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1.
Structure and properties of polyurethane/polyacrylate latex interpenetrating networks hybrid emulsions 总被引:3,自引:0,他引:3
Some new kinds of novel polyurethane (PU)/polyacrylate (PA) latex interpenetrating networks (LIPNs) were synthesized. Firstly PU dispersions were synthesized by self-emulsification polymerization. Then PU/PA LIPNs using PU dispersion as the seed were prepared by soap free emulsion polymerization. The effects of different PU/PA ratios, the blending method and the NCO/OH molar ratio of PU components on PU/PA LIPNs performance were also investigated. The structure and properties of PU/PA LIPNs such as mechanical properties, particle size, morphology of the surface were characterized by dynamic mechanical analysis, scanning electron microscopy, and dynamic light scattering. It was found that PU/PA LIPNs can markedly improve the water resistance and the mechanical properties of PU latex much more than those of PU/PA physical blends due to a great deal of interpenetrating and entangling between PU and PA latex. Moreover, the particle size of PU/PA LIPNs is related to the PA content and NCO/OH molar ratio of PU components: the higher the NCO/OH molar ratio in PU dispersions, the larger is the particle size of PU/PA LIPNs, and the average particle size of PU/PA LIPNs becomes larger with an increase in PA content. 相似文献
2.
超浓乳液聚合制备PU/PS的SIPN粉状树脂研究 总被引:7,自引:0,他引:7
将聚氨酯予聚体 (PU ) 苯乙烯 (St)的复合体系 ,用超浓乳液聚合方法制备了半互穿聚合物网络(SIPN)复合聚合物 ,得到了用聚氨酯予聚体改性的聚苯乙烯 (PU/PS)SIPN粉状树脂 .研究了分散相的比例(α)和聚合温度对聚合稳定性及聚合转化率 -时间的关系 ;测定了聚合物胶乳粒子的大小、形态 ,玻璃化温度 ,动态力学性能等 .结果表明 ,超浓乳液聚合较之本体聚合具有较高的聚合速率 ,容易控制所制备的胶乳粒径 ,能够制得PU/PS复合聚合物的SIPN粉状树脂 .该粉状树脂便于加工 ,具有良好的强韧性 ,有利于扩大应用 相似文献
3.
Flexible polyurethane (PU) nanocomposite foams were synthesized using organically modified montmorillonite clay (Cloisite 30B). The dispersion of organoclay was considered both in the isocyanate and polyol matrixes. Silicate layers of organoclay can be exfoliated in PU matrix by use of two steps mixing process. The presence of clay increased the cell density and reduced the cell size compared to the conventional PU foam. Clay dispersion was investigated by X-ray diffraction (XRD). The morphology and properties of PU nanocomposite foams were also studied. Generally, mechanical properties by addition of clay were improved. Foams in which clay was firstly dispersed in the isocyanate, showed better dispersion due to affinity of OH group on the clay surface to react with NCO groups. Better properties have been achieved with these nanofoams. 相似文献
4.
Thermoanalytical and morphological studies of cross-linked latex films by advanced techniques 总被引:1,自引:0,他引:1
R. Joshi E. Lefevre C. Patel T. Provder R. Crombez W. Shen F. Jones 《Journal of Thermal Analysis and Calorimetry》2008,93(1):19-26
In the present report, thermal analysis (TMDSC, DMA, TG, stress-strain analysis), nano-indentation and AFM morphological characterization
of cross-linkable latexes, prepared with either a pre-coalescence cross-linker (1,3-butylene glycol dimethacrylate) or post-coalescence
cross-linker (adipic dihydrazide) at various levels of cross-linking, were done. The study assesses the effect of type and
level of cross-linking on the film formation process through the evolution of mechanical properties and latex morphology.
In addition, the final fundamental thermal and mechanical properties, specific end-use properties and latex morphology resulting
from the film formation process are reported. 相似文献
5.
Min Hee Lee 《European Polymer Journal》2007,43(10):4271-4278
To modify the surface of UV cured polyurethane dispersion (UV-PUD), fluorinated PU called surface modifying agent (SMA) was blended with base PU prior to dispersion in water. X-ray photoelectron spectroscopy (XPS) and contact angle measurements showed that surfaces of dispersion cast film are significantly enriched with fluorine groups. Atomic force microscopy (AFM) showed that surface was roughened with the addition of SMA, which provided possible mechanism of increased water resistance as well as low friction coefficient of the film. On the other hand, hardness, mechanical and dynamic mechanical properties indicated that the bulk properties are marginally altered by the additive amount of SMA. 相似文献
6.
Telford AM Thickett SC James M Neto C 《Langmuir : the ACS journal of surfaces and colloids》2011,27(23):14207-14217
We investigated the dewetting of metastable poly(N-vinylpyrrolidone) (PNVP) thin films (45 nm) on top of polystyrene (PS) thin films (58 nm) as a function of annealing temperature and molecular weight of PS (96 and 6850 kg/mol). We focused on the competition between dewetting, occurring as a result of unfavorable intermolecular interactions at the PNVP/PS interface, and spontaneous cross-linking of PNVP, occurring during thermal annealing, as we recently reported (Telford, A. M.; James, M.; Meagher, L.; Neto, C. ACS Appl. Mater. Interfaces 2010, 2, 2399-2408). Using optical microscopy, we studied how the dewetting morphology and dynamics at different temperatures depended on the relative viscosity of the top PNVP film, which increased with cross-linking time, and of the bottom PS film. In the PNVP/PS96K system, cross-linking dominated over dewetting at temperatures below 180 °C, reducing drastically nucleated hole density and their maximum size, while above 180 °C the two processes reversed, with complete dewetting occurring at 200 °C. On the other hand, the PNVP/PS6850K system never achieved advanced dewetting stages as the dewetting was slower than cross-linking in the investigated temperature range. In both systems, dewetting of the PNVP films could be avoided altogether by thermally annealing the bilayers at temperatures where cross-linking dominated. The cross-linking was characterized quantitatively using neutron reflectometry, which indicated shrinkage and densification of the PNVP film, and qualitatively through selective removal of the bottom PS film. A simple model accounting for progressive cross-linking during the dewetting process predicted well the observed hole growth profiles and produced estimates of the PNVP cross-linking rate coefficients and of the activation energy of the process, in good agreement with literature values for similar systems. 相似文献
7.
Tapani Harjunalanen 《European Polymer Journal》2003,39(4):817-824
Aqueous anionic polyurethane (PU) dispersions were synthesised from a polyester polyol, isophorone diisocyanate and α,α-dimethylol propionic acid using the prepolymer mixing process. Samples were neutralised by the addition of triethyl amine. The polymer chains were dispersed in water and extended with 1,2-ethylene diamine. The differences in the dispersion characteristics and the mechanical properties of the polymer films cast and dried from the dispersions caused by altered reaction conditions were determined.The reaction conditions proved to affect both the colloidal properties of the dispersions as well as the mechanical properties of the films. The neutralisation, the dispersion and the chain extension methods had all an influence on the average size of the formed PU particles. For the films, a change in the mechanical properties and probably in the amount of hard and soft domain separation was also observed. A good control over the properties was obtained by selecting the reaction parameters carefully. In particular, the dispersion method in which the prepolymer solution was added to water and not vice versa led to a considerably lower viscosity during the dispersion process. Thus a wider choice of raw materials was facilitated. 相似文献
8.
反应性复合乳液的合成、表征及其交联反应 总被引:1,自引:0,他引:1
利用种子半连续乳液聚合方法合成了核层或壳层带有环氧基以及壳层带有羧基的3种不同核/壳结构的乳胶粒子,通过物理共混带环氧基和羧基的乳胶粒子,得到了两种反应性复合乳液.利用透射电镜和激光动态光散射对乳胶粒子进行了表征,其粒径分布较窄,粒径分布的多分散系数为0.062,平均粒径约76 nm,乳胶粒子具有明显的核/壳结构.通过胶膜的凝胶率和膨胀率的测定和红外光谱分析对反应性复合乳液中乳胶粒子的扩散及交联反应进行了研究,并探讨了不同核壳结构复合乳液对涂膜机械性能的影响.研究表明,当反应性复合乳液中的环氧基和羧基分别分布在乳胶粒子的核层和壳层时,有利于聚合物分子链的充分扩散和化学交联反应的进行,从而提高涂膜的物理化学性能,当甲基丙烯酸缩水甘油酯(GMA)含量为10 wt%时,涂膜的拉伸强度达20.3 MPa. 相似文献
9.
Water-Resistant Films and Coatings Based on Cross-Linking Styrene-Acrylate Latex Copolymers 总被引:1,自引:0,他引:1
S. S. Ivanchev V. N. Pavlyuchenko N. A. Byrdina M. Skrifvars J. Koskinen 《Russian Journal of Applied Chemistry》2001,74(2):309-315
Water-resistant films and coatings were prepared from latexes of copolymers of styrene, n-butyl acrylate, 2-hydroxyethyl methacrylate, glycidyl methacrylate, and methacrylic acid. The degree of cross-linking of the copolymers in the course of film formation and the water resistance of the films and coatings, associated with this parameter and evaluated by the water absorption and mechanical properties of wet films, were studied in relation to the gross composition of the latex copolymer, conditions of its synthesis, distribution of functional groups responsible for cross-linking in a latex particle, and temperature of film formation. 相似文献
10.
Poly(epsilon-caprolactone)/polystyrene (PCL/PS) blends, where nonamphiphilic PS is glassy in the bulk state at the experimental temperature of 22.5 degrees C, are immiscible as Langmuir films at the air/water (A/W) interface. Surface pressure-area per monomer isotherm analyses indicate that the surface concentration of amphiphilic PCL is the only factor influencing the surface pressure below the collapse transition. For PS-rich blends, Brewster angle microscopy (BAM) studies at the A/W interface and atomic force microscopy studies on Langmuir-Schaefer films reveal that PS nanoparticle aggregates formed at very low surface pressures can form networks upon further compression. The morphologies seen in PS-rich blends (networklike rings) are consistent with a recent study of a nonamphiphilic polyhedral oligomeric silsesquioxane (POSS), octaisobutyl-POSS, blended with amphiphilic poly(dimethylsiloxane), suggesting that the nonamphiphilic PS aggregates at the A/W interface produce domains with dipole densities that differ from that of pure PCL. In all composition regimes, the amphiphilic PCL phase tends to spread and form a continuous surface layer at the A/W interface, while simultaneously improving the dispersion of nonamphiphilic PS domains. During film expansion, BAM images show a gradual change in the surface morphology from highly continuous networklike structures (PS-rich blends) to broken ringlike structures (intermediate composition) to small discontinuous aggregates (PCL-rich blends). This study provides valuable information on the morphological evolution of semicrystalline PCL-based polymer blends confined in a "two-dimensional" geometry at the A/W interface and fundamental insight into the influence of microstructure (domain size, phase-separated structures, crystalline morphology, etc.) on the interfacial properties of blends as Langmuir films. 相似文献