LDPE-g-GMA增容LDPE/木质素复合泡沫材料研究

以低密度聚乙烯(LDPE)为基体树脂,木质素为填料,LDPE接枝甲基丙烯酸缩水甘油酯(LDPE-g-GMA)为增容剂,辅以发泡剂和交联剂,制备LDPE/木质素复合发泡材料,考察了LDPE-g-GMA及其用量对泡沫材料性能的影响,并分析了泡沫材料的微观形态。结果表明:LDPE-g-GMA可以有效降低LDPE/木质素复合泡沫材料的表观密度,使泡沫材料泡孔均匀细密;随着LDPE-g-GMA用量的增加,LDPE/偶联剂处理木质素(M-木质素)复合泡沫材料泡孔的平均直径先增大后减小,LDPE-g-GMA的用量存在最佳值,当用量为4份时,比强度达到10.96 MPa/(g·cm-3),表观密度为0.533g/cm3。     

LDPE/nano-CaCO_3复合发泡材料的制备工艺与性能研究

采用模压发泡法制备了低密度聚乙烯/纳米碳酸钙(LDPE/nano-CaCO3)复合发泡材料。研究不同含量的nano-CaCO3、发泡剂AC、交联剂DCP等对LDPE/nano-CaCO3力学性能及发泡效果的影响,确定了最佳工艺路线。结果表明:随着nano-CaCO3用量的增加,LDPE/nano-CaCO3复合发泡材料拉伸强度和表观密度逐渐增大,发泡倍率逐渐减小。当nano-CaCO3用量为30%,AC用量为9%～11%,DCP用量为0.08%时,发泡材料的综合性能最佳。热重分析表明:加入nano-CaCO3后,LDPE发泡材料的热稳定性得到提高。     

发泡剂和催化体系对软质聚氨酯泡沫结构和性能的影响

研究了发泡剂和催化体系对软质聚氨酯泡沫(PUF)形态结构和性能的影响,并对PUF进行了表观密度、泡孔结构分析和拉伸性能的测试。结果表明:随着发泡剂用量的增大,泡沫结构呈现由柔软易碎到结构良好再到开裂的变化过程,PUF的表观密度逐渐降低,数均泡孔直径逐渐变大;当水用量为3.0 phr时,PUF的形态结构和力学性能均较好,压缩永久形变最小,为4.3%,拉伸强度达39.4 k Pa;当二月桂酸二丁基锡用量为1.0 phr、胺催化剂用量为0.5 phr时,凝胶反应和发泡反应达到较好的"平衡"状态,制备的PUF力学性能较为优良,压缩永久变形为4.3%,拉伸强度为41.2 k Pa。     

NR/LLDPE热塑性弹性体泡沫材料的制备与性能研究

采用化学交联模压法制备天然橡胶/线性低密度聚乙烯（NR/LLDPE）共混型热塑性弹性体泡沫材料。研究了橡塑比、发泡剂用量、硫磺用量以及模压发泡成型压力对泡沫材料的力学性能和相对密度的影响,并对泡沫材料的微观结构进行了荧光显微镜分析。结果表明：橡塑比、发泡剂用量、硫磺用量和压力对材料的性能影响较大,且当橡塑共混比为70/30、发泡剂用量为10 phr、硫磺用量为1.5phr和压力为1 MPa时,可制得密度较低且具有较好综合力学性能的泡沫材料;微观结构表征显示,此条件下制得的泡沫材料的泡孔较小、大小均一、分布均匀且以闭孔为主。     

纳米二氧化硅/聚氨酯酰亚胺复合泡沫材料的制备与性能

采用预分散法和一步法制备了纳米SiO2/聚氨酯酰亚胺(PUI)复合泡沫材料,考察了纳米SiO2对PUI发泡过程的影响,研究了纳米SiO2/PUI复合泡沫材料的泡孔结构及性能。结果表明,在PUI发泡过程中,随着纳米SiO2用量的增加,复合泡沫材料的开孔率增大,可有效防止泡沫收缩,且密度也减小;当纳米SiO2用量为10份时,纳米SiO2/PUI复合泡沫材料具有比较均匀的泡孔结构,且具有较高的开孔率、良好的阻燃性和热稳定性;柔软性泡沫还具有较好的吸声性能     

软质PVC发泡材料的研究

采用化学发泡一步法模压成型制备了软质PVC发泡材料,研究了发泡剂、泡孔成核剂、改性剂等主要助剂用量对软质PVC发泡材料密度、泡孔结构以及力学性能的影响,并进行了软质PVC发泡材料的配方筛选.结果表明加入吸热发泡剂N能提高发泡体系的发泡效果,降低材料的密度,改善材料的力学性能,当发泡剂AC用量为2份,用量为0.6份时,材料的综合性能优异;当成核剂用量为1份时,体系发泡效果较好;加入粉末NBR不仅能提高发泡材料的断裂伸长率和柔韧性,还可降低发泡材料密度,改善泡孔结构;当NBR用量为20份时,发泡材料密度达到0.44 g/cm3,力学性能优异.     

注塑成型低发泡PP的研究

采用注塑成型工艺制备了聚丙烯(PP)低发泡材料,分别探讨了发泡剂、交联剂用量及填料对PP发泡材料拉伸强度、缺口冲击强度、硬度、密度及热变形温度等性能的影响,并用扫描电子显微镜(SEM)对泡孔结构进行了观察。结果表明:当发泡剂用量为0.5phr,交联剂用量为0.05phr及CaSO4填充母料用量为10phr时,PP低发泡材料的综合性能最佳。     

LDPE/芦荟皮粉发泡材料性能研究

采用硅烷偶联剂、帚化及帚化+偶联剂3种改性方法制备改性芦荟皮粉。研究了芦荟皮粉的改性方法及其用量对低密度聚乙烯(LDPE)/芦荟皮粉发泡材料的力学性能、热稳定性能及微观结构的影响。结果表明,添加帚化+偶联剂方法改性的芦荟皮粉的发泡材料力学性能明显提高,改性芦荟皮粉用量为10份时,发泡材料比强度提升了37.50%。改性方法对发泡材料的热稳定性有影响。帚化+偶联剂改性方法能够改善芦荟皮粉在LDPE基体中的分散性能,其制品泡孔质密且均匀,平均直径可达42.58μm。     

纳米碳酸钙/IFR对聚丙烯发泡材料的协效阻燃

通过氧指数(LOI)、力学性能、泡孔结构及热重分析(TG),探究了纳米碳酸钙/IFR复合阻燃体系对PP发泡材料性能的影响和机理。结果表明:Nano-Ca CO_3与IFR存在协效作用,能有效改善PP复合泡沫材料的阻燃性能,使氧指数显著提升;Nano-Ca CO_3的添加能提升阻燃PP发泡材料的力学性能,并且添加量存在最优值。另外通过扫描电镜发现:Nano-Ca CO_3的添加可以提高IFR与PP的相容性,使阻燃PP复合发泡材料的泡孔结构更规整,泡孔孔径减小,孔密度增大。TG结果表明:Nano-Ca CO_3能提高阻燃PP复合发泡材料的热稳定性,形成更致密的炭层,提升了热失重率。随着Nano-Ca CO_3添加量的增大,PP/IFR/Nano-Ca CO_3复合发泡材料的氧指数、力学性能和热稳定性都呈现先增大后减小的趋势,因此当PP/IFR/Nano-Ca CO_3质量比为80:20:2时,复合发泡材料综合性能较优。     

甘蔗渣/LDPE发泡木塑复合材料的研究

用模压法制备了甘蔗渣／LDPE发泡木塑复合材料。考察了发泡剂用量、甘蔗渣含量及预热温度对发泡木塑复合材料性能的影响，并在扫描电镜下观察了材料断面的微观形态。结果表明：发泡后木塑材料的密度降低，发泡剂用量为1．0份时材料密度降低了近30％，化学发泡法可有效减轻材料的自重；冲击强度提高了近20％；虽然发泡造成拉伸强度和弯曲强度的降低，但由于发泡后密度也降低了，所以其比强度反而得到提高。甘蔗渣的加入降低了材料的性能，且随着用量的增加降低的幅度越大。预热温度为200℃时，材料的各项性能最佳。由扫描电镜可以看出，AC发泡剂为1．0份时的发泡木塑材料中分布着较均匀统一的圆形泡孔，而AC发泡剂为3．0份时，局部有泡孔坍塌破裂。     

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.     

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.     

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.     

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。