玻璃纤维增强尼龙复合材料新型增韧剂研究

以马来酸酐接枝反式-1,4-聚异戊二烯(TPI-g-MAH),马来酸酐接枝乙烯–辛烯共聚物(POE-g-MAH)、马来酸酐接枝三元乙丙橡胶(EPDM-g-MAH)和马来酸酐接枝氢化苯乙烯–丁二烯–苯乙烯共聚物(SEBS-g-MAH)为增韧剂,以质量分数为15%的玻璃纤维(GF)为增强剂,通过双螺杆挤出机制备了一系列增韧型GF增强尼龙(PA)6复合材料,研究了增韧剂种类及含量对复合材料力学性能和熔体流动速率(MFR)的影响。结果表明,随着增韧剂含量的增加,复合材料的缺口冲击强度逐渐上升,拉伸强度、弯曲强度和MFR逐渐下降;其中,EPDM-g-MAH对复合材料的增韧效果最好,TPI-g-MAH和POE-g-MAH次之,SEBS-g-MAH的增韧效果最差;当增韧剂质量分数均为10%时,TPI-g-MAH增韧的复合材料的缺口冲击强度与EPDM-g-MAH增韧的已相差不大,且相对于其它增韧剂,TPI-g-MAH增韧的复合材料的拉伸强度、弯曲强度和MFR下降幅度最小。综合可知,TPI-g-MAH对GF增强PA6复合材料增韧效果明显且对其强度和MFR影响最小,是一种新型高效的增韧改性剂。     

共聚PA6/66在PA66/GF复合材料中的应用

以共聚尼龙(PA)6/66和POE-g-MAH作为增韧剂,采用熔融共混法对PA66/玻璃纤维(GF)复合材料进行增韧改性,考察两种增韧剂用量对其结晶行为、力学性能、热变形温度(HDT)和熔体流动速率(MFR)的影响。结果表明,高用量的POE-g-MAH对复合材料中PA66的结晶有一定阻碍作用,而共聚PA6/66对PA66的结晶性能影响较小;随着共聚PA6/66和POE-g-MAH用量的提高,PA66/GF复合材料的冲击强度明显提高,拉伸强度、弯曲强度和HDT则逐渐下降;与POE-g-MAH相比,共聚PA6/66对拉伸及弯曲强度和HDT的不利影响较小,且略微提高了复合材料的MFR,而POE-g-MAH大幅降低了复合材料的MFR。当两种增韧剂的质量分数均为12%时,共聚PA6/66和POE-g-MAH增韧的复合材料的无缺口冲击强度和缺口冲击强度基本相当,但前者在拉伸强度、弯曲强度、HDT和MFR方面均有更明显的优势。     

POE-g-MAH对PA66/纳米TiO_2复合材料力学性能及相容性的影响

采用熔融共混法制备了尼龙(PA)66/马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)/纳米TiO2复合材料,通过万能材料试验机、冲击试验机、熔体流动速率(MFR)测试仪等研究了POE-g-MAH对复合材料力学性能及MFR的影响,利用Molau实验和FSEM考察了POE-g-MAH与PA66的相容性。结果显示,POE-g-MAH与PA66基体有很好的相容性;随着POE-g-MAH用量的增加,PA66/POE-g-MAH/纳米TiO2复合材料的缺口冲击强度逐渐增加,拉伸强度、弯曲强度、拉伸弹性模量及MFR逐渐降低;当POE-g-MAH质量分数为12%时,复合材料的综合性能最佳,缺口冲击强度、拉伸强度、弯曲强度、拉伸弹性模量和MFR分别为20.89kJ/m2,41.15MPa,64.2MPa,1428.15MPa和19.2g/(10min)。     

玻璃纤维增强聚乳酸复合材料的增韧改性研究

通过双螺杆挤出共混的方式制备了玻璃纤维增强聚乳酸复合材料,并采用乙烯/醋酸乙烯共聚物(EVA)、马来酸酐接枝乙烯辛烯共聚物(POE-g-MAH)、马来酸酐接枝高密度聚乙烯(HDPE-g-MAH)增韧剂对该复合材料进行了增韧改性,系统研究了玻璃纤维添加量、增韧剂用量对复合材料力学性能的影响,并结合扫描电镜等仪器对其增强及增韧改性的机理进行了研究。结果表明:EVA,POE-g-MAH,HDPE-g-MAH不仅改善复合材料的冲击性能,而且所制备的复合材料的拉伸强度、弯曲强度也得到了一定程度的提高;与HDPE-g-MAH相比,EVA与POE-g-MAH对复合材料表现出更佳的增强增韧效果。     

玻璃纤维改性PA66冲击强度的影响因素分析

以质量分数33%的玻璃纤维改性聚己二酰己二胺(PA 66)切片为基础,分析了基料黏度、玻璃纤维粗细、增韧剂、挤出工艺等对PA 66复合材料的冲击性能的影响。结果表明:随基料树脂黏度增大,PA 66复合材料的冲击性能增加,其中无缺口冲击强度增加幅度大;玻璃纤维直径越小,PA 66复合材料的冲击强度越高,玻璃纤维直径以13~15μm为宜;增韧剂本体强度小,增韧效果好,马来酸酐接枝茂金属乙烯-辛烯共聚物(POE-g-MAH)的性价比最佳;PA 66复合材料缺口冲击强度随增韧剂用量增加而增加,无缺口冲击强度呈先增大后减小再增大的趋势,复合材料中加入增韧剂质量分数2.5%较适宜;采用高温低转速挤出工艺时PA 66复合材料冲击强度较好。     

HDPE含量对PA1012/POE-g-MAH/HDPE共混物性能的影响

采用双螺杆挤出机,通过熔融共混法制备了尼龙1012(PA1012)/马来酸酐接枝乙烯-辛烯共聚物(POEg-MAH)/高密度聚乙烯(HDPE)合金材料。固定PA1012/POE-g-MAH/HDPE的含量比为80/(20-x)/x(x=0~20),通过机械性能、扫描电镜(SEM)、熔体质量流动速率(MFR)测试,考查了HDPE含量对POE-g-MAH增韧PA1012性能的影响。当(20-x)∶x小于3∶2时,随着HDPE含量的提高,合金材料的冲击强度、弯曲模量均增大。当PA1012/POE-g-MAH/HDPE的含量比为79.8/12/8时,与20%POE-g-MAH增韧PA1012相比,悬臂梁缺口冲击强度提高了30.4%,弯曲模量提高了19.8%,有效实现了增韧PA1012的刚韧平衡。     

家具用PP基木塑复合材料的制备与力学性能

以聚丙烯(PP)为木塑复合材料基体,分别加入4种增强剂和3种增韧剂,通过共混挤出制备PP基木塑复合材料,研究了4种增强剂含量和粒径以及3种增韧剂含量对复合材料力学性能的影响。结果表明,随着增强剂含量增加,复合材料的弯曲强度表现出先升后降趋势,随着增强剂粒径减小,复合材料的弯曲强度提高,增强效果从高到低依次为硅灰石、滑石粉、碳酸钙和硫酸钡;当硅灰石粒径为10μm、质量分数为15%时,复合材料具有最优的拉伸、弯曲以及缺口冲击强度。增韧剂乙烯–辛烯共聚物(POE)、三元乙丙橡胶(EPDM)和苯乙烯–丁二烯–苯乙烯共聚物(SBS)可以大幅提高复合材料的缺口冲击强度,增韧效果从高到低依次为POE,EPDM和SBS。当粒径为10μm的硅灰石和POE质量分数分别为15%和20%时,复合材料综合力学性能最好,缺口冲击强度为17.61 k J/m2、拉伸强度为27.65 MPa、弯曲强度为30.28 MPa,其弯曲强度优于目前常用木质人造板材,可满足家具行业应用。     

BP神经网络在POE-g-MAH/HDPE增韧PA6研究中的应用

运用BP神经网络研究了马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)/高密度聚乙烯(HDPE)对尼龙6(PA6)的增韧作用,并在此基础上建立了PA6/POE-g-MAH/HDPE复合材料各组分用量与复合材料冲击强度的关系模型。结果表明:该模型和实验结果基本吻合,可信度较高;当POE-g-MAH质量分数为12%,HDPE质量分数为16%时,PA6的缺口冲击强度达到95.02 kJ/m2。     

PA6/ABS合金的增韧改性研究

采用马来酸酐接枝丙烯腈-丁二烯-苯乙烯共聚物(ABS-g-MAH)、马来酸酐接枝乙烯-辛烯共聚物(POE-g-MAH)和苯乙烯-马来酸酐共聚物(SMA)为相容剂,研究了相容剂种类、相容剂含量、增韧剂含量及挤出机螺杆转速对尼龙6/丙烯腈-丁二烯-苯乙烯共聚物(PA6/ABS)合金力学性能的影响。研究表明,ABS-g-MAH为PA6/ABS合金的最佳相容剂,且质量分数为20%时合金的缺口冲击强度最高;采用ABS-g-MAH和POE-g-MAH复合增容增韧可得到力学性能优越的PA6/ABS合金;降低挤出机螺杆转速可使PA6/ABS合金的缺口冲击强度提高。     

玻璃纤维增强SAN的研制及其在电器上的应用

利用硅烷偶联剂改善玻璃纤维(GF)与(苯乙烯/丙烯腈)共聚物(SAN)之间的相容性,采用聚烯烃弹性体(POE)接枝马来酸酐(POE-g-MAH)对GF增强SAN体系进行增韧,制备了综合性能较好的GF增强SAN材料.结果表明,当GF、POE-g-MAH、偶联剂的质量分数分别为20%、6%和0.4%时,材料的综合力学性能最好:缺口冲击强度达到8.9 kJ/m2,拉伸强度、弯曲强度分别为104、130 Mpa;所研制的GF增强SAN材料已于空调轴流、贯流风扇等产品中批量应用.     

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.     

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.     

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。     

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。