氯化锌对聚酰胺1010/氯化锌复合材料结构与性能的影响

利用熔融挤出法制备了聚酰胺1010(PA1010)/氯化锌(ZnCl2)复合材料,研究了ZnCl2的含量对PA1010/ZnCl2复合材料的结晶行为、力学性能、光学性能的影响。结果表明:随着ZnCl2含量的增加,PA1010/ZnCl2复合材料的结晶不完善程度增大,熔点降低。另外,PA1010/ZnCl2复合材料的拉伸强度随着ZnCl2含量的增加逐渐增大,当ZnCl2含量为8%时,复合材料的拉伸强度达到最大值66.2 MPa,与PA1010(52.2 MPa)相比提高了26.7%。当ZnCl2含量为8%时,可以得到熔点较低,力学性能优良和透光率较好的PA1010/ZnCl2复合材料。     

火焰喷涂PA1010/nano-ZrO2复合涂层的非等温结晶动力学

利用火焰喷涂法制备了聚酰胺1010 (PA1010)/纳米氧化锆（nano-ZrO₂）复合涂层。采用示差扫描量热法（DSC）研究其非等温结晶行为，对所得的数据分别用Jeziorny法、Ozawa法和Mo法进行处理。结果表明，用Jeziorny法和Mo法处理非等温结晶过程比较理想，而Ozawa法不适用。用Jeziorny法求出的参数Z_c(结晶速率常数）和n（Avrami指数)均随降温速率的增加而增加;nano-ZrO₂的加入使复合涂层的Z_c和n略大于纯PA1010涂层;并使复合涂层结晶半衰期降低、结晶速率及结晶度增大。表明nano-ZrO₂具有明显的成核剂作用，加快PA1010的结晶速率，提高涂层的结晶度。     

偶联剂对火焰喷塑复合涂层结构和性能的影响

利用拉力试验机、扫描电子显微镜及付里叶变换红外光谱仪,研究了偶联剂TPM对火焰喷涂尼龙1010/石墨复合涂层微观结构、化学结构和力学性能的影响。结果表明,偶联剂TPM能明显改善尼龙1010大分子与石墨之间的相容性,使复合涂层性能得到改善,获得了自拉伸强度大于35MPa,结合强度大于17MPa的复合涂层。     

水热电沉积法制备羟基磷灰石/氧化钛复合涂层的研究

采用水热电沉积法．在钛金属基体￡：成功制备了羟基磷灰石(hydroxyapatite,HA)氧化钛(HA／TiO2)复合涂层．对涂层的表面形貌、相组成、TiO2共沉积量、热稳定性和结合强度进iir研究。实验结果表明：复合涂层具有较均匀的微观结构。TiO2的加入明显改善了涂层与基体的结合强度．涂层中TiO2含量越高．结合强度的提高也越显著。在200℃．100g／L TiO2条件下．电沉积制备的HA／TiO2复合涂层的结合强度为21.0MPa,约为纯HA涂层的2倍。TiO2共沉积量随电解液中TiO2浓度的提高逐渐增加;随电解液温度的提高先增后降,在160C达到最大。涂层经800℃热处理后,TiO2促使HA部分分解为β-磷酸钙(β-tricalciumphosphate,β-TCP)和CaO;经1200℃热处理后,HA和TiO2发生相互作用生成α-TCP和CaTiO3。     

PA6/CaCl_2/E44复合体系的结构与性能研究

利用熔融挤出法制备了聚酰胺6(PA6)/CaCl2/环氧树脂(E44)复合材料,研究了E44用量对PA6/CaCl2/E44复合体系的结晶、力学、耐热、光学及加工性能的影响。结果表明:随着E44含量的增加,复合体系的熔融温度向低温方向移动,PA6结晶受到限制。复合体系的冲击强度、拉伸强度、弯曲强度、维卡软化温度均随E44含量的增加而表现为先增大后减小的趋势,当E44含量为3份时,复合体系的冲击强度、拉伸强度、维卡软化温度均达到极值,分别为8.9 kJ/m2、78.2 MPa、64.8℃,与PA6/CaCl2(6.0 kJ/m2、47.0 MPa、57.7℃)相比分别提高了48%、66%、12%。结合复合体系PA6/CaCl2/E44的光学性能得知,当E44含量为3份时,可以得到力学性能优良、维卡软化温度较高、透明性及加工性能较好的低熔点PA6/CaCl2/E44复合材料。     

PA11/PA1010共混物的性能研究

采用熔体共混的方法制备了聚酰胺11/聚酰胺1010(PA11/PA1010)共混物,通过力学性能和差示扫描量热(DSC)测试,研究了PA11/PA1010共混物的力学与结晶性能。测试结果表明:PA1010对PA11同时具有增韧、增强作用;当PA11/PA1010为70/30时,共混物开始出现两个结晶峰和低温熔融峰;共混物的结晶和熔融以PA11为主,兼具有PA11和PA1010的优良性能;断裂伸长率、拉伸强度与缺口冲击强度均达到极大值。     

火焰喷涂聚酰胺12/n-SiO2复合涂层工艺及性能

采用火焰喷涂法制备了聚酰胺12(PA12)及聚酰胺12/纳米SiO2(n-SiO2)复合涂层,并利用电子拉力机、摩擦磨损试验机、红外光谱仪(FTIR)和示差扫描量热仪(DSC)等对涂层的结构与性能进行了研究.红外光谱分析表明PA12及PA12/n-SiO2粉末在火焰喷涂过程中没有发生氧化或降解反应,表明火焰喷涂法适宜制备PA12及PA12/n-SiO2复合涂层;DSC分析结果表明n-SiO2具有成核剂作用,能提高PA12大分子的结晶速度及结晶度;涂层力学性能及摩擦磨损性能分析表明n-SiO2能提高涂层的力学性能,改善涂层的耐老化性能和摩擦磨损性能.当n-SiO2添加量为1.5%(质量)时,涂层综合性能最佳.     

(PA1010/66)/SEBS-g-MAH/DIDP/BSBA共混物的制备与性能研究

将尼龙(PA)1010盐和PA66盐按照质量比为9∶1的比例制备了PA1010/66共聚物。选择(苯乙烯/乙烯-丁烯/苯乙烯)共聚物接枝马来酸酐(SEBS-g-MAH)和两种小分子增塑剂邻苯二甲酸二异癸酯、N-丁基苯磺酰胺(D IDP、BSBA),采用共混挤出法制备了(PA1010/66)/SEBS-g-MAH/D IDP/BSBA共混物,并对其力学性能进行了研究。结果表明,随着SEBS-g-MAH含量的增加,共混物的冲击强度明显提高。当SEBS-g-MAH质量分数为15%时,其缺口冲击强度为72.7 kJ/m2,是PA1010/66共聚物的16倍左右;拉伸强度保持率是PA1010/66共聚物的83%左右。通过SEM研究发现,SEBS-g-MAH对PA1010/66共聚物的增韧机理为银纹剪切带增韧机理。     

PA1010含量对PLA/PA1010共混物性能的影响

通过双螺杆挤出机制备了不同尼龙1010含量的聚乳酸/尼龙1010 (PLA/PA1010)共混物。用差示扫描量热分析(DSC)、熔体质量流动速率(MFR)、扫描电镜(SEM)、力学性能测试等方法研究了PLA/PA1010共混物的结晶行为、断面形态和力学性能。研究表明,加入PA1010后,改善了聚乳酸的结晶能力,特别是当PA1010质量分数为10%时,对促进聚乳酸的结晶比较有效。当PA1010质量分数为10%时,熔体黏度最小,熔体质量流动速率最好,充分显示出PA1010较好的熔体流动性。共混物力学性能测试结果表明,当PA1010质量分数达到10%时,共混物的断裂伸长率和缺口冲击强度分别达到最佳值;分别为13. 43%和3. 84 k J/m~2,与纯PLA相比分别提高了52. 79%和19. 63%。     

OMMT和CaCO_3对PA1010纳米复合材料体系力学性能和形貌的影响

用有机蒙脱土(OMMT)和nano-CaCO3作为填充粒子与聚酰胺1010(PA1010)一起,通过双螺杆挤出机用熔融共混法制备两种体系的PA1010/OMMT/nano-CaCO3三元纳米复合材料,通过扫描电子显微镜(SEM)和力学性能测试研究了OMMT作用的PA1010/nano-CaCO3体系和nano-CaCO3作用的PA1010/OMMT体系。结果表明:OMMT/PA1010/nano-CaCO3中,OMMT与基体间的界面吸附力弱化了nano-CaCO3与基体的吸附力,使得OMMT在小含量添加范围内(<2份)体系韧性提高的同时,明显改善了拉伸强度和弯曲强度。而加入nano-CaCO3的nano-CaCO3/PA1010/OMMT,由于两种无机粒子之间对基体的作用处于一种相互抵消的平衡状态,使得体系韧性改变不明显。     

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.