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橡胶增韧PP为多相结构体系,橡胶粒径、粒子微区结构和界面层结构是影响共混物增韧效果的主要因素;界面层结构是PP非晶部分和橡胶链段的相互扩散和缠结粘合的结果;通过对共混界面的增容和交联增容.加强界面相容稳定性和粘结力,充分发挥橡胶微区结构和界面层结构在共混物中的韧性作用。 相似文献
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综述了橡胶增韧PS系列树脂的原理及相关的增韧理论:微裂纹理论、多重银纹理论、剪切屈服理论、剪切带-银纹理论、空穴化理论和逾渗理论,阐述了各个理论的基本观点,分析了不同增韧理论的优缺点。详尽概述了橡胶增韧高抗冲聚苯乙烯(HIPS)和丙烯腈-丁二烯-苯乙烯共聚物(ABS)性能影响因素:增韧体系、增韧橡胶的种类及结构、增韧橡胶用量、橡胶粒径、橡胶离子接枝度,并重点介绍了采用低顺式聚丁二烯橡胶(LCBR)和线性丁苯嵌段共聚物(LBS)增韧体系的优点。此外,还简要介绍了聚苯乙烯(PS)系列树脂专用增韧橡胶LCBR和LBS的特征和性能。通过对PS系列树脂增韧改性的深入研究,为扩大其应用领域和生产发展提供理论基础。 相似文献
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乙丙橡胶增韧聚丙烯共混物中橡胶相形态 总被引:7,自引:1,他引:7
通过电子扫描电镜(SEM),研究了乙丙橡胶增韧聚丙烯共混物中作为分散相的橡胶粒子的形态。结果表明,在交联剂等助剂的作用下进行过动态硫化的共混物中橡胶相的粒子形状、粒径、粒径分布以及橡胶粒子与连续相聚丙烯所形成的界面形态与单纯的橡塑共混物和PP/EPDM反应器共混物相比有着截然不同的区别。正是由于这些区别,提高了经过动态硫化的共混物的冲击性能。 相似文献
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《塑料工业》2017,(8)
采用乳液聚合技术合成一系列具有核-壳结构的丙烯酸酯类抗冲改性剂(ACR),将其与聚氯乙烯(PVC)进行熔融共混制备PVC/ACR共混物。研究ACR的核/壳比、橡胶的粒子尺寸和交联剂三烯丙基异三聚氰酸酯(TAIC)含量对PVC/ACR共混物力学性能与形态结构的影响。结果表明,随着核/壳比的增大,ACR的增韧效率有了明显的提高;交联剂的加入改变了ACR的刚性与韧性,进而对共混物的性能有了较大的影响,随着交联剂含量的增加,共混物的冲击强度先变大后减小,当交联剂的含量为4%,ACR的添加量为8 phr时,共混物的冲击强度达到了1 196.70 J/m;随着橡胶粒子尺寸的增加,共混物的韧性逐渐降低。扫描电子显微镜分析表明,ACR增韧PVC的主要增韧机理是橡胶的空洞化和基体的剪切屈服。 相似文献
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通过种子乳液聚合方法合成聚丁二烯接枝甲基丙烯酸甲酯(PB-g-MMA)核-壳改性剂。将PB-g-MMA、聚氯乙烯(PVC)和聚甲基丙烯酸甲酯(PMMA)在160℃下熔融共混,制得橡胶含量为16%(质量含量)的一系列的橡胶改性PVC/PMMA共混物。研究了基体组成对共混物力学性能和形态结构的影响。结果表明在宽组成范围内PVC和PMMA是相容的,并且当PVC含量较少时,共混物以脆性方式断裂,银纹是其主要的形变机理;当PVC含量较多时,共混物以韧性方式断裂,此时主要的形变机理是橡胶粒子的空洞化和基体的剪切屈服。在橡胶改性PVC/PMMA共混物中,随着基体组成的改变形变,机理存在着从银纹到剪切屈服的转变。 相似文献
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It is well established that a wide range of drugs of abuse acutely boost the signaling of the sympathetic nervous system and the hypothalamic–pituitary–adrenal (HPA) axis, where norepinephrine and epinephrine are major output molecules. This stimulatory effect is accompanied by such symptoms as elevated heart rate and blood pressure, more rapid breathing, increased body temperature and sweating, and pupillary dilation, as well as the intoxicating or euphoric subjective properties of the drug. While many drugs of abuse are thought to achieve their intoxicating effects by modulating the monoaminergic neurotransmitter systems (i.e., serotonin, norepinephrine, dopamine) by binding to these receptors or otherwise affecting their synaptic signaling, this paper puts forth the hypothesis that many of these drugs are actually acutely converted to catecholamines (dopamine, norepinephrine, epinephrine) in vivo, in addition to transformation to their known metabolites. In this manner, a range of stimulants, opioids, and psychedelics (as well as alcohol) may partially achieve their intoxicating properties, as well as side effects, due to this putative transformation to catecholamines. If this hypothesis is correct, it would alter our understanding of the basic biosynthetic pathways for generating these important signaling molecules, while also modifying our view of the neural substrates underlying substance abuse and dependence, including psychological stress-induced relapse. Importantly, there is a direct way to test the overarching hypothesis: administer (either centrally or peripherally) stable isotope versions of these drugs to model organisms such as rodents (or even to humans) and then use liquid chromatography-mass spectrometry to determine if the labeled drug is converted to labeled catecholamines in brain, blood plasma, or urine samples. 相似文献
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Cheng-Le Zhao Shane Porzio Alan Smith Haiyan Ge H. T. Davis L. E. Scriven 《Journal of Coatings Technology and Research》2006,3(2):109-115
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. 相似文献
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ICP-MS法测定地球化学样品中As、Cr、Ge、V等18种微量痕量元素的研究 总被引:15,自引:0,他引:15
建立了测定地球化学样品中包括As、Cr、Ge、V等18种微量、痕量元素的ICP-MS方法。地化试样用HF-HNO3混酸分解后,以1 1 HNO3溶解干渣。由于制样不使用盐酸,避免了Cl对As、Cr、Ge、V的质谱干扰。用国家一级地球化学标准物质GBW 07309制备溶液优化仪器工作参数,并用于校准。方法测定限(6s)为:0.007~6.4μg/g,精密度(RSD%,n=12)为:29%~9.4%,经过国家一级地球化学标准物质的分析验证,结果与标准值吻合。方法已应用于国土资源调查的试样分析。 相似文献
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M. S. J. Simmonds W. M. Blaney F. Delle Monache M. Marquina Mac-Quhae G. B. Marini Bettolo 《Journal of chemical ecology》1985,11(12):1593-1599
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. 相似文献
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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. 相似文献
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以大分子引发剂氯乙酰化聚苯乙烯微球(PS-acyl-Cl)经原子转移自由基聚合(ATRP)法引发丙烯酰胺(AM)和甲基丙烯酸缩水甘油酯(GMA)单体的共聚接枝,制得一种触角状亲水性环氧载体(PS-acyl-g-P(AM-co-GMA)),再经二乙醇胺(DEA)的环氧基开环胺化反应,得到一种含多个-NCH2CH2OH螯合配基的多齿-五元螯合环的触角状亲水性羟胺树脂(PS-acyl-g-P(AM-co-GMA)-DEA)。将此树脂用于硼吸附研究,结果表明,PS-acyl-g-P(AM-co-GMA)-DEA树脂对硼的吸附满足Langmuir方程,为单分子层吸附;饱和吸附量约为37.7 mg·g-1,且树脂5 min即可达到吸附平衡,与其它已报道的吸硼树脂相比,该树脂具有更高的吸附量和吸硼速率。吸附动力学研究表明,树脂吸附硼的过程主要由颗粒扩散过程控制。重复使用5次后该树脂的吸附量基本不变,解吸率均在90%以上,重复使用性能良好。 相似文献