HDPE埋地排水管专用树脂的工业开发

根据国家标准、欧洲标准中对高密度聚乙烯(HDPE)埋地排水管材专用树脂的要求,确定了产品的质量控制指标和生产工艺参数。在HDPE淤浆法工艺生产装置上,开发了具有优良的物理性能、加工性能和耐环境应力开裂(ESCR)性能的埋地排水管材专用树脂6360M。6360M屈服拉伸强度大于25 MPa;弯曲模量大于1200MPa;ESCR(F50)在1000 h以上;通过了耐内压性能测试。     

滚塑成型用聚乙烯专用树脂的性能

研究了滚塑成型用聚乙烯专用树脂DNDC7150A的基本物性、耐紫外光老化性能、耐环境应力开裂(ESCR)性能和加工性能.结果表明:DNDC7150A经过1 176 h紫外光老化实验后,拉伸断裂应变保留率仍在50%以上:ESCR超过6 000 h:具有良好的加工性能.     

耐热聚乙烯管材专用树脂的结构与性能

研究了3种耐热聚乙烯管材专用树脂的结构与性能。它们的共同特征为熔体流动速率低于0.7 g/10 min,密度为0.930~0.944 g/cm3,相对分子质量为(1.5~2.5)×105,可以为窄相对分子质量分布,也可以为中等相对分子质量分布。1-己烯共聚产品与1-辛烯共聚产品性质较为接近,都是窄相对分子质量分布,而1-丁烯共聚产品具有相对分子质量高(2.0×105以上),相对分子质量分布中等(10左右),熔体流动速率低(低于0.3 g/10min)、密度高(大于0.940 g/cm3)、拉伸屈服强度高、弯曲模量高、熔融峰温高、结晶峰温高的特点。相同条件下,1-丁烯共聚产品具有较高的黏度和模量。     

分子结构对双峰管材专用树脂流变性能的影响

对3种双峰聚乙烯管材专用树脂进行了结构性能及毛细管流变行为、拉伸流变行为的研究。结果表明:双峰管材专用树脂熔体流动速率低(0.23～0.25 g/10 min),结晶性能好(熔点128℃以上,结晶温度115℃以上,结晶度大于65%),相对分子质量分布宽。不同管材专用树脂的结构差异决定了其流变加工性能。少量低相对分子质量尾端组分对挤出流变行为的影响显著,可以降低低剪切速率下的黏度和压力。提高高相对分子质量组分所占比例,比增大高相对分子质量组分的相对分子质量大小对提高熔体强度的效果更明显。     

吹塑级大中空专用料TR571M的质量改进

分析测试了高密度聚乙烯树脂大中空专用料TR571M的相对分子质量及其分布、力学等性能,并与进口树脂对比,找出TR571M冲击性能低和耐堆码性差的原因。结果表明:熔体流动速率(MFR)偏高,平均相对分子质量较低,是造成TR571M性能差的原因。经改进后,TR571M冲击性能显著提高,达到了下游客户的要求。     

薄膜专用PP树脂加工性能的凝胶渗透色谱评价

用凝胶渗透色谱测定了不同批号的薄膜专用聚丙烯(PP)树脂T38F的相对分子质量及其分布,评价了产品的相对分子质量及其分布对加工性能的影响.测定结果的重复性和再现性良好.根据分析结果调整相关工艺条件后生产的PP T38F能够满足用户的加工要求.实验结果表明:薄膜专用PP树脂的重均分子量(Mw)控制在(25.0～29.0)...     

中密度聚乙烯光缆护套专用料的性能

研究了乙烯/1-丁烯共聚中密度聚乙烯(MDPE)光缆护套专用料QHK15BK的耐环境应力开裂(ESCR)性能、耐老化性能和加工性能.结果表明:QHKl5BK的ESCR在1 500 h以上;200℃氧化诱导期在90 min左右;具有良好的加工性能,可满足高速牵引的需要.     

PE100级管材专用HDPE树脂的开发

采用 Innovenes 工艺,双环管淤浆法,1-已烯为共聚单体开发生产了 PE100级管材专用高密度聚乙烯(HDPE)树脂PN049-030-122,分析了其结构、力学性能及加工应用情况,并与国内外同类产品进行了对比.HDPEPN049-030-122的熔体流动速率为0.290～0.300 g/10 min,密度为0.949g/cm3,拉伸弹性模量达1 100 MPa以上,简支梁缺口冲击强度大于30 kJ/m2,各项性能达到指标要求,相对分子质量分布曲线呈双峰.     

埋地排水管材专用聚丙烯树脂的结构与性能

利用核磁共振波谱仪、凝胶渗透色谱仪、X射线衍射仪、差示扫描量热仪、偏光显微镜及动态流变仪等研究了埋地排水管材专用聚丙烯(PP)树脂与给水管材专用PP树脂的结构与性能.结果表明:与给水管材专用 PP树脂相比,埋地排水管材专用PP树脂具有更高的相对分子质量、适宜的相对分子质量分布、合理的乙烯含量及不同的分子链序列结构.埋地排水管材专用PP树脂的弯曲模量大于1 600 MPa,简支梁缺口冲击强度大于80 kJ/m2,负荷变形温度大于100℃,具有优异的刚韧平衡性能和较高的熔体强度.     

LDPE 2100TN00在软管包装容器中的应用

介绍了低密度聚乙烯(LDPE)2100TN00在软管包装容器中的应用,并与进口原料进行了对比.结果表明,2100TN00与进口原料物理性能相似,相对支化度、熔点、相对分子质量近似,都具有优良的耐环境应力开裂(ESCR)性能.应用表明,2100TN00还具有良好的加工、印刷性能,热封性能满足厂家要求,ESCR性能也满足要求.     

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.     

Many Drugs of Abuse May Be Acutely Transformed to Dopamine,Norepinephrine and Epinephrine In Vivo

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.     

Novel polyurethane coating technology through glycidyl carbamate chemistry

Glycidyl carbamate chemistry combines the excellent properties of polyurethanes with the crosslinking chemistry of epoxy resins. Glycidyl carbamate functional oligomers were synthesized by the reaction of polyfunctional isocyanate oligomers and glycidol. The oligomers were formulated into coatings with several amine functional crosslinkers at varying stoichiometric ratios and cured at different temperatures. Properties such as solvent resistance, hardness, and impact resistance were dependent on the composition and cure conditions. Most coatings had an excellent combination of properties. Studies were carried out to determine the kinetics of the curing reaction of the glycidyl carbamate functional oligomers with multifunctional and model amines. Detailed kinetic analysis of the curing reactions was also undertaken. The results indicated that the glycidyl carbamate functional group is more reactive than a glycidyl ether group. Presented at the 82nd Annual Meeting of the Federation of Societies for Coatings Technology, on October 27–29, 2004, in Chicago, IL.