Simulation and experiment study on adhesive ejection behavior in jetting dispenser

In this paper, fundamental equations for jetting dispenser are presented to express the influence of adhesive pressure, nozzle diameter, and needle movement law, and the equations are then verified by flow behavior simulation. Subsequently, a novel jetting dispenser system is built to finish experiments about the mentioned influence parameters, and simulation results verify the regularities from experiment are correct. Flow velocity in the central nozzle will be faster and radius of the droplet will be bigger if the pressure in the chamber became higher, flow velocity in the central nozzle will be constant and the radius of the droplet will be bigger if the dead time became longer, and bigger nozzle diameter can lead to faster flow velocity in the central nozzle and bigger droplet. Besides, these mentioned works prove that our designed jetting dispenser is practical and useful for adhesive jetting.     

Viscoelastic and adhesive properties of polystyrene-hydrogenated (3,4-polyisoprene and 1,4-polyisoprene)-polystyrene and polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate-based HMPSA

In the current study, hot melt pressure sensitive adhesives (HMPSA) were prepared by blending polystyrene-hydrogenated (3,4-polyisoprene and 1,4-polyisoprene)-polystyrene (HYBRAR7311), polymethyl methacrylate-polybutyl acrylate-polymethyl methacrylate (LA2250), tackifier, and other additives in an internal mixer. The compatibility of LA2250, HYBRAR7311, and glycerol rosin ester was investigated on the basis of transparency, differential scanning calorimeter, and scanning electron microscope. The results indicated that glycerol rosin ester was compatible with HYBRAR7311 and LA2250, while HYBRAR7311 was only partly compatible with LA2250. Besides, styrene-ethylene-butene-styrene block copolymers grafted MALEIC ANLYDRIDE was used as compatibilizer added into HMPSA. Although it increased the compatibility and shear strength yet the tack and peel strength were sharply decreased. Simple variable method was used to study the effect of main components on the tack, peel strength, and shear strength of HMPSA. The relationship between adhesive properties and viscoelastic properties of HMPSA was studied via dynamic mechanical analysis. The investigation showed that the smaller storage modulus at low frequency (0.01–0.1?1/s), the larger the tack. Peel strength was found proportional to G′′(f₁)/G′(f₂)(f₁?=?32.03?1/s, f₂?=?0.07?1/s). Similarly, the effect of this blend on damping performance and substrate on peel strength of HMPSA was investigated which was found excellent in this case. The peel strength of polypropylene was larger when HYBRAR7311 content was more than LA2250. However, the peel strength of polycarbonate and polyethylene glycol terephthalate was larger when LA2250 content was more than HYBRAR7311. Furthermore, the mechanical properties of HYBRAR7311/LA2250 HMPSA were found to be superior to the one-polymer HMPSA.     

Preparation of core–shell latex for the pigmented ink of textile inkjet printing

A core–shell latex comprising poly(butyl acrylate) as core and poly(styrene‐methyl methacrylate) as shell was synthesized by emulsion polymerization using allyloxy nonylphenoxy propanol polyoxyethylene ether ammonium sulfonate (ANPS) as emulsifier. Transmission electron microscope, differential scanning calorimeter, and thermogravimetric analyses suggested the prepared latex had a core–shell structure. The particle size of the core–shell latex was about 102.8 nm with a molar ratio of butylacrylate, methyl methacrylate, and styrene at 6 : 2 : 2, a mass ratio of ANPS and monomers, ammonium persulfate and monomers at 15% and 1.0%, respectively. The core–shell latex showed high centrifugal stability and excellent freeze‐thaw stability. The clogging nozzle rate of the pigmented ink containing 20 wt % core–shell latex was small, whereas the printed fabrics with this pigmented ink exhibited high rub and washing fastness. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Internal bias field relaxation in poled Mn-doped Pb(Mn1/3Sb2/3)O3–Pb(Zr,Ti)O3 ceramics

The frequency, electric field cycling and temperature dependences of the polarization–electric field (P–E), strain–electric field (S–E) loops in poled Mn-doped 0.05Pb(Mn_1/3Sb_2/3)O₃–0.50PbZrO₃–0.45PbTiO₃ ceramics have been investigated. The P–E and S–E loops are strongly asymmetric corresponding to the presence of an internal bias field E_i after poling and aging, indicating that the domain walls are strongly pinned by preferentially oriented defect dipoles formed by the acceptor dopant ions (Mn²⁺/Mn³⁺) and O²⁻ vacancies. Whereas, the loops exhibit a tendency of changing from asymmetric shapes to normal symmetric ones with increasing electric field amplitude or decreasing frequency. Repeated electric field cycling as well as high temperature results in a similar effect. Meanwhile, the E_i reduces consequently, providing evidence of domain depinning or internal bias field relaxation. It is suggested that the reorientation of the defect dipoles and depinning of domain walls arising from high temperature or electric field cycling are responsible for this extrinsic internal bias field relaxation process.     

FRIPP加氢裂化技术研发新进展

阐述了中国石化抚顺石油化工研究院（FRIPP）在加氢裂化工艺及催化剂技术研发方面的新进展情况。为满足工业实现清洁生产和产品质量持续升级的需求,FRIPP在完成加氢裂化技术系列化后,积极进行工艺技术应用拓展与技术水平的提升,可以根据用户特定需求进行设计,先后开发了提高加氢裂化装置原料适应性技术、高芳烃含量催化柴油加氢转化生产高辛烷值汽油或轻芳烃FD2G技术、加氢裂化掺炼催化柴油技术、氧化态加氢裂化催化剂湿法开工技术和Sheer新型高能效加氢裂化技术,满足了企业的多元化需求。在加氢裂化催化剂开发方面,利用UDRM加氢裂化催化剂制备技术平台,实现了催化剂各组分均匀分布,加氢活性中心和裂化活性中心匹配更加合理,可充分发挥出催化材料的性能,先后开发出FC-32、FC-34和FC-46等新一代加氢裂化催化剂,性能获得了明显的提升。     

化工原理课程设计教学内容和模式探索与实践

本文针对化工原理课程设计存在的题目单一、物系和案例库不完善、考核方式过于简单、工程能力和创新能力训练不理想、抄袭严重等问题,对课程设计的教学内容、教学模式和考核方式等方面提出了改进措施。我校的实践表明,这些改进措施有效地提高了课程设计教学质量。     

石油树脂用抗氧剂的研究进展

综述了石油树脂所用抗氧剂的主要种类及其抗热氧化机理,并介绍了石油树脂用抗氧剂的研究进展,最后指出了石油树脂用抗氧剂的发展方向。     

蒙脱土对脲醛树脂性能的影响

以有机蒙脱土(OMMT)作为脲醛树脂(UF)胶粘剂的改性剂,制备UF/OMMT纳米复合材料;然后将其用于刨花板的制备,并采用红外光谱(FT-IR)法和X-射线衍射(XRD)法对纳米复合材料的结构进行了表征。结果表明:刨花板的力学性能随OMMT含量增加呈先升后降(或先升后降再升)态势,并且在w(OMMT)=3%时相对较好;当w(OMMT)=1%时,经硅烷偶联剂(KH-550)处理后的OMMT在UF反应终了阶段加入时,刨花板的综合力学性能相对最好;在纳米复合材料体系中,OMMT的层状纳米片层已被剥离,并且OMMT和UF之间发生了一定程度的化学反应,而偶联剂和OMMT之间并没有形成化学键。     

Adsorption of phenol and 1-naphthol onto XC-72 carbon

XC-72 carbon (XC-72) was characterized by SEM, XPS, N₂ adsorption-desorption, particle size distribution analysis and potentiometric acid-base titration. The adsorption of phenol and 1-naphthol on XC-72 was studied as a function of contact time, pH, adsorbent content and temperature. The kinetic adsorption data were described well by the pseudo-second-order model. The adsorption isotherms of phenol were described well by Freundlich model, while the adsorption isotherms of 1-naphthol were fitted well by Langmuir model. The results demonstrated that XC-72 had much higher adsorption capacity for 1-naphthol than for phenol. The adsorption thermodynamic data were calculated from the temperature-dependent adsorption isotherms at T=293, 313 and 333 K, and the results indicated that the adsorption of phenol was an exothermic process, whereas the adsorption of 1-naphthol was an endothermic process. XC-72 is a suitable material for the preconcentration of phenol and 1-naphthol from large volumes of aqueous solutions.