改性氢氧化镁/PVC复合材料的制备

采用不同改性剂对Mg(OH)2粒子进行改性,吸油值为考察指标,考察了不同改性剂对Mg(OH)2粒子的改性效果。研究了改性Mg(OH)2对PVC的阻燃性能和力学性能的影响。实验结果表明:改性剂为硬脂酸锌时,改性效果最佳,吸油值为33.39%,并对样品进行了红外和扫描电镜表征;随着改性Mg(OH)2的添加量不断增加,氧指数逐渐增大,但拉伸强度逐渐下降。当改性Mg(OH)2添加量为40份时,综合性能较好。     

改性氢氧化镁的制备及在HDPE中的应用

以低品位菱镁矿为原料,γ-(甲基丙烯酰氧)丙基三甲氧基硅烷(KH570)为改性剂,通过蒸氨-沉镁改性-水热过程制备改性氢氧化镁[KH570-Mg(OH)₂],改性剂在Mg(OH)₂生成体系中加入。采用吸油值、活化指数、红外光谱(FTIR)、X射线衍射(XRD)等手段对改性结果进行表征,在改性时间为60min,改性剂用量为2%,并进行水热处理工艺制备的Mg(OH)₂改性效果最好,改性后Mg(OH)₂活化指数达到了98.75%,吸油值为53.05 mL/100g,接触角为149°。整个工艺连续且可循环,为制备疏水性Mg(OH)₂工业生产提供实验基础。并将改性前后的Mg(OH)₂应用于高密度聚乙烯(HDPE),测试其阻燃和力学性能,结果表明,KH570-Mg(OH)₂添加量为40%时,HDPE/KH570-Mg(OH)₂复合材料的氧指数为29.5%,达到阻燃级别,拉伸强度为18.40 MPa,断裂伸长率为217.11%...     

甘蔗渣纤维素吸油材料的制备及性能研究

在1-丁基-3-甲基氯咪唑([Bmim]Cl)离子液体均相反应介质体系下,以易改性甘蔗渣为原材料,经1%的Na OH预处理后,选用N,N’-亚甲基双丙烯酰胺(MBA)为交联剂、过硫酸铵(APS)为引发剂、甲基丙烯酸甲酯(MMA)为单体,采用均相接枝共聚制备天然纤维素基吸油材料。探究接枝反应中单体、引发剂、交联剂用量以及反应时间和反应温度对接枝效果的影响。采用SEM、FT-IR和XRD对甘蔗渣纤维素接枝前后的形态、结构以及结晶度进行表征,结果表明,接枝共聚物表面变粗糙且结晶度降低已成功接枝。最优条件下所制备甘蔗渣纤维素接枝率可达471.25%,水面浮油回收率为22.56 g/g,吸水率为2.55 g/g。通过均相共聚法实现对甘蔗渣的化学改性,所制备的吸油材料可应用于海洋石油污染处理。     

低成本秸秆基吸油材料的制备

以农业固体废弃物秸秆为基材,采用Na OH/H2O2复合体系进行预处理后,与苯乙烯通过悬浮接枝聚合法制备吸油材料。文中主要考察了接枝单体苯乙烯与秸秆的配比、过氧化苯甲酰(BPO)用量、二乙烯基苯用量及反应温度等因素对产物的吸油性能的影响。试验结果表明:当m(苯乙烯):m(纤维素)=4﹕3,ω(引发剂)=0.5%,ω(交联剂)=0.5%,θ=70℃,t=4 h时,所得产物对煤油的吸收倍率可达8.53 g/g。     

正交实验优化纳米氢氧化镁复合改性工艺

采用油酸/聚乙二醇6000对纳米Mg(OH)_2进行复合改性,通过正交实验得出最佳改性工艺条件为:油酸/聚乙二醇6000用量分别为纳米Mg(OH)_2质量的4%,1%(wt,质量分数),反应时间为30 min,反应温度为60℃,超声时间为10 min。利用接触角测试、扫描电子显微镜(SEM)、X射线衍射(XRD)、活化指数来表征改性前后纳米氢氧化镁的润湿情况、分散性、物相结构及活化程度。结果发现:改性后的纳米Mg(OH)_2与水的接触角由8°变成115°,分散性得到了很好的改善而晶型结构并未发生改变,活化程度高达99.30%。     

纳米聚丙烯酸酯改性纳米Mg(OH)_2及其在LDPE中的应用

采用纳米聚丙烯酸酯乳液改性纳米Mg(OH)2,通过单螺杆挤出机制备了纳米Mg(OH)2/低密度聚乙烯(LDPE)复合材料,利用红外光谱、扫描电镜、透射电镜等方法对改性前后的Mg(OH)2及Mg(OH)2/LDPE复合材料进行了表征。结果表明:纳米Mg(OH)2表面经纳米聚丙烯酸酯乳液改性后吸附上了一层聚丙烯酸酯;纳米聚丙烯酸酯乳液改性提高了纳米Mg(OH)2的热稳定性,分解温度提高了27℃;改性纳米Mg(OH)2在LDPE基体中分散更为均匀;改性纳米Mg(OH)2的用量为LDPE的15%时复,合材料的拉伸强度比纯LDPE提高了6.5%。     

无卤阻燃型聚丙烯的制备及性能研究

利用双螺杆挤出机挤出制备了超细Mg(OH)2改性阻燃聚丙烯(PP)复合材料,研究了Mg(OH)2、复合增容剂的用量对复合材料力学性能、阻燃性能的影响.结果表明,Mg(OH)2经硬脂酸表面改性后,其在PP中的分散性及与PP的界面相容性明显得到改善,当Mg(OH)2用量为90份时,材料的氧指数达到27.5%;(乙烯/辛烯)共聚物接枝马来酸酐/(乙烯/丙烯/二烯)共聚物接枝马来酸酐复合增容剂能明显改善材料的力学性能和阻燃性能,当复合增容剂用量为15份时,材料的断裂伸长率达到141.06%,缺口冲击强度达到22.24 kJ/m2,拉伸强度达到18.51MPa,氧指数增至28.0%.     

Mg(OH)_2阻燃热塑性聚烯烃弹性体的研究

采用5种表面处理剂对氢氧化镁(Mg(OH)2)进行表面改性,并以热塑性聚烯烃弹性体(TPO)为基体树脂,制备了TPO/Mg(OH)2阻燃材料。通过氧指数(OI)、垂直燃烧和拉伸性能测试,研究了表面处理剂的种类、Mg(OH)2用量和粒径等对TPO/Mg(OH)2阻燃材料燃烧性能和力学性能的影响。OI测试结果表明,钛酸酯改性的粒径为2μm的Mg(OH)2使体系的OI达27.8%;改性Mg(OH)2用量为70份时成为难燃材料。垂直燃烧测试结果表明,100份改性Mg(OH)2使材料的燃烧等级达到FV-0级,无法引燃。力学性能测试结果表明,钛酸酯改性的粒径为2μm的Mg(OH)2使材料保持较高的应变;70份的Mg(OH)2使阻燃材料的拉伸屈服应力和拉伸断裂应力达到最大值。     

探究导热填料氧化铝表面改性处理的最佳条件

以乙醇作为溶剂,采用硅烷偶联剂γ-缩水甘油醚氧丙基三甲氧基硅烷(KH560)对填料氧化铝(Al2O3)进行表面改性处理。研究偶联剂的预水解条件,偶联剂的用量以及反应条件(反应温度、时间、搅拌速率)对Al2O3改性的影响。采用红外光谱(IR)对改性后的Al2O3(M-Al2O3)进行结构表征,并利用扫描电镜(SEM)对M-Al2O3的微观结构进行观察。通过测试M-Al2O3的吸油值以及环氧树脂/M-Al2O3的黏度进一步表征改性效果。实验结果表明,KH560已经成功接枝在Al2O3表面,M-Al2O3粉体的棱角圆滑,颗粒无明显团聚现象。M-Al2O3的吸油值比未表面改性的Al2O3低,下降了43.4%左右。与环氧树脂/Al2O3复合材料相比,环氧树脂/M-Al2O3复合材料的黏度降低约16.1%。最后确定Al2O3表面改性处理的最佳条件为:KH560用量为5%,KH560预水解pH值为7,KH560预水解时长1 h,反应温度60℃,反应时间1 h,搅拌速率1500 r/min。     

KH-550/SA改性硅灰石及其在顺丁橡胶中的应用

采用硅烷偶联剂KH-550和硬脂酸SA复合的改性剂对硅灰石进行改性处理,并将改性后的硅灰石填充于顺丁橡胶中,研究了硅灰石/顺丁橡胶复合材料的性能.通过对比改性前后硅灰石粉体的活化率、吸油值、界面接触角及红外光谱,确定硅灰石的最佳改性条件为:复合改性剂用量(质量分数)2％,KH-550与SA质量比1:1,反应温度60℃,...     

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.