4A分子筛和SiO2对EVA/IFR复合材料性能的影响

以聚磷酸铵(APP)复配季戊四醇(PER)为膨胀型阻燃剂(IFR)制备了无卤阻燃乙烯-醋酸乙烯共聚物(EVA)/IFR复合材料,通过极限氧指数仪、热失重分析仪及扫描电子显微镜研究分析了4A分子筛和SiO2的加入对复合材料阻燃性能、热稳定性能及复合材料残炭表面形貌的影响。结果表明,加入4A分子筛可以明显提高复合材料的极限氧指数,当添加1份4A分子筛时,复合材料的极限氧指数达到31%,比未添加时提高了2%;4A分子筛的加入使复合材料在燃烧过程出现熔融滴落现象;继续加入SiO2可以进一步提高复合材料的极限氧指数,当添加3份SiO2时,复合材料的垂直燃烧测试达到V-0级。     

微晶纤维素对阻燃聚乳酸复合材料力学性能、阻燃与热稳定性的影响

以经硅烷偶联剂(KH570)处理的微晶纤维素(MCC)为填料,三嗪系膨胀阻燃剂(CFA)与聚磷酸铵(APP)的复配体系为阻燃剂(C-IFR),聚乳酸(PLA)为基体树脂,采用熔融共混方法制备阻燃MCC/PLA复合材料,研究了MCC对阻燃PLA复合材料的力学、阻燃性能、热稳定性的影响。力学试验结果显示,MCC加入使PLA和阻燃PLA均比纯基体树脂的拉伸强度、弯曲强度有所降低,对悬臂梁缺口冲击强度影响小。MCC在小添加量时可以提高PLA复合体系的极限氧指数,MCC与APP具有的协同效应降低了PLA的燃烧速率,提高了材料的成炭性能。热降解动力学表明,MCC增加了PLA和阻燃PLA材料的活化能,提高了PLA复合材料的热稳定性,同时MCC降低PLA的玻璃化转变温度。     

膨胀型阻燃PP纳米复合材料的燃烧性能

将纳米SiO2、磷系阻燃剂1,3,5-三(5,5-二甲基-1,3-二氧杂环己内磷酸基)苯(FR)和聚磷酸铵(APP)加入聚丙烯(PP)中,制备膨胀型阻燃PP纳米复合材料.采用氧指数测定仪、垂直燃烧测定仪、锥形量热仪对PP纳米复合材料的燃烧性能进行研究.结果表明:FR/APP/SiO2提高了PP的氧指数、垂直燃烧等级和残炭率,降低了热释放速率,燃烧烟气中的CO、CO2浓度.在ω(FR):ω(APP):ω(SiO2)=15:7:3,IFR的含量为25%的情况下,PP的氧指数为29.4%,UL-94等级达到V-0.     

乙醇再生微晶纤维素的分级及其结构表征

在微晶纤维素（MCC）的Na OH/尿素溶液中加入不同质量的无水乙醇进行分级沉降，得到分级再生微晶纤维素。通过黏度法测定了再生微晶纤维素的聚合度，采用FTIR、XRD、XPS、TG和SEM对再生微晶纤维素的结构、结晶度、热稳定性和形貌进行了表征。结果表明，随着分级次数的增加，再生微晶纤维素的聚合度逐渐降低，3次分级后微晶纤维素的聚合度由MCC的203降至77；微晶纤维素形貌由表面光滑的棒状纤维结构变为粗糙多孔的结构；再生微晶纤维素的晶型由MCC的Ⅰ型转变为Ⅱ型，3次分级后微晶纤维素的结晶度由MCC的65.58%降至32.05%。分级再生微晶纤维素的自由羟基增加，参与成键的羟基减少；再生微晶纤维素的热稳定性随着分级次数的增加而降低，3次分级后初始分解温度由MCC的310℃降至257℃。     

PP/APP/磷系阻燃剂FR复合材料的燃烧性能研究

将新型磷系阻燃剂1,3,5-三(5,5-二甲基-1,3-二氧杂环己内磷酸基)苯(FR)、无规聚丙烯(APP)加入聚丙烯(PP)中制备了 PP/APP/FR 复合材料,采用极限氧指数测定、垂直燃烧实验(UL94)、锥形量热分析对复合材料燃烧性能进行了研究。结果表明,APP/FR 提高了 PP 复合材料的氧指数和垂直燃烧性能级别,延长了点燃时间,降低了热释放速率和燃烧烟气中的 CO、CO_2浓度,阻燃效果显著。当15%(质量分数,下同)FR 和10%APP 复配阻燃 PP 时,复合材料的氧指数达29.6%,UL94 V-0级。     

不同天然大分子在膨胀型阻燃TPV复合材料中的作用

选择了纤维素、壳聚糖、淀粉三种天然大分子作为碳源,聚磷酸铵(APP)作为酸源和气源,按1∶2的质量比复配成三种不同的膨胀型阻燃剂。然后将三种膨胀阻燃剂添加到热塑性动态硫化橡胶(TPV)材料中,通过熔融共混的加工方法,制备得到阻燃TPV复合材料。力学性能测试实验显示,不同碳源的阻燃TPV复合材料的力学性能依次为:纤维素>壳聚糖>淀粉。极限氧指数和垂直燃烧实验结果表明:当阻燃剂质量分数达到30%时,以纤维素作为碳源的TPV复合材料的阻燃性能最好,其氧指数最高为25%,相对于纯TPV的19%,提高了6%,而且能达到V-1等级;壳聚糖和淀粉为碳源TPV复合材料的氧指数分别达到了23%和22%,且都能达到V-2等级。通过TGA和SEM研究了阻燃机理,结果表明,与其他两种碳源相比,纤维素为碳源的TPV复合材料的热稳定性最高,且在燃烧时能形成更加致密的炭层。     

EG协同三嗪系大分子膨胀型阻燃剂阻燃HDPE研究

研究了EG协同三嗪系大分子膨胀型阻燃剂阻燃HDPE,通过极限氧指数(LOI)、热重分析(TGA)、扫描电镜(SEM)等测试手段进行了分析。结果表明当EG与APP/CFA/SiO2共同使用阻燃HDPE的氧指数比单独加入两种阻燃剂的氧指数都有所提高,SEM测试表明EG与APP/CFA/SiO2共同使用燃烧后表面形成一层致密的保护层,阻止了聚合物的进一步燃烧。     

新型成炭剂对EVA/APP体系的阻燃性能影响研究

以新型成炭剂聚对苯二甲酰乙二胺(PETA)和聚磷酸铵(APP)复配制备了无卤阻燃乙烯-醋酸乙烯共聚物(EVA)/APP/PETA复合材料,通过极限氧指数法和垂直燃烧法表征了复合材料的阻燃性能,通过热失重分析仪(TGA)和扫描电镜(SEM)分析了复合材料的热稳定性能和残炭表面形貌。结果表明:APP与PETA复配(IFR)后可以极大地提高EVA的阻燃性能,EVA/APP/PETA(质量比70/25/5)体系极限氧指数(LOI)达到39%,较纯EVA提高了88.4%,UL 94测试为V-0级别;EVA/APP/PETA复合材料在600℃下的残炭率达到了42%,较纯EVA残炭率高37%。SEM表明:30%IFR(APP与PETA质量比5:1)的加入提高了样品残炭表面致密性。     

基于离子液体再生的纤维素热解特性

利用离子液体1-丁基-3-甲基咪唑氯([Bmim]Cl)溶解PH-101微晶纤维素,通过不同的再生方法获得两种再生的纤维素,并利用XRD确定其结晶度,场发射扫描电镜(SEM)获得其形貌特征,热重(TG)分析表征其热稳定性.采用Py-GC/MS 对不同结晶度纤维素进行快速热解,并对热解挥发分进行在线分析,观察结晶度对纤维素热解特性的影响.研究表明左旋葡聚糖产率随结晶度降低而减少,而小分子产物随结晶度降低而增多.     

PP/纳米SiO2复合材料的阻燃性能研究

将磷系阻燃剂1,3,5-三（5,5-二甲基-1,3-二氧杂环己内磷酸基）苯（FR）、聚磷酸铵（APP）、纳米SiO2复配,制备聚丙烯(PP)纳米复合阻燃材料。采用氧指数测定仪、水平垂直燃烧测定仪、热重分析仪、锥形量热仪对PP纳米复合阻燃材料的阻燃性能进行了研究。结果表明,FR/APP/SiO2提高了PP的氧指数、水平燃烧等级、热稳定性和残炭率,降低了热释放速率。当阻燃剂FR/APP/SiO2的总体含量为25 %,FR/APP/SiO2配比为15/7/3的情况下,PP纳米复合阻燃材料的氧指数为29.4 %,水平燃烧等级为FH-1。     

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.