酚醛树脂固化动力学研究及其耐热性能评价

利用差示扫描量热(DSC)法分析了甲醛、苯酚物质的量之比为1.9:1、1.7:1、1.5:1、1.3:1时酚醛树脂(PF)的固化性能,采用Kissinger法计算了4批PF固化反应的表观活化能。用热失重分析(TG)法对4批PF的耐热性能进行了考察。试验结果表明,甲醛、苯酚物质的量之比为1.7:1时,PF的固化反应活化能最低,即固化时需要较少的热量,易固化,其耐热性能最好。     

热致性液晶/酚醛树脂复合体系固化反应动力学

采用非等温DSC方法研究了不同升温速率下热致性液晶聚合物(TLCP)/酚醛树脂(PF)复合体系的固化行为,利用3种现象学模型(Ozawa及Kissinger简单模型、Kissinger-Akahira-Sunose(KAS)等转化模型)分析对比了TLCP/PF复合体系及纯PF体系的固化反应动力学,研究TLCP含量对TLCP/PF复合体系固化反应动力学的影响。结果表明,采用Ozawa和Kissinger2种方法计算得到TLCP/PF复合体系的固化反应活化能(Ea)结果一致;通过KAS模型得到TLCP/PF复合体系不同的固化度下的Ea;TLCP的加入加速了酚醛树脂固化反应,降低了酚醛树脂固化反应活化能,当TLCP的质量分数为10%时,Ea最小。     

聚乳酸/聚丁二酸丁二酯扩链改性材料研究

以左旋乳酸(L–LA)为原料合成聚左旋乳酸(PLLA),再与及聚丁二酸丁二酯(PBS)共混,通过使用高效的反应型扩链剂2,2′–(1,3–亚苯基)–二恶唑啉(PBO)和4,4′–二苯基甲烷二异氰酸酯(MDI)合成新的嵌段聚合物。第一步利用PBO易与羧基反应而对脂肪醇呈惰性的特点,生成端基多为羟基的共混体系,并用酸值滴定法验证了PBO对羧基的反应选择性;第二步再加入易与羟基反应的MDI,使得分子链进一步增长,并且提高两相相容性。对产物分别进行了核磁共振谱、傅里叶变换红外光谱、扫描电子显微镜、差示扫描量热、热重分析、熔体流动速率及力学性能测试。结果表明,反应生成了酰胺基团,并验证了PBO对羧基的反应选择性,通过增容扩链,改善了PLLA/PBS的相容性、加工流动性和热稳定性。随着PBO和MDI加入量的增加,材料的拉伸强度和断裂伸长率呈先增大后减小的趋势,且冲击强度显著提高,改变了材料的脆性特征。     

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℃。     

非等温DSC研究PBT/TDI固化反应动力学

采用非等温差示扫描量热法(DSC)对PBT [3, 3–双(叠氮甲基)氧杂环丁烷–四氢呋喃共聚醚]/TDI(甲苯二异氰酸酯)反应体系在不同催化剂用量、不同升温速率条件下的固化反应进行了研究,并通过Kissinger-Crane方程求解得到了表观活化能和反应级数等动力学参数。结果表明,催化剂含量不会影响PBT/TDI固化反应级数,但能显著改变固化反应活化能。     

对甲苯磺酰氯催化酚醛树脂固化工艺及反应动力学研究

采用对甲苯磺酰氯作为酚醛树脂的固化促进剂,利用差热扫描量热技术（DSC）研究了对甲苯磺酰氯对酚醛树脂体系固化反应及其动力学的影响,分析了不同百分比含量的对甲苯磺酰氯/酚醛树脂反应体系的固化性能。实验结果表明：随着对甲苯磺酰氯含量的增加,固化反应温度降低,固化时间缩短。并采用Kissinger法和Ozawa法分别计算了固化反应的表观活化能和反应级数,发现采用对甲苯磺酰氯催化时,PF体系的固化反应活化能降低。     

TLCP含量对TLCP/PF复合体系固化反应动力学的影响

采用非等温DSC方法研究了不同升温速率下热致性液晶聚酯酰亚胺(TLCP)/酚醛树脂(PF)复合体系的固化行为,利用3种现象学模型(Ozawa及Kissinger简单模型、Kissinger-Akahira-Sunose(KAS)等转化模型)分析对比了TLCP/PF复合体系及纯PF体系的固化反应动力学,研究了不同含量的TLCP对TLCP/PF复合体系固化反应动力学的影响。结果表明:采用Ozawa和Kissinger 2种方法计算得到的TLCP/PF复合体系的固化反应活化能(Ea)结果一致;TLCP的加入一定程度上影响了PF的固化反应,改变了PF的Ea;当TLCP的质量分数为3%时,Ea最小。     

落叶松树皮生物油改性酚醛树脂胶粘剂固化动力学研究

采用差热分析(DTA)技术测定了普通酚醛树脂(PF)和生物油改性PF在固化反应过程中的热行为,综合运用Kissinger方程、Ozawa方程和Crane方程计算出两者的固化反应动力学参数。研究结果表明,普通PF和生物油改性PF的反应级数分别为0.95和0.93,平均活化能分别为118.24kJ/mol和83.62kJ/mol,指前因子分别为8.302×1010s-1和6.235×103s-1;两者的反应级数较为接近,均可归结为复杂反应,说明生物油改性PF和普通PF的固化反应模式基本相同;与普通PF相比,生物油改性PF具有相对较低的平均活化能(即固化能耗相对较低)。     

糠醛对酚醛树脂固化反应动力学影响的研究

采用DSC法研究不同升温速率下糖醛(FUF)/酚醛树脂(PF)体系的固化行为,结合Kissinger方程和Ozawa方程分析了不同含量的糠醛对FUF/PF固化反应动力学的影响。结果表明:随着糠醛的加入,固化反应温度略有降低;当糠醛用量超过5%时,酚醛树脂固化反应活化能迅速下降,由138 J/g降至115 J/g;随着温度升高,Ozawa指数下降,同时糠醛的加入也会降低Ozawa指数,但当糠醛含量达到7%时,在高温时Ozawa指数略微升高。     

无卤阻燃PF/EP/GF布复合材料的固化性能和阻燃性能

采用环氧树脂(EP)作固化剂,2,4,6-三(二甲胺基甲基)-苯酚(DMP30)作固化促进剂改善酚醛树脂(PF)的固化性能,以氢氧化铝和有机磷阻燃剂协同改性其阻燃性能,将其涂覆于玻璃纤维(GF)布上,压制成无卤阻燃PF/EP/GF布复合材料.用傅立叶变换红外光谱(FTIR)仪和差示扫描量热(DSC)仪对无卤阻燃PF/EP/GF布复合材料的固化反应机理、固化反应动力学进行了分析研究,并测试了该复合材料的阻燃性能.结果表明,无卤阻燃PF/EP/GF布复合材料的固化反应表观活化能Ea=75.7 kJ/mol、反应级数n=0.91,起始固化温度、固化峰顶温度、固化终止温度分别为108.6、133.2、152.9℃;当氢氧化铝质量分数为14%、DMP30质量分数为1%、有机磷阻燃剂质量分数为4.8%时,无卤阻燃PF/EP/GF布复合材料的固化性能、阻燃性能均达到较佳状态.     

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。