相转移催化制备羧甲基壳聚糖的研究

采用相转移催化剂制备羧甲基壳聚糖,考察了催化剂种类、反应温度、反应时间和溶剂中水醇比对羧甲基壳聚糖取代度(DS)和溶解性的影响。得到最佳反应条件为：以三乙基苄基氯化铵(TEBA)作催化剂,反应温度55℃,反应时间4h,溶剂中水醇比为1：4(体积比),羧甲基壳聚糖取代度和溶解率分别达到1．12和98．3％。     

羧甲基壳聚糖的制备及膜性能测试

用氯乙酸与壳聚糖反应制备了羧甲基壳聚糖 ,测定了羧甲基壳聚糖取代度。考察了氯乙酸浓度、反应时间、反应温度对羧甲基壳聚糖取代度的影响。将羧甲基壳聚糖制成膜 ,测定了膜的机械强度。结果表明 ,在壳聚糖∶NaOH∶氯乙酸 (质量比 ) =1∶1 3∶1 8和室温条件下反应 2h、升温至 6 5℃再反应 2h时 ,所得的羧甲基壳聚糖取代度较高 (为 0 6 7)。羧甲基壳聚糖膜有较好的韧性度     

羧甲基壳聚糖席夫碱的制备及抗菌性能研究

在超声波作用下,以自制的低分子量羧甲基壳聚糖与香草醛为原料,制备了低分子量羧甲基壳聚糖香草醛席夫碱。利用FI-IR对其结构进行了表征,研究了香草醛与羧甲基壳聚糖中氨基的反应摩尔比、反应温度、反应时间及超声波功率对产物氨基取代度的影响。结果表明：当香草醛与羧甲基壳聚糖中氨基的摩尔比为1∶0.8、反应时间为3 h、反应温度为70℃、超声波作用功率为70 W时,羧甲基壳聚糖香草醛席夫碱的氨基取代度可达到82.5%;将羧甲基壳聚糖席夫碱与羧甲基壳聚糖的抗菌性能进行了比较,发现羧甲基壳聚糖香草醛席夫碱对金黄葡萄球菌和大肠埃希菌的抑菌圈宽度分别比羧甲基壳聚糖的抑菌圈宽0.7 mm和0.5 mm。     

高取代度木薯羧甲基淀粉的合成及表征

以机械活化60min的木薯淀粉为原料,采用乙醇溶剂法合成了高取代度的木薯羧甲基淀粉.通过正交实验优化羧甲基淀粉的合成工艺条件,探讨了反应时间、反应温度、催化剂用量、醚化剂用量、乙醇浓度及淀粉乳浓度等因素对羧甲基淀粉取代度的影响.结果表明,其合成的最优工艺条件为:反应温度50℃,乙醇浓度90%,反应时间120min,ClCH2COOH与淀粉摩尔比0.80,淀粉乳浓度35%(ω),NaOH与淀粉摩尔比0.80.在此条件下合成的羧甲基淀粉的取代度为1.24.并对产物的结构进行了表征.     

两步加碱法制备N,O-羧甲基壳聚糖—反应条件对取代度的影响

利用两步加碱法制备羧甲基壳聚糖,并采用等电点沉降法对其精制。结果表明,在m(壳聚糖)∶m(氯乙酸)∶m(氢氧化钠)=1∶4 8∶4 8,反应时间6h,温度60℃,异丙醇用量50mL,水用量22mL的较适宜反应条件下,制得的羧甲基壳聚糖取代度高达1 7,与传统方法制得的产物取代度最大1 1相比,有较大幅度的提高。同时,对影响产物取代度因素的研究表明:碱量、氯乙酸用量和反应温度是影响产物取代度的关键因素;产物取代度随碱量的增加而增加,随氯乙酸用量和反应温度的提高,呈现先增后减的规律。最后,对产物进行的红外光谱分析表明,产物为N,O 羧甲基壳聚糖,且主要是氧位取代。     

利用废弃淡水龙虾壳制备羧甲基壳聚糖

以废弃龙虾壳为原料,通过酸碱循环处理方式提取甲壳素,对其进行脱乙酰化后制备可溶性壳聚糖。以非质子溶剂二甲亚砜作为反应溶剂,利用两步加碱法制得羧甲基壳聚糖(CMC)。反应条件为:温度60℃,m(壳聚糖)∶m(氯乙酸)∶m(氢氧化钠)=1∶4.8∶4.8;反应时间6h。所得羧甲基壳聚糖的取代度为1.75,略高于传统两步加减法所得产物的取代度。对产物进行的红外光谱分析表明,产物为N,O-羧甲基壳聚糖。     

两步加碱法制备N，D-羧甲基壳聚糖-反应条件对取代度的影响

利用两步加碱法制备羧甲基壳聚糖，并采用等电点沉降法对其精制。结果表明，在m(壳聚糖)：m(氯乙酸)：m(氢氧化钠)=1：4．8：4．8，反应时间6h，温度60℃，异丙醇用量50mL，水用量22mL的较适宜反应条件下，制得的羧甲基壳聚糖取代度高达1．7，与传统方法制得的产物取代度最大1．1相比，有较大幅度的提高。同时，对影响产物取代度因素的研究表明：碱量、氯乙酸用量和反应温度是影响产物取代度的关键因素；产物取代度随碱量的增加而增加，随氯乙酸用量和反应温度的提高，呈现先增后减的规律。最后，对产物进行的红外光谱分析表明，产物为N，D-羧甲基壳聚糖，且主要是氧位取代。     

氨基甲酰乙基淀粉的半干法制备

以水为反应介质 ,在氢氧化钠碱催化剂存在下 ,半干法制备了氨基甲酰乙基淀粉。考察了碱用量、反应温度、反应时间、丙烯酰胺浓度对反应效率和取代度的影响。当淀粉为 5 .7g、丙烯酰胺 2 .2g、水 2mL时 ,最佳反应条件为 :氢氧化钠 /葡萄糖剩基的摩尔比为 0 .32、反应温度 60℃、反应时间 2h ,此时取代度可达 0 .64 ,反应效率为 64 %。随着丙烯酰胺浓度的提高 ,取代度逐渐增加 ,反应效率逐渐下降     

羧甲基壳聚糖的制备与性能研究

以壳聚糖为原料制备了羧甲基壳聚糖,考察了NaOH用量、一氯乙酸用量、反应时间和反应温度对羧甲基壳聚糖取代度的影响,得出羧甲基化的最佳条件为：壳聚糖／一氯乙酸／氢氧化钠（m／m）=1：3．2：4,反应时间为3h,反应温度为60℃,制得产物的水溶性有较大提高,并利用红外光谱对产物结构进行了表征。     

己酰酯化羧甲基淀粉的制备及粘度性质研究

以羧甲基淀粉(CMS)为原料,己酰氯为酯化试剂,二甲基亚砜(DMSO)为溶剂,吡啶为有机碱合成了己酰酯化羧甲基淀粉(HCMS)。研究了反应温度、反应时间、催化剂用量、溶剂用量对己酰酯化取代度(DS)和反应效率(RE)的影响,确定了最佳反应条件为:5 g CMS,40 mL DMSO,反应温度为50℃,反应时间为30 min,有机碱用量为1.0 g。通过IR、流变仪对产物进行了结构及溶液黏度性质研究。通过对不同质量分数和己酰酯化取代度(DShexyl)的羧甲基淀粉溶液黏度性质(剪切速率0～500 s-1)的研究表明,达到临界聚集质量分数2.0%时,适当己酰基取代度(DShexyl=0.3)的HCMS,可以使羧甲基淀粉溶液的黏度由420 mPa.s提高到34 000 mPa.s(γ=5 s-1)。     

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.     

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.     

2005～2006年国外塑料工业进展

收集了2005年7月～2006年6月国外塑料工业的相关资料，介绍了2005—2006年国外塑料工业的发展情况。提供了世界塑料产量、消费量及全球各类树脂生产量以及各国塑料制品的进出口情况。作为对比，介绍了中国塑料的生产情况。按通用热塑性树脂（聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂）、工程塑料（聚酰胺、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚）、通用热固性树脂（酚醛、聚氨酯、不饱和树脂、环氧树脂）、特种工程塑料（聚苯硫醚、液晶聚合物、聚醚醚酮）的品种顺序，对树脂的产量、消费量、供需状况及合成工艺、产品开发、树脂品种的延伸及应用的扩展作了详细的介绍。     

2007～2008年世界塑料工业进展

收集了2007年7月～2008年6月世界塑料工业的相关资料,介绍了2007～2008年国外塑料工业的发展情况,提供了世界塑料产量、消费量及全球各类树脂的需求量及产能情况.按通用热塑性树脂(聚乙烯、聚丙烯、聚苯乙烯、聚氯乙烯、ABS树脂)、工程塑料(尼龙、聚碳酸酯、聚甲醛、热塑性聚酯、聚苯醚)、特种工程塑料(聚苯·硫醚、液晶聚合物、聚醚醚酮)、通用热固性树脂(酚醛、聚氨酯、不饱和聚酯树脂、环氧树脂)不同品种的顺序,对树脂的产量、消费量、供需状况及合成工艺、产品应用开发、树脂品种的延伸及应用的进一步扩展等技术作了详细介绍.