近红外原位研究杂多酸引发的环氧-四氢呋南阳离子聚合

用近红外光谱原位跟踪的方法,研究了杂多酸催化的环氧树脂和四氢呋喃的阳离子聚合过程.发现在低环氧树脂含量下,环氧消耗速率在整个聚合过程中维持不变;而在高环氧树脂含量下,环氧消耗速率则随时间有所下降.通过红外光谱在碳氢区域的分峰分析,证明环氧树脂与四氢呋喃发生了共聚反应,二维红外光谱的结果也确证了这一结果.此外,还探讨了环氧转化速率与环氧含量间的关系.     

UV界面聚合法制备含磷环氧微胶囊及其性能研究

通过双酚A环氧与DOPO反应,合成含磷环氧树脂,并以此为囊芯,环氧丙烯酸酯和可聚合乳化剂共聚物为囊壁,通过UV界面自由基聚合制备兼具阻燃性和自修复性能的含磷环氧微胶囊,并对产物微胶囊的性质进行了进一步研究。用红外光谱(FT-IR)和扫描电镜(SEM)表征了含磷环氧微胶囊的核―壳化学结构和表面形态。采用差热扫描(DSC)分析了囊芯环氧树脂与固化剂的反应活性。通过热重分析法(TG)和极限氧指数法(LOI)研究了含磷环氧微胶囊的热稳定性及其在环氧复合材料中的阻燃性。结果表明:通过UV界面自由基聚合,在相分离作用下,能方便地实现微胶囊化,且所制含磷环氧微胶囊囊芯具明显的反应活性,其热稳定性和阻燃性能满足自修复复合材料性能要求。     

基于介孔分子筛MCM-41“有机-无机”互穿结构纳米复合材料体系研究

采用硅烷偶联剂KH550对介孔分子筛MCM-41内、外表面进行改性,并利用氮气吸附-脱附,傅里叶红外光谱以及小角X衍射等进行表征,其结果显示KH550分子被引入MCM-41纳米孔道中,且—NH_2基团成功嫁接到MCM-41纳米颗粒表面.凝胶液相色谱实验结果证实本文中采用的双酚A型环氧树脂为低分子量环氧.随后,采用原位聚合的方法制备不同MCM-41含量环氧树脂纳米复合材料.最后,利用正电子湮没寿命谱测量复合材料自由体积孔洞;利用透射电镜,动态热机械分析和交流击穿对复合材料宏观性能进行研究.复合材料超薄切片TEM观察结果显示,在低MCM-41添加含量时,MCM-41颗粒可在复合材料中良好分散.同时,环氧分子在外施作用力和硅烷偶联剂功能作用下引入纳米孔道,形成"有机-无机"互穿结构复合材料体系,增强MCM-41和环氧树脂间相互作用力,在低MCM-41添加含量下提高复合材料玻璃化温度(15.1%↑)和击穿电压(22.6%↑).     

硅烷化学改性环氧涂层的耐蚀性能

利用"活性"与"非活性"硅烷化学改性环氧涂层以提高其耐蚀性."活性"硅烷指含有可以与环氧树脂的环氧端基发生开环反应官能团的硅烷,通常为氨基硅烷;"非活性"硅烷指不与环氧端基发生反应,但在有机锡催化剂存在下可与环氧树脂骨架上的羟基发生缩合反应的硅烷.红外光谱显示,两类硅烷均可成功接枝在环氧树脂上.电化学阻抗谱(EIS)和加速腐蚀试验(Machu试验)测试表明,经硅烷化学改性后的环氧涂层均能提高其耐蚀性能.     

紫外光引发环氧树脂的下行前线聚合行为

采用紫外光(UV)引发法研究了221型脂环族环氧树脂的下行前线聚合行为.探讨了光引发剂、热引发剂用量和预热温度等对聚合前线的推动速率Vf和前线引发时间ti的影响,并利用傅里叶变换红外光谱(FTIR)、热重(TG)和差示扫描量热(DSC)等对固化物结构和热性能进行了表征.研究结果表明,提高光引发剂浓度、热引发剂浓度或预热温度,均可提高聚合前线的推动速率Vf,缩短引发时间ti.采用该技术制备的环氧树脂固化物具有较好的均一性及热稳定性.     

基于UV-LED茂铁盐体系对脂环族环氧单体的阳离子光聚合动力学研究

本文利用实时傅里叶变换红外光谱(real-time FTIR)研究了脂环族环氧单体(CE)在405 nm UV-LED光源下的光聚合动力学。以η6-异丙苯茂铁六氟磷酸盐(I-261)作为阳离子光引发剂,2-异丙基硫杂蒽酮(ITX)、姜黄素(CC)和1-[4-(苯基偶氮)苯基偶氮]-2-萘酚(SudanⅢ)作为光敏剂,探究该茂铁盐体系对CE单体环氧基团转化率及聚合速率的影响。结果表明,尽管所有光敏剂都能有效地引发光聚合,但是ITX和CC体系在405 nm光源的辐照下表现出更高的聚合效率。在8.0%(质量分数)I-261和0.5%ITX条件下,CE的单体转化率从74.4%提高至89%以上,最大聚合速率提高了1.9倍。在8.0%(质量分数)I-261和1.0%CC条件下,CE的单体转化率从74.4%提高至88%以上,最大聚合速率提高了1.7倍。     

4-乙烯基-1-环己烯二环氧化物阳离子单体光聚合性能研究

本文用实时红外光谱研究了4-乙烯基-1-环己烯二环氧化物(TTA22)单体的光聚合性能。分别考察了光引发剂浓度、光源、光强及增感剂浓度对其光聚合性能的影响。选用3,4-环氧环己基甲酸-3′,4′-环氧环己基甲酯(TTA21)作为参照,比较了不同单体的光固化性能。结果表明,随着引发剂浓度以及光强的增加,环氧基转化率及转化速率随之增加。LED光源下单体的转化率和转化速率低于UV汞灯。对TTA22和TTA21光固化后材料的热稳定性进行分析,结果显示TTA21的热稳定性优于TTA22的。     

不同应变速率下纳米橡胶颗粒对环氧树脂的增韧特性与机理分析

为了解释不同应变速率下纳米橡胶颗粒对环氧树脂基体的增韧机理,制备了质量分数为6%的纳米橡胶颗粒/环氧树脂复合材料,分别测试了该材料在3种低应变速率(5×10-4s-1,1×10-1s-1,2.5×10-1s-1)和高应变速率下(90 s-1)的I型平面断裂韧性.结果表明,纳米橡胶颗粒在3种低应变速率下可以显著提高环氧树脂的断裂韧性,提高幅度分别为158%,283%和309%.在高应变速率下,纯环氧树脂的断裂韧性由于动态效应而显著升高,然而纳米橡胶颗粒对环氧基体的增韧效果却不明显,增韧幅度仅为2%.由光学显微镜照片可知,随着应变速率的提高,纳米橡胶颗粒/环氧树脂复合材料断口表面的应力发白区域逐渐较少,甚至在高应变速率(90 s-1)下消失.偏光显微镜照片表明,纯环氧树脂与纳米橡胶颗粒/环氧树脂复合材料的裂纹尖端塑性形变尺寸随着应变速率的升高而减小.通过扫描电子显微镜对断口形貌进行分析可知,不同应变速率下纳米橡胶颗粒在环氧基体中空穴增长程度不同,进而导致纳米橡胶颗粒对环氧基体的增韧效果的不同.     

2,4,6-三(羟基苯甲基氨基)-均三嗪的合成及其与双酚A型环氧树脂的固化行为研究

合成了一种含三嗪环结构的环氧树脂固化剂2,4,6-三(羟基苯甲基氨基)-均三嗪(MFP).用动态DSC和原位红外光谱对MFP/DGEBA(双酚A型环氧树脂)体系的固化行为进行了研究.动态DSC研究表明,由于MFP分子结构中存在两种活泼氢(酚羟基氢和仲胺氢),固化反应存在明显的两个峰,相对应的表观活化能分别为70.5 kJ.mol-1和86.5 kJ.mol-1(Kissinger法),通过与另一相似化合物固化DGEBA的比较可知,在MFP固化DGEBA的过程中,酚羟基与环氧基反应相对较难.原位红外动力学结果很好地支持了上述结论.     

铊胁迫水稻的电感耦合等离子体质谱及原位红外光谱分析

采用电感耦合等离子体质谱分析铊胁迫水稻中的Tl、Cr、Co、Ni、Cu、Zn、Mo、Ag、Cd及Pb等重金属元素,并利用原位衰减全反射红外光谱分析了水稻活体叶片的光谱特征。结果表明,铊在水稻叶茎中的含量显著高于谷粒。铊会影响水稻对其它元素吸收,并且在叶与种子中不同元素的吸收积累规律存在差异。水稻叶片的原位衰减全反射红外光谱进一步显示,铊胁迫下叶片的CO2消耗速率明显减少,表明叶片的光合作用受到一定抑制。利用原位衰减全反射红外光谱可直观表现重金属铊对水稻生理过程的胁迫作用。     

The linear relations and living feature in cationic ring-opening copolymerization of epoxy/THF system

The cationic copolymerization of diglycidyl ether of bisphenol-A with tetrahydrofuran (THF) initiated by phosphotungstic acid H₃PW₁₂O₄₀ (PW₁₂) was in situ investigated by Fourier transform near infrared spectroscopy. The gelation point of the reaction was determined by rheometrics mechanical spectroscopy. It was found that the conversion of epoxy group at 4,530 and 6,073 cm^?1 increased linearly with reaction time up to a high conversion (~90%), during which gelation (at ~51%) had no effect. The slope-indicating reaction rate of epoxy group also increased linearly with the content of PW₁₂. In addition, the peak splitting pattern of the overlapping C–H vibration region (5,700–6,200 cm^?1) was developed here. The peak-splitting analysis showed that the epoxy behavior agreed with above results, but the reaction rate of THF slowed down gradually with reaction time as the viscosity of the system increased. The results suggest that the kinetic behavior of cationic polymerization shows living feature of the propagating chains in this system and near infrared (NIR) technology could be applied to study such kinetic behavior.     

Graft Copolymerization of 4-Vinylpyridine Onto Partially Carboxymethylated Cellulose. the Degree of Substitution Effect

The graft copolymerization of 4-vinylpyridine (4-VP) onto partially car-boxymethylated cotton (PCMC), having different carboxymethyl contents, was investigated. Under similar reaction conditions, both the graft yield and eerie ion consumption increased by increasing the degree of substitution of carboxymethyl groups of PCMC up to a value of 0.11, beyond which grafting and Ce(IV) consumption decreased. Proof for grafting onto PCMC was provided through IR analysis. the eerie salt-initiated polymerization of 4-VP in the absence of PCMC was also studied. Three series of homo-polymerization reactions of 4-VP directly initiated by eerie ammonium nitrate were carried out with varying reaction times. Each series was run at a different nitric acid concentration. Both conversion and eerie ion consumption, as well as molecular weight, increased with reaction time. Increasing the nitric acid concentration increased both conversion and eerie ion consumption while the molecular weight decreased.     

新型水性环氧树脂的合成研究

以2-丙烯酰胺基-2-甲基丙磺酸(AMPS)为改性剂,过氧化苯甲酰(BPO)为引发剂,通过溶液聚合,使环氧树脂获得水分散性。以改性环氧树脂的收率、粒径分布、反应体系酸值随时间的变化为指标,对反应历程进行了推断,并对改性产物的结构进行了红外光谱分析。结果表明,在整个反应中,AMPS与环氧树脂主链接枝反应和与环氧树脂的环氧基团的开环反应同时进行。高聚物收率可达76.72%,体系中的环氧基团约70%被保留下来。改性环氧树脂体系不需中和即可分散于水中。     

Cationic copolymerization of tetrahydrofuran with propylene oxide. V. Effect of diol cocatalyst structure and concentration with antimony pentachloride as catalyst

The effects of the chemical nature and the concentration of diol cocatalysts in the copolymerization of propylene oxide (PO) and tetrahydrofuran (THF) catalyzed by antimony pentachloride were studied. The least bulky diol, 1,2-ethanediol, was found to be the most active species, judging from the highest rate of copolymerization. The variation of rate was much smaller with the other diols used. Furthermore, the position of the hydroxyl groups did not have much effect on the rate. The concentration of cocatalyst strongly influenced the rate of consumption of both monomers. This is explained by the effect of diol concentration on the equilibrium that exists between the catalyst and the cocatalyst on one side, and the active oxonium complex on the other. The mechanism of cocatalytic effects is discussed in terms of newer concepts of ionic polymerization. Specific solvation of ion-pairs is visualized as partly responsible for the overall effect of the cocatalysts. Water in quantities commeasurable with those of the cocatalyst was found to retard the reaction. It also gave rise to oligomeric products, as evidenced by gel-permeation chromatography.     

Branching kinetics of epoxy polymerization of 1, 4-butanediol diglycidyl ether with cis-1, 2-cyclohexanedicarboxylic anhydride

The copolymerization of an epoxy resin [1, 4-butanediol diglycidyl ether (DGEB) (Note a)] with an anhydride [cis-1, 2-cyclohexanedicarboxylic anhydride (CH)] in the presence of N, N-benzyldimethylamine (CA) as a catalyst produces a branched epoxy polymer. We show that the branching kinetics of the copolymerization reaction and the molecular weight distribution of the branched polymers can be approximated by using Smoluchowski's coagulation equation. In the simplest relevant application of this equation to our problem, the overall rate kernel w(u, v) that describes the branching probability in the equation turns out to be proportional to the sum of active sites on the two polymers with a time dependent coefficient. The molecular weight distribution (MWD) and the weight average molecular weight of the branched copolymers at different reaction stages before the gelation threshold are calculated theoretically. The calculated values are then compared with the experimental results obtained by using small angle X-ray scattering (SAXS), laser light scattering (LLS), and chemical analysis. Satisfactory agreement between experimental results and the use of the coagulation equation is attained when it is assumed that the distribution of epoxy polymer molecules is exponential in the number of branching points or, equivalently, active sites, at an early stage of the polymerization reaction.     

聚氨酯/环氧树脂互穿网络硬质泡沫塑料反应过程和微观结构

聚氨酯／环氧树脂互穿网络(PU／EPIPN)硬泡中异氰酸根的消耗速度较纯PU硬泡高，是由于环氧树脂的固化荆同时也是异氰酸根反应的催化荆。而PU／EP IPN硬泡中环氧基的反应速度和反应程度均较纯EP网络低，归因于互穿网络对基团扩散的阻碍。在互穿网络硬泡形成过程中，存在环氧开环中所新产生的羟基与异氰酸根的反应、大分子多元醇中羟基与环氧基的反应以及异氰酸根与环氧基形成嗯唑烷酮的反应三种形成网络间的化学键的途径。同时由于PU／EPIPN硬泡高度的交联，使得IPN硬泡中两个网络具有良好的相容性。动态力学性能表明所有IPN样品都只有一个玻璃化温度。透射电镜表明IPN样品无明显的相界面。     

基于季铵化烯丙基缩水甘油醚改性的阴离子交换固定相的制备北大核心CSCD

制备了一种季铵化烯丙基缩水甘油醚(allyl glycidyl ether,AGE)改性聚合物基质的阴离子固定相应用于离子色谱系统。它是利用AGE与水解的聚甲基丙烯酸缩水甘油酯-二乙烯基苯poly(glycidylmethacrylate-divinylbenzene,GMA-DVB)微球表面残留双键通过表面自由基共聚,再通过N,N-二甲基乙醇胺(一种叔胺)进行开环反应制备得到的。通过考察有机叔胺类型、微球水解、单体和引发剂用量、反应温度和时间对7种阴离子分离性能的影响,优化了制备条件。采用扫描电镜、元素分析对所得阴离子固定相进行了表征。结果表明,采用预先水解的GMA-DVB微球(水解过程中微球表面丰富的环氧基团转化为羟基)相对于直接采用GMA-DVB微球有助于降低固定相的交换容量和微球自身的非离子吸附作用;通过淋洗液浓度和目标离子保留因子的拟合结果证实了该固定相保留机理为典型的离子交换作用。使用碳酸根淋洗液,在优化的色谱条件下,该固定相可在13 min内实现常见7种无机阴离子的基线分离,并表现出较高的柱效(Cl-理论塔板数为49000块/m)。该色谱柱实用性通过分析自来水实际样品进行了验证。     

In-situ copolymerization of aniline with alkyl amine by APS： Kinetics and application

The kinetic study of in-situ eopolymerization of aniline with o- and p-methylaniline by ammonium persulfate （APS） has been carried out. UV-vis spectroscopic method was used to investigate the course of copolymerization. Structural characterization was studied by PT-IR spectral analysis. The electronic spectra of the copolymers poly（aniline-co-p-toluidine） and poly（aniline-co-o- toluidine） show blue shift. The shift has been observed in the bands corresponding to π→π^＊ transition as well as in the exciton transition. The increase in absorbance recorded during the reaction for different concentration of aniline, o- and p-toluidine at various intervals of time of polymerization reaction indicates a growth in the polymer formation. The resulting first-order rate constant was used to calculate the rate of copolymer formation using the rate equation -d[A]/dt = kc^n.     

载体型钛系催化剂的丙烯与乙烯共聚合研究

以载体型钛系齐格勒-纳塔催化剂进行了丙烯和乙烯无规共聚合的研究。对聚合温度、铝钛摩尔比、给电子体浓度和加氢等行为作了考察。共聚合速度和共聚物的比浓粘度呈规律性变化。用~(13)C-NMR和DSC测定了共聚物的组成、序列分布、熔点和结晶度.结果表明,在共聚合反应速度曲线上,在丙烯和乙烯分别为10mol％组成处,出现两个最大值。随共聚物中乙烯含量增加(2—10mol％),其熔点和结晶度降低,DSC峰变低、变宽,在乙烯含量达10mol％处出现双峰(128/116℃)反映出无规共聚链出现不同的序列分布。     

Synthesis of Epoxy Methacrylate Resin and Coatings Preparation by Cationic and Radical Photocrosslinking

This work involves the synthesis of hybrid oligomers based on the epoxy methacrylate resin. The EA resin was obtained by the modification of industrial-grade bisphenol A-based epoxy resin and methacrylic acid has been synthesized in order to develop multifunctional resins comprising both epoxide group and reactive, terminal unsaturation. Owing to the presence of both epoxy and double carbon–carbon pendant groups, the reaction product exhibits photocrosslinking via two distinct mechanisms: (i) cationic ring-opening polymerization and (ii) free radical polymerization. Monitoring of EA synthesis reactions over time using PAVs, MAAC and NV parameters, and the FT-IR method reveals that esterification reactions proceed faster at the start, exhibiting over 40% of conversion within the initial 60 min, which can be associated with a relatively high concentration of reactive sites and low viscosity of the reaction mixture at the initial reaction stage. With the further increase in the reaction time, the reaction rate tends to decrease. The control of the EA synthesis process can guide how to adjust reactions to obtain EAs with desired characteristics. Based on obtained values, one can state that the optimum synthesis time of about 4–5 h should be adopted to prepare EAs having both epoxy groups and unsaturated double bonds. The structure of the obtained EA was confirmed by FT-IR and NMR methods, as well as the determination of partial acid value and epoxy equivalent. Samples at various stages of synthesis were cured with UV radiation in order to study the kinetics of the process according to cationic and radical polymerization determined via photo-differential scanning calorimetry (photo-DSC) and real-time infrared spectroscopy (RT-IR) and then the properties of the cured coatings were tested. It turned out that the cationic polymerization was slower with a lower conversion of the photoreactive groups, as compared to the radical polymerization. All the obtained EA coatings were characterized by good properties of cured coatings and can be successfully used in the coating-forming sector.