负载钛催化1-丁烯聚合动力学

采用TiC l4/MgC l2-A l(i-Bu)3催化剂合成聚1-丁烯热塑性弹性体,研究了不同单体浓度、催化剂浓度和反应温度下及催化剂陈化后的聚合动力学。结果表明,聚合初期聚合速率与单体浓度和催化剂浓度的一次方成正比,在20~40℃,聚合的表观活化能为14 kJ/mol,聚合的速率方程为Rp=kp[Ti][B t];0℃陈化催化剂的1-丁烯聚合速率较非陈化时快。     

Ziegler-Natta催化剂催化1-丁烯聚合

采用9,9-双(甲氧基甲基)芴(BMMF)作为内给电子体,制备了聚1-丁烯高效载体型Ziegler-Nana催化剂.研究了催化剂浓度、n(Al)/n(Ti)、聚合温度、外给电子体种类及用量对该催化剂催化1-丁烯聚合的影响,并将该催化剂与无内给电子体及以邻苯二甲酸酯(DNBP)为内给电子体的聚1-丁烯催化剂进行对比.结果...     

负载型钛催化剂催化1-十二烯溶液聚合动力学

采用TiCl4/MgCl2-Al(i-Bu)3催化剂,溶液聚合法合成了聚1-十二烯烃油溶性减阻剂.使用Brookfield DVⅢ型流变仪对以正已烷、正庚烷和环已烷为溶剂的原料进行流变性研究,以此考察不同溶剂体系对聚合速率的影响,测定了主催化剂TiCl4/MgCl2浓度与助催化剂Al(i-Bu)3浓度的反应级数和聚合反应的表观活化能,并由此建立聚合反应速率方程,探讨了聚合速率对聚合物特性粘数的影响.结果表明,以正已烷、正庚烷和环已烷为溶剂时,聚合速率依次降低,但对单体浓度均呈一级反应;在本研究催化剂加量范围内,聚合速率对主催化剂浓度呈一级关系,而刘助催化剂浓度呈零级关系.聚合速率与特性粘数不成正比关系,需在合适聚合速率下才能得到较高特性粘数.在-5～5℃,聚合的表观活化能为56.64 kJ/mol.     

双(正丁基环戊二烯基)二氯化锆催化1-丁烯齐聚的研究

本文系统研究了双(正丁基环戊二烯基)二氯化锆与甲基铝氧烷催化剂体系催化1-丁烯的齐聚反应,详细考察了反应温度、Al与Zr的摩尔比、催化剂的用量及反应时间对1-丁烯聚合反应的影响。研究结果表明,反应的最佳条件为:聚合温度60℃、Al与Zr摩尔比为1500、催化剂中双(正丁基环戊二烯基)二氯化锆的用量为6mg、反应时间1.5h。     

新型铁系催化剂催化乙烯齐聚的研究

合成了新型配合物氯化2-乙酰基-6-(2-甲基苯亚胺基)乙基吡啶铁,研究了它与甲基铝氧烷(MAO)、促进剂(1,1,2,2-四氯乙烷)共同组成的三元催化体系催化乙烯齐聚的性能。在40°C、3.0 MPa、n(Al)/n(Fe)=1200、反应时间为30 min,主催化剂浓度为18μmol/L,促进剂用量为0.4ml的条件下,催化剂活性高达3.8×106g/mol.h,而且丁烯-1选择性小于10%,己烯-1选择性大于22%,辛烯-1选择性大于23%。     

四氢呋喃聚合中活性中心向醋酸酐链转移的研究

本文介绍在有醋酸酐存在时采用乙酰基四氟硼酸盐CH_3COBF_4为催化剂进行四氢呋喃(THF)聚合反应;讨论了THF聚合及链转移的反应机理,发现醋酸酐对聚合速度有明显的影响。计算出0℃,6℃和15℃时的表观聚合反应速度常数K_p 分别为3.59,5.11和11.53×10~(-3)/mol·s;表观链转移速度常数K_(tr)分别为2.03,3.95和8.23×10~(-3)/mol·s;表观聚合反应活化能E_p 和链转移反应活化能E_(tr)分别为51.2和61.3 kJ/mol。     

气相法全密度聚乙烯高效催化剂的研究

本文从探讨乙烯在钛系催化剂上聚合的机理出发,进行钛系催化剂组份的筛选及活化剂的选择。从而得到聚合效率高、氢调敏感、共聚性能好、适合于乙烯气相聚合工艺的催化剂。催化剂聚合效率:乙烯均聚为35×10~4g·PE/g·Ti,乙烯—1-丁烯共聚时达50×10~4g·PF/g·Ti(操作压力为0.83MPa)。树脂熔体指数0～0.6可调,产品密度0.915～0.97g/cm~3可调。     

负载钛催化1-丁烯本体聚合动力学

采用TiCl4/MgCl2-Al(i-Bu)3催化体系在10 L聚合釜中研究了本体法1-丁烯的聚合动力学.结果表明,在反应温度为20 ℃的条件下,聚合的速率方程为Rp=157[Ti]1.1[Bt]PH20.4;在10～30 ℃时的聚合活化能为46 kJ/mol.提高催化剂浓度、聚合温度和氢气压力均能明显提高单体转化率,加快聚合速率.     

1-丁烯聚合制备润滑油基础油

为了扩宽聚α-烯烃合成润滑油基础油(PAO)的原料来源,以1-丁烯为原料,对TiCl₄催化体系与阳离子Al Cl3体系下制备润滑油基础油的两步聚合工艺进行了研究,考察了反应条件对聚合反应结果及产品性能的影响。实验结果表明：通过两步法合成的产品综合性能较AlCl₃一步法合成的明显提高。较佳的工艺条件为：第一步聚合的催化剂TiCl₄用量为2%(质量分数,基于1-丁烯的质量)、AlEt₂Cl为助催化剂、铝钛物质的量比为1.0,反应温度为85℃,压力为1-丁烯在此温度下的饱和蒸汽压,反应时间为2h;第二步聚合的催化剂为AlCl₃,催化剂用量为2%(质量分数,基于二步聚合起始原料),反应温度为50℃,聚合3h。在此条件下得到的产品黏度约为30 mm²/s,黏度指数达126,倾点为-33℃。     

中国专利

一种经过2～5个碳原子的直链α-烯烃和3-甲基-1-丁烯相继预聚合处理的烯烃聚合催化剂组分;采用该烯烃聚合催化剂组分可制成烯烃聚合催化剂;可在该烯烃催化剂存在下聚合和共聚合烯烃;并可制备聚丙烯薄膜及其注塑制品。     

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.