聚乙烯醇-SiO2/聚酯无纺布膜的制备及性能研究

采用聚酯无纺布(PET)作为支撑层,利用相转换法在PET表面制备聚乙烯醇(PVA)或PVA-SiO₂活性层,得到了PVA/PET复合膜与PVA-SiO₂/PET复合膜。考察了2种复合膜的过滤性能和污染行为。结果表明,PVA中加入质量分数4%纳米SiO₂颗粒,复合膜的接触角降至33.1o,亲水性显著增强,而膜孔径减小至3.1 nm,降低了85.5%,PVA/PET超滤膜转变为PVA-SiO₂/PET纳滤膜(0.6 L/(m²·h))。PVA-SiO₂/PET复合纳滤膜对海藻酸钠的抗污染性能较强。纳米SiO₂对复合膜的污染机制无明显影响,模拟污染物对复合膜的污染机制以标准堵塞为主。     

芳纶纳米纤维增强聚乙烯醇复合膜的制备与性能

以芳纶纤维Kevlar@49为原料,在温和条件下制备了芳纶纳米纤维分散体(ANFS),并利用分散体制备了芳纶纳米纤维/聚乙烯醇(ANFs/PVA)复合膜。通过傅里叶红外光谱(FTIR)仪、差示扫描量热(DSC)仪、原子力显微镜(AFM)、扫描电子显微镜(SEM)、电子万能试验机及透光度/雾度测定仪等考察了复合膜的微观结构、热学、光学及力学性能。FTIR证明,复合膜中ANFs与PVA具有一定的分子间氢键作用,促进了ANFs在PVA基体中的分散。由AFM和SEM可以清晰观察到直径为20~30 nm的芳纶纳米纤维分散体,并且通过SEM观察到复合膜表面较为平整。当芳纶纳米纤维质量分数为6.0%时,复合膜的抗拉强度为17.86 MPa,断裂伸长率为442%;透光度为82.63%,雾度为27.56%;玻璃化温度,熔融温度和结晶温度分别为75.20、208.82和174.51℃,表明其透光性良好,力学和热学性能达到最佳。     

静电纺丝PBT/PVA复合膜的制备及性能研究

以三氟乙酸和二氯甲烷为混合溶剂,采用静电纺丝法制备聚对苯二甲酸丁二酯(PBT)/聚乙烯醇(PVA)复合膜。用旋转粘度计和电导率仪测定溶液的黏度和电导率,用扫描电子显微镜、拉伸和水接触角测试PBT/PVA不同比例对纤维膜的形貌、力学和亲水性能的影响。结果表明,随着PVA比例的增加,混合溶液的黏度逐渐增大,而电导率先增大后减小;当PBT/PVA的比例为90/10时,纳米纤维的平均直径最小,为323 nm,而其纳米纤维膜的力学性能与纯PBT纤维膜相比显著提高,拉伸强度、弹性模量和断裂伸长率分别增加了213%,260%和57%;PVA的加入改善PBT纤维的亲水性,制备出力学性能优异且亲水的PBT/PVA纤维膜。     

聚乙烯醇/凹凸棒黏土纳米复合膜的制备及其性能

以聚乙烯醇(PVA)和提纯凹凸棒黏土(APT)为原料,采用溶液流延成膜法,制备了系列不同APT含量的PVA/APT纳米复合膜。采用XRD、FTIR和SEM对复合膜的结构进行了表征,测试了复合膜的热性能、力学性能和耐水性能。结果表明,APT可均匀分散在PVA基体中,APT的加入使得PVA的结晶度有所下降但并未改变其晶型。APT与PVA通过氢键作用,改善了复合膜的热稳定性、力学性能和耐水性。当APT含量为4%时,纳米复合膜有最优的性能。     

冷冻处理凹凸棒黏土对PVA/APT纳米复合膜性能的影响

以聚乙烯醇(PVA)和经过不同时间冷冻处理的凹凸棒黏土(APT)为原料,采用溶液-流延成膜法,制备了PVA/APT纳米复合膜,通过红外光谱、XRD和SEM对纳米复合膜的结构和形貌进行了表征,并对复合膜的力学性能及耐水性能进行了测试.结果表明,与未冷冻处理APT相比,经冷冻处理后APT的棒晶可以更好的分散在PVA基体中,纳米复合膜的力学性能和耐水性有明显提高.其中,以冷冻处理16 h APT制备的纳米复合膜性能最优,其拉伸强度、断裂延伸率和耐水性分别提高了17.4％、25.4％和19.2％.     

PHBV/PVA复合膜的制备及其性能研究

采用静电纺方法制备聚羟基丁酸/戊酸酯共聚物(PHBV)纤维膜材料,通过调节纺丝液中无水乙醇的含量制备出形态均匀的PHBV静电纺纤维膜。用浇铸法将聚乙烯醇(PVA)涂敷在PHBV静电纺纤维膜上,制备PHBV/PVA复合膜,通过调节PVA的浓度及涂覆量,研究复合膜配比对其力学性能及过滤性能的影响。结果表明,当PVA浓度为8%,PHBV/PVA体积比为2/3时,得到最佳性能的PHBV/PVA复合膜,水通量达到996 L/(m2.h),截留率为86%。     

纳米ZnO/纤维素纳米晶/聚乙烯醇复合膜的制备及性能

采用球磨法制备的纤维素纳米晶(CNC)及市售纳米ZnO对聚乙烯醇(PVA)进行改性,改善了PVA膜的力学性能,并且,赋予其抗菌性,测试复合膜的力学性能、水蒸气透过性能及抗菌性能。结果表明,加入CNC后,提高了PVA膜的力学性能和阻湿性能,加入纳米ZnO后,复合膜对金黄色葡萄球菌具有一定的抗菌性能,并且,能进一步提高复合膜的拉伸强度,但是,降低了复合膜的阻湿性能。当CNC的添加量为3%、纳米ZnO∶CNC=2∶1(摩尔比)时,复合膜综合性能较好,拉伸强度为73.7 MPa,与纯PVA膜相比,提高了77.2%;断裂伸长率为3.8%,与纯PVA膜相比,提高了46.1%;水蒸气透过系数为3.44×10^-13 g·cm/(cm²·s·Pa),与纯PVA膜相比,提高了11.7%。     

聚乙烯醇/壳聚糖复合电纺纤维膜的制备及表征

利用静电纺丝法制备了聚乙烯醇PVA/壳聚糖CS纳米纤维复合膜,并采用戊二醛蒸气对其交联处理。通过扫描电子显微镜(SEM)观察探讨了不同质量配比、助纺剂的添加以及电纺环境条件对复合纤维膜纤维直径及表面形貌的影响。通过傅里叶变换红外光谱(FTIR)对PVA/CS复合纳米纤维膜做了特征官能团分析,并对其热力学性能及其耐水性进行了表征。结果表明滴加7%(V/V)二甲基亚砜、0.5%(V/V)丙三醇、0.5%(V/V)吐温80的3%(V/V)的乙酸为溶剂,PVA和CS质量配比为90/10,环境湿度0±15%电纺条件下制备的复合纤维形态均一,无珠串无液滴;FTIR研究显示,复合纤维的两种组分发生一定的相互作用,成功制备了戊二醛交联PVA/CS纳米纤维膜;热重(TG)、差热(DSC)结果都进一步说明CS和PVA之间形成氢键,戊二醛交联后复合纤维的热稳定性进一步增强。交联前后纤维膜的耐水性结果表明交联后的共混纤维膜有良好的抗溶解性,在水中可以很好的保持纤维的结构。     

加盐提高聚乙烯醇纳米纤维膜的力学和热稳定性能

对含有NaCl、KCl、Na2SO4、Na2CO3的聚乙烯醇(PVA)溶液进行静电纺丝,成功制备出含盐PVA纳米纤维膜。通过扫描电子显微镜(SEM)对各纤维膜的形貌进行表征,发现这些无机盐的加入对PVA纳米纤维的形貌造成明显影响,如纤维之间发生粘连或扁平带状纤维。此外通过单轴拉伸对各纤维膜的力学性能进行测试,结果表明:少量NaCl、KCl、Na2SO4或Na2CO3的加入,可以明显提高PVA纳米纤维膜的力学性能。进一步通过热失重分析(TGA)对各纤维膜热稳定性的考察表明:NaCl、KCl、Na2SO4的加入可以有效提高PVA纳米纤维膜的热稳定性,而Na2CO3的加入则对PVA纳米纤维膜的热稳定性无明显提高。     

PVA/Au纳米复合纤维的制备及表征

以聚乙烯醇(PVA)为还原剂和保护剂,采用PVA还原氯金酸(HAuCl4)制备纳米金(Au),一步法制备PVA/Au溶液,通过静电纺丝制备了PVA/Au纳米复合纤维.利用紫外可见光谱仪、透明电镜和扫描电镜对PVA/Au纳米复合纤维进行了表征.结果表明:随着HAuCl4浓度的增加,Au纳米粒子的粒径逐渐增大;HAuCl4...     

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。