乙烯基单体对聚氨酯丙烯酸酯性能的影响

分别以苯乙烯(SM)、甲基丙烯酸甲酯(MMA)、甲基丙烯酸(MA)和丙烯酸(AA)作为活性稀释剂,研究它们对聚氨酯丙烯酸酯性能的影响。结果表明,4种乙烯基单体与聚氨酯丙烯酸酯的相容性均很好,对体系稀释能力的大小顺序为MMA>SM>MA>AA。SM与MMA的反应活性相对较低,制得的样品力学性能较差。AA与MA的反应活性高,其中AA制备的样品断裂伸长率较高,柔韧性较好;MA制备的样品拉伸强度、硬度、压缩强度和压缩弹性模量较高,且随其含量增加,样品的凝胶时间、黏度和断裂伸长率降低,强度和刚度增大。在中后期(≥168 h),随着龄期增加,样品的压缩强度和压缩弹性模量增大,拉伸强度和硬度变化不大。     

交联单体TMP对水性聚氨酯性能的影响

以异佛尔酮二异氰酸酯(IPDI)和聚醚(N210)为主要原料,三羟甲基丙烷(TMP)为交联单体,合成自交联型水性聚氨酯乳液.探讨交联单体TMP用量对聚氨酯乳液性能及胶膜性能的影响,并与未交联和外交联型水性聚氨酯进行比较.结果表明:TMP用量为40%时,自交联型水性聚氨酯乳液粒径小,具有较好的稳定性;涂层织物耐静水压为239 mm,耐洗次数可达26次,具有较高的耐静水压和较好的耐洗性,与外交联型水性聚氨酯相当.     

自乳化聚氨酯乳液胶粘剂的制备

本文用二羟甲基丙酸作为亲水单体合成了自乳化聚氨酯乳液。该乳液稳定性达到半年以上,胶膜强度大于10MPa,扯断伸长率大于350％。     

EPDM-g-MAH增韧PA 6

制备了三种不同黏度的马来酸酐接枝三元乙丙橡胶(EPDM-g-MAH),将其用于增韧聚酰胺(PA)6。通过傅里叶变换红外光谱、扫描电子显微镜、差示扫描量热法、力学性能测试等表征了三元乙丙橡胶(EPDM)对增韧PA 6体系结构与性能的影响。结果表明:EPDM-g-MAH改善了PA 6与EPDM的相容性,用黏度适中的EPDM得到的EPDM-g-MAH与PA 6(质量比为85∶15)共混,分散相尺寸较小且分散均匀,共混体系的力学性能得到提高,特别是Izod缺口冲击强度几乎为PA 6的10倍。     

改性环氧树脂涂料的制备及性能研究

采用马来酸酐单体(MA)对双酚A型环氧树脂(E-51)改性,得到改性环氧树脂(EpM),通过正交实验法确定了改性树脂的制备及固化工艺,并通过红外光谱和热失重分析对产物及固化物进行了表征。结果表明,EpM最佳制备工艺:催化剂N,N-二甲基苯胺添加质量分数2.0%,阻聚剂质量分数0.075%(基于对苯二酚),反应温度80℃,反应时间2.0 h。固化最佳工艺:氧化剂过氧化苯甲酰添加质量分数2%,促进剂N,N-二甲基苯胺质量分数0.6%,交联剂苯乙烯质量分数20%。EpM的合成机理为环氧开环酯化反应;产物中出现了马来酸酐的特征官能团;其热分解温度可提高到418℃;漆膜耐腐蚀性、附着力、冲击强度均有提高。     

Preparation of cationic functional polymer latexes and measurement of involatile monomer conversion

A series of poly(styrene‐co‐methacryloxyethylhexadecyldimethyl ammonium bromide), P(St‐DMHB), cationic particles were prepared by emulsion polymerization using 2,2′‐azobis(2‐methylpropionamide) dihydrochloride as the initiator with different levels of DMHB as the cationic functional comonomer. ζ potential, particle size, and size distribution of the particles were determined. Large discrepancy was observed between the particle size from dynamic light scattering and that from transmission electron microscopy. Results showed that particle size and ζ potentials were closely dependant on DMHB level used. A flocculation process for the cationic latex was established, and a method to estimate DMHB conversion was proposed. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Enhanced Adsorption of Malachite Green by EDTAD-modified Sugarcane Bagasse

Abstract

Ethylenediaminetetraacetic dianhydride (EDTAD) modified sugarcane bagasse (SB) was prepared and characterized by Fourier transform infrared spectroscopy (FTIR). Due to the presence of a large number of carboxyl groups, the adsorption capacity of the EDTAD modified SB (EDTAD-SB) for malachite green (MG) showed a significant increase compared with SB. Increase in ion strength of solution-induced decline of MG sorption. The maximum adsorption capacities were 157.2 mg g^?1 for MG, according to the Langmuir equation. Kinetic studies showed better correlation coefficients for a pseudo-second-order kinetic model, confirming that the sorption rate was controlled by a chemisorption process.     

Monomer cast polyamide 6 composites and their treatment with high‐energy electrons

At first, the impact of selected spherically structured nanofillers made of different polar materials (carbon, silicon carbide, surface‐modified silica, 2 wt % each) on mechanical properties of monomer cast polyamide 6 (MCPA6) was examined. Only the low‐polar carbon‐based nanofiller showed an average particle size below 100 nm in the liquid phase before polymerization was initiated. With regard to neat MCPA6, mechanical properties of the composite loaded with the carbon nanoparticles like tensile strength, Young's modulus, and heat distortion temperature could be improved by 6.4%, 13.5%, and 27.5%, respectively. The efficiency of carbon as filler material for MCPA6 was also shown for carbon short‐cut fibers. A fiber content of 15% improved tensile strength from 78 to 93 MPa (19%) and Young's modulus could be doubled from 2660 MPa to nearly 5300 MPa. Regardless of the improved mechanical properties, the composites showed reduced degrees of crystallinity. Therefore, electron beam irradiation was applied to crosslink the polymer chains as an alternative to improve material properties. Crosslinking was supported by the application of a curing agent (CA). Two strategies for crosslinking experiments were tested: (1) Irradiation of CA‐containing neat MCPA6 to find the most effective dose and subsequent treatment of the composites under this special condition; (2) Optimization of the properties by irradiation of the composites itself at graduated dose values. The second way was more convenient and showed, with regard to the composites without CA, improvements of tensile strength and Young's modulus of 6% each. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

Atom transfer radical polymerization of methylmethacrylate and styrene initiated by 3,5‐bis(perfluorobenzyloxy)benzyl 2‐bromopropanoate

The synthesis of polymethylmethacrylate (pMMA) and polystyrene (pSt) were realized with newly synthesized initiator, 3,5‐bis(perfluorobenzyloxy)benzyl 2‐bromopropanoate (FBr) in the presence of copper bromide (CuBr) and N,N,N′,N″,N″‐pentamethyl‐diethylenetriamine (PMDETA) by using atom transfer radical polymerization (ATRP). The perfluorinated aromatic group containing initiator was prepared by esterification of the (3,5‐bis[(perfluorobenzyl)oxy]‐phenyl alcohol. Both initiator and polymers were characterized by ¹H‐NMR spectroscopy, gel permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. The ATRP was supported by an increase in the molecular weight of the forming polymers and also by their monomodal molecular weight distribution. Contact angle measurements of water and ethylene glycol on films of synthesized polymers indicated higher degree of hydrophobicity than that of pure pMMA and pure pSt. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

高效液相色谱法测定农田人参中9种人参皂苷单体含量

为评价农田人参质量,建立同时测定农田人参中9种人参皂苷单体含量的方法。采用反相高效液相色谱法(reversed phase-high performance liquid chromatography,RP-HPLC)对农田人参与伐林人参中9种人参皂苷单体含量进行比较分析,色谱条件:色谱柱(4.6mm×150mm,5μm),乙腈(A)-水(B)为流动相,梯度洗脱[0min(18%A)→24min(22%A)→26min(26%A)→30min(32%A)→50min(33.5%A)→55min(38%A)],流速为1.0mL/min,检测波长203 nm,柱温35℃。结果表明:农田人参含有与伐林人参相同种类的9种人参皂苷Rg 1、Re、Rf、Rg2、Rb1、Rc、Rb2、Rb3、Rd;6年生农田人参9种皂苷含量均高于6年生伐林人参,但除Rg1含量差异显著外(P<0.05),其他8种皂苷含量均不显著(P>0.05);4年生农田人参除Rg1、Rf显著高于4年生伐林人参(P<0.05)外,其他7种皂苷含量与4年生伐林人参差异均不显著(P>0.05)。农田人参中Rgl、Rb1的含量、Rgl和Re含量之和、Rgl和Re含量之和均超过中国药典、欧洲药典与美国药典的要求。