线型低密度聚乙烯固相接枝丙烯酸丁酯的研究

利用固相接枝共聚的方法,制备了线型低密度聚乙烯接枝丙烯酸丁酯(LLDPE-g-BA)共聚物。讨论了反应温度、反应时间、引发剂用量、单体浓度对接枝率的影响,结果表明:随着反应温度的升高,反应时间的延长,引发剂用量以及单体/聚合物比例的增加,接枝率提高,最高接枝率达到10.12%。并用红外光谱表征产物的结构。LLDPE-g-BA可明显改善PET/LLDPE复合材料的界面相容性及力学性能。     

水相原子转移自由基聚合制备PVC-g-BA共聚物

以不同不稳定氯含量的聚氯乙烯(PVC)为大分子引发剂,CuCl2/三(2-吡啶甲基)胺(TPMA)为催化体系,抗坏血酸(AA)为还原剂,通过水相电子转移催化再生原子转移自由基聚合(ARGETATRP)制备PVC接枝丙烯酸丁酯(BA)共聚物(PVC-g-BA),研究聚合条件对BA聚合转化率和接枝率的影响。发现其它聚合条件相同时,采用不稳定氯含量高的PVC为大分子引发剂制备的PVC-g-BA的接枝PBA的平均分子量较低;随着BA单体用量增加,聚合转化率和接枝率增大;随着催化剂CuCl2用量和聚合温度的增加,转化率和接枝率先增加后减小;当PVC为1.589 g,BA为2.70 g,CuCl2用量为0.0048 g,AA/TPMA/CuCl2(mol)=15/5/1,聚合温度为70℃,可获得BA转化率为56.06%、接枝率为95.14%的PVC-g-BA产物;由于PVC仅部分溶胀于BA,导致PVC接枝不均匀,PVC-g-BA分子量分布出现双峰现象,接枝PBA的分子量大于理论分子量。     

丙烯酰胺/甲基丙烯酸丁酯改性纤维素的研究

以纤维素为基体,丙烯酰胺(AM)、甲基丙烯酸丁酯(BMA)为接枝单体,过硫酸钾为引发剂,N,N'-亚甲基双丙烯酰胺为交联剂,聚乙烯吡咯烷酮为分散剂,通过悬浮接枝聚合法制备出了纤维素基吸水吸油材料;考察了单体用量、引发剂用量、反应时间、反应温度及交联剂用量等因素对接枝聚合物的吸水、吸油性能的影响。结果表明:在单体与纤维素的质量比为3.0∶1.0,AM∶BMA的质量比为2.0∶1.0,相对于单体,引发剂质量分数为6.0%,交联剂质量分数为0.5%,分散剂质量分数为0.5%,反应温度为70℃,反应时间为4 h的条件下,得到纤维素-AM-BMA接枝共聚物,其吸油倍率为11.55 g/g,吸水倍率为23.51 g/g,聚合度为534.6。     

聚合方法对硅胶表面接枝聚合物过程的影响研究

分别用溶液聚合与分散聚合两种方法,在硅胶载体表面实施了苯乙烯的接枝聚合,重点考察了聚合方法对接枝聚合过程的影响。结果表明,在基本相同的反应条件下,分散聚合体系的接枝率明显高于溶液聚合体系的接枝率,最高可达47%(即47g/100g);除聚合方法之外,影响聚合物在硅胶表面接枝率的因素还有硅胶表面的双键含量、单体浓度、引发剂浓度、温度等。     

两亲性改性剂PP-g-PEGMA的制备及其表征

以聚甲基丙烯酸乙二醇酯(PEGMA)为接枝单体,聚丙烯(PP)为接枝主链,过氧化二异丙苯(DCP)为聚合引发剂,采用熔融接枝法制备了两亲性改性剂PP-g-PEGMA,考察了单体用量和引发剂用量对改性剂接枝率、接枝效率的影响,并通过傅里叶红外光谱(FTIR)、X射线光电子能谱分析(XPS)、接触角测试对接枝聚合物进行了表征。结果表明:接枝聚合物在1 730cm-1处出现吸收峰,说明PEGMA成功地接枝到PP大分子链上;当单体用量在15份,引发剂质量分数在0.3%时,接枝效果最佳;接枝聚合物PP-g-PEGMA具有很好的亲水性,当PP-g-PEGMA的接枝率为3.21%时,接触角可降低至70°。     

固相接枝双单体制备极性聚丙烯的研究

以马来酸酐(MAH)和甲基丙烯酸(MAA)为复合单体,采用固相接枝法,制备了具有高极性的接枝聚丙烯[PP-g-(MAA/MAH)]样品;并表征与分析了该接枝物结构,研究了反应时间、反应温度、复合单体用量和引发剂浓度对接枝率和润湿角的影响.结果表明:当反应时间为105 min,反应温度是125℃,复合单体用量8 g/100gPP,引发剂用量为0.4 g/100g PP时,能够制备出接枝率4.01%的PP-g-(MAA/MAH).     

线性低密度聚乙烯反应挤出接枝马来酸酐的研究

以过氧化二异丙苯(DCP)为引发剂,在双螺杆挤出机中进行了马来酸酐(MAH)熔融接枝线性低密度聚乙烯(LLDPE)的研究,用红外光谱表征了接枝反应的存在。考察了引发剂用量、单体用量、螺杆转速以及温度对接枝反应的影响,并探讨了苯乙烯(St)作共单体对接枝反应的影响。研究表明:在引发剂含量较低时,用苯乙烯作共单体能够显著提高接枝率。     

双马来酰亚胺熔融接枝聚丙烯的研究

以二叔丁基过氧化物(DTBP)为引发剂,采用双官能团极性单体双马来酰亚胺(BMI)对聚丙烯(PP)进行熔融接枝改性,用红外光谱对接枝反应进行了表征,并分析了BMI对PP接枝率的影响。考察了引发剂用量、单体用量对PP流动性能、冲击性能和热稳定性能的影响。结果表明:PP接枝率随着BMI用量的增加而增大,最高可达37.5%;在DTBP用量为0.1～0.2份时,通过调整BMI用量,PP的熔体流动速率可在30～90 g/10min范围内调节并,使其冲击强度维持在22 J/m左右;BMI的接枝可以提高PP的热稳定性能。     

反应挤出法制备LLDPE-g-(GMA-co-St)的研究

以甲基丙烯酸缩水甘油酯(GMA)为接枝单体,苯乙烯(St)为接枝共单体,在双螺杆挤出机上对线型低密度聚乙烯(LLDPE)进行熔融接枝,制备了LLDPE-g-(GMA-co-St).研究了引发剂用量、单体用量、共单体用量和抑交联剂亚磷酸三苯酯等对LLDPE接枝物接枝率和熔体质量流动速率的影响,利用红外光谱对接枝物进行了表征.研究表明,St的加入能有效提高GMA的接枝率,亚磷酸三苯酯有效抑制了LLDPE的交联.最佳配方为:过氧化二异丙苯(DCP)为0.15份,GMA为3份,St为3份,亚磷酸三苯酯为1份.     

ST-g-NMA-AM的制备及其吸附性能

以红薯淀粉(ST)为原料,丙烯酰胺(AM)为单体,N-羟甲基丙烯酰胺(NMA)为单体和交联剂,采用反向乳液聚合法制备了NMA-AM接枝ST(ST-g-NMA-AM)。考察了NMA用量、引发剂过硫酸铵用量及反应温度对接枝率的影响,利用傅里叶变换红外光谱对其结构进行表征。以亚甲基蓝为吸附质,考察了ST-g-NMA-AM对亚甲基蓝的吸附性能。结果表明:当NMA用量为0.75 g,引发剂用量为0.0500 g,反应温度为55℃时,单体转化率和接枝率最高,分别为90.41%,45.38%;当亚甲基蓝质量浓度为20 mg/L,吸附剂ST-g-NMA-AM质量浓度为1 g/L时,吸附量随着NMA用量的增加而先增大后减小,当引发剂用量为0.0500 g,NMA用量为0.75 g时,吸附量最大,为16.140 mg/g。     

Sapindaceae,cyanolipids, and bugs

Scentless plant bugs (Heteroptera: Rhopalidae) are so named because adults of the Serinethinae have vestigial metathoracic scent glands. Serinethines are seed predators of Sapindales, especially Sapindaceae that produce toxic cyanolipids. In two serinethine species whose ranges extend into the southern United States,Jadera haematoloma andJ. sanguinolenta, sequestration of host cyanolipids as glucosides renders these gregarious, aposematic insects unpalatable to a variety of predators. The blood glucoside profile and cyanogenesis ofJadera varies depending on the cyanolipid chemistry of hosts, and adults and larvae fed golden rain tree seeds (Koelreuteria paniculata) excrete the volatile lactone, 4-methyl-2(5H)-furanone, to which they are attracted.Jadera fed balloon vine seeds (Cardiospermum spp.) do not excrete the attractive lactone. Loss of the usual heteropteran defensive glands in serinethines may have coevolved with host specificity on toxic plants, and the orientation ofJadera to a volatile excretory product could be an adaptive response to save time.Mention of a commercial product does not consititute an endorsement by the USDA.     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples.     

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.     

2008～2009年世界塑料工业进展

收集了2008年7月～2009年6月世界塑料工业的相关资料,介绍了2008～2009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、环氧树脂、不饱和聚酯树脂)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。