马来酸酐接枝HDPE的性能特征

采用熔融接枝法制备了高密度聚乙烯(HDPE)与马来酸酐(MAH)接枝物,通过调整引发剂(DCP、BPO)和反应物马来酸酐(MAH)的用量来控制接枝率.研究结果表明,随着引发剂和MAH用量的增加,接枝率呈现先增大后降低的趋势.且DCP接枝物的接枝率大于BPO接枝物的接枝率,BPO接枝物的剪切黏度大于DCP接枝物的剪切黏度.     

LDPE熔融接枝MAH及其增容PA6/LDPE合金的研究

以过氧化二异丙苯(DCP)为引发剂,马来酸酐(MAH)为接枝单体,采用熔融法制备了MAH接枝低密度聚乙烯(LDPE-g-MAH)。研究了不同DCP和MAH配比对接枝反应的影响,并以相对接枝率较高的LDPE-g-MAH作为增容剂,讨论了其用量对尼龙6(PA6)/LDPE合金力学性能的影响。结果表明:LDPE/DCP/MAH质量比为100/0.2/2时,相对接枝率较高,该种配方的接枝物可显著改善PA6/LDPE体系的相容性,在PA6/LDPE(质量比50/50)和PA6/LDPE(质量比80/20)两种体系中,增容剂的最佳用量分别为4~5 phr和2~3 phr。     

PE/PP共混物熔融接枝马来酸酐的研究

研究了聚乙烯(PE)和聚丙烯(PP)共混物接枝马来酸酐(MAH)时，引发剂(DCP)、接枝单体(MAH)和PP用量对接枝率的影响。结果表明，DCP与MAH的交互作用是影响接枝率的重要因素，在低DCP、MAH用量时，它们之间的交互作用并不明显，当用量均提高至一定程度后，且DCP用量为MAH用量的10％时，产物的接枝效率最高。在体系中加入适当粘度和结构的PP，可以获得接枝率变化不大，而熔体质量流动速率明显增大的接枝物。     

聚丙烯固相接枝马来酸酐的接枝率影响因素的研究

研究了聚丙烯(PP)固相接枝马来酸酐(MAH)的反应温度,MAH和引发剂(BPO)用量等对产物接枝率和熔体质量流动速率等的影响.结果表明:120℃左右是制备高接枝率产物的最适宜反应温度;MAH和BPO用量分别为10%和5%左右时接枝产物的接枝率相对较高,同时其熔体质量流动速率和接枝效率也较为适当和合理;溶胀PP固相粒子的二甲苯用量也应适当控制,过量会造成操作及对接枝率不利等问题;接枝产物的熔点比PP纯样的低,而MAH的引入有利于结晶成核.     

LDPE熔融接枝的研究

本文介绍了马来酸酐（MAH）、丙烯酸（AA）、乙烯在三乙氧硅烷（A151）与LDPE的挤出熔融接枝工艺以及枝物与氢氧化铝（ATH）配合后填充体系的力学性能。研究了挤出温度、DCP用量和MAH用量对接枝物分子结构的影响，得出温度在210－230℃的范围内挤出物的接枝及MFI变化不大，当温度升到250℃后接枝率及MFI均不下降，DCP用量达到0．10phr以后，接枝率渐趋平衡而物料的MFI却迅速下降，表明有严重的交联反应；随MAH用量的增加，接枝率相应增加，当用量达0．5phr后接枝率基本稳定，不随MAH用量增加而继续提高。由接枝物－ATM填充体系的拉伸强度（σ拉）表明，虽然三种不同单体接枝的LDPE自身的σ拉与纯LDPE基本相同，但填充体系的σ拉均明显高于未接枝的。PE与ATH以1：1双例配合时，测得PE接枝MAH和枝A151的σ拉分别为15．3MPa和14.9MPa，比相同配比下未接枝的7．4MPa提高一倍以上。     

MAH熔融接枝LDPE及其产物在PC／HDPE共混物中的应用研究

利用熔融接枝的方法对于马来酸酐（MAH）接枝低密度聚乙烯（LDPE）的反应规律进行了研究，并对接枝产物（LDPE－g-MAH)在聚碳酸酯／高密度聚乙烯（PC／HDPE）（80／20）共混物的影响进行了研究。探讨了MAH用量在1.25-10份，DCP用量为0.125-1份范围内接枝产物中接枝率和凝胶的变化规律。接枝产物在PC／HDPE（80／20）共混物应用结果表明，接枝率为0.8%的接枝产物对PC／HDPE（80／20）共混物的增容作用优于0.3%的接枝产物。PC／HDPE（80／20）共混物的断裂伸长率和冲击强度随着接枝产物的用量的增加而增大。而拉伸强度在接枝产物用量为1.2份时出现极大值。扫描电子显微镜观察表明LDPE－g-MAH能够有效改善PC／HDPE（80／20）共混物的相分散形态。     

悬浮法聚乙烯接枝马来酸酐反应的影响因素

用悬浮法以低密度聚乙烯(LDPE)为分散相,水作分散介质,分别以过硫酸铵(APS)和过氧化二苯甲酰(BPO)作引发剂,引发LDPE与马来酸酐(MAH)的接枝反应.在讨论引发剂用量、MAH浓度、反应时间、反应温度等单因素对接校率影响规律的基础上,考察了界面剂对交联度的作用.结果表明;APS和BPO都能引发LDPE与MAH接枝反应,但APS的接枝率低(不大于0.31%,质量分数),BP0的较高;采用BPO作引发剂时,随MAH浓度和引发剂用量的增加、反应时间的延长、反应温度的升高,产物的接枝率均有所提高,但产物的交联度也随之增加;界面剂的加入不仅大大地提高了产物的接枝率(达到3.00%),而且检测不到产物的交联度.     

POE溶融挤出接枝MAH的研究

采用熔融法制备POE接枝MAH,利用红外光谱对其结构进行表征。考察了MAH和过氧化二异丙苯(DCP)用量对接枝率及熔融指数的影响。实验结果表明,MAH用量增加,接枝率逐渐增大,熔体流动速率逐渐下降;随着引发剂用量的增加,接枝率也随之增加,熔体流动速率却显著下降。同时对POE接枝MAH的机理进行了探讨。     

UHMWPE混炼接枝马来酸酐研究

讨论了超高相对分子质量聚乙烯(UHMWPE)混炼接枝马来酸酐(MAH)过程中，单体MAH用量、引发剂DCP用量、交联抑制剂己内酰胺(CAILA)用量、流动改性剂硬脂酸钙(CaSt2)用量及混炼温度、时间等工艺条件对UHMWPE接枝率和凝胶含量的影响。用红外光谱表征了接枝物的存在。并用滴定分析法和重量分析法测定了接枝物UHMWPE～g～MAH的接枝率和凝胶含量。实验表明，MAH用量为5份、DCP为0．15份、CALA为0．1份、CaSt2为1份时。混炼温度175∽180℃。混炼时间14min时，可得到接枝率0．75％、凝胶含量1．48%的UHMWPE接枝物。     

聚乙烯熔融挤出接枝马来酸酐的研究

通过低密度聚乙烯熔融挤出接枝MAH(马来酸酐)研究了单体及复配单体、引发剂及复配引发剂对LDPE接枝的影响,并用红外光谱法证实了接枝反应。研究表明:复配单体和复配引发剂用量对接枝率有较大影响,AA(丙烯酸)的加入提高了接枝率,DCP/BPO为3/1时接枝率最高。在聚乙烯防雾膜中加入PE g MAH接枝共聚物可提高膜的防雾性。     

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.     

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.     

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。     

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.     

基于ATRP法制备的触角状亲水性羟胺树脂的吸硼性能的研究

以大分子引发剂氯乙酰化聚苯乙烯微球(PS-acyl-Cl)经原子转移自由基聚合(ATRP)法引发丙烯酰胺(AM)和甲基丙烯酸缩水甘油酯(GMA)单体的共聚接枝,制得一种触角状亲水性环氧载体(PS-acyl-g-P(AM-co-GMA)),再经二乙醇胺(DEA)的环氧基开环胺化反应,得到一种含多个-NCH2CH2OH螯合配基的多齿-五元螯合环的触角状亲水性羟胺树脂(PS-acyl-g-P(AM-co-GMA)-DEA)。将此树脂用于硼吸附研究,结果表明,PS-acyl-g-P(AM-co-GMA)-DEA树脂对硼的吸附满足Langmuir方程,为单分子层吸附;饱和吸附量约为37.7 mg·g-1,且树脂5 min即可达到吸附平衡,与其它已报道的吸硼树脂相比,该树脂具有更高的吸附量和吸硼速率。吸附动力学研究表明,树脂吸附硼的过程主要由颗粒扩散过程控制。重复使用5次后该树脂的吸附量基本不变,解吸率均在90%以上,重复使用性能良好。