乙烯基树脂复合材料湿热老化性能研究

本文研究了乙烯基树脂复合材料层合板在80℃湿热老化条件下的老化性能。研究表明,湿热老化42d后,复合材料拉伸强度保留率为60%,弯曲强度保留率为63%,这是由于湿热老化对界面产生的影响造成的;DMA数据表明,复合材料的玻璃化转变温度以及损耗因子都呈现下降的趋势。     

碳纤维/聚三唑树脂复合材料的湿热老化行为

本文研究了碳纤维/聚三唑树脂复合材料(T700/PTA)在80℃、相对湿度98%条件下的湿热老化行为。分别采用静态力学性能测试、吸湿称重、动态热机械分析、扫描电子显微镜观察等手段考察了复合材料在湿热条件下的力学性能变化、吸湿特性和形貌变化;利用半经验数学模型对复合材料进行强度拟合和寿命预测。结果表明,复合材料的弯曲强度、层间剪切强度受湿热影响显著,尤其在老化初期;复合材料吸湿第一阶段符合Fick扩散定律,扩散系数D=1.129×10-6mm2/s;吸湿后试样的动态热机械分析谱图上出现两个转变,干燥后次级转变消失;湿热老化后,纤维与树脂基体之间的界面作用减弱;利用数学模型预测复合材料弯曲强度保留率为50%时的老化寿命为33600h,T700/PTA复合材料具有优良的耐湿热老化性能。     

玻纤/聚醚砜/环氧复合材料老化性能研究

以聚醚砜/环氧树脂为基体的复合材料具有高韧性和高耐热等优点,人们对其耐温和抗冲击性能进行了较为系统的研究,但对其老化性能研究不多。本文分别以双氰胺、二氯苯基二甲脲为潜伏性固化剂和促进剂,采用湿法制备了无碱玻璃纤维/聚醚砜/胺酚基三官能度环氧树脂预浸料,通过模压工艺制备了复合材料,对复合材料试样进行了湿热和紫外光老化处理,研究了老化条件对试样力学性能的影响。结果表明,经过28d湿热老化处理后,试样的拉伸、弯曲、压缩和冲击强度保留率分别为68.3%、60.9%、72.7%和82.8%,经过28d紫外光老化处理后,试样的拉伸、弯曲、压缩和冲击强度保留率分别为83.9%、78.9%、82.5%和72.0%。     

单向CF/PA6复合材料性能劣化及老化寿命预测

利用热压成型工艺制备出碳纤维(CF)/尼龙6(PA6)复合材料单向板,并将复合材料试样置于蒸馏水热水浴中,分别在25,60,80℃下进行不同时间的湿热老化,再对湿热老化后复合材料试样进行吸湿测试、三点弯曲测试、微观形貌表征,探究复合材料的吸湿规律、力学性能劣化规律和微观形貌变化,并对复合材料的长期寿命进行预测。结果发现,复合材料在25,60℃下的吸湿行为基本符合Fick扩散定律,而80℃下在老化最后阶段出现了背离Fick扩散定律现象。复合材料的弯曲强度随老化温度、老化时间的增加呈下降趋势,分别在25,60,80℃下老化120 d后,试样弯曲强度分别下降了22.78%,25.0%,26.25%。但是老化温度、老化时间对弯曲弹性模量无显著影响,且CF与PA6树脂之间的界面黏合性能随着温度、时间的增加逐渐变差。以绍兴2021年平均温度作为服役温度,基于加速老化测试模型和阿伦尼乌斯理论建立了CF/PA6复合材料在服役环境下剩余弯曲强度的预测模型,可预测到1 400 d后,CF/PA6复合材料的弯曲强度保留率在64.8%左右。     

PMI泡沫夹芯复合材料湿热老化性能研究

通过对夹芯结构复合材料湿热老化性能的研究,探究环境对夹芯结构复合材料性能的影响。实验中采用了聚甲基丙烯酰亚胺(PMI)、玻璃纤维增强环氧树脂(SW110C/608)复合材料面板制备了PMI泡沫夹芯结构复合材料,研究了PMI泡沫夹芯结构复合材料的耐湿热老化特性,并讨论了湿热对PMI泡沫夹芯结构复合材料的压缩性能以及弯曲性能的影响。结果发现,PMI泡沫夹芯结构复合材料浸泡在水中时的饱和吸湿时间为30d,饱和吸水率为4.08%,通过Fick第二扩散定律发现水分子在PMI泡沫中的扩散系数为水分子在面板扩散系数的29.29倍,由于水分子的增塑作用以及浓度梯度扩散的影响,湿热处理后的PMI泡沫夹芯复合材料的平压强度下降了32.86%,侧压强度下降了16.73%,弯曲强度下降了23.94%。     

运动训练器材用碳纤维复合材料的湿热老化行为研究

采用真空辅助成型的方法制备运动训练器材碳纤维复合材料层合板,研究了40℃和60℃的湿热老化环境下碳纤维复合材料的吸湿率、拉伸强度、弯曲强度、压缩强度和剪切强度变化,并观察了不同老化条件下的拉伸断口形貌。结果表明,温度越高,运动训练器材碳纤维复合材料的平衡吸湿率、线性段斜率和扩散系数越大。当湿热老化温度为40℃和60℃时,随着老化时间延长,碳纤维复合材料的拉伸强度、弯曲强度都先增后减,分别在老化时间为14d和7d时取得最大值。当湿热老化温度为40℃和60℃时,随着老化时间延长,碳纤维复合材料的压缩强度先增大后减小,在老化时间为35d时取得最大值。当湿热老化温度为40℃时,随着老化时间延长,碳纤维复合材料的剪切强度先增大后减小,在老化时间为7d时取得最大值;当湿热老化温度为60℃时,随着老化时间延长,碳纤维复合材料的剪切强度逐渐减小。碳纤维复合材料在湿热环境下的力学性能变化,主要与温度和湿度共同作用下碳纤维复合材料的增塑和固化有关。     

玻纤增强热塑性聚酯复合材料湿热老化研究

研究了玻璃纤维增强热塑性聚酯（PET、PBT）复合材料在加速老化条件下力学性能的变化。结果表明,复合材料在湿热环境下的老化是由水解和界面脱粘共同作用引起的。依据树脂基体不同,材料老化速度和老化后强度均有所不同;老化温度提高,老化加快。采用拉伸强度与冲击强度测试、端基分析及扫描电镜分析等手段探讨了PET、PBT复合材料的老化机理和老化性能。     

湿热老化对PBO/T700层间混杂复合材料力学性能的影响

分别利用材料万能试验机和DMA研究了湿热老化时间对PBO/T700层间混杂复合材料静态力学性能和动态力学性能的影响。结果表明,在湿热环境下加速老化不同时间后,PBO/T700层间混杂复合材料的拉伸强度和模量、弯曲强度和模量并未发生明显变化;压缩强度和层间剪切强度均出现了一定程度的下降,最大降幅分别为14.4%和9.5%;湿热老化使得PBO/T700层间混杂复合材料的耐热性有所提高,当老化时间为30d时,混杂复合材料的T_g从127.6℃升高到136.3℃,随着老化时间进一步延长,混杂复合材料的T_g降低,E'和E″向低温方向移动,表明混杂复合材料的耐热性又开始下降。     

丙烯酸酯齐聚物和微凝胶增韧环氧粘接件的湿热耐久性

以铝合金LY12CZ为基材 ,以丙烯酸酯齐聚物和微凝胶分别改性环氧树脂粘合剂 ,进行了湿热老化试验和楔子试验 ,观察了粘接件在湿热条件下剪切强度的变化和耐久性。结果表明丙烯酸酯齐聚物作为增韧剂 ,经湿热老化试验后 ,PACR1、PACR2有较好的湿热老化性 ,剪切强度保留率分别为 81.7%、80 .0 % ,而且PACR2耐久性较好 ;微凝胶作为增韧剂 ,微凝胶 1# 有较好的湿热老化性和耐久性     

湿热环境下泡桐木复合材料夹芯结构Ⅰ型界面剥离试验研究

采用人工加速老化的方法模拟湿热环境,通过泡桐木玻璃纤维增强复合材料夹芯结构的双悬臂梁拉伸剥离试验,研究湿热环境对玻璃纤维增强复合材料(GFRP)面板和泡桐木芯材的粘结性能的影响。试验结果表明,90 d湿热加速老化后泡桐木复合材料夹芯结构的能量释放率下降了32.3%,芯材泡桐木顺纹抗拉强度下降了11.6%,GFRP面板拉伸模量下降了11.0%。     

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。