子给苯乙烯而生成环氧苯乙烷。而后，环氧苯乙烷在四丁基溴化铵的催化作用下开环，并通过CO₂插入反应和分子内闭环反应最终生成环状碳酸酯。     

新型非对称希夫碱铜催化苯乙烯环氧化研究

主要是以NaClO为氧源,研究5种含有不同推拉电子效应的非对称Salen-Cu(Ⅱ)催化剂催化苯乙烯环氧化效果,通过考察反应底物与氧化剂的摩尔比、反应时间、反应温度、溶剂、催化剂用量、催化剂结构等因素对烯烃环氧化的影响,探索了催化剂应用于苯乙烯环氧化的最佳工艺条件。实验结果表明:吸电子基团可提高催化活性有利于环氧化,而给电子基团降低催化活性,不利于环氧化。最佳反应条件为:配合物5用量为0.01 mmol时,苯乙烯/NaClO摩尔比为1∶4,反应时间为6 h,反应温度为50℃,溶剂为CH_3CN 3 mL,苯乙烯的转化率和环氧化苯乙烷选择性最高可达87%和31.9%。     

以NaCl改性的Ag/SiO_2催化苯乙烯环氧化反应的研究

以NaC l改性Ag/S iO2为催化剂,分子氧为氧化剂,对苯乙烯环氧化制备环氧苯乙烷的反应进行了研究,考察了Ag负载量、NaC l修饰量、焙烧温度、反应温度、n(苯乙烯)/n(O2)等因素对反应性能的影响。结果表明,Ag和NaC l的最佳负载量分别为10%和1%,Ag/S iO2催化剂在600℃下焙烧效果最好,在250℃,n(苯乙烯)/n(O2)为10,N2为平衡气,空速为3600 h-1的条件下反应,催化剂的性能最佳,苯乙烯的转化率和环氧苯乙烷的选择性分别为35%和68%。     

苯乙烯环氧化制备环氧苯乙烷的合成研究

采用苯乙烯和过氧化氢环氧化制备环氧苯乙烷的研究。考察了反应物料摩尔比、反应温度、反应时间、溶剂用量等因素对苯乙烯环氧化的影响。实验结果表明,n(30%过氧化氢)∶n(苯乙烯)=2∶1,甲酰胺25 m L,反应温度25℃,反应时间3 h。在此条件下,苯乙烯的转化率为16.1%。用过氧化氢氧化,绿色环保,环境友好。     

新型苯乙烯挥发抑制剂及低苯乙烯挥发树脂

通过对华昌公司苯乙烯挥发抑制剂Merican 109加入树脂前后的固化性能及树脂对玻璃钢表面的粘接性能测试和对粘接测试后剥离表面的扫描电镜分析研究了Merican 109在树脂常温固化过程中对苯乙烯挥发的抑制作用。同时将华昌公司新型低苯乙烯挥发树脂MEF-2LSE、Merican 9709LSE、Merican 9406LSE等在常温固化过程中苯乙烯的挥发性与通用树脂进行了比较。结果表明,Merican 109与德国公司BYK 740作用相当,苯乙烯挥发量降低了50%～90%,且固化性能、粘接强度未受影响。MEF-2LSE树脂的低挥发性表现优异,15℃时挥发量为普通树脂的1/8。     

丁苯橡胶生产中苯乙烯脱气塔的改造

通过对苯乙烯脱气塔的综合改造,降低了胶浆中游苯和污水中苯乙烯的含量,同时减少了蒸汽消耗,达到了节能减排的目的,取得了较好的经济效益和社会效益.     

Anionic polymerization of styrene: Integration with styrene monomer production

Anionic polymerization and ethylbenzene dehydrogenation were carried out in the laboratory using continuous reactor designs and conditions typical of current commerical processes. The dehydrogenator was operated at 43–55% conversion with continuous distillation of the ethylbenzene/styrene mixture to remove byproducts that would interfere with the subsequent anionic polymerization. The anionic polymerization was carried out using a reactor of the CSTR type which operated at > 99% conversion of styrene. The volatiles were recovered from the polymer syrup and recycled back to the dehydrogenator. During 4 months of continuous operation the integrated process showed no detrimental buildup of impurities which affected the anionic polymerization or dehydrogenation. The polystyrene produced had excellent color, clarity, thermal stability, and polydispersity (M_w/M_n = 2.1–2.4). The ability to control weight average molecular weight was within a range of 20,000 using an on-line GPC in concert with a colorimeter.     

Rheological properties of styrene butadiene styrene polymer modified road bitumens

The use of polymers for the modification of bitumen in road paving applications has been growing rapidly over the last decade as government authorities and paving contractors seek to improve road life in the face of increased traffic. Currently, the most commonly used polymer for bitumen modification is the elastomer styrene butadiene styrene (SBS) followed by other polymers such as styrene butadiene rubber, ethylene vinyl acetate and polyethylene. This paper describes the polymer modification of two penetration grade bitumens with SBS. Six polymer modified bitumens (PMBs) were produced by mixing the bitumens from two crude oil sources with a linear SBS copolymer at three polymer contents. The rheological characteristics of the SBS PMBs were analysed by means of conventional as well as dynamic mechanical analysis using a dynamic shear rheometer (DSR). The results of the investigation indicate that the degree of SBS modification is a function of bitumen source, bitumen-polymer compatibility and polymer concentration, with the higher polymer concentrations in a high aromatic content bitumen producing a highly elastic network which increases the viscosity, complex modulus and elastic response of the PMB, particularly at high service temperatures. However, ageing of the SBS PMBs tends to result in a reduction of the molecular size of the SBS copolymer with a decrease in the elastic response of the modified road bitumen.     

Spectrophotometric determination of the styrene content of alpha-methylstyrene — styrene copolymers

Summary The electronic absorption spectra of polystyrene and poly (alpha-methylstyrene) show a great difference in the extinction coefficient values at 226nm. On basis of this fact, it is shown that the styrene content of styrene — alpha-methylstyrene copolymers can be determined by ultraviolet spectrophotometry. The relationship between the extinction coefficient at 226nm and the polystyrene content in the mixture shows a linear dependence.     

溴化苯乙烯/苯乙烯/丙烯腈乳液聚合试验条件探索

以过硫酸钾为引发剂,十二烷基硫酸钠为乳化剂,叔十二烷基硫醇为链转移剂,通过乳液法对溴化苯乙烯、苯乙烯、丙烯腈进行共聚得到溴化苯乙烯-丙烯腈共聚物.考察了引发剂、乳化剂、链转移剂的添加量,反应温度,反应时间,水和单体比例等对聚合反应收率的影响.研究表明：较适宜的反应条件为反应温度80℃,反应时间6h,水与单体质量比4∶1,引发剂质量为单体总质量的0.4％,乳化剂质量为单体总质量的4％,叔十二烷基硫醇为单体总物质的量的2％;上述条件下的产物收率高,相对分子质量4万左右,热分解温度高于350℃.     

Performance of biomimetic coating modified fiber incorporated styrene butadiene styrene modified asphalt

This study reports the effect of polydopamine bionic coating and γ-methacryloxypropyltrimethoxysilane (KH570) composite modified polyacrylonitrile (PAN) fiber as a secondary modifier on the performance of styrene-butadiene-styrene (SBS) modified asphalt. Dynamic shear rheometer test indicated the complex shear modulu, storage modulus, and loss modulus of modified PAN (KD-PAN) incorporated SBS modified asphalt was increased by 12.4, 20.5, and 11.2%, respectively compared with PAN/SBS modified asphalt. The master curve of G^* of fiber/SBS composite modified asphalt shows that the deformation resistance of KD-PAN/SBS modified asphalt is greater than that of PAN/SBS modified asphalt in the entire loading frequency range. The cone penetration test showed significantly enhanced shear strength of KD-PAN/SBS modified asphalt. The adhesion work test results and SEM images of interface between fiber and SBS modified asphalt revealed that the adhesion effect of KD-PAN and SBS modified asphalt is better than that of PAN and SBS modified asphalt. SEM and AFM images of fiber further showed that the fiber surface becomes rough after modification. The increased surface roughness of KD-PAN facilitated the adherence of SBS modified asphalt to it, which in turn led to the enhanced performance of KD-PAN/SBS composite modified asphalt at the same fiber content and temperature.     

Blends of styrene butadiene styrene TRI block copolymer/polyaniline-Characterization by WAXS

Electrically conductive blends based on polyaniline-dodecylbenzene sulphonic acid (Pani.DBSA)/styrene-butadiene-styrene (SBS) block copolymer have been prepared by two methods namely melt mixing and polymerization of aniline in the presence of SBS using in situ polymerization method. The influence of composition and synthetic methods on the performance of SBS/Pani blends was established. The obtained SBS/Pani blends have been characterized by mechanical, morphological and electrical properties. A great reduction in volume resistivity values with increase in Pani content was noticed for in situ polymerization method compared to melt mixing method. The microstructural parameters were also computed using Wide Angle X-ray Scattering (WAXS). The results are compared with mechanical and electrical properties.