Effects of formulation and processing parameters on the morphology of extruded polypropylene‐(waste ground rubber tire powder) foams

This paper presents an experimental study of the foaming behavior of polypropylene (PP)/(waste ground rubber tire powder) (WGRT) blends when using a chemical blowing agent in an extrusion foaming process. The effects of formulations (i.e., WGRT content, blowing agent content, compatibilizer) and the processing parameters (i.e., die temperature, screw speed) on the void fraction, average cell size, cell density, and cell morphology of the PP/WGRT foams were investigated. The blowing agent loading affected the cell structure of the foams and the average cell size, and the void fraction increased with increasing blowing agent loading. Both increasing the screw speed and decreasing the die temperature could establish a high pressure drop in the extruder die, and these were beneficial to the foaming extrusion. J. VINYL ADDIT. TECHNOL., 2009. © 2009 Society of Plastics Engineers     

Study on the creep behavior of polypropylene

The creep behavior and creep failure law of polypropylene (PP) were investigated by using a multifunctional stress‐aging testing machine under different aging environmental conditions (temperature, UV, and stress). Photoinduced changes in samples were studied using gel permeation chromatography and X‐ray photoelectron spectrometer. Surface morphologies were also observed by scanning electron microscopy. It was found that there is a critical failure strain (ε_crit) for PP during the creep course. Once the creep deformation exceeds the ε_crit, creep failure of PP takes place very rapidly. The value of ε_crit is independent of the tensile stress and UV irradiation, whereas it is only affected by the temperature and the nature of the PP, such as molecular weight and molecular structure. With increasing temperature, the value of ε_crit increases gradually. In addition, the creep rate of PP increases rapidly with increasing tensile stress and temperature as well as under irradiation with UV light. This study may provide a new way to predict the service lifetime of PP. POLYM. ENG. SCI., 2009. © 2009 Society of Plastics Engineers     

Dielectric and dynamic mechanical relaxation behavior of exfoliated nano graphite reinforced flouroelastomer composites

Dynamic mechanical analysis and dielectric relaxation spectra of exfoliated nano graphite reinforced flouroelastomer composites were used to study their relaxation behavior as a function of temperature (−80°C to +40°C) and frequency (0.01 to 10⁵ Hz). The effect of filler loadings on glass transition temperature was marginal for all the composites and T_g value was in the narrow range of 7.8–8.4°C, which has been explained on the basis of relaxation dynamics of polymer chains in the vicinity of fillers. Strain‐dependent dynamical parameters were evaluated at dynamic strain amplitudes of 0.01–10%. The nonlinearity in storage modulus has been explained on the concept of filler‐polymer interaction and filler aggregation of the nano graphite platelets. The variation in real and complex part of impedance with frequency has been studied as a function of filler. The percolation of the nano graphite as studied by conductivity measurements is also reported. POLYM. COMPOS., 2009. © 2008 Society of Plastics Engineers.     

F型环氧树脂的NMR表征

用核磁共振波谱技术对两种Ｆ型环氧树脂的结构进行了表征,并通过二维１Ｈ—１Ｈ相关谱（ＣＯＳＹ）及１Ｈ—１３Ｃ化学位移相关谱（ＨＥＴＣＯＲ）对１Ｈ、１３Ｃ谱中各共振峰进行了指认。     

紫外线吸收剂UV—9生产新工艺

完善了由三氯甲基苯与间苯二酚缩合成中间体２,４－二羟基二苯甲酮,进而用硫酸二甲酯将对位醚化成标的物２－羟基－４－甲氧基二苯甲酮（ＵＶ－９）的生产工艺。本工艺具生产操作简便、安全、三废排放少并且成本低廉等优点。     

Adsorption and inhibition effect of 6-benzylaminopurine on cold rolled steel in 1.0 M HCl

The adsorption and inhibition effect of 6-benzylaminopurine (BAP) on cold rolled steel (CRS) in 1.0 M HCl at 25-50 °C was studied by weight loss and potentiodynamic polarization methods. The results showed that BAP was a good inhibitor in 1.0 M HCl, and the inhibition efficiency (IE) increased with the inhibitor concentration. The adsorption of BAP on the CRS surface obeyed the Langmuir adsorption isotherm equation. Both thermodynamic parameters (adsorption heat ΔH⁰, adsorption free energy ΔG⁰ and adsorption entropy ΔS⁰) and kinetic parameters (apparent activation energy E_a and pre-exponential factor A) were calculated and discussed. Polarization curves showed that BAP acted as a mixed-type inhibitor in hydrochloric acid. Good agreement between weight loss and polarization methods was obtained. The adsorbed film on CRS surface containing optimum dose of BAP was investigated by Fourier transform infrared spectroscopy (FTIR) and atomic force microscope (AFM). Quantum chemical calculation was applied to elucidate the adsorption mode of the inhibitor molecule onto steel surface. Depending on the results, the inhibitive mechanism was proposed from the viewpoint of adsorption theory.     

Fabrication of Ni-matrix carbon nanotube field emitters using composite electroplating and micromachining

Ni-matrix carbon nanotube (CNT) field emitters have been fabricated by composite electroplating and micromachining (CEMM) at room temperature. Pretreated multi-walled CNT and Ni are deposited onto a Cr/Cu conducting layer by composite electroplating and protruding tips of CNTs are obtained as emitters by etching away a layer of Ni, followed by emitter pixels which are formed by micromachining. Through the process of CEMM, CNTs are vertically embedded in the flat Ni substrate. No further treatment is needed to initiate or augment field emission and the field emitters exhibit good field-emission properties such as high current density (13 mA cm⁻² at an applied electric field of 3.4 V μm⁻¹), low turn-on field (0.53 V μm⁻¹), and good stability (110 h for 10% degradation of current density from 400 μA cm⁻²).     

PMMA/蒙脱土纳米复合材料的结构及热性能

以甲基丙烯酸二甲胺基乙酯和1-溴正十六烷为原料合成了1种新型的带双键长碳链季铵盐甲基丙烯酰氧乙基十六烷基二甲基溴化铵(MHAB).用MHAB对钠基蒙脱土进行改性得到有机蒙脱土(OMMT).通过本体原位插层聚合制备了的聚甲基丙烯酸甲酯/蒙脱土纳米复合材料.MHAB的结构通过核磁共振氢谱(1H-NMR)表征.X射线衍射(XRD)测得OMMT的001面层间距(d001)从1.25 nm扩大到2.72 nm.XRD和透射电镜(TEM)测试证明蒙脱土质量分数为5%,8%时完全以剥离片层形式存在于复合材料中.差示扫描量热仪(DSC)和热失重仪(TG)测试表明复合材料的玻璃化转变温度和外推起始热失重温度都随着蒙脱土的含量增加而提高.     

亚临界甲醇中麻疯树油制备生物柴油的研究

对麻疯树油在催化剂对甲苯磺酸作用下与亚临界甲醇反应制备脂肪酸甲酯(生物柴油)进行了研究。结果表明在反应温度170℃、醇油摩尔比40:1、催化剂用量占油重的0.75%和反应时间30 m in的条件下,反应产物中脂肪酸甲酯含量可达93%以上。制备的生物柴油,各项指标与柴油相似。主要性能指标,符合ASTMPS121-99(USA)和0#矿物柴油标准。     

橡胶防老剂双酚F的清洁化合成工艺研究

研究了橡胶防老剂双酚F[2,2'-亚乙基双(4,6-二叔丁基苯酚)]的清洁化生产工艺方法。以2,4-二叔丁基苯酚、三聚乙醛为反应原料,水乳化液为反应溶剂,其中含有表面活性剂、分散剂、硫酸催化剂,经缩合反应制备2,2'-亚乙基双(4,6-二叔丁基苯酚)。当n(2,4-二叔丁基苯酚):n(三聚乙醛)=2:1.2,m(2,4-二叔丁基苯酚):m(硫酸催化剂):m(乳化剂)=1:0.1:0.05,反应温度92～93℃,反应时间6.0h时,得到产品双酚F的收率为96.6%。经液相色谱分析,产品质量分数99.66%,熔点164.6～165.2℃。反应母液可循环使用,解决了传统生产工艺中所产生的含酚废水处理问题。