The limiting value of ZDMC formation: new insight into the reaction of ZNO and TMTD

The reaction of ZnO and tetramethylthiuram disulfide (TMTD) was reinvestigated in detail. Under conditions where evaporation of volatiles is possible, TMTD and an excess of ZnO are found to produce bis(dimethyldithiocarbamato)zinc(II) (ZDMC) in limiting amounts close to 60 mol %, irrespective of the ratio between ZnO and TMTD. This result points to the operation of more than one route toward ZDMC. When ZnO and TMTD are reacted in closed vessels in inert atmosphere, a nucleophilic reaction of ZnO with TMTD was confirmed by GC–mass spectroscopy (MS) detection of COS and NMR observation of tetramethylthiourea (TMTU). This route is found to account for about 70 mol % of the total amount of ZDMC formed. A previously unrecognized redox reaction between ZnO, sulfur, and TMTD, furnishing ZnSO₄ and ZDMC, is responsible for approximately 15 mol % of the amount of ZDMC. Other products that were detected are CO₂, CS₂, and tetramethylurea, whereas ZnSO₃, ZnS, and dioxygen were absent. Based on the latter observation, the operation of a mechanism constituting radical reduction of water by TMTD, yielding dioxygen, was excluded. © 1999 John Wiley & Sons, Inc. J Appl Polym Sci 73: 1247–1257, 1999     

氯化锌负载羟基磷灰石催化合成对苄基苯甲醚

以苄氯和苯甲醚为原料,氯化锌负载羟基磷灰石(ZnCl2/HAP)为催化剂,经Friedel-Crafts反应合成了对苄基苯甲醚,收率84.3%,纯度98.8%。产品经IR、1HNMR和元素分析表征。考察了苯甲醚体积、反应时间、催化剂用量及催化剂循环使用等因素对产率的影响,并得出了最适应的工艺条件:苯甲醚50mL、回流反应时间5min、催化剂0.3g(相对于0.05mol苄氯)。催化剂可循环使用4次,收率基本不变。     

Mechanism of the copolymerization of styrene with methyl,ethyl, and n-butyl acrylates in the presence of zinc chloride

The complexes of methyl acrylate (MA), ethyl acrylate (EA) and n-butyl acrylate (BA) with zinc chloride (ZnCl₂) were prepared at 300 K and found to be polar in nature. The viscosity and density of the complexes increased while the tendency to form a binary complex decreased with increase in size of the alkyl substituents of the acrylate monomers. The copolymerization of MA and BA with styrene (Sty) followed a cross-propagation mechanism, whereas the copolymerization of EA with Sty followed a radical-complex mechanism in the presence of their complexes with ZnCl₂.     

Some factors affecting the electrical properties of carbon-black-loaded butyl rubber during vulcanization

Butyl rubber mixtures loaded with 70 phr general purpose furnace black (GPF) and tetramethyl thiuram disulphide (TMTD)/S as vulcanizing system were prepared. The kinetics of their electrical conductivity development during the vulcanization process were followed by using an especially devised system. It was found that the increase in the electrical conductivity during vulcanization obeys an exponential growth function with time constant τ, which markedly decreases with increasing vulcanization temperature as well as with the efficiency of the vulcanizing system. After completion of the vulcanization process, about 80 min, the samples obtained possess reasonable stability and reproducibility of electrical conductivity.     

在橡胶加工设备中制备溴化丁基橡胶

选用无溶剂的本体法,以N-溴代琥珀酰亚胺与少量丁基橡胶(IIR)和稳定剂的预混物为溴化剂,在橡胶加工设备中对IIR进行化学改性,制备溴化丁基橡胶(BIIR)。通过红外光谱、核磁共振氢谱对产物BIIR的结构进行分析,并考察反应时间、温度和溴化剂用量等对BIIR硫化特性和物理性能的影响。结果表明:采用该方法可以制得BIIR,没有观察到腐蚀设备的情况,产物BIIR的硫化速率相比原料IIR有明显提高,硫化特性和物理性能达到了商品BIIR的水平;溴化反应温度应在60~100℃范围内,在所考察的范围内,溴化剂用量和反应时间对BIIR的硫化特性和物理性能影响不大。     

聚丙烯种类对丁基橡胶/聚丙烯热塑性硫化胶性能的影响

以辛基酚醛树脂为硫化剂,采用动态硫化法,制备丁基橡胶/聚丙烯热塑性硫化胶（IIR/PP-TPV）,探究PP种类对IIR/PP-TPV力学性能及热性能的影响。结果表明：由均聚聚丙烯PP-1制得IIR/PP-TPV的综合性能较好,可对标道恩汽车密封条类相关产品,其邵尔A硬度、拉伸强度和断裂伸长率分别为76.7、8.6 MPa和365%,压缩永久变形率仅22 ~ 23%,且老化后的拉伸强度、断裂伸长率保持率分别为98%和87%;而由乙丙嵌段共聚物PP-2、乙丙无规共聚物PP-3制得IIR/PP-TPV的综合性能不佳。这一工作可为低成本、绿色环保型汽车密封条用IIR/PP-TPV的制备提供参考。     

硫化促进剂NS的开发研究

在非离子表面活性荆存在下采用微压一步缩合法合成了N-叔丁基-2-苯并噻唑次磺酰胺,并讨论了原料配比、反应温度、反应时间等条件对反应的影响。     

氟橡胶及硫化机理概述

介绍了氟橡胶的主要种类及特点、常用的4种硫化体系和硫化机理,分析了有机二胺类、双酚类、有机过氧化物类及辐射交联类硫化体系的优缺点及其对硫化胶性能的影响,指出了双酚类硫化体系是目前常用的硫化体系,认为有机过氧化物类硫化体系可为氟橡胶带来优异的性能.     

Benzothiazole‐accelerated sulfur vulcanization. I. 2‐Mercaptobenzothiazole as accelerator for 2,3‐dimethyl‐2‐butene

2,3‐Dimethyl‐2‐butene (TME) was used as a model compound for polyisoprene in a study of 2‐mercaptobenzothiazole (MBT)‐accelerated sulfur vulcanization. Mixes that contained curatives only were heated in a DSC to various temperatures, while those that also contained TME were heated isothermally at 150°C in evacuated, sealed glass ampules. Heated mixtures were analyzed for residual curatives, intermediates, and reaction products by HPLC. It is proposed that MBT forms polysulfidic species (BtS_xH) in the presence of sulfur and that these react with TME via a concerted, substitutive reaction pathway to form polysulfidic hydrogen‐terminated pendent groups of varying sulfur rank (TME–S_xH). MBT is released as a by‐product of this reaction. Crosslinking occurs slowly as a result of the interaction of polythiol pendent groups, the rate being dependent on the pendent group concentration. H₂S is released on crosslinking. 2,3‐Dimethyl‐2‐butene–1‐thiol was synthesized and reacted in the presence of sulfur to confirm the formation of crosslinked products (TME–S_x–TME). Benzothiazole‐terminated pendent groups (TME–S_xBt) were not observed. © 2000 John Wiley & Sons, Inc. J Appl Polym Sci 76: 1377–1385, 2000     

炭黑/白炭黑双相填料补强BIIR/PP热塑性弹性体的性能研究

通过动态硫化工艺制备了溴化丁基橡胶（BIIR）/聚丙烯（PP）热塑性弹性体,研究了加工时间、填料、硫化剂对弹性体力学性能的影响。结果表明,动态硫化制备热塑性弹性体的时间约为13 min;使用炭黑N330/白炭黑双相填料的热塑性弹性体具有较好的力学性能;在氧化锌、硫磺、溴化辛基酚醛树脂及硫磺/溴化辛基酚醛树脂并用硫化体系中,溴化辛基酚醛树脂硫化的热塑性弹性体力学性能最佳。     

改性丁基橡胶PMIIR的动态力学性能研究

采用氢化钠(NaH)/马来酸酐(MAH)体系和无溶剂的本体方法,在橡胶加工设备中对丁基橡胶(IIR)进行了多官能化改性反应,得到了加工改性丁基橡胶(PMIIR)。通过红外光谱对产物结构进行了分析表征,该反应在丁基橡胶分子链上同时引入了不饱和的碳碳双键和羧基官能团。采用动态机械分析(DMA)和橡胶加工分析(RPA)方法对PMIIR的动态力学性能进行了分析。结果表明,混炼胶在低应变和高应变时储能模量的差值(ΔG′)受改性剂用量的影响不大,而硫化胶的ΔG′随改性剂用量的增加而增加,说明改性剂的用量对硫化体系网络有一定影响,IIR中引入极性基团,橡胶与填料的相互作用增强。硫化胶的动态模量受应变影响较大,随应变增加而大幅降低,损耗因子随应变的增加而增加。     

溴化丁基橡胶胶料硫化特性稳定性的研究

研究混炼工艺对溴化丁基橡胶(BIIR)胶料硫化特性稳定性的影响。结果表明:终炼时使用双台开炼机的胶料硫化特性稳定性优于使用单台开炼机的胶料;增加终炼回炼工艺,胶料的硫化特性稳定性提高,正硫化时间稍有缩短,但符合工艺要求;调整氧化锌和硬脂酸的加料顺序对胶料硫化特性稳定性的改善作用不明显;不同混炼工艺方案胶料的工艺性能均较好,胶料在后续工序中使用未出现异常。BIIR胶料终炼采用双开炼机并结合终炼回炼工艺,可以改善胶料的硫化特性稳定性,但需要关注胶料t_(90)的变化。     

动态硫化氯化丁基橡胶/聚丙烯酸乙酯共混物的熔体流变行为

研究了由不同动态硫化时间制备的氯化丁基橡胶(CIIR)和聚丙烯酸乙酯(PEA)共混物熔体的流变行为。结果表明,在不同的动态硫化时间里,CIIR／PEA共混物熔体的黏度均随着剪切速率的增加而先增后减,共混物熔体显示出膨胀性流动和假塑性流动相复合的复杂流变行为;动态硫化时间越长,熔体的最大黏度越小,动态硫化时间越短,熔体的最大黏度越大。在高剪切速率下,共混物熔体均具有适宜于模塑的良好流动性。     

2-正丁基-4-氯-5-甲酰基咪唑合成新工艺

以戊腈为原料,经加成、取代得到脒（2）,再与乙二醛缩合、脱一分子水得到眯唑啉酮化合物（3）,最后经氯代、氧化后得到2-正丁基-4-氯-5-甲酰基咪唑,收章40．5％。该工艺具有原料易得,反应条件温和,合成路线短,易于工业化生产等特点,是-条新的2-正丁基-4-氯-5-甲酰基咪唑（1）合成路线。     

动态硫化溴化丁基橡胶/三元共聚尼龙热塑性弹性体力学性能的影响因素

采用动态硫化法制备了溴化丁基橡胶/三元共聚尼龙热塑性弹性体(BIIR/CO-PA TPV),考察了硫化体系、增容剂、橡塑比、硫化温度、返炼次数对BIIR/CO-PA TPV力学性能的影响,并对TPV脆断面的微观形貌进行了观察。结果表明,无论采用过氧化二异丙苯还是ZnO为硫化体系,BIIR混炼胶的硫化效果均较好。添加增容剂可以改善BIIR与CO-PA的相容性,提高TPV的力学性能;马来酸酐接枝乙烯-辛烯共聚物与氯化聚乙烯的增容效果相当。橡塑比(质量比)为7∶3~6∶4、硫化温度为180℃时,制备的TPV力学性能最好。随着返炼次数的增加,TPV的力学性能降低。     

有机碱催化合成8-氯4(2’-氯4’-氟苯氧基)喹啉

4,8 二氯喹啉和 2 氯 4 氟苯酚在三乙胺催化下合成了题示化合物 ,其收率为 75%,比熔融缩合法高 2 6%。最佳反应条件为 :n( 4 ,8 二氯喹啉 )∶n( 2 氯 4 氟苯酚 )∶n(三乙胺 ) =1 0 0∶1 75∶1 0 0 ,回流时间为 2 0h。     

V带硫化胶套胶料的配方优化

研究V带硫化胶套胶料的配方优化。主体材料采用价格低、货源足的氯化丁基橡胶(CIIR)1066替代价格昂贵、货源不稳定的CIIR1068的胶料优化配方为:CIIR1066 100,炭黑N330/N774 60,白炭黑10,硅粉B66 15,无机补强剂JC-069 10,抗撕裂树脂HR-801 5,古马隆树脂5,耐磨剂JTH-315 3,耐高温微晶蜡2,防老剂RD 1.5,防老剂BLE 1.5,苯甲酸2,偶联剂Si69 1.5,抗硫化返原剂TDB680 1.5,硫黄0.2,促进剂3。通过优化胶料配方和在胶套胶中内衬一层薄帆布,胶套的使用寿命显著延长。