聚丙烯酸酯/聚硅氧烷乳胶粒核壳结构相反转及控制

采用乳液聚合法,以丙烯酸丁酯(BA)、甲基丙烯酸甲酯(MMA)、八甲基环四硅氧烷(D4)为单体,甲基丙烯酰氧丙基三甲氧基硅烷(MATS)或甲基丙烯酸羟乙酯(HEMA)为偶联剂,十二烷基苯磺酸钠(SDBS)为乳化剂,过硫酸铵(APS)和十二烷基苯磺酸(DSBA)为复合引发剂,经乳液自由基与缩聚同步反应,制得具有核壳结构的聚丙烯酸酯(核)/聚硅氧烷(壳)共聚物乳液。考察了交联剂二缩三丙二醇双丙烯酸酯(TPGDA)对乳胶粒核壳结构的影响,结果表明不加交联剂的共聚乳液放置一定时间.乳胶粒核壳结构发生相反转,最终变成以聚硅氧烷为核、聚丙烯酸酯为壳的热力学稳定结构;加入交联剂可以有效控制乳胶粒核壳结构,乳液放置一定时间乳胶粒核壳结构不变。     

原位聚合法制备纳米TiO2/有机硅改性丙烯酸酯复合乳液

用硅烷偶联剂对纳米二氧化钛(TiO2)粒子表面进行预处理，使其表面由亲水性变为疏水性，并在其表面接枝上可反应的有机官能团。通过改性纳米TiO2表面上的原位聚合反应，制备了纳米TiO2／硅丙复合乳液。透射电子显微镜观察结果显示，乳液中存在两种结构的乳胶粒子：一种是以聚丙烯酸酯为核、有机硅聚合物为壳的核壳结构硅丙乳胶粒子；另一种是以纳米TiO2为核、有机聚合物为壳的纳米TiO2／聚合物复合结构乳胶粒子。乳胶粒子的结构形态可由乳化剂的用量控制。该复合乳液具有较好的杀菌效果，在较短时间内对细菌的杀灭率可达90％以上。     

聚苯乙烯/聚丙烯酸酯核壳粒子形态的研究

在简化及限制的实验条件下,利用界面张力的简化推算方法,通过调和平均法和几何平均法计算了苯丙体系复合乳胶粒子的界面张力,进而得到不同粒子形态的界面自由能变化值。根据自由能变化最小的判据推测了苯丙乳液粒子的热力学平衡形态。并采用种子半连续乳液聚合法制备了聚苯乙烯/聚丙烯酸酯核壳复合乳胶,利用透射电镜和激光粒度仪对粒子的最终核壳形态进行了证实。     

硅溶胶/聚丙烯酸酯复合乳液的结构和性能研究

采用普通乳液聚合的方法,制备了硅溶胶/聚丙烯酸酯复合乳液.通过透射电镜(TEM)、傅里叶红外光谱仪(FT-IR)和动态激光散射仪(DLS)等对复合乳液中乳胶粒子的结构进行表征,并对复合乳液的涂膜性能进行研究.结果表明,所制备的复合乳液粒子具有核-壳结构,其中核是纳米级的SiO2粒子,壳是聚丙烯酸酯.性能测试结果表明,核-壳结构的存在使得复合乳液的涂膜在硬度、附着力和化学稳定性等方面均优于纯丙乳液及硅溶胶/聚丙烯酸酯的共混乳液.     

交联剂含量对核壳型聚丙烯酸酯乳液及胶膜性能的影响

以三羟甲基丙烷三甲基丙烯酸酯(TMPTMA)为交联单体,采用半连续种子乳液聚合法,以甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA)为主要单体合成了核壳型聚丙烯酸酯乳液,研究了核层TMPTMA含量对乳液及胶膜性能的影响。结果表明,在一定范围内,随着核层TMPTMA含量的增加,乳胶粒子的平均粒径减小,凝聚率增大;胶膜的拉伸强度及断裂伸长率均增大,与水的接触角变小;在反应条件、单体种类及配比相同的情况下,核壳型丙烯酸酯乳胶膜比非核壳型乳胶膜的杨氏模量及拉伸强度明显变大。     

表层含羟基核壳乳胶粒子PBA-P(MMA-VA)的制备

采用预乳化-半连续种子乳液聚合法制备了聚丙烯酸丁酯(PBA)-聚(甲基丙烯酸甲酯-乙酸乙烯酯)[P(MMA-VAc)]核壳乳胶粒子,然后经醇解得到表层含羟基的PBA-聚(甲基丙烯酸甲酯-乙烯醇)[P(MMAVA)]核壳乳胶粒子。采用傅里叶变换红外光谱仪、差示扫描量热仪及透射电子显微镜等表征了核壳乳胶粒子的结构和形态。结果表明:PBA-P(MMA-VAc)为核壳结构,核壳乳胶粒子的平均粒径为340 nm,其中PBA核的平均粒径为270 nm;功能单体乙酸乙烯酯(VAc)参与了壳层共聚合,并且部分P(MMA-VAc)成功接枝到PBA核上;VAc用量增加导致壳层交联度提高、玻璃化转变温度上升,当VAc用量为壳层单体质量的20%时,壳层中以化学键连接在PBA核上的乙烯醇质量分数达5.44%。     

丙烯酸改性氯化聚丙烯乳液

采用溶液法对氯化聚丙烯进行接枝改性,得到丙烯酸改性的氯化聚丙烯和聚丙烯酸酯的混合物,加胺中和后用水直接分散得到自乳化水性丙烯酸改性氯化聚丙烯乳液。考察了单体用量对改性乳液性能的影响,结果表明,当单体与氯化聚丙烯的质量比为0.6～1.5时,制得的乳液具有良好的稳定性和优异的附着力。用光学显微镜对改性乳液的粒子形态进行了观察,结果表明接枝氯化聚丙烯处于乳胶粒的核层,而聚丙烯酸酯处于乳胶粒的壳层。     

广州研制出聚硅氧烷/丙烯酸酯复配乳液

<正>中科院广州化学有限公司近日研制出一种交联聚硅氧烷/丙烯酸酯复配乳液。该乳液由有机硅氧烷单体、水和复合乳化剂通过剪切乳化和高压均质制备硅氧烷单体乳液,然后添加交联剂制备交联聚硅氧烷乳液,最后将交联聚硅氧烷乳液与连续乳液聚合法制备的聚丙烯酸酯乳液通过简单工艺进行复配,得到稳定且相容性     

核壳型复合高分子乳液乳胶粒子形态学

系统阐述了核壳型复合高分子乳液乳胶粒子形态方面的研究进展。探讨了单体亲水性、聚合工艺、加料方式、引发剂、聚合场所的粘度、种子交联度、聚合温度及反应体系pH值等对乳胶粒子形态的影响。介绍了热力学研究的概况 ,并通过计算界面自由能变化最小来控制和预测粒子的形态。讨论了粒子核壳结构对乳液性能的影响 ,如最低成膜温度 ,核壳结构在热处理后机械、光学性能的变化。总结了用来表征乳胶粒子核壳结构常用的手段 ,包括透射电镜法 (TEM) ,扫描电镜法(SEM) ,示差量热扫描法 (DSC) ,最低成膜温度法 (MFT)以及通过测定两阶段聚合物中羧基的分布来确定粒子的形态等     

A-187改性核壳型聚丙烯酸酯乳液的制备及性能表征

以甲基丙烯酸甲酯、丙烯酸丁酯、丙烯酸-2-乙基己酯、γ-(2,3-环氧丙氧基)丙基三甲氧基硅烷(A-187)等为原料,过硫酸铵为引发剂,通过种子乳液聚合法制备了具有核-壳结构的A-187改性聚丙烯酸酯(SACR)系列微复合高分子乳液。表征了乳胶粒子的结构形态及粒度分布,测定了聚合物的玻璃化转变温度、拉伸强度和聚合物薄膜的吸水率。所得SACR系列微复合聚合物乳液的乳胶粒子具有核壳结构,粒径分布较窄,聚合物的玻璃化转变温度随A-187加量的增加有所升高,聚合物的力学性能和聚合物的耐水性能有所改善。     

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。