玻纤毡增强聚丙烯复合材料的增容及力学性能

通过玻璃纤维(GF)毡与双螺杆挤出相容剂改性聚丙烯(PP)膜的多层叠合,以熔融浸渍法制得PP基GF毡增强热塑性塑料(GMT)复合材料,研究了相容剂PP接枝马来酸酐(PP-g-MAH)和PP接枝丙烯酸(PP-g-AA)的用量(为PP基体质量的百分数)及其复配改性,以及相容剂改性PP基体分布和毡体种类对GMT力学性能的影响。结果表明,PPg-MAH可明显提高GMT的拉伸与弯曲性能,但降低了冲击性能;PP-g-AA可明显提高GMT的冲击性能,但不利于拉伸与弯曲性能的提高,只有当PP-g-AA用量超过5%后,拉伸性能才有所提升。在PP-g-MAH用量为3%的条件下,将其与不同用量的PP-g-AA进行复配改性没有对GMT力学性能产生协同作用。在各相容剂用量相近(3%~3.5%)的情况下,与相容剂复配改性GMT相比,以两层PP-g-AA改性PP为芯层、PP-g-MAH改性PP为上下表面层作为改性基体分布时,GMT拉伸与弯曲强度分别提高17%和27%、缺口冲击强度提高48%;而以两层PP-g-MAH改性PP为芯层、PP-g-AA改性PP为上下表面层作为改性基体分布时,在不损失强度与刚性的同时,缺口冲击强度提高了88%。采用连续GF毡的GMT力学性能比采用短切GF毡的GMT高,尤其是缺口冲击强度提高了89.6%。     

长玻璃纤维增强PP/m-PA6复合材料的制备及性能研究

采用熔融拉挤工艺技术制备了长玻璃纤维增强聚丙烯/聚酰胺6[LFT- (PP/m-PA6)]粒料,并研究了材料的界面相互作用情况、力学性能和流变性能。结果表明, m-PA6改善了PP树脂与玻纤之间的润湿性和浸淆性, 提高了界面粘接强度, 使LFT-(PP/m-PA6)的拉伸强度和弯曲强度增加、刚性增强、韧性基本不变; 当长玻纤含量相同时, 以均聚PP（F401）为基质的长玻纤增强聚丙烯（LFT-PP）和LFT-(PP/m-PA6)的力学性能高于以共聚PP（K712）为基质的LFT-PP和LFT-(PP/m-PA6),特别是缺口冲击强度明显提高;在-30 ℃下,LFT-PP（F401）的缺口冲击强度提高了3.91 %,LFT-PP（K712）的缺口冲击强度提高了7.53 %; m-PA6起到了界面润滑作用, 能使LFT-(PP/m-PA6)的流动性能更好。     

成核剂对聚丙烯结晶形态和力学性能的影响

研究了聚丙烯(PP)／成核剂共混物的结晶形态及力学性能。结果表明：加入成核剂后，提高PP的结晶温度，加快了结晶速度，使PP球晶细化；成核剂用量在0—0．2份之间时，PP的冲击强度、拉伸强度、硬度、热变形温度均随成核剂用量的增加而提高。     

剑麻纤维增强聚丙烯复合材料的力学性能研究

本文介绍了剑麻纤维(SF)增强聚丙烯(PP)复合材料的制备方法，测定了不同纤维长度下．采用不同PP含量复合材料的无缺口冲击强度、弯曲强度和弯曲模量．并借助扫描电子显微镜对SF/PP复合材料的无缺口冲击破坏断口进行观察。结果表明，在一定范围内增加纤维长度和降低基体含量有利于复合材料力学性能的提高。     

后背门用长纤维增强聚丙烯复合材料的性能研究

研究了不同长玻璃纤维含量、不同拉伸速率以及不同的润滑体系对长纤维增强聚丙烯复合材料(LFT-PP)的力学性能的影响。结果表明,LFT-PP材料的拉伸强度和拉伸模量随着应变速率和纤维含量的增加而有不同程度的上升,而断裂伸长率则随之下降。不同润滑体系对LFT-PP的力学性能影响不同,而对于同一种润滑体系来说,随着润滑剂含量的上升,LFT-PP的力学性能先稍有提升而后趋于稳定。     

高流动性GMT材料制备

采用过氧化二异丙苯(DCP)来调节聚丙烯(PP)的摩尔质量,考察了DCP对PP的熔体质量流动速率(MFR)和力学性能的影响,并以此降解产物制得高流动性的增强增韧GMT材料.结果表明:随DCP用量的增加,基体树脂的MFR几乎呈线性增大,其弯曲模量与强度在DCP用量为0.1%时达最大值,分别提高30%和16%,拉伸性能变化不大,但冲击强度不断下降;高流动性GMT材料的力学性能较原基体增大10%～20%;在高流动性GMT中加入增韧剂后,保持其它性能不变的情况下冲击强度增大45%以上.     

长玻璃纤维增强聚丙烯复合材料的力学性能

采用自主开发的在线混合生产设备,以玻璃纤维(GF)和聚丙烯(PP)为原料,制备了长玻璃纤维增强聚丙烯(LFT-PP)复合材料。研究了GF长度、分散度以及界面改性剂对LFT-PP力学性能的影响。结果表明,GF长度的增加,有利于提高LFT-PP的弯曲强度和冲击强度,对弯曲模量的影响很小。添加适量的界面改性剂有利于提高复合材料的弯曲性能,但是降低了其冲击强度。     

芳纶纤维对丁腈橡胶绝热材料性能的影响

比较了不同规格芳纶纤维在软丁腈橡胶胶料中的分散性，并研究了芳纶纤维/软丁腈橡胶的耐烧蚀性和力学性能。结果表明，不同长度但同一用量的芳纶纤维加入到丁腈橡胶中，芳纶纤维长度较小，分散性较好，其硫化胶耐烧蚀性较好。随着芳纶纤维用量的增大，胶料延伸率下降；当芳纶纤维用量大于6.1份时，胶料延伸率急剧下降且不足100%,几乎没有使用价值；当芳纶纤维用量超过一定值时，随着芳纶纤维用量的增大，硫化胶拉伸强度增大；与短切芳纶纤维相比，芳纶浆粕易与丁腈橡胶混炼均匀，可使胶料保持良好的加工工艺性能。     

长玻璃纤维增强聚丙烯复合材料的韧性

以玻璃纤维和聚丙烯为原料,制备了长玻璃纤维增强聚丙烯(LFT-PP)复合材料,研究了基体韧性、纤维长度和界面相容剂对LFT-PP韧性的影响。结果表明LFT-PP韧性随基体韧性增加而增加;当玻璃纤维长度从2.06mm增加到4.66mm时,LFT-PP的悬臂梁缺口冲击强度从134.4J/m提高到238.0J/m,增加了约80%;添加界面改性剂降低了LFT-PP悬臂梁缺口冲击强度,从311.4J/m降为181.8J/m。     

高性能木纤维增强聚丙烯复合材料的制备

采用双螺杆挤出机制备了木纤维（松木粉）增强聚丙烯（PP）复合材料，并对其力学性能及形态结构进行了研究。结果表明，用马来酸酐接枝PP（PP-g-MAH)作增容剂可有效地增加基体与木纤维之间的粘合作用，使木纤维增强PP复合材料的拉伸强度，弯曲强度和弯曲弹性碍都得到很大提高；在木纤维增强PP复合材料中加入三元乙丙橡胶（EPDM）进行增韧，可在高木纤维含量下使复合材料基本保持纯PP的力学性能。     

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.