PEGMA改性的光固化水性聚氨酯/二氧化硅纳米复合体系

采用水溶性大分子单体(PEGMA)改性纳米二氧化硅水溶胶(R301-PEGMA),并通过反相乳液法制备光固化水性聚氨酯纳米复合乳液。R301-PEGMA的引入使得复合乳液的粒径和黏度明显增大,透射电镜(TEM)、扫描电镜(SEM)和原子力显微镜(AFM)对复合膜微观结构的分析表明,改性纳米二氧化硅均匀分散在聚氨酯基体和涂层表面,动态力学分析表明,改性纳米二氧化硅可显著提高复合膜储存模量,并且tanδ峰出现明显宽化现象,说明R301-PEGMA与聚氨酯之间存在很强的相互作用。     

光固化水性聚氨酯/SiO_2纳米复合乳液的合成和膜性能

以异佛尔酮二异氰酸酯、聚乙二醇、2,2-双羟甲基丙酸、甲基丙烯酸-2-羟基乙酯(HEMA)为主要原料,通过丙酮法合成光固化水性聚氨酯丙烯酸酯预聚体,三乙胺中和后原位引入纳米二氧化硅水溶胶制备光固化水性聚氨酯/二氧化硅纳米复合乳液(WPU/SiO2)。研究了纳米二氧化硅对复合乳液粒径、黏度以及复合膜微观结构和力学性能的影响。经X射线衍射(XRD)、扫描电镜(SEM)和原子力显微镜(AFM)对复合膜微观结构分析表明,纳米二氧化硅与聚氨酯之间存在很好的相互作用,纳米二氧化硅均匀分散在聚氨酯基体中。动态力学分析表明纳米二氧化硅可提高复合膜的储能模量。     

光敏性聚氨酯低聚物改性纳米二氧化硅及在光固化聚氨酯体系的应用

设计合成了异氰酸酯基(NCO)半封端光敏性聚氨酯低聚物,将其接枝到氨基硅氧烷改性的二氧化硅表面,制备了光固化聚氨酯/二氧化硅纳米复合膜。红外光谱和热重分析分析表明低聚物成功接枝到二氧化硅表面,透射电镜和扫描电镜分析表明低聚物改性的二氧化硅在甲苯、聚氨酯树脂中均匀分散,流变、动态力学分析和应力-应变分析表明纳米二氧化硅表面接枝的低聚物与聚氨酯分子之间存在较强相互作用,复合膜的弹性模量、储能模量和拉伸强度得到显著提高。     

纳米二氧化硅粒径对橡胶复合材料力学性能的影响

以不同粒径的纳米二氧化硅为填料加到天然橡胶中制备纳米二氧化硅/天然橡胶(NR)复合材料。研究了不同粒径纳米二氧化硅(15,30和80nm)对复合材料的力学性能、应力软化效应、Payne效应、动态热机械性能、压缩生热和损耗因子等基本特性的影响。结果表明,随着纳米二氧化硅粒径的增大,复合材料的抗拉强度变大,应力软化效应增大;同时,复合材料的Payne效应和损耗因子越低,其动态压缩温升越低。Payne效应分析及扫描电镜观察还表明,大粒径纳米二氧化硅在橡胶基体中易于分散均匀,粒子间聚集程度更小,而小粒径的则表现出较明显的团聚现象,粒子在橡胶基体中的分散性对复合材料力学性能有直接影响。     

细乳液聚合制备纳米二氧化硅-丙烯酸酯复合乳液的研究

采用硅溶胶和丙烯酸酯单体通过细乳液聚合制备纳米二氧化硅/丙烯酸酯复合高分子乳液。考察了聚合过程中硅溶胶量对于单体转化率和聚合物粒子粒径的影响,并用GPC、XPS表征所得的复合乳液。实验结果表明:二氧化硅的引入提高了聚合反应速率,增加聚合物的分子量并使分子量分布变窄;在复合乳液粒子中,二氧化硅主要以分散相分布在连续的丙烯酸酯相内部;复合乳液的力学性能明显优于不含二氧化硅的纯丙烯酸酯聚合物乳液。     

纳米SiO2对聚氨酯清漆性能的影响

通过表面改性技术获得疏水性的纳米二氧化硅粒子,粒径约50nm.在机械搅拌和超声场的共同作用下,将纳米二氧化硅分散到聚氨酯清漆中,制得纳米二氧化硅复合涂料.失重法腐蚀实验、阳极极化曲线和交流阻抗测试结果表明,加入纳米二氧化硅后,聚氨酯清漆的耐蚀性能提高.同时改性后的聚氨酯清漆漆膜的附着力增加,抗老化性能提高.     

纳米二氧化硅/聚丙烯酸酯复合双重固化乳液的结构与性能

采用核壳乳液聚合法制得了纳米二氧化硅/聚丙烯酸酯复合双重固化乳液。系统研究了纳米二氧化硅的加入对紫外光-热双重固化乳液的固化速率、乳液性能及乳液涂层性能的影响,并对复合乳液的核壳结构进行了表征。实验结果表明,合成的复合双重固化乳液具有核壳结构,复合粒子的平均粒径在200nm左右。当乳液中硅溶胶的含量为5%时,乳液及其涂膜的性能最佳,此时乳液的涂膜硬度达到4H,附着力0级,耐乙醇擦拭234次不破膜,且硅溶胶的引入有助于提高乳液涂膜的耐热性能。     

聚苯乙烯/纳米SiO2复合颗粒制备与表征

为改善二氧化硅(SiO2)纳米粒子与聚合物基体间的亲和性,使SiO2表面功能化,将硅烷偶联剂KH-570引入C=C基团,采用乳液聚合方法在纳米SiO2粒子表面接枝苯乙烯(St)单体,实现了纳米二氧化硅表面的聚苯乙烯(PS)高分子包覆改性,制备了具有核/壳结构的SiO2-PS复合纳米粒子,产物的单体转化率和接枝效率在80%以上.研究了二氧化硅含量和偶联剂用量对聚合反应的单体转化率和接枝效率的影响,探讨了偶联剂的作用机理,利用FT-IR、TEM、TG对SiO2-PS复合粒子的表面结构进行了表征.结果表明,复合粒子具有明显的核壳结构,壳层厚度在20nm左右,乳液聚合过程可有效使二氧化硅的团聚体剥离呈纳米级颗粒.     

前驱体对水性PU/SiO_2复合材料结构与耐水性能的影响

在阴离子水性聚氨酯分散体(WPU)存在下,通过前驱体正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES)的共水解缩合反应,在m(前驱体)/m(WPU)为1时制备出WPU/SiO2(WPUS)复合材料。研究了n(MTES)/n(TEOS)对WPUS复合乳液平均粒径及粒子形貌、膜表面形貌及耐水性能的影响。结果表明,随着n(MTES)/n(TEOS)由0增大到1.5,复合乳液平均粒径由130 nm逐渐减小为107 nm;没有加入MTES的乳液中SiO2粒子以无规则形态非均匀分布,而加入MTES后乳液中SiO2为均匀分布的规则球形;随n(MTES)/n(TEOS)增大,复合膜表面SiO2分布均匀度逐渐提高,表面粗糙度逐渐减小,同时膜的水接触角逐渐增大,吸水率逐渐下降。     

溶胶-凝胶法超疏水含氟硅聚氨酯丙烯酸酯/SiO2杂化涂层的制备

以正硅酸乙酯(TEOS)和甲基三乙氧基硅烷(MTES)为前驱体,在含氟硅聚氨酯丙烯酸酯(FSiPUA)复合乳液中采用溶胶-凝胶法制备了超疏水杂化涂层。考察了MTES/TEOS的摩尔比和FSiPUA复合乳液用量等对涂层表面粗糙度、疏水性、成膜性等表面性能的影响。通过扫描电镜和接触角仪表征了涂层的微观结构及疏水性,利用马尔文粒度分析仪和傅里叶红外光谱仪分析了二氧化硅(SiO2)的平均粒径和化学结构。结果表明,随着MTES/TEOS摩尔比增加,杂化涂层的表面粗糙度逐渐下降,疏水性先增大后减小;随着FSiPUA复合乳液用量增加,涂层的成膜性逐渐变好;当(TEOS+MTES)∶C2H5OH∶NH3·H2O∶AMP-95的摩尔比为1∶6.67∶1.83∶0.24,MTES/TEOS摩尔比值为5,FSiPUA复合乳液用量为20%时,涂层具有超疏水特性,其水接触角(WCA)和滚动角(SA)分别为161.5°和2.8°,涂层表面对水滴具有优异的不粘附性。     

Study on the morphology and tribological properties of acrylic based polyurethane/fumed silica composite coatings

Two fumed silica (one hydrophilic and one hydrophobic) were used in the high solid acrylic based polyurethane coatings by directly mixing. The dispersion of fumed silica particles in the bulk of polyurethane coats was characterized by transmission electron microscope (TEM) and surface morphology examined using a scanning probe microscope (SPM). Micro indentation and scratching tests were carried out with a nano-indenter. Both hydrophilic and hydrophobic fumed silica nearly have the same dispersion in acrylic based polyurethane coats. The surface roughness of polyurethane coats increases as fumed silica increases, however, the surfaces of polyurethane coatings containing hydrophobic fumed silica are rougher than that containing hydrophilic fumed silica at the same content. Addition of fumed silica can obviously enhance the micro indentation hardness (MIH) and elastic modulus of polyurethane coats and the higher the content of fumed silica is, the higher the MIH is for hydrophilic one but for hydrophobic one only under normal load less than 20 mN. In the micro scratch experiment, the elastic response and plastic deformation nearly keep constant with normal force increasing for pure acrylic based polyurethane coats. But the percentage of elastic response decreases and the percentage of plastic deformation increases as normal force increases for the polyurethane coats with fumed silica. Crack occurs when scratching under normal force higher than 50 mN for the polyurethane coats with fumed silica, and as the content of fumed silica increases, the critical force for crack increases. Additionally, both hydrophilic and hydrophobic fumed silica have no obvious influence on the response to marring stress and micro mar resistance (MMR) of acrylic based polyurethane.     

Improvement in properties of epoxy-based electrophoretic coating by silica/polyurethane nanocomposites

Silica/polyurethane (SiO₂/PU) nanocomposites, prepared by in situ formation of silica from tetraethoxysilane (TEOS) in cationic polyurethane microreactor, are used to modify epoxy resin-based electrophoretic coating. The co-electrophoresis property of silica/PU nanocomposites with epoxy particles is verified by X-ray photoelectronic spectroscopy (XPS) analysis of the electrophoretically prepared membrane. The particle sizes and size distribution in the aqueous paint show a considerable reduction as demonstrated by dynamic light scattering. The surface morphology is investigated by scanning electron microscope. The properties of SiO₂/PU-modified electrophoretically prepared membrane have a significant improvement compared to those of unmodified and PU-modified membranes. It is noteworthy that both strength and toughness of the electrophoretically prepared membrane increase considerably due to incorporation of rigid silica encapsulated by tough PU.     

超支化聚氨酯的合成与性能

以异佛尔酮二异氰酸酯(IPDI)和聚乙二醇2000(PEG2000)为单体,通过逐步聚合反应合成了-NCO封端的聚氨酯顸聚体(PPU);再通过接枝使PPU与端羟基超支化聚合物(HPAE)共聚得到一种新型超支化聚氨酯(HBPU).利用红外光谱仪(FT-IR)、核磁共振(1H-NMR)、热重分析仪(TGA)、X射线衍射(X...     

Microstructure Control of Nanoporous Silica Thin Film Prepared by Sol-gel Process

Nanoporous silica films were prepared by sol-gel process with base, acid and base/acid two-step catalysis.Transmission electron microscope （TEM） and particle size analyzer were used to characterize the microstructure and the particle size distribution of the sols. Scanning electron microscopy （SEM）, atomic force microscopy （AFM） and spectroscopic ellipsometer were used to characterize the surface microstructure and the optical properties of the silica films. Stability of the sols during long-term storage was investigated. Moreover,the dispersion relation of the optical constants of the silica films, and the control of the microstructure and properties of the films by changing the catalysis conditions during sol-gel process were also discussed.     

Preparation and characterization of epoxy nanocomposites by using PEO-grafted silica particles as modifier

EP/SiO₂ nanocomposites, which contained PEO flexible chain, have been prepared via epoxy resin and PEO-grafted silica particles. The PEO-silica particles were obtained by endcapping PEO-1000 with toluene 2,4-diisocyanate (TDI), followed by a reaction with silica sols. The chemical structure of the products was confirmed by IR measurements, and the mechanical properties of composites such as impact strength, flexural strength, dynamic mechanical thermal properties were investigated. The results showed that the addition of the PEO-grafted silica particles to the epoxy/DDS curing system, the impact strength is 2 times higher than that of the neat epoxy. While the storage modulus and the glass transition temperature are a little changed. The morphological structure of impact fracture surface and the surface of the hybrid materials were observed by scanning electron microscope (SEM) and atomic force microscopy (AFM), respectively.     

Acoustic properties of polyurethane compositions enhanced with multi‐walled carbon nanotubes and silica nanoparticles

In this study, in order to enhance acoustic properties of polyurethane (PU) foams multi‐walled carbon nanotubes (MWCNT) and/or silica nanoparticles were added to polyol‐isocyanate composition up to 2 wt%, and acoustic properties of polyurethane foam samples with small amount of carbon nanotubes and silica nanoparticles (spherical and/or amorphous types) were determined in the frequency range from 50 Hz up to 6400 Hz. Acoustic properties, especially absorption coefficient of the produced samples were measured for all the prepared samples and results were investigated to come up with the best polyurethane samples that can be applied for sound absorption application at the desired frequency range. It was found that double combination of carbon nanotubes and silica nanoparticles, especially 0.7 wt% carbon nanotubes and 0.2 wt% spherical silica nanoparticle added polyurethane composition has better sound absorption ratio overall all frequencies levels compared to the other samples. Thus, it is possible to obtain polyurethane nanocomposite with a higher amount of carbon nanotube by weight at the same time enhancing sound absorption properties. Moreover, there is a synergic effect between carbon nanotubes and silica nanoparticles when mixed and added into polyurethane matrix at predetermined levels to get enhanced acoustic response with a higher level of carbon nanotube in polyurethane foam.     

气相二氧化硅的异氰酸酯改性及其对浇注型聚氨酯弹性体力学性能的影响

为了改善气相二氧化硅(FS)/浇注型聚氨酯(PU)体系成型流动性,在制备预聚体的过程中,采用2, 4-甲苯二异氰酸酯(TDI)进行改性获得异氰酸酯改性的二氧化硅(NCO@FS),通过原位聚合法制备了NCO@FS/PU弹性体复合材料。采用FTIR、XPS及动态接触角对NCO@FS及FS进行了表征。结果表明：FS的表面羟基与TDI的-NCO基团发生反应生成了氨酯基(-NHCOO),改善了FS与PU间的界面相容性及界面结合。复合材料中NCO@FS质量分数为1.5wt%时,NCO@FS/PU复合材料的拉伸和撕裂强度分别为57 MPa和110.5 kN/m,比纯浇注型PU分别提高了31.6%和23.6%;玻璃化转变温度由3.4℃下降到-11.2℃,损耗因子tanδ由0.59下降到0.46。异氰酸酯改性FS适合制备FS增强浇注型聚氨酯复合材料。     

Polymerization Process and Morphology of Polyurethane/Vinyl Ester Resin Interpenetrating Polymer Networks

A series of polyurethane （PU）/vinyl ester resin （VER） simultaneous IPNs （interpenetrating polymer networks） with different component ratios and comonomers types introduced to VER were synthesized and the polymerization processes were traced by Fourier transform infrared spectroscopy （FTIR） to study the kinetics of IPNs and hydrogen bonding action within multi-component. Furthermore, the relationship of polymerization process with morphology was investigated in detail for the first time by the morphological information given by chemical action between two networks besides physical entanglement, atomic force microscope （AFM） observation and dynamic mechanical analysis （DMA）. The results indicated that the degree of hydrogen bonding （Xb,UT,%）, calculated from functional group conversional rate and fine structures gained from FT-IR spectra of two networks, were affected by PU/VER weight ratios and comonomer types of VER. The relationship of formation kinetics and morphology showed that the change of Xb,UT （%） values exhibited excellent consistency with that of phase sizes observed by AFM and detected by DMA.     

Superhydrophobic optically transparent silica films formed with a eutectic liquid

A eutectic liquid (choline chloride and urea) that served as a templating agent in sol-gel processing was used to prepare thin silica films on glass microscope slides. Subsequent extraction of the eutectic liquid yielded a film with a rough surface. After treating the film surface with a fluoroalkyl silane, the surface became superhydrophobic with a contact angle ∼ 170° and a contact angle hysteresis < 10°. The optical transmittance of the film coated on the glass slide was comparable to that of the microscope glass slide. Atomic Force Microscopy (AFM) was used to characterize the surface structures; a tipless probe allowed measurement of the force of interaction with superhydrophobic surfaces. The interaction force between the AFM probe and the superhydrophobic surface was reduced greatly compared to that between the probe and the flat surface treated with fluoroalkyl silane.     

汽车仪表板用聚氨酯搪塑粉料:组成、加工及流变性能

本工作研究了汽车仪表板用聚氨酯搪塑粉料的组成与其加工及流变性能的关系。利用傅里叶变换红外光谱仪、核磁共振波谱仪、示差扫描量热仪、扫描电镜能谱仪、X射线衍射仪、热重分析仪和激光共聚焦显微镜研究发现,商用聚氨酯搪塑粉料的主要成分为热塑性聚酯型聚氨酯,无机填料为二氧化硅、二氧化钛和高岭土等无机粒子。通过光学显微镜观察聚氨酯搪塑粉料的熔融合并过程,得到了搪塑加工过程中适宜的加工温度和塑化时间。利用流变仪的线性频率扫描实验方法研究发现,聚氨酯搪塑粉料的熔体在高频区(短时间尺度)表现为类液性(损耗模量大于储能模量),在低频区(长时间尺度)表现出类凝胶特性(储能模量与损耗模量接近,且低频区模量出现平台)。上述实验结果表明,聚氨酯搪塑粉料的组成导致其熔体具有特殊的流变性能,即搪塑粉料中的热塑性聚酯型聚氨酯赋予搪塑粉料熔体类液性,而搪塑粉料中的无机粒子与聚氨酯相互作用形成网络结构,导致其熔体在长时间尺度下具有类凝胶特性。同时,研究发现,在搪塑加工过程中(搪塑模具上下旋转),由于聚氨酯搪塑粉料的熔体在长时间尺度下的类凝胶行为,当搪塑粉料粘附在搪塑模具表面时,熔体只熔融合并而不滴落或流挂,从而得到厚度更均匀的汽车仪表板表皮。并且搪塑成型的表皮不同位置的花纹粗糙度一致性较好。