PF用低收缩添加剂的研究

通过调整物料配比合成了端羟基封端和端羧基封端的聚氨酯 (PU)预聚物 ,并分别与酚醛树脂 (PF)固化 ,制备了两种低收缩体系的复合物 ,利用红外光谱对其结构进行表征。通过测试固化物的体系收缩率表明 :随着聚氨酯预聚物加入量的增加 ,PF/PU共混物的体积收缩率明显变小 ,并能达到负值。端羧基PU的低收缩性能更为显著 ,当其加入量在 5 相似文献   

缩水甘油封端聚氨酯的合成及其增韧改性环氧树脂的研究

以甲苯二异氰酸酯、聚丙二醇为主要原料,制得异氰酸酯基(—NCO)封端的聚氨酯预聚体(NCOPUR),然后利用缩水甘油进行再封端,制得缩水甘油封端聚氨酯(GAPUR)。采用FTIR对GAPUR的结构进行表征,用DSC分析GAPUR的微相分离,并研究了以间苯二甲胺作为固化剂固化GAPUR/环氧树脂(EP)复合体系的力学性能,利用在线FTIR监测复合体系的固化过程,用SEM观察固化体系拉伸断面的表面微观形貌。结果表明,间苯二甲胺在60℃固化2 h,体系可完全固化;GAPUR的加入显著提高了EP的韧性。     

热固性PF/PU复合体系的收缩性能

将端羟基封端和端羧基封端的聚氨酯 (PU)预聚物分别与酚醛树脂 (PF)固化 ,制备了两种体系的复合物。通过测试其体系收缩率 ,结果表明 :随着聚氨酯预聚物加入量的增加 ,PF/PU共混物的体积收缩率明显变小 ,并能达到负值。端羧基PU的低收缩性能更为显著 ,当其加入量在 5 相似文献   

FT-IR法研究IPDI与GAP预聚及预聚物和NC的固化反应

用傅里叶变换红外光谱(FT-IR)对聚叠氮缩水甘油醚(GAP)-异佛尔酮二异氰酸酯(IPDI)预聚物以及-NCO基团封端的GAP预聚物/硝化棉(NC)体系固化反应动力学进行了研究。结果表明,两种体系的固化速率均随着温度的升高而加快;当固化催化剂T12的质量分数为0.025%时,两种体系固化反应的表观活化能分别为64.88kJ/mol和111.19kJ/mol,且均表现为二级动力学反应。     

微波在PU/MOCA固化反应中的应用

武汉大学采用微波固化技术，以MOCA为交联剂，研究了苯酚封端的聚氨酯预聚物(PU)的固化过程，并将其与热固化方法进行了比较。结果发现：(1)苯酚封端的聚氨酯预聚物与MOCA在微波辐照下能很快进行，而且固化时问随微波功率增加而缩短；(2)微波固化反应过程中体系的升温速率在起始阶段随微波功率增加而增加，在后期阶段升温速率下降幅度也随功率增加而增加；(3)300W功率下的固化与120℃下的热固化相比，     

硅氧烷封端星形有机低聚物/环氧树脂复合材料的性能研究

通过溶胶-凝胶技术,利用合成的硅氧烷封端星形有机低聚物对环氧树脂进行改性,并固化试样。研究了硅氧烷封端星形有机低聚物/环氧树脂复合材料的拉伸强度和耐热性能,并利用SEM分析了拉伸样断面的微观结构。结果表明:硅氧烷封端星形有机低聚物改性环氧树脂固化后,复合材料的拉伸强度、断裂伸长率明显提高。随着偶联剂(KBE-9103 )的加人,试样的拉伸强度、断裂伸长率上升。复合材料中由于引人Si-O-Si网络结构,其热稳定性能也明显提高。     

硅烷封端蓖麻油改性聚氨酯预聚物合成及性能研究

以可再生的蓖麻油、聚酯多元醇、甲苯二异氰酸酯为原料,合成出异氰酸酯基封端蓖麻油改性聚氨酯预聚体;再与γ-氨丙基三乙氧基硅烷(KH 550)反应,制备出硅烷封端蓖麻油改性聚氨酯预聚物。采用红外光谱对预聚体结构进行了定性分析,采用热失重对成膜物进行热性能分析,并测试了成膜物的力学性能。结果表明,异氰酸酯基封端蓖麻油改性聚氨酯与KH 550的较佳反应温度为70℃,反应时间为4 h;随固化温度的增加,硅烷封端蓖麻油改性聚氨酯胶膜的表干时间缩短,固化温度大于30℃后下降趋势趋于平坦;固化膜能在230℃前保持稳定,其拉伸强度达到11.6 MPa、拉断伸长率为460%,与蓖麻油改性聚氨酯相比分别提高37.8%、22.1%。     

微波固化环氧树脂/苯酚封端的聚氨酯预聚体系的热膨胀行为研究

以二苯甲烷二胺(DDM)为交联剂，研究了环氧树脂／苯酚封端的聚氨酯(EP／PU)预聚体系在微波固化条件下的热膨胀行为；并通过热膨胀行为考察了体系热膨胀系数、玻璃化转变及其与微波功率、体系组成之间的关系。结果表明：当体系组成一定时，随着微波功率的增加，体系中富EP相和富PU相的玻璃化转变移向高温，过渡相的转变加宽，膨胀系数变小。在一定组成范围内，体系具有两个玻璃化转变，随着PU和EP含量的接近，富EP相和富PU相的玻璃化转变温度差值缩小。组成相同的体系，微波固化产品的热膨胀系数低于热固化。     

环氧封端聚苯醚/环氧树脂共混体系的固化动力学研究

以羟基封端低分子量聚苯醚、环氧氯丙烷为原料，制备出环氧封端的改性聚苯醚（PPOE）。采用示差扫描量热法（DSC）研究了PPOE与双酚A酚醛型环氧树脂（BNE-200）复合体系的固化动力学，计算了共混物固化反应的表观活化能和反应级数。结果表明：各样品在不同升温速率下均只有一个固化峰，固化体系接近于1级固化反应，说明PPOE与BNE-200具有比较好的相容性。随着PPOE用量的增加，固化特征温度呈降低趋势，固化的表观活化能降低。当PPOE用量为80%时，复合体系表观活化能为63.25 kJ/mol，比BNE-200的93.62 kJ/mol降低了32.4%，说明PPOE比BEN-200具有更高的反应活性。     

汽车用单组分湿固化聚氨酯胶粘剂研究进展

分别从异氰酸酯封端和硅烷封端两方面概述了近年采国内外汽车用单组分湿固化聚氨酯胶粘剂(PU胶)的研究开发进展。     

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.