羟基封端聚甲基苯基硅氧烷的制备及表征

以低摩尔质量的羟基硅油和甲基苯基环硅氧烷为原料、四甲基氢氧化铵[(CH3)4NOH]硅醇盐为催化剂,通过平衡共聚反应制备了羟基封端聚甲基苯基硅氧烷.研究了原料配比、催化剂用量、反应时间、反应温度等因素对聚合物制备的影响.通过红外光谱,热裂解气质联用等方法对制备的产物进行了结构表征.结果表明,当(CH3)4NOH质量分数为0.04%, 反应温度110 ℃,反应时间为6 h,甲基苯基硅氧链节与二甲基硅氧链节的量之比为1:1,可制得不同苯基含量的羟基封端聚甲基苯基硅氧烷.     

高透明液体苯基硅橡胶的制备

以八甲基环四硅氧烷(D_4)、八苯基环四硅氧烷(D_4~(Ph))及四甲基四乙烯基环四硅氧烷(V_4)为单体,以乙烯基封端的低聚硅氧烷(ViD_2Vi)为封端剂,通过KOH催化聚合制得乙烯基封端的聚二甲基二苯基硅油或乙烯基封端的聚甲基乙烯基二甲基二苯基硅油。再以上述苯基硅油为原料,添加白炭黑或MQ硅树脂等,制得高透明液体苯基硅橡胶。研究了苯基硅油合成中催化剂的选择、平均摩尔质量的控制;以及苯基含量对折射率及苯基液体硅橡胶透明度的影响。结果表明,催化剂优选氢氧化钾或氢氧化钾硅醇盐;苯基硅油的平均摩尔质量、苯基含量易控制,透明度高;使用高比表面积白炭黑作增强填料时,苯基硅油的折射率为1.43~1.46,液体硅橡胶的透明度较好;使用MQ硅树脂增强时,苯基硅油的折射率为1.41~1.46,硅橡胶透明度也较好。     

发泡硅橡胶的制备及应用性能研究

以D_4(八甲基环四硅氧烷)、D_4~(Vi)(四甲基四乙烯基环四硅氧烷)和D_2~(Vi)(四甲基二乙烯基二硅氧烷)为原料,THMA(四甲基氢氧化铵)为催化剂,制备得到生胶,通过添加其他组分得到发泡硅橡胶。研究结果表明:合成甲基乙烯基生胶的反应温度应为110℃,反应时间应为5 h;以100 g甲基乙烯基生胶为基胶,当补强剂、发泡剂、硫化剂、结构化控制剂以及发泡助剂的用量分别为40份、8份、2.5份、5份、0.2～0.3份时制得的发泡硅橡胶孔致密均匀,发泡倍率大,力学性能最佳。     

端羟基聚二甲基硅氧烷制备的改进

同济大学的高群等人以八甲基环四硅氧烷(D4)为单体,四甲基四乙烯基环四硅氧烷为改性单体,羟基硅油为封端剂和摩尔质量调节剂,四甲基氢氧化铵为催化剂,在羟基质量分数小于0 1 3%、催化剂质量分数为0 0 0 4 %～0 0 0 7%时,采用共聚法制备了摩尔质量大于45×1 0 4 、收率大于90     

含氢氟硅油对加成型氟硅橡胶性能的影响

以四甲基环四硅氧烷(DH4)、三氟丙基甲基环三硅氧烷(DF3)、四甲基二硅氧烷为原料,磺酸树脂球为催化剂,合成了不同活性氢质量分数的含氢氟硅油,再将其与端乙烯基或侧乙烯基氟硅液体胶进行加成反应,考察了含氢氟硅油活性氢质量分数和用量对加成型氟硅橡胶性能的影响。结果表明,当含氢氟硅油用量一定时,随着活性氢质量分数的提高,端乙烯基氟硅橡胶硬度升高,拉伸强度先增后减,拉断伸长率减小;当活性氢质量分数一定时,随着含氢氟硅油用量的增加,端乙烯基氟硅橡胶硬度和拉伸强度降低,拉断伸长率提高;当活性氢质量分数为0.3%,n(Si—H)∶n(Si—Vi)=3.5时,端乙烯基氟硅橡胶邵尔A硬度为40度,拉伸强度为6.4 MPa,拉断伸长率为589%。     

加成型固化氟硅橡胶的制备及性能

以三氟丙基甲基环三硅氧烷(D_3F)、八甲基环四硅氧烷(D_4)、四甲基四乙烯基环四硅氧烷(D_4Vi)作为单体,以短链乙烯基硅油作为封端剂,通过阴离子开环聚合的方式合成氟含量不同的乙烯基氟硅液体胶;通过阳离子开环聚合的方式分别合成了交联剂含氢氟硅油及Karstedt铂金催化剂,考察氟含量、乙烯基含量、填料含量等因素对加成型固化氟硅橡胶物理性能的影响。结果表明,当端乙烯氟硅液体胶含氟基团摩尔分数为30%、填料DM-30S的用量为31.5份时,固化后氟硅橡胶的邵尔A硬度可以达到44,拉伸强度达到8 MPa,断裂伸长率达到689%,撕裂强度达到38.9 kN/m。     

聚甲基倍半硅氧烷的合成

以甲基三氯硅烷（CH3SiCl3)为主要原料，乙二胺为梯形控制剂，合成了聚甲基倍半硅氧烷，讨论了梯形控制剂，水解介质，催化剂，单体浓度，温度等因素对聚合物摩尔质量及结构规整性的影响，筛选出较佳的梯形控制剂和聚合条件。结果表明：nCH3SCl3:n乙二胺为1：1.1，产物收率接近90%，小解对nCH3SiCl3:nH2O为1：15产物摩尔质量大，且规整性好；水解后，若以四甲基氢氧化铵为催化剂。缩合反应温度为35℃时，若反应时间长，聚合物摩尔质量高，分布宽；反应时间短，则聚合物摩尔质量低，分布窄。若以酸作催化剂，缩合反应温度为80℃时，聚合物摩尔质量较低，分布也较窄。     

甲基苯基硅油合成反应的影响因素

以甲基苯基二甲氧基硅烷和四甲基二乙烯基二硅氧烷为原料,通过水解缩合反应制得甲基苯基硅油。采用正交实验研究了催化剂、水解反应时间、水的用量、缩合反应温度和时间等对甲基苯基硅油合成反应的影响。结果表明,缩合温度是反应最主要的影响因素,且聚合物的平均摩尔质量可通过封端剂用量来控制。最佳合成条件为:KOH作催化剂、用量1.5%,水与甲基苯基二甲氧基硅烷的量之比为1.7∶1,原料在72℃水解回流反应2 h后,于110℃缩合反应5 h。在此条件下,可制得高透明、高折射率性质稳定的甲基苯基硅油,能用于LED封装材料等领域。     

高折射率苯基乙烯基硅油

正浙江大学的蒋立纯等人以八甲基环四硅氧烷、甲基苯基混合环体为原料,1,3-二乙烯基-1,1,3,3-四甲基二硅氧烷为封端基,四甲基氢氧化铵硅醇盐为催化剂,通过阴离子开环聚合反应合成了乙烯基封端的甲基苯基硅油。较佳工艺为反应温度100℃、反应时间4 h、催化剂用量为环体总质量的1.5%。甲基苯基硅油的折射     

氟硅树脂的制备及其性能研究

以单体三氟丙基甲基环三硅氧烷(D3F)、四甲基四乙烯基环四硅氧烷为原料,以平均相对分子质量为3 000、乙烯基摩尔分数为10％的乙烯基氟硅油作封端剂,以硅氧烷醇钠作催化剂,聚合成平均摩尔质量约8×10 5g/mol、乙烯基含量0.5％的氟硅树脂。讨论了催化剂用量、反应温度及时间原料中水分的含量、乙烯基含量和中和剂对氟硅树脂性能的影响。结果表明:采用高纯度D2F,硅氧烷醇钠催化剂用量为0.4％,在(130±5)℃反应60min制备出的氟硅树脂经硫化测试,其邵氏硬度为71,撕裂强度为31.5kN/m,拉伸强度8.6MPa,断裂伸长率404％,其结果表明符合市场使用要求。     

Insect antifeedant properties of anthranoids from the genusVismia

Vismiones and ferruginins, representatives of a new class of lypophilic anthranoids from the genusVismia were found to inhibit feeding in larvae of species ofSpodoptera, Heliothis, and inLocusta migratoria.     

Direct observation of freeze-thaw instability of latex coatings via high pressure freezing and cryogenic SEM

Despite its industrial importance, the subject of freeze-thaw (F/T) stability of latex coatings has not been studied extensively. There is also a lack of fundamental understanding about the process and the mechanisms through which a coating becomes destabilized. High pressure (2100 bar) freezing fixes the state of water-suspended particles of polymer binder and inorganic pigments without the growth of ice crystals during freezing that produce artifacts in direct imaging scanning electron microscopy (SEM) of fracture surfaces of frozen coatings. We show that by incorporating copolymerizable functional monomers, it is possible to achieve F/T stability in polymer latexes and in low-VOC paints, as judged by the microstructures revealed by the cryogenic SEM technique. Particle coalescence as well as pigment segregation in F/T unstable systems are visualized. In order to achieve F/T stability in paints, latex particles must not flocculate and should provide protection to inorganic pigment and extender particles. Because of the unique capabilities of the cryogenic SEM, we are able to separate the effects of freezing and thawing, and study the influence of the rate of freezing and thawing on F/T stability. Destabilization can be caused by either freezing or thawing. A slow freezing process is more detrimental to F/T stability than a fast freezing process; the latter actually preserves suspension stability during freezing. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, October 27–29, 2004 in Chicago, IL. Tied for first place in The John A. Gordon Best Paper Competition.     

Ethanol and (−)-α-Pinene: Attractant Kairomones for Bark and Ambrosia Beetles in the Southeastern US

In 2002–2004, we examined the flight responses of 49 species of native and exotic bark and ambrosia beetles (Coleoptera: Scolytidae and Platypodidae) to traps baited with ethanol and/or (−)-α-pinene in the southeastern US. Eight field trials were conducted in mature pine stands in Alabama, Florida, Georgia, North Carolina, and South Carolina. Funnel traps baited with ethanol lures (release rate, about 0.6 g/day at 25–28°C) were attractive to ten species of ambrosia beetles (Ambrosiodmus tachygraphus, Anisandrus sayi, Dryoxylon onoharaensum, Monarthrum mali, Xyleborinus saxesenii, Xyleborus affinis, Xyleborus ferrugineus, Xylosandrus compactus, Xylosandrus crassiusculus, and Xylosandrus germanus) and two species of bark beetles (Cryptocarenus heveae and Hypothenemus sp.). Traps baited with (−)-α-pinene lures (release rate, 2–6 g/day at 25–28°C) were attractive to five bark beetle species (Dendroctonus terebrans, Hylastes porculus, Hylastes salebrosus, Hylastes tenuis, and Ips grandicollis) and one platypodid ambrosia beetle species (Myoplatypus flavicornis). Ethanol enhanced responses of some species (Xyleborus pubescens, H. porculus, H. salebrosus, H. tenuis, and Pityophthorus cariniceps) to traps baited with (−)-α-pinene in some locations. (−)-α-Pinene interrupted the response of some ambrosia beetle species to traps baited with ethanol, but only the response of D. onoharaensum was interrupted consistently at most locations. Of 23 species of ambrosia beetles captured in our field trials, nine were exotic and accounted for 70–97% of total catches of ambrosia beetles. Our results provide support for the continued use of separate traps baited with ethanol alone and ethanol with (−)-α-pinene to detect and monitor common bark and ambrosia beetles from the southeastern region of the US.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料,介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比,介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序,对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。