掺杂氧化锌晶须的聚氨酯涂料抗静电性能研究

针对目前高分子抗静电材料制备过程中,存在因氧化锌晶须电阻率较高导致的氧化锌晶须添加量过大和抗静电效果较差等问题,采用新的铝掺杂方法,显著地降低了氧化锌晶须的本体电阻率,研究了铝掺杂对氧化锌晶须电阻率的影响。含20%掺量的氧化铝使氧化锌晶须的表面电阻率从107~108Ω.cm降低到1.6×106Ω.cm,体积电阻率从108~109Ω.cm降低到7.1×105Ω.cm;进一步研究了铝掺杂氧化锌晶须对聚氨酯涂料抗静电性能的影响,铝掺杂氧化锌晶须的添加量为8%,涂层的表面电阻率降低到2.4×107Ω.cm。铝掺杂氧化锌晶须可替代氧化锌晶须作为抗静电高分子复合材料的白色导电添加剂。     

掺杂氧化锌晶须对工程塑料抗静电性的影响

采用新的铝掺杂方法,降低了氧化锌晶须电阻率,研究了铝掺杂对氧化锌晶须电阻率的影响。含20%掺量的氧化铝使氧化锌晶须的表面电阻率从107～108Ω降低到1.6×106Ω,体积电阻率从108～109Ω·cm降低到7.1×105Ω·cm;研究了掺杂氧化锌晶须对塑料抗静电性能的影响,铝掺杂氧化锌晶须的添加量为8%(质量分数),使环氧树脂的表面电阻率降低到7.2×1010Ω;铝掺杂氧化锌晶须的添加量为12%(质量分数),使聚苯硫醚的表面电阻率降低到2.0×1010Ω。     

T-ZnOw在水性聚氨酯涂料中的应用研究

采用铝掺杂四针状氧化锌晶须作为功能性填料制备得到多功能水性聚氨酯涂料,其具有良好的抗静电性能、高耐磨性能以及优异的自清洁功能。采用硅烷偶联剂制备了分散性良好的晶须,并研究了晶须含量对涂层抗静电性能和耐磨性能的影响。当晶须含量为8%时,涂层的体积电阻率和表面电阻率分别从10~(15)Ω·cm和10~(16)Ω降低至10~7Ω·cm和10~7Ω,且涂层的磨耗量从22 mg降低至12 mg;此外,铝掺杂氧化锌晶须/聚氨酯涂层具有光催化功能和一定的自清洁功能。     

添加氧化锌晶须的聚丙烯腈纤维抗静电性研究

在聚丙烯腈纺丝原液中添加四针状氧化锌晶须对聚丙烯腈纤维抗静电性具有改善作用。研究表明:氯化锌晶须添加量为1%(相对于聚丙烯腈干粉质量)就可以使聚丙烯腈纤维达到抗静电要求,体积比电阻率为5.4×1010赘·cm。     

氧化锌晶须渗入聚丙烯腈纤维的抗静电性能

在乳液中悬浮的氧化锌晶须渗入聚丙烯腈纤维中,起到抗静电作用,聚丙烯腈纤维的体积比电阻率可降到4.1×108Ω.cm;四针状和单针状的氧化锌晶须的渗入能力不同,得到抗静电性能不同;渗入工艺简单方便,同时解决了氧化锌晶须添加入聚丙烯腈纺丝原液所造成的喷丝孔阻塞问题。     

四角状氧化锌晶须／聚丙烯复合材料的导电性能研究

采用热压成型工艺制备了氧化锌晶须(T-ZnOW)/聚丙烯(PP)复合材料,研究了晶须用量、不同偶联剂处理对复合材料导电性能、介电性能的影响。研究结果表明,T-ZnOW能有效提高PP树脂的导电性能;随着氧化锌晶须含量的增加,复合材料的体积电阻率迅速下降。当v(T-ZnOW)达到3%时,复合材料电阻率降低到109Ω.cm以下,可以满足一般抗静电材料的要求。     

掺铝氧化锌的合成及其电学性能

采用直接沉淀法制备掺铝氧化锌,通过XRD、TEM、UV-Vis和四探针法等手段对样品进行了表征。结果表明,合成的掺铝氧化锌颗粒的粒径大小分布较均匀且均值在20nm左右。同时,我们研究了不同Al掺杂量对材料电阻率的影响,当掺杂量在3mol%时,样品的电阻率最低,其平均值达到了1000Ω.cm。     

磺酸掺杂煤基聚苯胺/HDPE导电复合材料的制备

采用热掺杂法制得十二烷基苯磺酸 (DBSA)掺杂态煤基聚苯胺 (CBP) ,并采用熔融共混工艺 ,制备出HDPE/CBP DBSA导电复合材料 ,研究了掺杂时间和掺杂温度对CBP电导率以及CBP DBSA用量对HDPE/CBP DBSA复合材料电阻率的影响。结果表明 :当m (DBSA)∶m (CBP) =1 6,70℃下退火 2h时 ,CBP DBSA的电导率可达0 179S/cm ;红外光谱说明DBSA对CBP起到了较好的掺杂作用。当CBP DBSA的质量分数为 13 %时 ,复合材料的体积电阻率达到 2 9× 10 7Ω·cm ,同时具有较好的力学性能     

掺杂型ZnOw/纳米ZnO并用对PP性能的影响

研究了铝掺杂氧化锌晶须(ZnOw)和纳米ZnO对聚丙烯共混物力学性能和抗静电性能的影响.结果表明,铝掺杂氧化锌晶须能提高聚丙烯的冲击强度、拉伸强度和表面电阻率.纳米ZnO与掺杂氧化锌晶须并用能协同增强和增韧聚丙烯,纳米ZnO/掺杂氧化锌晶须/聚丙烯的质量比为2/16/82时,共混体系的综合力学性能较好.     

Ni掺杂对Cu_3N薄膜结构与性能的影响

采用射频反应磁控溅射方法在玻璃基底上制备了Ni掺杂Cu3N薄膜,并研究了Ni掺杂对Cu3N的结构、电学性能和光学性能的影响。研究发现:Ni的加入使得Cu3N薄膜的(111)晶面向小角度偏移;随着Ni含量的增加,Cu3N薄膜的电阻率从1450×10-6Ω.cm减小到184×10-6Ω.cm,光学能隙从1.09eV增加到1.52eV。     

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.     

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.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.     

Methyl 2,4,6-decatrienoates Attract Stink Bugs and Tachinid Parasitoids

Halyomorpha halys (Stål) (Pentatomidae), called the brown marmorated stink bug (BMSB), is a newly invasive species in the eastern USA that is rapidly spreading from the original point of establishment in Allentown, PA. In its native range, the BMSB is reportedly attracted to methyl (E,E,Z)-2,4,6-decatrienoate, the male-produced pheromone of another pentatomid common in eastern Asia, Plautia stali Scott. In North America, Thyanta spp. are the only pentatomids known to produce methyl 2,4,6-decatrienoate [the (E,Z,Z)-isomer] as part of their pheromones. Methyl 2,4,6-decatrienoates were field-tested in Maryland to monitor the spread of the BMSB and to explore the possibility that Thyanta spp. are an alternate host for parasitic tachinid flies that use stink bug pheromones as host-finding kairomones. Here we report the first captures of adult and nymph BMSBs in traps baited with methyl (E,E,Z)-2,4,6-decatrienoate in central Maryland and present data verifying that the tachinid, Euclytia flava (Townsend), exploits methyl (E,Z,Z)-2,4,6-decatrienoate as a kairomone. We also report the unexpected finding that various isomers of methyl 2,4,6-decatrienoate attract Acrosternum hilare (Say), although this bug apparently does not produce methyl decatrienoates. Other stink bugs and tachinids native to North America were also attracted to methyl 2,4,6-decatrienoates. These data indicate there are Heteroptera in North America in addition to Thyanta spp. that probably use methyl 2,4,6-decatrienoates as pheromones. The evidence that some pentatomids exploit the pheromones of other true bugs as kairomones to find food or to congregate as a passive defense against tachinid parasitism is discussed.