The application of reed-vibration mechanical spectroscopy for liquids to detect chemical reactions of an acrylic structural adhesive

There remain a number of unsolved problems about chemical reactions, and it is significant to explore new detection methods because they always offer some unique information about reactions from new points of view. For the first time, the solidification course of a modified two-component acrylic structural adhesive is measured by using reed-vibration mechanical spectroscopy for liquids （RMS-L） in this work, and results show that there are four sequential processes of mechanical spectra with time. The in-depth analyses indicate that RMS-L can detect in real-time the generation and disappearance of active free radicals, as well as the chemical cross-link processes in the adhesive. This kind of real-time detection will undoubtedly facilitate the study of the chemical reaction dynamics controlled by free radicals.     

The Effect of Polymer Microstructure and Thermal Post-Treatment on Latex-Based Pressure Sensitive Adhesive Performance

Summary: Butyl acrylate/acrylic acid/2-hydroxyl methacrylate (BA/AA/HEMA, weight ratio: 96/2/2) latexes were produced via starved seeded semi-batch emulsion polymerization. The microstructure of the latex polymers was controlled by varying the amount of chain transfer agent (1-dodecanethiol). The latexes were characterized for gel content, M_c (molecular weight between two adjacent cross-linking points), M_w (molecular weight of sol polymers) and M_e (molecular weight between entanglements). From these latexes, PSA films were cast, dried, conditioned and then thermally post-treated at 120 °C to react the carboxyl and hydroxyl groups from the AA and HEMA units. Tack, peel strength and shear strength of the PSA films were then measured. The thermal post-treatment was shown to be an effective way to improve latex-based PSA performance. The effectiveness of the post-treatment was observed to depend on the polymer microstructure (M_c relative to M_e relative to M_w) of the untreated latex-based PSAs and on the gel content.     

直接衍生/高效液相色谱法分析水基胶中羰基化合物

建立了直接衍生/高效液相色谱分析水基胶中8种痕量羰基化合物(甲醛、乙醛、丙酮、丙烯醛、丙醛、丁烯醛、2-丁酮和丁醛)的方法.对影响分析效率的因素进行了考察,确定最佳衍生条件为:水基胶样品与2,4-二硝基苯肼衍生剂在40℃下反应20 min;最佳色谱分析条件为:采用DIONEX Acclaim Explosives E2...     

气相色谱法快速同时测定室内装饰装修材料胶黏剂中的苯、甲苯、二甲苯的含量

建立了快速、同时测定室内装饰装修材料胶黏剂中苯、甲苯、二甲苯含量的气相色谱检测法.样品用乙酸乙酯溶解处理后,用改性的聚乙二醇(FFAP)毛细管色谱柱分离,氢火焰离子化检测器检测,外标法定量.胶粘剂中苯、甲苯、二甲苯的浓度分别在8.58～171.40μg/mL、9.04～180.62μg/mL、8.80～175.92μg...     

碳硼烷聚酯及其改性聚氨酯胶黏剂的合成及性能研究

以实验室自制的十硼烷和1,4-二乙酰氧基-2-丁炔为原料,经过一系列反应合成了单体1,2-二羟甲基碳硼烷,并与己二酰氯经缩合反应合成了羟基封端的聚己二酸-1,2-双(羟甲基)碳硼烷酯,通过红外光谱,1H-核磁共振,11B-核磁共振和元素分析等手段对单体和聚合物的结构和纯度进行了分析;以合成的聚酯为甲组分,分别以脂肪族缩...     

Z箍缩动态黑腔负载装配用胶粘剂

由于Z箍缩动态黑腔负载中的低密度聚合物泡沫柱具有多孔结构和极低的力学强度,在装配过程中对胶粘剂有一定的特殊要求。实验以聚氨酯丙烯酸酯为主体树脂,丙烯酸异冰片酯为活性单体,配以光引发剂和偶联剂制得了适用于低密度泡沫粘接用的紫外光固化胶粘剂。测试表明,所研制的胶粘剂的体积收缩率仅为2.25%,且具有较高的固化速率和适当的粘接强度,能够满足稳固、快速装配的要求。通过对粘接界面的观测发现,胶粘剂在诊断孔内没有明显的扩散,且在低密度致密结构泡沫中的扩散厚度较小,均匀性好。     

Anisotropic elastic materials capable of a three-dimensional deformation (static or dynamic) with only one displacement component and uncoupling of all three displacement components

It is shown that there are anisotropic elastic materials that are capable of a non-uniform three-dimensional deformation with only one displacement component. For wave propagation, the equation of motion can be cast in the form of the differential equation for acoustic waves. For elastostatics, the equation of equilibrium reduces to Laplace’s equation. The material can be monoclinic, orthotropic, tetragonal, hexagonal or cubic. There are also anisotropic elastic materials that uncouple all three displacement components. The governing equation for each of the uncoupled displacement can be cast in the form of the differential equation for acoustic waves in the case of dynamic or Laplace’s equation in the case of static. The material can be orthotropic, tetragonal, hexagonal or cubic.     

Influence of adhesive layer properties on laser-generated ultrasonic waves in thin bonded plates

This paper studies quantitatively the generation of Lamb waves in thin bonded plates subjected to laser illumination, after considering the viscoelasticity of the adhesive layer. The displacements of such plates have been calculated in the frequency domain by using the finite element method, and the time domain response has been reconstructed by applying an inverse fast Fourier transform. Numerical results are presented showing the normal surface displacement for several configurations: a single aluminum plate, a three-layer bonded plate, and a two-layer plate. The characteristics of the laser-generated Lamb waves for each particular case have been investigated. In addition, the sensitivity of the transient responses to variations of material properties (elastic modulus, viscoelastic modulus, and thickness) of the adhesive layer has been studied in detail.     

利用全范德华力作用原理制备仿生干型高分子粘合材料--"壁虎胶带"

壁虎脚足与物体表面是完全的范德华力。介绍一种全新的模仿壁虎脚足刚毛、利用全范德华力作用原理制造的干型高分子粘合材料——“壁虎胶带”及其粘合原理。     

鞋用水性聚氨酯胶黏剂的制备及表征

通过预聚体分散法,以二羟甲基丙酸(DMPA)、蔗糖(sucrose)为亲水扩链剂和交联剂制备了一种鞋用水性聚氨酯胶黏剂.通过FTIR、DSC、力学性能、固化速度等研究了蔗糖用量对聚氨酯结构与性能的影响.结果表明蔗糖己引入聚氨酯主链.随着蔗糖用量的增加,相同处理温度下聚氨酯胶液的固化速度提高,胶膜的吸水率降低,拉伸强度增大,断裂伸长率减小,粘接试样的T-剥离强度逐渐增大.当蔗糖用量超过5.52 wt%时,合成及乳化过程中体系容易凝聚,且所制得的胶黏剂粘接强度有所下降.总之,通过改变蔗糖用量可以显著改变水性聚氨酯结构与性能.