SBS对PLA/PC合金结构与性能的影响

用苯乙烯-丁二烯-苯乙烯嵌段共聚物(SBS)对聚乳酸/聚碳酸酯(PLA/PC)合金进行增韧改性,研究了SBS用量对合金力学性能、热性能、微观形貌的影响。结果表明:加入一定量SBS后,PLA/PC(50/50)合金的拉伸强度有所降低,弯曲强度变化不大,而冲击强度明显提高;合金的热变形温度略有下降,两相相容性有所提高。     

增韧剂MBS对PC/PBT合金性能的影响

通过添加酯交换抑制剂磷酸二氢钠(NaH_2PO_4)以及两种不同的甲基丙烯酸甲酯-丁二烯-苯乙烯(MBS)共聚物,制备了增韧改性的聚碳酸酯/聚对苯二甲酸丁二醇酯(PC/PBT)合金,对其力学性能、耐热性能、相形态进行了研究。结果表明,增韧剂MBS能够显著提高PC/PBT合金的冲击性能,其中MBS2602能够显著改善低温冲击性能,当MBS2602含量为16%,PC/PBT质量比50/50时,-20℃下的冲击强度为648.6 J/m。热变形温度、拉伸强度以及模量随着MBS含量的提高而有所降低。MBS均匀地分散于基体中,其含量增加会使共混物相界面更加模糊,冲击性能更好。     

ABS树脂中胶含量对PC/ABS合金性能及微观结构的影响

采用胶含量(质量分数,下同)为60％的丙烯腈-丁二烯-苯乙烯接枝共聚物(ABS)接枝粉料与苯乙烯-丙烯腈共聚物(SAN)以不同比例进行共混,制备了胶含量范围为10％～55％的ABS树脂.将胶含量不同的ABS树脂与聚碳酸酯(PC)以30/70、50/50、70/30的质量比利用熔融共混技术,制备了组成不同的PC/ABS共混物,考察了ABS树脂胶含量对不同组成的PC/ABS合金性能的影响.研究结果表明:随着ABS树脂中胶含量的增加,ABS树脂的冲击强度不断提高,屈服强度、模量及熔体流动速率逐渐降低.随着PC/ABS合金中ABS胶含量的增加,合金的冲击强度显著提高,ABS树脂中胶含量大于30％以后,合金的冲击强度变化不大,且3种组成的PC/ABS合金的冲击强度相差不大.合金的屈服强度、模量及熔体流动速率却随着ABS中胶含量的增加不断降低,其中组成为30/70的PC/ABS合金最低.利用扫描电镜观察了PC/ABS组成为70/30合金的微观结构,研究表明,ABS树脂形成连续相,PC为分散相,随ABS树脂胶含量的增加,合金的相形态变得更精细.     

高性能PC/ABS合金的制备

聚碳酸酯(PC)、丙烯腈-丁二烯-苯乙烯共聚物(ABS)的比例对PC/ABS合金的性能具有显著的影响,当PC与ABS质量比为1∶1时,加工性能最佳。对比了不同增韧剂(甲基丙烯酸甲酯-丁二烯-苯乙烯三元共聚物MBS、有机硅增韧剂和高胶粉)对PC/ABS(0215A)合金性能的影响,结果表明,MBS对提高合金的增韧效果较好,综合性能最佳,其适宜添加量为5%。采用耐热ABS(D-2400)和有机硅增韧剂制备了高性能PC/ABS(D-2400)合金,当PC含量为50%时,合金热变形温度为102℃,常温缺口冲击强度为65 kJ/m~2,低温缺口冲击强度(-30℃)为25.5 kJ/m~2。进一步提高PC含量至70%时,合金热变形温度高达112.5℃,常温缺口冲击强度高达73.2 kJ/m~2。     

SAN/CPE/PC合金的制备与性能研究

利用氯化聚乙烯(CPE)弹性体、苯乙烯-丙烯腈(SAN)以及聚碳酸酯(PC)共混制备了高韧性的SAN/CPE/PC合金。研究了不同含量的PC对PC/SAN/CPE合金性能的影响。结果表明:随着PC用量的增加,合金的缺口冲击强度逐渐增加,拉伸强度逐渐降低。当SAN/PC的质量比为50/50,CPE质量分数为10%时,缺口冲击强度达到14 kJ/m2,接近于SAN/CPE二元体系CPE质量分数为40%时的缺口冲击强度。合金熔体质量流动速率随着PC含量的增加逐渐降低。     

ABS树脂中胶含量对PC/ABS合金微观结构的影响

本实验采用胶含量为60%的ABS接枝粉料与SAN树脂以不同比例进行共混,制备了胶含量范围为10%～55%的ABS树脂。将胶含量不同的ABS树脂与PC以30/70、50/50、70/30的比例利用熔融共混技术,制备了组成不同的PC/ABS共混物。利用SEM电镜观察了PC/ABS合金的微观结构。研究表明,ABS树脂含量为30%时,在合金中形成分散相;ABS树脂含量为70%时,形成连续相;ABS树脂含量为50%时与PC形成双连续相结构。在三种结构中,ABS树脂胶含量的增加都使合金的相形态变得更精细。     

PA6含量对PVC/PA6共混物形态结构与力学性能的影响

以EVA-g-MAH为相容剂,将PVC与自制的低熔点PA6共混制备了PVC/PA6共混物。通过扫描电子显微镜(SEM)和力学性能测试研究了PA6含量对PVC/PA6共混物形态结构及力学性能的影响。SEM分析结果显示:随着PA6含量的增加,PVC/PA6共混物的分散相尺寸逐渐增大,当PA6含量为10%时,共混物中分散相的分散尺寸最小为1μm;当PA6含量为50%时,共混物为两相共连续结构;当PA6含量为60%时,共混物中PA6为连续相,PVC为分散相。力学性能测试结果表明:当PA6含量为10%时,共混物的缺口冲击强度和拉伸强度都较PVC有明显提高,分别提高了约50%与30%,达到了6.29kJ/m2和60MPa。采用差示扫描量热仪(DSC)研究了PVC/PA6共混物的结晶温度,检测结果显示:PVC/PA6共混物呈现非晶结构。     

耐热抗冲PC/ABS合金的研究

通过共混挤出的方法制备不同PC含量的合金,研究了不同PC含量对PC/ABS和PC/ABS/MBS合金力学性能和热变形温度的影响,探讨了PC/ABS/SAN/MBS四元共混体系的效果,结果表明:PC含量与合金的拉伸强度和热变形温度成正比关系,当PC含量60%时冲击韧性最佳,MBS对合金有增容增韧作用,可明显提高合金的冲击性能,但会使合金的刚性和耐热能力下降,在PC/ABS/MBS的基础上,保持PC与MBS用量,使用SAN替换40%的ABS,制备的PC/ABS/SAN/MBS四元共混合金可在保持冲击强度的同时大幅提高合金的拉伸强度和热变形温度,使合金具有更优异的综合性能。     

SGF增强PPSU/PC复合材料的结构与性能

采用熔融共混挤出制备短切玻璃纤维(SGF)增强聚亚苯基砜树脂(PPSU)/聚碳酸酯(PC)复合材料,探讨了PC组分用量变化对所形成的PPSU/PC合金和SGF/PPSU/PC复合材料加工性能、力学性能、耐热性能等的影响。研究表明PPSU中添加10 wt%的PC后,熔体流动性能增加47%,可加工温度降低20℃,且拉伸强度与弯曲强度略有增加;30 wt%的SGF对PPSU/PC体系增强作用明显,拉伸强度随PC添加量的增加而增加。采用差示扫描量热法以及刻蚀除去PC组分的方法研究表明合金中PPSU与PC相互作用较弱,两相结构较明显。冲击断面的扫描电镜照片分析表明SGF在PPSU/PC合金基体中分散均匀,界面结合牢固。     

PTT/PC合金的动态力学行为研究

研究了聚对苯二甲酸丙二酯(PTT)/聚碳酸酯(PC)合金的动态力学行为,探讨了增容剂环氧树脂(EP)和三元乙丙橡胶接枝甲基丙烯酸缩水甘油酯(EPDM-g-GMA)对合金动态力学行为的影响.结果表明,未增容的PTT/PC合金显示两个独立的、随配比而稍变化的玻璃化转变松弛峰Tg(PTT)和Tg(PC);PTT对PC玻璃化转变时链段运动的影响远大于PC对PTT玻璃化转变时链段运动的影响;PC能显著提高PTT的模量和热变形温度.EP强烈地影响了PTT/PC合金的松弛行为,使Tg(PTT)和Tg(PC)相互靠近,且损耗强度显著增加;当PC质量分数为30％且EP用量为2.7份时,PTT/PC合金热变形温度明显提高,高弹态平台消失,材料高温刚性增加.EPDM-g-GMA对PTT/PC合金松弛行为的影响不如EP,当EPDM-g-GMA的用量为5份以下时,仅使Tg(PTT)和Tg(PC)略有靠近,但损耗强度无明显变化,当其用量为10份时,Tg(PTT)和Tg(PC)在宽广温度区间内融合为一,损耗强度显著增加;EPDM-g-GMA使PTT/PC的玻璃态模量和高弹态模量均显著降低,但对热变形温度影响不大.     

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。