PP/HYBRAR共混物非等温结晶动力学的研究

采用熔融共混法制备了聚丙烯/苯乙烯热塑性弹性体(PP/HYBRAR)共混物,利用差示扫描量热仪(DSC)研究了PP和PP/HYBRAR的非等温结晶动力学,通过Jeziorny法、Ozawa法和Mo法分析了非等温结晶数据。结果表明:Jeziorny法和Mo法适用于描述PP及PP/HYBRAR的非等温结晶过程,而Ozawa法则不适用;Jeziorny法求得的参数n和Z随降温速率的增加而增加,PP/HYBRAR共混c物的n和Z均大于PP;Mo法求得的参数F(T)随结晶度的增加而增加,PP的F(T)大于PP/HYBRAR;由c Kissinger法计算的PP和PP/HYBRAR之活化能分别是185 86.k J/mol、239 56.k J/mol。     

PP/PA6/SiO_2纳米复合材料的非等温结晶动力学

采用熔融插层法在双螺杆挤出机上制备聚丙烯(PP)/聚酰胺(PA) 6/二氧化硅(SiO_2)纳米复合材料。通过差示扫描量热仪对体系的非等温结晶动力学进行研究,并采用莫志深(Mo)法对PP复合材料的非等温结晶动力学数据进行分析。结果表明,加入PA6和SiO_2,对PP有异相成核的作用,能提高PP的结晶速率和结晶度;随着降温速率增加,PP/PA6/SiO_2复合材料的结晶度增大。运用Mo法研究纯PP和PP/PA6/SiO_2复合材料的非等温结晶动力学过程,效果理想。结果显示,随着结晶度的增大,PP及其复合材料在单位时间内需要更大的冷却速率才能达到特定的结晶度。并且在相同的结晶度条件下,PP/PA6/SiO_2复合材料的结晶速度比纯PP的结晶速度快。     

PP/空心玻璃微珠复合材料非等温结晶研究

采用熔融共混挤出的方法,制备了聚丙烯(PP)/空心玻璃微珠(HGB)复合材料,用差示扫描量热法研究了PP和PP/HGB复合材料的非等温结晶过程,并通过Jeziorny和莫志深方程研究了非等温结晶动力学。结果表明,随降温速率的增大,PP和PP/HGB复合材料的结晶峰温和结晶度降低,结晶速率增大;HGB的加入降低了PP的结晶速率。     

滑石粉对PLA/PBAT共混物非等温结晶行为的影响

采用差示扫描量热法研究了滑石粉(Talc)对聚乳酸/聚己二酸-对苯二甲酸丁二醇酯(PLA/PBAT)共混物非等温结晶行为的影响。结果表明,随着Talc用量的增加,结晶完成时间缩短,结晶温度向高温移动,且结晶度增大,这说明Talc可以起到异相成核剂的作用,显著提高共混物的结晶能力。此外,降温速率对共混物的非等温结晶行为也有显著影响。较低的降温速率有利于得到结晶度更高的PLA/PBAT共混材料。利用Jeziorny法对共混物的非等温结晶动力学进行研究。结果发现,在相同降温速率下,随着Talc含量的增加,结晶速率常数显著增大,而半结晶时间随之减小。在不同降温速率下得到的含Talc共混物的Avrami指数(n)接近3,故其成核机理是以异相成核为主,球晶生长方式为三维生长。     

废旧丁腈橡胶粉/聚丙烯复合材料的非等温结晶行为

采用熔融共混法制备了废旧丁腈橡胶粉/聚丙烯(WNBR/PP)和废旧丁腈橡胶粉/聚丙烯接枝马来酸酐/聚丙烯(WNBR/PP-g-MAH/PP)复合材料,采用差示扫描量热仪研究了PP、WNBR/PP及WNBR/PP-g-MAH/PP复合材料的非等温结晶过程,并通过Jeziorny方程研究了复合材料的非等温结晶动力学。结果表明,随降温速率的增大,所有试样的结晶峰温和结晶起始温度均向低温偏移,结晶度减小,结晶速率增大。WNBR能起到异相成核的作用,提高了PP的结晶速率,并且导致PP结晶成核和生长机理发生改变。     

PP-TPEE共混物的结晶性能

采用双螺杆挤出机,制备了聚丙烯(PP)、热塑性聚酯弹性体(TPEE)、聚丙烯接枝甲基丙烯酸缩水甘油酯(PP-g-GMA)共混体系。通过X射线衍射仪(XRD)与差示扫描量热仪(DSC)考察了共混物的结晶行为。XRD分析结果表明:TPEE与PP-g-GMA的加入使PP的晶面参数发生变化,晶面间距增大。DSC测试结果表明:TPEE的加入使得共混物的热结晶温度升高、结晶度降低;随着PP-g-GMA含量的增加,共混物的结晶度进一步减小;随DSC测试降温速率的增大,纯PP与PP-TPEE共混物的热结晶温度向低温方向移动。     

HYBRAR对PP结晶形态和性能的影响

采用熔融共混法制备了聚丙烯（PP）和两种牌号的高性能热塑性弹性体HYBRAR的共混物。通过观察共混物的结晶形态，研究共混物结晶性能以及测试共混物的透光率，结果表明：加入HYBRAR后，PP的主要晶型（α晶）不变，结晶温度升高，同时结晶尺寸变小，结晶度显著提高；PP／HYBRAR7125共混体系的结晶速率呈现不规律变化，而PP／HYBRAR7311体系则先降低再升高；加入HYBRAR后，PP的透光率明显提高。     

高相对分子质量成核剂改性聚丙烯的非等温结晶动力学和力学性能研究

采用差示扫描量热仪(DSC)研究了高相对分子质量成核剂（PNA）改性聚丙烯( PP)在不同的降温速率下的非等温结晶动力学,并使用电子万能试验机测定了PP和PNA改性PP的力学系能。用修正Avrami 方程的Jeziorny 法来处理PNA改性PP 的非等温结晶行为。结果表明,在各个降温速率下,PNA的加入都能够明显降低PP相对结晶度达到50%的时间（t1/2）,加入0.3份PNA的PP与纯PP相比,其t1/2仅为纯PP的64.9 %,加入PNA后,结晶动力学常数( Zc ) 增加,结晶速率增加; PP的n值随着降温速率的增加而降低,而加入PNA后,n值随着降温速率的增加而升高,加入PNA后,PP的拉伸强度和冲击强度能够同时提高。     

动态硫化对三元乙丙橡胶/聚丙烯共混体系等温结晶行为和形态结构的影响

研究了三元乙丙橡胶/聚丙烯(EPDM/PP)共混物和动态硫化EPDM/PP热塑性弹性体(TPV)的等温结晶行为及形态结构,并用Avrami方程对其进行等温结晶动力学分析。结果表明,EPDM/PP共混物和EPDM/PP TPV的等温结晶行为符合Avrami方程,在相同的结晶温度下,TPV比共混物的Avrami指数小,半结晶时间短,结晶速率常数大;EPDM/PP共混物为双连续相结构,而EPDM/PP TPV是以硫化的细小橡胶颗粒为分散相、PP为连续相的"海-岛"结构,橡胶颗粒尺寸约为0.5μm。     

金属粉末注射成型用催化脱脂黏结剂 POM/PP 共混物非等温结晶动力学研究

利用聚甲醛(POM)在酸性气氛下发生快速降解、聚丙烯(PP)耐腐蚀性优良的特点,采用POM/PP共混物作为金属粉末注射成型用催化脱脂黏结剂的主要组分。通过差示扫描量热法研究了POM和POM/PP共混物的非等温结晶过程及不同冷却速率对POM/PP(90/10)共混物结晶行为的影响。分别采用Jeziorny法、Ozawa法和Mo法进行处理。结果表明,随着冷却速率的增大,POM及其共混物的结晶峰变宽,结晶峰值温度(T_c)逐渐降低;在相同冷却速率下,共混物的T_c较纯POM有所降低;Jeziorny法和Mo法处理非等温结晶过程比较理想,而由于次级结晶的存在Ozawa法并不适用;Jeziorny法和Mo法处理所得的数据表明,PP的加入能够降低POM的结晶速率,延长半结晶时间(t_(1/2)),并导致POM的结晶成核和生长发生了改变,减缓POM的结晶。     

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。