动态硫化增韧Co-PP/EVA共混物研究

研究了动态硫化和简单共混增韧共聚级聚丙烯(Co-PP)/乙烯-醋酸乙烯酯共聚物(EVA)共混物的力学性能、流动性能、形态结构和脆韧转变。结果表明:动态硫化共混物力学性能尤其是冲击强度明显优于简单共混物的,流动性则差于简单共混物的,动态硫化共混物中EVA颗粒尺寸小于简单共混物的;采用Wu氏增韧理论对2种共混物的脆韧转变进行了分析,动态硫化共混物的临界基体层厚度约为0.55μm,简单共混物的临界基体层厚度约0.60μm。     

基体分子量对PP/EPR共混物力学性能的影响

以二元乙丙橡胶(EPR)增韧的聚丙烯(PP)共混物为研究对象,探究PP基体分子量对PP/EPR共混物力学性能的影响。结果表明：随着基体分子量的增加,PP/EPR共混物的冲击韧性、拉伸强度和弹性模量均明显提高,且发生脆韧转变所需的临界EPR含量和脆韧转变温度均显著降低。当基体数均分子量(Mn)由3.8×10⁴g/mol增至8.8×10⁴g/mol,临界EPR含量从28%减至10%,脆韧转变温度从-17℃降至-30℃。分子量对基体结晶度和结晶形貌没有明显影响,但共混物的力学性能随分子量的变化不是单纯线性关系。当基体数均分子量为(5～7)×10⁴g/mol的范围内,共混物的临界EPR含量和缺口冲击强度呈现跳跃性转变,该转变可能与EPR分散相尺寸减小有关,EPR粒子的尺寸越小,增韧效果越好。     

超细全硫化粉末NBR/EPDM共混物的结构与性能

试验研究超细全硫化粉末NBR（UFPNBR）／EPDM共混物的硫化特性、相态结构、动态力学性能，加工性能及物理性能。UFPNBR粒子加入EPDM中明显影响了EPDM的硫化性能，UFPNBR／EPDM共混物采用过氧化物硫化体系硫化效果较好；透射电子显微镜和扫描电子显微镜观察表明，UFPNBR粒子在UFPNBR／EPDM共混物中始终为分散相，但在EPDM基体中没有分散成预期的纳米尺寸；动态力学热分析结果显示，共混物存在两个玻璃化温度，呈两相结构且界面结合较弱；橡胶加工分析仪分析结果表明，UFPNBR粒子在EPDM基体中形成了填料网络结构，使共混物的流动性能变差；UFPNBR对EPDM有一定补强作用，但补强作用不如传统的纳米无机填料。     

PP/EPDM/纳米弹性体粒子三元共混体系的脆韧转变

研究了PP／EPDM／纳米弹性体粒子(ENP)三元共混体系的脆韧转变行为。结果表明，与PP／EPDM二元共混物相比，三元共混物的脆韧转变可以在EPDM质量分数较低的情况下发生；在橡胶总质量分数相同的情况下，三元共混物有更高的冲击强度，拉伸强度有一定提高。从脆断样条的扫描电镜照片观察到，在相同EPDM质量分数下，PP／EPDM／ENP三元共混物中的EPDM粒子明显细化，分布均一，粒子间距减小，这是脆韧转变提前的原因。     

EPDM增韧聚丙烯及其脆韧转变机理的研究

聚丙烯/EPDM共混物韧性的测定可以在很宽的温度（25～132 ℃）和组分（EPDM质量分数为0～26%）中进行.发现了增加温度和增加EPDM组分对EPDM增韧的聚丙烯的脆韧转变有相同的影响,发现了聚丙烯/EPDM共混物的脆韧转变温度与EPDM组分之间的相互关系以及聚丙烯/EPDM共混物的拉伸强度和断裂伸长率与EPDM组分之间的相互关系.     

聚合物材料脆韧转变判据及影响因素分析

综述了聚合物共混增韧机理包括弹性体增韧、刚性粒子增韧、弹性体与刚性粒子协同增韧等研究进展；着重介绍了临界基体层厚度、损伤竞争准数、分子链参数、临界界面黏结条件、临界特征长度等几种源于单一粒子填充的脆韧转变判据，并分析其在复合粒子填充改性聚合物中的适用性。此外，还结合增韧机理和脆韧转变判据讨论了基体性能、分散相状态及相间界面黏结强度等因素对复合体系韧性的影响，提出寻找合适的复合分散相、适当调整复合粒子的结构比例、改善相间界面黏结以及设计最佳断裂路径仍将是今后努力的方向。     

MBS对聚碳酸酯的增韧作用及其增韧机理的探讨

研究了甲基丙烯酸甲酯-丁二烯-苯乙烯共聚物（MBS）对光盘级聚碳酸酯的增韧作用。结果表明，MBS对PC增韧效果显著，且MBS分散性越好，根据逾渗理论，达到脆一韧转变时所需的MBS含量越少。求得达到脆-韧转变时的临界粒间距为50nm。对共混物损伤机制的研究表明，MBS增韧PC共混物的增韧机理为MBS粒子的空洞化引发基体的剪切屈服。     

动态硫化增韧PP/EVAL共混物的研究

研究了简单共混和动态硫化增韧聚丙烯/皂化乙烯-醋酸乙烯酯共聚物(PP/EVAL)共混物的结构和性能。结果表明:以马来酸酐(MAH)为交联剂,用EVAL动态硫化增韧PP是一种可行的PP增韧方法;随着EVAL用量的增加,共混物的力学性能均随之变化,但动态硫化物的力学性能始终优于简单共混物;当EVAL质量分数为20%时,动态硫化物具有最佳综合性能,冲击强度达到26.5 kJ/m2,较纯PP增加了173.2%,为简单共混物的2.14倍;动态硫化可改善共混物中EVAL颗粒的分散效果;动态硫化可诱导PPβ晶型的形成并提高PP结晶度;动态硫化可增大共混物的内耗,从而增强材料韧性。     

动态硫化对三元乙丙橡胶/聚丙烯共混体系等温结晶行为和形态结构的影响

研究了三元乙丙橡胶/聚丙烯(EPDM/PP)共混物和动态硫化EPDM/PP热塑性弹性体(TPV)的等温结晶行为及形态结构,并用Avrami方程对其进行等温结晶动力学分析。结果表明,EPDM/PP共混物和EPDM/PP TPV的等温结晶行为符合Avrami方程,在相同的结晶温度下,TPV比共混物的Avrami指数小,半结晶时间短,结晶速率常数大;EPDM/PP共混物为双连续相结构,而EPDM/PP TPV是以硫化的细小橡胶颗粒为分散相、PP为连续相的"海-岛"结构,橡胶颗粒尺寸约为0.5μm。     

ABS接枝共聚物对PVC树脂的增韧改性

对聚氯乙烯(PVC)/丙烯腈-苯乙烯-丁二烯接枝共聚物(ABS)共混物的脆韧转变、相形态以及动态力学性能进行研究。将不同摩尔质量的PVC与ABS熔融共混制备测试样品。结果表明:低摩尔质量PVC共混物比高摩尔质量PVC共混物的脆韧转变出现时所需的橡胶含量低。在体系中加入增塑剂DOP后,测试结果得到明显改善。通过透射电镜观察发现,高摩尔质量PVC共混物中存在未完全塑化的PVC,其相区尺寸大于PVC初级粒子的尺寸。并得出PVC与SAN部分相容,不影响橡胶粒子在基体中的均匀分散。     

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。