炼胶工艺改进对胎面挤出气孔的影响

正半成品胶部件生产是轮胎制造过程中的一个主要工序,胎面部件的挤出是该工序中的重要组成部分,胎面部件尺寸的波动会严重影响成品的质量。半钢子午线轮胎胎面中的面胶一般由Φ250冷喂料螺杆挤出机出型。该复合挤出工艺的优点是胎面更换规格、尺寸比较容易,劳动生产率高。半钢胎生产所需的胎面规格种类多,在挤出过程中经常出现胎面表面不平滑和尺寸波动较大的问题,特别是断面气孔较多,气孔率有时达到7%~8%,返回率较高,甚至     

挤出提速产生质量问题原因分析及改进措施

我厂轮胎胎面挤出采用两台ＸＪ 2 0 0型挤出机。随着产量不断增加 ,挤出速度不断提高 ,挤出速度提高后 ,挤出生热、变形增大 ,随之产生胎面熟芯、气孔和尺寸不稳定等质量问题 ,对轮胎内、外质量影响较大。本文针对这些质量问题进行原因分析 ,并提出相应的改进措施。1　原因分析(1 )胎面熟芯大规格汽车轮胎胎面胶料挤出时 ,机头内部压力较大 ,生热高。挤出提速后 ,胶料在机头内部的生热进一步增大 ,如果降温效果不好 ,则会产生熟芯现象。(2 )胎面气孔大规格拖拉机轮胎胎面断面尺寸较大 ,要求挤出机吃胶量较大且机头内部压力较小。挤出提速后 …     

SSM一步法炼胶工艺对胎面气孔率的影响

试验研究SSM一步法炼胶工艺对半钢子午线轮胎胎面气孔率的影响。结果表明,与传统胎面四段炼胶工艺相比,SSM一步法炼胶工艺生产的胎面胶料的炭黑分散度等级和分散性指数均较高,胶料的流动性提高,物理性能提升,可降低挤出胎面的断面气孔率,最终提升成品轮胎的胎面稳定性、外观质量及耐磨性能。     

冷喂料胎面挤出断面气孔原因分析及解决措施

胎面挤出是轮胎制造过程中的重要工序之一,胎面挤出质量的好坏与轮胎质量息息相关。目前冷喂料挤出是国内比较先进的胎面生产方式,但挤出的半成品胎面断面气孔会影响到轮胎的耐磨性,容易出现崩花、掉块、沟裂等质量问题,因此解决冷喂料挤出胎面断面气孔是一个很重要的课题。一、原因分析对断面气孔产生的机理和影响因素从人、机、料、法、环等方面进行分析。人员方面:要求熟悉挤出工艺知识、掌握操作技能;机械方面:要求保证设备正常运转;原料方面:要求胎面胶料符合工艺性能要求;挤出工艺方面:一是螺杆吃料是否很密实,二是主机各段温度是否设…     

胶料混炼方式对胎面气孔率的影响

分析验证了轮胎胎面半成品挤出时产生气孔的本质。对比了胶料混炼方式,包括：转子类型、下密炼机开口设计方式、保温工艺、混炼时间、加料顺序等对挤出胎面时气孔率影响,最终总结认为,相同挤出工艺条件下,密炼机转子类型对胎面气孔率差异有决定性影响。     

优化全钢胎面口型设计降低胎面气孔率

针对目前大规格胎面挤出存在质量、尺寸以及气孔较多问题进行分析,制定相应的改进方案(主要是优化胎面终口型设计)。通过对改进后实际使用效果进行跟踪对比,适当的改进可以解决现有问题、满足工艺要求、降低能耗、提高质量和效益等作用。     

全钢载重子午线轮胎胎面挤出口型改进

针对目前大规格胎面挤出存在质量和尺寸波动大且气孔较多的问题进行分析,制定相应的改进方案:胎面口型厚度增大60%;胎面口型胶料流动方向与水平方向角度由原来的0°增大为11°。胎面挤出口型改进后,基本解决了上述问题,胎面半成品一次合格率和质量提高,制造成本降低。     

全钢载重子午线轮胎胎面混炼胶停放时间对挤出效果的影响

研究全钢载重子午线轮胎胎面混炼胶停放时间对挤出效果影响。结果表明:胎面混炼胶停放时间与挤出部件的气孔率、质量和尺寸有密切关系;胎面混炼胶需要停放一定时间,但停放时间不宜太长,一般控制在96 h内,以降低混炼胶停放时间对挤出半成品的影响,提升产品质量。     

FNS-78T炭黑分散剂对降低冷喂料挤出胎面气孔的影响

胎面挤出是轮胎制造过程中的重要工序之一,胎面挤出质量的好坏对轮胎质量的好坏有重要影响。目前国内比较先进的胎面生产方式是冷喂料挤出,但采用该方法挤出的半成品胎面断面很容易产生气孔。气孔的存在会影响到轮胎成品的耐磨性,容易出现崩花、掉块、沟裂等质量问题。     

优化炼胶工艺降低胎面气孔率

试验研究优化炼胶工艺对半钢子午线轮胎胎面气孔率的影响。结果表明,与传统胎面胶三段混炼工艺相比,四段混炼工艺生产的胎面胶料的炭黑分散度等级和分散性指数均较高,胶料的流动性提高,物理性能提升,可降低挤出胎面的断面气孔率,最终提升成品轮胎的胎面稳定性、外观质量及耐磨性能。     

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.     

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.     

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.     

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.     

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.     

Highly moisture-proof polysilsesquioxane coating prepared via facile sol-gel process

A highly moisture-proof polysilsesquioxane coating was obtained from a new bis-silylated precursor, which was synthesized from 3-aminopropyltriethoxysilane (APTES) and m-xylylene diisocyanate (m-XDI) in tetrahydrofuran (THF) and verified by ¹H MAS NMR. For direct comparison purposes, an SiO₂ coating was also prepared by the Stöber method using tetraethoxysilane (TEOS) as the reactant. Interestingly, the coating obtained from the polysilsesquioxane sol exhibited a much higher moisture resistance capability than its counterpart, which was attributed to its more compact feature between nanoparticles as characterized by N₂ absorption experiment and transmission electron microscopy (TEM). Furthermore, its high transparency of about 92% showed potential for application in the protection of optical crystals.