葛根淀粉基胶黏剂制备与性能研究

研究开发以淀粉为主要原料的环保型胶黏剂替代"三醛类"木材胶黏剂,对彻底解决人造板及其制品的甲醛释放问题具有重要意义。以野生葛根淀粉为原料,通过降黏处理,并与聚醋酸乙烯酯和异氰酸酯复配,制备出胶合强度达到国家Ⅱ类要求的淀粉基木材胶黏剂。研究了降黏剂用量、降黏时间、聚醋酸乙烯酯和异氰酸酯用量对淀粉基木材胶黏剂胶合强度的影响。优化工艺条件下制备胶黏剂胶接胶合板的胶合强度为1.89 MPa,能够满足国家Ⅱ类胶合板强度要求。     

生物油淀粉胶黏剂制备工艺研究

对快速热解制得的杨木生物油进行GC-MS分析,确定其含有多种对制备淀粉基胶黏剂有益的有机组分。以生物油质量分数、生物油加入后淀粉乳液pH、生物油与淀粉乳液的反应时间以及固化剂质量分数4个关键条件为实验因素,胶合强度为考核指标,采用正交试验法优选出制备生物油淀粉胶黏剂的最佳工艺条件为:生物油质量分数为20%,pH为7.5,反应时间为45 min,固化剂质量分数为18%。用该胶黏剂制备的胶合板的胶合强度达到GB/T 9846.3—2004标准中Ⅱ类胶合板要求。     

Ⅰ型淀粉基API木材胶粘剂的研究

利用复合变性玉米淀粉制备了Ⅰ型淀粉基水性高分子异氰酸酯(API)胶粘剂。以复合变性淀粉乳液、二元酸、聚乙烯醇(PVA)和聚异氰酸酯(PMDI)为主要影响因素,以压缩剪切强度为评价目标,通过正交试验优化出满足JISK6806-1995要求的Ⅰ型淀粉基API胶粘剂的配方,对影响胶粘剂理化性能的因素进行了系统分析。经验证性试验证明,所优化出的最佳配方具有明显的生产可操作性,交联剂PMDI可不经封闭直接使用,完全能满足现有的木材胶合制品的生产工艺要求,其原料成本为同类进口胶粘剂的1/3,具有明显的社会环境效益和经济效益。     

生物油对生物油基淀粉胶黏剂性能的影响

我国的生物质资源丰富,将其快速热解成生物油,作为优质化工原料应用,可实现其高值高效应用。本文对以生物油制备的环境友好型生物油淀粉胶黏剂基本性能进行研究,结果表明,其湿胶合强度可达到国标Ⅱ类胶合板标准,其黏度可以满足胶合板工业化生产需求;生物油淀粉胶黏剂流变行为呈现出明显的剪切变稀特征,是典型的假塑性流体,流动活化能△E_η为9.67 kJ·mol^-1,表明其具有良好的流动性和应用潜力;通过对比不同生物油加入量的BOS胶黏剂湿胶合强度、流变性和热稳定性的研究发现,生物油的加入可改善BOS胶黏剂的耐水性,促进其固化,并增强其热稳定性。     

环氧氯丙烷改性淀粉基胶黏剂的制备及性能研究

以玉米淀粉为原料,经双氧水氧化、环氧氯丙烷交联改性后以碱糊化制得环氧氯丙烷改性淀粉基胶黏剂。通过单因素实验及正交设计实验优化了环氧氯丙烷交联改性的实验条件。最佳工艺条件为:环氧氯丙烷用量为2%(相对于淀粉的质量分数)、反应温度为50℃、反应时间为4 h、交联反应体系的pH值为11。制备的胶黏剂的胶合强度可达4.4 kg/m~2,耐水时间为10 h,交联度为1.2。环氧氯丙烷交联改性淀粉基胶黏剂的性能明显优于氧化淀粉胶黏剂。     

玉米淀粉基可燃性胶黏剂的配方研究

采用正交试验法,以统计分析方法为主要手段,研究了新型可燃性胶黏剂的制备工艺。结果表明:以玉米淀粉为原料制备可燃性胶黏剂的工艺是可行的,淀粉、氢氧化钠、稳定剂质量比为5:3:0.5,制得的胶黏剂黏度适中、颜色较浅、化学稳定性较好。将此胶黏剂和炭粉胶合可以制备出结构紧实,不易碎裂,能在5 s内点燃,燃烧时无烟、无味的成型炭,该成型炭燃烧剩余物质量分数为5.47%,燃烧时间可以持续12.20 min/g,抗压系数达到11.03 N/mm²,热值达到35762.76 kJ/kg。     

生物油对生物油基淀粉胶黏剂性能的影响

我国的生物质资源丰富,将其快速热解成生物油,作为优质化工原料应用,可实现其高值高效应用。本文对以生物油制备的环境友好型生物油淀粉胶黏剂基本性能进行研究,结果表明,其湿胶合强度可达到国标Ⅱ类胶合板标准,其黏度可以满足胶合板工业化生产需求;生物油淀粉胶黏剂流变行为呈现出明显的剪切变稀特征,是典型的假塑性流体,流动活化能ΔE_η为9.67 kJ·mol~(-1),表明其具有良好的流动性和应用潜力;通过对比不同生物油加入量的BOS胶黏剂湿胶合强度、流变性和热稳定性的研究发现,生物油的加入可改善BOS胶黏剂的耐水性,促进其固化,并增强其热稳定性。     

API胶主剂-改性聚乙酸乙烯酯乳液的研制

用共聚方法对聚乙酸乙烯酯乳液进行改性，研究了共聚单体、助剂以及改性淀粉作为添加剂对乳液性能的影响。确定了相对较佳的配比方案，合成了一种胶合板用水性高分子-异氰酸酯（API）胶主剂。用异氰酸酯作API胶的固化剂，测得胶黏剂对木材的湿胶合强度达到1．3MPa以上，胶合板的甲醛释放量仅为0．0144mg·L^-1。实验得到了一种耐水性好、低成本、环保的API胶用主剂。     

衣康酸改性淀粉胶粘剂的制备及性能

为提高淀粉胶黏剂的胶合强度和耐水性，以玉米淀粉为主要原料、衣康酸和硅溶胶为接枝单体，采用接枝共聚法制备了一种高性能生物质胶黏剂。以单因素法考察了反应条件对淀粉胶黏剂的接枝率、黏度、胶合强度以及耐水性的影响，并通过FTIR、TGA、XRD和SEM等对淀粉胶黏剂的化学结构与性能进行表征。结果表明，衣康酸成功地接枝到淀粉分子上，接枝率为6.35%，接枝效率为87.03%，且当淀粉质量分数为30%，衣康酸含量为7.5% ，反应温度为70 ℃，反应时间为3.5 h时，改性淀粉胶黏剂的性能最佳，耐水时间达到95 h（原淀粉胶黏剂为4 h），干湿态强度分别达到2.28 MPa和1.52 MPa（原淀粉胶黏剂为0.85 MPa和0 MPa），满足国家Ⅲ类胶合板的使用要求，同时淀粉胶黏剂热稳定性得到提高。     

无醛玉米秸秆木质素基木材胶黏剂的制备与性能

将玉米秸秆木质素进行羟乙基化改性,添加一定量环氧氯丙烷制备了无醛人造板用木材胶黏剂。利用胶接强度测试以及红外光谱分析和热重分析对胶黏剂的性能进行了表征。结果表明,随着环氧氯丙烷添加量的增大,胶合板的剪切强度呈现先增大后降低的趋势,添加量为30份时,剪切强度最大(干胶合强度1.58MPa),达到国家II类胶合板标准,此时胶黏剂固化样品的热稳定性最好。木质素基胶黏剂中添加一定量聚丙烯酸酯乳液可以明显提升胶黏剂的粘接性能和耐水性能,其干胶合强度最高可达2.73MPa,湿胶合强度最高可达1.09MPa。聚丙烯酸酯乳液的加入对胶黏剂在400℃以内的耐热性没有明显影响。     

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.