邻苯二甲酸二烯丙基酯树脂固化特性的研究

运用示差扫描量热(DSC)法研究了邻苯二甲酸二烯丙基酯(DAP)树脂的固化反应历程。讨论了引发剂对DAP固化特性的影响,并由DSC曲线得到了DAP树脂的固化工艺和动力学参数。通过固化度、FT-IR的测试对DAP树脂在中温条件下的固化情况进行了研究。结果表明:在过氧化二异丙苯(DCP)固化体系中引入BPO可以使DAP树脂在更低温度下引发固化;在BPO、DCP用量均为2%的条件下,确定了体系的凝胶温度、固化温度、后处理温度分别为:100.5℃,124.3℃,137.8℃,表观活化能为129.3 kJ/mol,反应级数为0.950。固化度、FTIR的测试结果表明:DAP树脂在中温条件下可以固化得较完全。     

乙烯基酯树脂固化条件及其复合材料的研究

研究了过氧化二苯甲酰(BPO)、过氧化二异丙苯(DCP)、过氧化苯甲酸叔丁酯(TBPB)3种固化剂对乙烯基酯树脂固化工艺的影响,并根据固化工艺制备出树脂浇铸体及其碳纤维复合材料。采用差示扫描量热(DSC)法研究了不同树脂固化体系的反应放热特性,采用扫描电镜(SEM)分析了浇注体的断面的表面形态。并对浇注体及复合材料进行了力学性能测试和热稳定性表征,结果表明制得的复合材料具有优良的力学性能和热稳定性。     

马来酸酐接枝POE改性SAN树脂的制备与性能研究

利用熔融接枝法制备了马来酸酐接枝乙烯-辛烯共聚物（POE-g-MAH），探讨了过氧化异丙苯（DCP）和马来酸酐（MAH）用量对POE—g—MAH接枝率的影响，得出了最佳的DCP和MAH用量分别为0．10份和2．0份。将不同接枝率的POE—g—MAtt与丙烯腈-苯乙烯共聚物（SAN树脂）共混，发现POE—g—MAH的接枝率越高，对POE—g-MAH／SAN体系的缺口冲击强度的提高越显著。     

DCP对PP/GF/UP复合材料性能的影响

以聚丙烯(PP)及玻璃纤维(GF)为原料,以不饱和树脂(UP)作为界面相容剂,研究过氧化二异丙苯(DCP)含量对玻璃纤维增强PP复合材料力学性能、界面和结晶行为的影响.结果表明:DCP的加入改善了PP/GF/UP复合材料的流动性,复合材料的拉伸、弯曲和冲击性能先上升后下降,且在UP和DCP质量含量分别为5%和0.2%时,出现极大值.随DCP的增加,结晶峰温度先向低温偏移,后向高温偏移,而结晶度变化趋势相反.     

动态DSC法研究UP树脂/CaCO3体系的固化工艺

采用差示扫描量热 (DSC)仪对UP树脂 (不饱和聚酯 ) /CaCO3 复合体系的固化过程进行动态研究 ,得出了体系在不同升温速率下固化过程中的DSC曲线 ,根据动态DSC曲线探讨了UP树脂 /CaCO3 复合体系分阶段变温固化新工艺。     

动态DSO法研究UP树脂／OaCO3体系的固化工艺

采用差示扫描量热(DSC)仪对UP树脂(不饱和聚酯)／CaCO3复合体系的固化过程进行动态研究，得出了体系在不同升温速率下固化过程中的DSC曲线，根据动态DSC曲线探讨了UP树脂／CaCO3复合体系分阶段变温固化新工艺。     

聚烯烃接枝马来酸酐的反应挤出研究

研究了聚乙烯（PE），聚丙烯（PP）接枝马来酸酐（MAH）的反应挤出，进行了反应体系的热分析，讨论了引发剂过氧化二异丙苯（DCP）和PE／DCP和PP／DCP体系的影响，以及DCP、MAH和电子给予体（EDA）和LDPE／DCP／MAH和PP／DCP／MAH两种接枝体系的影响。     

ABS树脂熔融接枝马来酸酐的研究

研究了在双螺杆挤出机中使用自制的引发剂进行马来酸酐（MAH）熔融接枝（丙烯腈／丁二烯／苯乙烯）共聚物（ABS）的反应，对反应机理进行了讨论，红外光谱分析证明，MAH成功地被接枝到ABS的主链上，对ABS的组分分离证明接枝发生在ABS的丁二烯部分。研究了MAH用量，引发剂含量，反应温度和螺杆转速及溶剂对接枝反应的影响，发现接枝率随着MAH用量的增加，反应时间和螺杆转速的增加而增大；当增大引发剂含量时，接枝率呈现先增加后降低的趋势，自制引发剂比常用的过氧化二异丙苯（DCP）或过氧化苯甲酰（BPO）引发剂接枝效果要好得多，而且受加工条件的影响小。     

PP熔融接枝MAH的研究

以PP（EPS30R）为基体树脂,过氧化二异丙苯DCP为引发剂,在反应体系中加入少量的DMF（N,N-二甲基甲酰胺）,在双螺杆挤出机中于175℃-190℃进行了PP熔融接枝MAH的反应。用红外光谱表征了接枝反应的存在,并考察了引发剂用量、N,N-二甲基甲酰胺（DMF）的用量、单体用量对接枝反应的影响。研究表明：DMF能抑制PP的降解,并且确定了较佳的原料配比为m（PP）：in（MAH）：m（DMF）：In（DCP）：100：3：0．6：0．4,其接枝率可达2．95％。     

HDPE接枝马来酸酐粘接树脂熔融接枝工艺的研究

制备了高密度聚乙烯(HDPE)接枝马来酸酐(MAH)粘接树脂,进一步对接枝工艺进行研究。结果表明,MAH的含量、过氧化二异丙苯(DCP)的含量、共混时间都会对粘接效果产生影响。共混时间为8 min时,接枝反应已经很充分;当添加1.5份MAH和0.1份DCP时,接枝率达到最大值0.815%,此时综合粘接效果最好。     

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.