聚酰胺6／乙烯-乙烯醇无规共聚物共混体系的相容性及性能研究

研究了不同比例乙烯-乙烯醇无规共聚物(EVOH)和聚酰胺6(PA6)共混物的相容性及性能。扫描电子显微镜下观察结果表明二者具有较好的相容性;红外光谱分析和流变实验证实了EVOH与PA6分子间氢键的存在,氢键的作用会随着EVOH含量的增加而增强;阻透性能的测试表明在PA基体中加入EVOH会极大提高基体的阻透性,在EVOH基体中加入少量的PA6对EVOH的阻透性影响很小。     

PA1012/SMA共混物的制备及性能研究

采用双螺杆挤出方法制备尼龙1012(PA1012)/苯乙烯-马来酸酐(SMA)共混物,研究了SMA含量对PA1012/SMA共混物力学性能的影响,并利用扫描电子显微镜(SEM)研究了PA1012/SMA共混物的微观形态。结果表明,加入SMA,共混物冲击强度呈先增加后降低趋势,共混物拉伸强度和弹性模量降低。当SMA含量为0.5%时,PA1012/SMA共混物冲击强度最大,高达298 J/m,为韧性断裂,力学性能较优;PA1012/SMA共混物比纯PA1012结晶温度升高10℃,有利于结晶;SEM观察到随着SMA分散相粒子含量的增加,在PA1012基质中分散更明显且均匀。     

过氧化物交联HDPE/硅橡胶/EPDM的研究

采用过氧化物交联法研究了高密度聚乙烯(HDPE)/硅橡胶/三元乙丙橡胶(EPDM)共混体系的工艺和性能,探讨了过氧化物用量对共混材料的力学性能和凝胶含量的影响。结果表明,共混体系的力学性能有明显的提高。随着过氧化二异丙苯(DCP)含量的增加,体系的凝胶含量提高,拉伸强度先增加后降低且在DCP含量为0.5%(质量分数)时出现最大值,而断裂伸长率则呈下降的趋势。采用复合抗氧剂可以使材料得到较好的耐老化性能。硅橡胶的加入和交联,改善了体系的耐高温性能。     

高阻隔PLA油瓶的制备及性能研究

以乙烯-乙烯醇共聚物(EVOH)为阻隔剂,与聚乳酸(PLA)通过熔融共混,然后注拉吹得到高阻隔PLA油瓶。对PLA/EVOH油瓶及共混物的热性能、力学性能、阻隔性能、熔体强度和分子量进行了研究。结果表明,EVOH的加入改善了PLA的阻隔性。随着EVOH含量(2%~10%)的增加,聚乳酸油瓶的阻氧性能提高59%~63%,阻水性能提高32~37%。而且,EVOH的加入也提高了PLA/EVOH共混物的拉伸强度及油瓶的垂直载压性能。熔体强度测试结果表明,随着EVOH含量的增加,PLA/EVOH共混物的熔融指数降低。     

EHA/PE复合薄膜的力学性能和阻透性能

分别使用氧气透过率分析仪、水蒸气透过率分析仪、拉伸试验机、紫外可见分光光度计以及差示扫描量热仪测试了乙烯乙烯醇共聚物(EVOH)、聚酰胺6(PA6)、EVOH/PA6(EHA)等薄膜以及EHA/聚乙烯(PE)复合薄膜的力学性能和阻透性能。结果表明,EVOH与PA6有较好的相容性,所制成的薄膜EHA与PE复合后的EHA/PE复合薄膜对氧气和水蒸气有良好的阻隔性,并且对可见光有很好的透过性,比较适合作食品包装材料。     

三层共挤阻透薄膜的加工与性能研究

选用乙烯-乙烯醇共聚物（EVOH）、聚酰胺6（PA6）、茂金属聚乙烯（mPE）和改性线形低密度聚乙烯（PE-LLD）为原料,制备了3种三层共挤阻透薄膜PA6/EVOH/PA6、PA6/PE-LLD/mPE和EVOH/PE-LLD/mPE。通过对原料树脂热性能与流变性能的分析,探讨了三层共挤薄膜的最佳加工工艺。结果表明,所得3种共挤薄膜中以PA6/EVOH/PA6三层共挤薄膜的力学性能和氦气阻透性能最佳。     

PP/EVOH/PA6共混物的性能研究

以聚丙烯接枝马来酸酐(PP-g-MAH)为相容剂,制备了聚丙烯(PP)/乙烯-乙烯醇共聚物(EVOH/)聚酰胺6(PA6)共混物,研究了PP/EVOH/PA6三元共混物的相容性、流变性能、阻隔性能、力学性能、热性能及形态结构。结果表明:相容剂与EVOH和PA6间发生了反应,提高了共混物的相容性;相容剂的加入提高了PP、EVOH、PA6的结晶温度,增强了PP与EVOH和PA6间的黏合力,降低了界面张力;EVOH占EVOH/PA6总量68%的三元共混物吸油率最小,当相容剂用量为5份时,PP/EVOH/PA6三元共混物吸油率比PP/EVOH二元共混物降低了8%。     

PA6/POE共混体系的性能研究

利用双螺杆挤出机将尼龙(PA)6与聚烯烃弹性体(POE)共混,研究添加过氧化二异丙苯(DCP)、马来酸酐(MAH)后的体系性能以及工艺条件对性能的影响。结果表明,POE含量在15份时缺口冲击强度仅提高了3 k J/m2,拉伸强度降低明显;当双螺杆挤出机的转速为100 r/min,DCP用量为0.2份,体系的力学性能达到最佳值;在DCP用量为0.2份时,添加0.4份MAH,体系的缺口冲击强度相对于纯PA6,提高约12 k J/m2;通过SEM分析冲击断面发现,加入了DCP或DCP/MAH后,POE分散相尺寸相对于单纯的两相共混体系的明显减小。     

PE-HD/EVOH共混阻透管材的研制

将高密度聚乙烯(PE-HD)、乙烯一乙烯醇共聚物(EVOH)和相容剂混合后,加人塑料管材挤出成型机中,经熔融共混、冷却定型、辅机牵引制得层状共混阻透管材。研究了相容剂用量、阻透树脂用量和成型工艺参数对管材阻透性能的影响,考察了树脂的流变性能及共混阻透管材的力学性能,并与PE-HD)/聚酞胺6(PA-6)共混管材性能进行比较。利用扫描电镜观察阻透管材壁面的层状结构。实验结果表明,与PE-HD/PA6共混管材相比,PE-HD/EVOH共混管材所需相容剂少,成型工艺参数易于控制,其阻透性能及力学性能更好。当阻透树脂用量为16~18份,相容剂用量为1-3份,加工温度在225℃左右,螺杆转速控制在20 r/min左右,牵伸速度为1. 5一1. 6 m/min时,PE-HD/EVOH共混管材的阻透性能得到明显提高     

尼龙66/聚酚氧共混体系的共混形态和力学性能

采用扫描电镜、动态力学分析仪和材料试验机研究了尼龙66(PA66)与聚酚氧(PHE)共混体系的共混形态和力学性能。研究表明:氢键作用使得二者熔融共混后形成部分相容的两相聚集态结构;以PA66为主体时,PHE以颗粒形态分散在PA66基体中,随PHE含量增加,分散相颗粒尺寸下降;此时尼龙相的玻璃化转变温度(Tg)增大,PHE相的Tg提高,共混体系拉伸强度增加,冲击强度下降。PA66/PHE质量比达到40/60后发生相反转,PA66分散相颗粒尺寸明显小于PHE为分散时相的颗粒尺寸。PHE相的Tg随PA66含量增加而增大,随PA66含量增加,共混体系拉伸强度和冲击强度均增大。     

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.     

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.     

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。     

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.     

ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究

建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。     

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.     

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.