耐热酚醛树脂固化机理研究

采用相同配比的酚类和醛类物质合成了两种酚醛树脂——普通酚醛树脂和耐热改性酚醛树脂。利用差示扫描量热仪(DSC)将两种树脂在不同升温速率下进行固化,并用Ozawa方程对这两种酚醛树脂固化过程的活化能进行了计算。结果表明:普通酚醛树脂的峰值固化温度为197.45℃,固化反应的活化能为41.4 k J/mol;耐热改性酚醛树脂的峰值固化温度为237.23℃,固化反应的活化能为50.0 k J/mol。     

基于高比例尿素改性PF树脂的固化特性及动力学研究

为探讨高比例尿素改性PF(酚醛树脂)的固化特性,采用差示扫描量热分析(DSC)方法,对不同升温速率条件下树脂的固化过程、特征放热峰温度等进行了检测分析;通过Kissinger和Ozawa方法,计算了固化反应表观活化能,建立了固化反应动力学模型。研究结果表明:高比例尿素改性PF树脂的固化反应活化能较低,反应易于进行,固化温度为131.3℃,较普通PF树脂降低了近20℃。     

牵引电机用双马改性环氧酸酐浸渍漆固化动力学研究

以二苯甲烷型双马来酰亚胺改性环氧酸酐浸渍漆体系,由动态DCS不同升温速率下跟踪体系固化反应过程,求得固化工艺参数:凝胶温度为149.53℃,固化温度为161.71℃,后处理温度为178.68℃。利用Kissinger和Crane方程对该固化反应进行了动力学分析,计算了固化动力学参数,固化反应表观活化能Eα=15.20k J/mol,反应级数n=0.83864。同时通过TG热失重分析测试双马树脂改性体系耐热指数为165.7℃。     

双氰胺与噁唑烷酮环氧树脂体系固化动力学

采用非等温DSC法对双氰胺固化剂与噁唑烷酮环氧树脂和双酚A环氧树脂混合树脂体系固化动力学进行了研究,随着升温速率的增大,固化反应放热量急剧增加,而且固化体系的放热峰向高温方向移动。采用T-β外推法,得到了混合固化体系的特征温度,Ti为156℃,Tp为178℃,Tf为210℃,为实践中的固化工艺提供了重要依据。采用Kissinger、Crane和Arrhenius方程,计算了固化反应的表观活化能为130.86k J/mol、反应级数为0.9443和固化反应速率常数,确定了固化反应的动力学方程。     

高固含量聚醚醚酮改性酚醛树脂固化动力学研究

采用溶液聚合法合成了高固含量(>80%)聚醚醚酮(PEEK)改性酚醛树脂(PF),用非等温DSC(差示扫描量热)法和T-β(温度-升温速率)外推法对其固化反应动力学过程进行了研究,并根据Kissinger方程、Ozawa方程和Crane方程等计算出该固化反应的动力学参数。结果表明:改性树脂的凝胶化温度为136.68℃,固化温度为167.16℃,后处理温度为197.39℃;其固化体系的表观活化能为100.02 kJ/mol,频率因子为1.84×106 s-1,反应级数为0.94(近似于1级反应)。     

热固性乙烯基酯树脂的反应动力学研究

采用差示扫描量热法(DSC)考察了乙烯基酯树脂DERAKANE~(TM)411-350的固化反应,采用不同的升温速率,得到了乙烯基酯树脂(VER)的固化温度与升温速率的曲线,分析计算得到合理的树脂固化工艺温度:可选择85℃为凝胶温度,100℃进行固化和后处理。分别采用Kissinger法和Ozawa法求出了VER固化反应的表观活化能ΔE,其值为:71.91 kJ·mol~(-1)(Kissinger法);74.41 kJ·mol~(-1)(Ozawa法)。此外,由Crane方程还得到了固化反应的反应级数n=0.92。     

E-51环氧/TA-70体系固化反应动力学研究

测试了E-51环氧/TA-70固化体系从0℃至180℃在不同升温速率下的DSC曲线,通过Ozawa方程、Kissinger方程计算该体系的活化能,利用Crane方程计算该体系的反应级数.结果表明,DSC曲线呈单峰,通过2种方程计算的活化能相近,为57.05 kJ/mol,反应级数为0.92,接近1级反应.通过凝胶化时间及力学性能、粘接性能测试得出E-51/TA-70体系是室温固化体系,具有高韧性、高强度的力学性能.     

二氧化硅粉体改性E—Si／CE固化动力学的研究

采用非等温差示扫描量热法（DSC）研究了纳米二氧化硅（SiO2）和微米SiO2的混合粉体改性环氧基硅烷（E—Si）／氰酸酯（CE）树脂体系固化动力学;用Kissinger、Crane和Ozawa法确定固化动力学参数。结果表明,Kissinger式求得的表观活化能为66．09kJ／mol;Ozawa法求得的表观活化能为7001kJ／mol;根据Crane理论计算该体系的固化反应级数为0.89。计算了不同升温速率所对应的不同温度的频率因子和反应速率常数;求得了改性体系的固化工艺参数：凝胶温度130．74℃、固化温度160．96℃和后处理温度199.16℃,确定了体系的最佳固化工艺。与E—Si／CE体系对比表明,SiO2的加入可以降低E—Si／CE体系的活化能,使其固化能在较低温度下进行。     

5405双马来酰亚胺树脂动态固化反应动力学研究

采用差示扫描量热(DSC)法对5405 BMI树脂的固化反应动力学进行研究。利用Kissinger方程和Crane方程分别得出不同升温速率下的非等温固化反应表观活化能(Ea)63.438 k J/mol,表观频率因子(A)2.25×104 S-1及反应级数(n)0.844。以自催化反应动力学模型为基础,建立了5405 BM I树脂的动态固化反应动力学方程。同时采用反应温度-升温速率外推法,获得了5405 BMI树脂的固化反应特征温度,凝胶化温度(Tgel.)153.2℃,固化温度(Tcur.)195.8℃,后处理温度(Ttre.)258.2℃。为优化树脂在实际应用中的固化工艺提供了一定的理论参考数据。     

纤维缠绕用环氧树脂固化动力学研究

采用非等温DSC法对一种纤维缠绕用环氧树脂体系进行了固化动力学研究。基于不同升温速率下的测试数据,确定了固化工艺参数,建立了n级动力学模型,并比较了通过Kissinger方程和Ozawa方程得到的活化能。研究表明:该树脂体系凝胶化温度为89.44℃,固化温度为114.5℃,后处理温度为155.04℃;固化反应过程符合n级动力学模型。     

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.     

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.     

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。