相容剂对PC/PLA共混体系性能的影响

研究了不同相容剂对聚碳酸酯/聚乳酸(PC/PLA)共混体系性能的影响,找出了增容效果明显的相容剂EMG,并进一步研究了EMG对PC/PLA共混体系相容性及力学性能的影响。结果表明:相容剂EMG的加入,促使共混体系中PC的玻璃化转变温度有所下降,PLA的玻璃化转变温度进一步提高,增强了两相间的界面黏结作用,改善了PC/PLA之间的相容性;EMG的加入,提高了PC/PLA共混物的力学性能,当相容剂质量分数为9%时,拉伸强度、断裂伸长率和缺口冲击强度均达到最大值。     

用于FDM的PLA共混改性

采用酰胺成核剂(NT–C)和聚乙二醇(PEG2000)对聚乳酸(PLA)进行熔融共混改性,制备了用于3D打印的PLA/NT–C/PEG2000共混物,并在200℃的温度下通过熔融沉积成型(FDM)工艺制备了共混物FDM打印件。研究了NT–C的用量对PLA/NT–C打印件结晶性能的影响,并在此基础上研究了PEG2000用量对共混物流变性能、共混物打印件的结晶性能和力学性能的影响。差示扫描量热分析表明NT–C可在一定程度上提高PLA/NT–C打印件的结晶度,一定用量的PEG2000的添加进一步提高了共混物打印件的结晶性能,当NT–C和PEG2000的质量分数分别为2%和5%时,打印件的结晶度达到17.1%,相比PLA提高了12倍;流变性能测试表明PEG2000提高了共混物的熔体流动速率,降低了共混物储能模量和损耗模量对温度的依赖性,扩宽了PLA在FDM工艺中的成型温度;力学性能测试表明PEG2000显著提高了PLA/NT–C/PEG2000共混物的缺口冲击强度,降低了打印中断丝的几率,FDM打印件弯曲和拉伸强度相比于PLA也有显著提高,当NT–C和PEG2000的质量分数分别为2%和5%时,打印件的弯曲和拉伸强度分别达到了注塑件的80%和70%以上,扩宽了PLA在FDM中应用。     

PLA/PBAT/OMMT生物基材料的制备及快速成型

对生物可降解材料聚乳酸(PLA)与聚己二酸对苯二甲酸丁二酯(PBAT)及有机蒙脱土(OMMT)材料进行共混,采用挤出成型制备PLA/PBAT/OMMT线材,再采用快速成型制备标准试样,通过对样件的力学性能、结晶行为、断面形貌和表观质量的测试和分析得出:纯PLA的拉伸强度和断裂伸长率分别为7.42MPa和1.8%,表现出硬而脆的特点;PLA/PBAT共混后,随着PBAT含量的增加,共混材料的断裂伸长率以及冲击强度不断提高,当PBAT含量为60%时,共混物的断裂伸长率达到405%,材料的冲击强度为31.11kJ/m2,约为纯PLA的11倍;而共混材料的拉伸强度表现出先增后减的趋势,当PBAT含量约为30%时,拉伸强度最佳,为37.08MPa;加入2%含量的OMMT后,共混材料的综合力学性能较之前又有不同程度的提高,其中拉伸强度以及冲击强度提升的较为明显;通过差示扫描量热和扫描电镜分析,PLA/PBAT共混体系为不相容体系,两相界面存在大量的孔洞,且结晶性能差,为半结晶聚合物,OMMT的加入使PLA/PBAT的两相界面变得模糊,极大地改善他们的相容性,而且还提高了共混物的结晶度;通过观察打印制件的表观质量,当PBAT的含量在30%左右,综合快速成型性能最佳。     

丙烯酸酯接枝改性天然橡胶增韧聚乳酸

通过在天然橡胶(NR)分子链上接枝甲基丙烯酸甲酯(MMA)和丙烯酸丁酯(BA),制备了三种丙烯酸酯接枝改性NR:NR-g-PMMA,NR-g-PBA和NR-g-(PMMA,PBA)。采用核磁共振氢谱对三种接枝物进行了化学结构鉴定。将接枝改性后的NR和未改性的NR与PLA采用哈克密炼机熔融共混,分别制备了PLA/NR,PLA/NR-gPMMA,PLA/NR-g-PBA和PLA/NR-g-(PMMA,PBA)共混物,研究了接枝改性NR和未改性NR含量对共混物力学性能和热性能的影响。各共混物的拉伸弹性模量和拉伸强度均随接枝改性NR和未改性NR含量的增加而降低,断裂伸长率和缺口冲击强度随接枝改性NR和未改性NR含量的增加而提高。其中,PLA/NR-g-PBA共混物的断裂伸长率和缺口冲击强度比其它共混物提高的幅度大,当NR-g-PBA的质量分数为5%时,PLA/NR-g-PBA共混物的断裂伸长率达到78%,缺口冲击强度为5.2 k J/m2,而纯PLA的断裂伸长率仅为7.7%,缺口冲击强度为2.5 k J/m2,说明NR接枝分子柔顺性较高的BA更有利于促进其与PLA共混物的韧性提高。热分析结果表明,PLA/NR-gPBA共混物的热稳定性相比于纯PLA也有所提高。     

PC/PBT改性聚丙烯的研究

以聚碳酸酯(PC)和聚对苯二甲酸丁二醇酯(PBT)并用且以马来酸酐接枝聚丙烯(PP-g-MAH)作为相容剂来改性聚丙烯(PP),详细研究了PC/PBT改性PP的工艺条件以及不同结构对PP共混物性能的影响。结果表明,当PC与PBT的质量分数分别为5.0%和2.5%时,改性PP共混物的拉伸强度为24.0 MPa,缺口冲击强度达到28.9kJ/m~2,比未改性PP的冲击强度提高了7倍。同时研究了PP-g-MAH的用量对PP共混物性能影响,当PC与PBT的质量分数分别为10.0%和5.0%时,PP-g-MAH的质量分数为2.0%时,共混物的缺口冲击强度达到27.8kJ/m~2。PP-g-MAH可有效提高PC/PBT与PP之间的相容性。     

乙烯-乙酸乙烯酯共聚物增韧改性聚甲醛的研究

通过熔融共混的方法制备了聚甲醛(POM)/乙烯-乙酸乙烯酯(EVA)共混物,并对共混物的力学性能、结晶性能以及形貌进行了研究。结果表明,纯POM的缺口冲击强度只有7.6 kJ/m2,加入EVA橡胶后,共混物的缺口冲击强度得到了明显提高,但随着橡胶用量的增加,材料的弯曲模量与拉伸强度不断下降;EVA 的存在影响着POM的结晶性能,使结晶度下降;POM与EVA的两相界面比较清晰,表明两者的相容性不好,但合适的分散相粒径分布有利于EVA增韧POM。     

等温冷结晶对PLA/PBAT共混物冲击韧性和耐热性能的影响

通过熔融共混法制备了聚乳酸/聚己二酸-对苯二甲酸丁二醇酯(PLA/PBAT)共混物,并对其微观形貌、热性能、冲击性能和耐热性能进行了研究。结果表明,随着PLA/PBAT共混物中PBAT含量的增加,共混材料的无缺口冲击强度逐渐增大,其中当PBAT含量为30%时,共混材料的无缺口冲击强度达到最大值。再通过等温冷结晶提高PLA/PBAT材料的结晶度,以改善材料的耐热性能。结果表明,等温冷结晶样品的维卡软化温度(VST)明显高于急冷样品,且结晶度越高,VST值则越大;此外,90℃等温冷结晶20 min的样条无缺口冲击强度高于急冷样条,但当等温冷结晶温度提高至130℃时,样条的无缺口冲击强度下降,且低于急冷样条。因此,较低冷结晶温度有利于得到兼具良好耐热性能和冲击性能的PLA/PBAT材料。     

PLA/GMS/ACR共混体系的制备与性能研究

采用熔融共混法制备了由核壳结构丙烯酸酯类冲击改性剂(ACR)和增塑剂单硬脂酸甘油酯(GMS)增韧增塑改性的聚乳酸(PLA),固定GMS用量为20%,研究了ACR对PLA/GMS/ACR共混体系相容性、力学性能以及流变行为的影响。结果表明:ACR的壳层与PLA具有部分相容性;随着ACR用量的增加,PLA/GMS/ACR共混物的冲击强度先增大后减小,当ACR用量为10%时,共混物的冲击强度最大,为63.7 kJ/m~2,断裂伸长率最大达到100%,与PLA/GMS相比,PLA/GMS/ACR共混物的储能模量和复数黏度均随着ACR用量的增加而提高。     

成核剂与增容剂调控聚乳酸/聚丙烯复合材料的结晶与力学性能研究

通过熔融共混法制备聚丙烯/聚乳酸(PP/PLA)复合材料,研究成核剂癸二酸二苯基二酰肼(TMC-300)和增容剂聚丙烯接枝马来酸酐(PP-g-MAH)对PP/PLA复合材料的结晶行为、热学性能、力学性能的影响。结果表明,TMC-300能够显著提高PP/PLA共混物的结晶速率和结晶度,降低球晶尺寸,并改善复合材料的力学性能。当TMC-300添加量为0.5%时,共混物的熔点从163.9℃提高到168.6℃,结晶度达到44.2%,比纯PP/PLA提高25.6%,拉伸强度和冲击强度分别增加了13.33%,49.86%。当增容剂与成核剂并用时,增容剂可改善PLA链段运动能力,并提供更多的成核位点,进一步促进PLA的结晶性能,且结晶的分布由海岛式结构变为双连续相结构,复合材料的拉伸强度比纯PP/PLA提升了19.25%。     

聚乳酸/聚乙醇酸共混合金界面改性研究

用熔融共混挤出法制备了不同配比的聚乳酸(PLA)/聚乙醇酸(PGA)共混合金,并分别加入环氧型扩链剂ADR 4370F进行对比分析,通过拉伸性能测试、弯曲性能测试、缺口冲击强度测试、扫描电子显微镜(SEM)和差示扫描量热(DSC)仪研究了共混合金力学性能、相容性和结晶性能。结果表明:与纯PLA和纯PGA相比,PLA/PGA共混合金的相容性差,导致力学性能降低,纯PLA、纯PGA和70%PLA/30%PGA合金的拉伸强度、弯曲强度、断裂伸长率和缺口冲击强度分别为58.6 MPa,123.5 MPa,8.52%,9.0 J/m;91.9 MPa,157.6 MPa,7.9%,5.2 J/m;41.2 MPa,91.2 MPa,3.8%,2.0 J/m。PLA和PGA可以互相加快结晶速度,加入环氧型扩链剂可以改善合金的相容性,上述四个力学性能可相应提高到49.2 MPa,96.0 MPa,4.5%,4.3 J/m,而且降低了PLA和PGA的结晶度。另外,向PLA中加入1%PGA时,PGA可以充当PLA的成核剂,使PLA的冷结晶温度降低10℃左右,结晶度提高1.3%。     

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。