Deformation behavior of high performance fiber reinforced cementitious composite prepared with asphalt emulsion

A novel engineered cementitious composite(ECC) was prepared with the complex binder of Portland cement and asphalt emulsion.By adjusting the amount of asphalt emulsion,different mixture proportions were adopted in experiments,including four-point bending test,compressive test,and scanning electric microscopy(SEM).The SEM observation was conducted to evaluate the contribution of polyvinyl alcohol(PVA) fiber and asphalt emulsion to the composite toughening mechanism.The tests results show that the most remarkable deflection-hardening behavior and saturated multiple cracking are achieved when the content of asphalt emulsion is 10%.However,excessive content of asphalt emulsion causes severe damages on the deformation behavior as well as loss in compressive strength of the mixture.SEM observation indicates that the influence of asphalt emulsion on the fiber/matrix interfacial property changes the dominant fiber failure type from rupture into pull-out mode,and thus causes beneficial effects for strain-hardening behavior.

Properties and Microstructure of Polymer Emulsions Modifi ed Fibers Reinforced Cementitious Composites

The synthesis and characterization of a new class of cementitious composites filled with polymer emulsions were investigated, and their superior mechanical strength and durability properties compared to composites devoid of fi llers were reported. Polymer emulsions were utilized to mechanically reinforce the composite and bridge the cement, fly ash, aggregate and fibers. The results reveal that the epoxy emulsion and poly（ethylene-co-vinyl acetate） emulsion markedly enhance the mechanical and durability properties of cemetitious composites. The fi bers can be pulled out in the form of slip-hardening and the abrasion phenomenon can be observed clearly on the surface of the fibers. The hydration extent of cement is higher than that of the pristine composites. The polymer modified cementitious composites designed on micromechanics, have fl exibility and plasticity which could be applied for a novel form of multifunctional materials with a range of pipeline coatings applications.

Application and Properties of Organic Emulsion Coated Phosphogypsum in Aluminous Rock Based Mineral Polymer Composite

A polarizing microscope,X-ray diffraction(XRD),fourier transform infrared spectrometer(FTIR),scanning electron microscope and energy dispersive spectrometer(SEM-EDS),X-ray photoelectron spectroscopy(XPS),and micro computed tomography(Micro CT)were used to investigate the relation between the structure and properties of the composite.Meanwhile,the physical properties,mechanical properties and strength mechanism were researched.The experimental results show that the structure and morphology of coated phosphogypsum remain intact in the composite,which shows good compatibility and forms a clear interface layer of transition zone between the coated phosphogypsum and the matrix,conforming to the structure of particle reinforced inorganic composites.The emulsion coated phosphogypsum has a certain strengthening effect on the aluminous rock mineral polymer composite.The compressive strength of the composite can reach 16.5 MPa when the amount of coated phosphogypsum is 40%,and the apparent density is 1.75 g·cm^(-3),which is significantly lower than that of common concrete;the thermal stability of the composite is also improved to a certain extent.Some certain chemical reactions occur in the process of forming the matrix of aluminous rock mineral polymer materials,with a structure of three-dimensional network.The research will provide a new way for the comprehensive utilization of phosphogypsum and low-grade aluminous rock.

Preparation of Composite Particles by Forming Pickering Emulsion Followed by Drying-In-Liquid and Effect of Stepwise Addition of Solid Powder on Structure of Composite Particles

It was tried to prepare composite particles made of polymer and two kinds of solid powders by forming Pickeringemulsion followed by the drying-in-liquid method and to investigate how the stepwise addition of solid powders affected the contained ratio and adhesion ratio of solid powders and the structure of composite particles. Limonene oil dissolving expanded polystyrene and ethylene glycol were adopted as the dispersed phase and the continuous phase, respectively. Magnetite and titanium dioxide were used as solid powders. Magnetite was added before or after formation of the (O/W) dispersion. Titanium dioxide was added at the various elapsed times from addition of magnetite. Titanium dioxide adhered only on the surface of composite particles irrespective of addition time. At the earlier addition of both solid powders, the surface-covering type composite particles were prepared. At the latter addition of titanium dioxide, a part of magnetite adhered on the surface and the remainder was dispersed into composite particle.

3D direct writing and micro detonation of CL-20 based explosive ink containing O/W emulsion binder

The booming development of DIW technology present an unprecedented prospect in energetic materials field and has attracted great interest due to its relative simplicity and high flexibility of manufacturing.Herein,a novel CL-20 based explosive ink formulation have been developed successfully for MEMS initiation systems via DIW technology.We designed PVA/GAP into an oil-in-water(O/W)emulsion,in the way that the aqueous solution of PVA as water phase,the ethyl acetate solution of GAP as oil phase,the combination of Tween 80 and SDS as emulsifier,BPS as a curing agent of GAP.The ideal formulation with good shear-thinning rheology properties and clear gel point was prepared using only 10 wt%emulsion.The dual-cured network formed during the curing process made the printed sample have good mechanical properties.The printed samples had satisfactory molding effect without cracks or fractures,the crystal form of CL-20 not changed and the thermal stability have improved.Deposition of explosive inks via DIW in micro-scale grooves had excellent detonation performances,which critical detonation size was 1×0.045 mm,detonation velocity was 7129 m/s and when the corner reaching 150°can still detonated stably.This study may open new avenues for developing binder systems in explosive ink formulations.

Synthesis of nano-CaCO_3 composite particles and their application

Nano-calcium carbonate composite particles were synthesized by the soapless emulsion polymerization technique of double monomers. The composite particles formation mechanism was investigated. The effects of composite particles on the mechanical properties of nano-CaCO3-ABS （acrylonitrile-butadiene-styrene copolymer） composite material were studied. It was validated that the composite particles are made up of the nano-calcium carbonate cores and the shells of alternating copolymers of butyl acrylate （BA） and styrene （St）. The shells are chemically grafted and physically wrapped on the surface of nano-calcium carbonate particles. When the composite particles were filled in ABS matrix, the CaCO3 particles are homogeneously dispersed in the composite material as nanoscales. The impact strength of the composite material is obviously enhanced after filling appropriate amounts of composite particles. It can be concluded that the soapless emulsion polymerization of double monomers is an effective method for nano-CaCO3 surface treatment. 2008 University of Science and Technology Beijing. All rights reserved.

Water-Based Processing of Fiberboard of Acrylic Resin Composites Reinforced With Cellulose Wood Pulp and Cellulose Nanofibrils

Despite the great potential of cellulose wood pulp and cellulose nanofibrils as reinforcing filler in thermoplastics,its use is limited due to its tendency to form agglomerates and due to its high hydrophilic character.Here we describe fiberboard composites with high contents of wood pulp or cellulose nanofibrils,and a resin of poly(styrene-methyl-methacrylate-acrylic acid)used as water-based emulsion.Cellulose wood pulp and cellulose nanofibrils were used directly in the form of water suspensions.The method is based on the flocculation of the polymer emulsion followed by agglomeration of a mixture of the polymer emulsion and cellulose suspension,leading to the co-precipitation of the composite material,which can be easily separated from the water phase.Composites with acrylic polymer/cellulose fibers in the proportions of 75:25,50:50 and 25:75 wt%were prepared.Composites were characterized by scanning electron microscopy(SEM),Fourier transform infrared spectroscopy(FTIR),thermogravimetric analysis(TGA),dynamic mechanical analysis(DMA)and water absorption tests.SEM analysis revealed a very good dispersion of the fibers without evidence of agglomeration,which led to superior mechanical properties.These results showed the effectiveness of the methodology and the potential of cellulose wood pulp and CNF as reinforcement fillers in fiberboard composites and any other high fiber-content materials.

STUDIES ON POLYSILOXANE-POLYSTYRENE COMPOSITE LATEXES

Polysiloxane-polystyrene composite latexes were prepared by two-stage emulsionpolymerization. Polymerization of styrene in swollen polysiloxane latex particles were studied.Formation of simple polystyrene particle in the 2nd-stage polymerization depends on the particlesize of the lst-stage latex and the polymerization temperature. Polystyrene domains in thevulcanizates reinforce the silicone rubbers effectively.

THE EFFECT OF MONOMERS FEEDING METHODS ON EMULSION COPOLYMERIZATION OF VINYLIDENE CHLORIDE AND ACRYLATES

The emulsion copolymerization of vinylidene chloride (VDC) with methyl-methacrylate(MMA) and acrylonitrile (AN) was carried out by batch, seeded batch and semicontinuous pro-cesses,respectively. Significant differences were found in the physical and mechanical propertiesof the latexes and films, depending on the methods of monomer feeding. The results both intheory and experiments demonstrated that the copolymer composition and the length of the VDC sequences in the copolymer could be controlled by the modes of monomer feeding process.

Rheological properties of magnetorheological fluid prepared by gelatincarbonyl iron composite particles

Gelatincarbonyl iron composite particle was prepared by micro emulsion method. The analysis of scanning electron microscope(SEM) shows that the ultrafine particles are spheroids coated by gelatin, and the average sizes of particles are 310μm. The specific saturation magnetization σ_s is 130.9A·m2/kg, coercivity H_c is 0.823A/m, and residual magnetism r is 4.98Am2/kg for the composite particles. It is shown that the particles possess properties of soft magnetic. The yield stress of magnetorheological fluid(MRF) with composite particle reaches 70kPa at 0.5T magnetic induction. Magnetorheological effects are superior in lower magnetic field intensity and the subsidence stability of the MRF is excellent compared with pure carbonyl iron powder.

Preparation of Chitosan/Poly(L-Lactide) Porous Composite Scaffolds

This research investigates the formation of chitosan/poly （L-lactide） （CS/PLLA） porous composite scaffold using a novel emulsion freeze-drying technique. First, an oil in-water （O/W） emulsification system was used in the presence of surfactant Tween-80, in which CS solution was used as the water phase and PLLA solution was used as the oil phase. The emulsion was observed by inverted microscope （× 200）. The emulsion droplet was spherical and uniform in size. FT-IR analysis revealed that there were hydrogen bonding interactions between CS and PLLA components. The microstructure and physical properties of the scaffolds were also analyzed. The SEM results showed that composite scaffolds formed well interconnected pore structure and homogenous distribution of CS and PLLA. When the content of PLLA reached 50%, the porosity of CS/PLLA composite scaffolds were between 83 %-91% and density in the range of 0.047 to 0.11 g/era3. The porosity showed a slight decrease and the density increased with the increase of PLLA dose. The compressive strength increased from 0.32 to 0.43 MPa, while the compressive modulus increased from 1.99 to 3.91 MPa as the PLLA contents increased from 10% to 50%.

醋酸纤维素水性高分子/SiO_(2)纳米复合皮革涂饰剂的制备

以A50为亲水剂,通过转换反应位点和反应官能团,调节分子链软硬段比例,引入纳米SiO_(2)提升乳液涂膜综合性能,制备WSCDA/SiO_(2)纳米复合乳液。结果表明,亲水剂A50用量为10.8%(质量分数),复合乳液及涂膜性能最优。最优条件下合成的复合乳液的平均粒径为109.5nm,粒径分布均匀,涂膜表面致密光滑,柔韧性、附着力、耐水性、耐黄变性、机械性能和热稳定性良好。WSCDA/SiO_(2)纳米复合乳液成膜时,在涂膜表面形成许多小“乳突”,产生荷叶效应,提高涂膜耐水、耐介质及耐黄变等性能。

咖啡酸-葡聚糖-肌原纤维蛋白酶解物乳液稳定性的研究

为了探究咖啡酸(Caffeic Acid,CA)、葡聚糖(Dextran,DEX)复合修饰联合胰蛋白酶不完全酶解对于肌原纤维蛋白(Myofibrillar Protein,MP)乳化特性的提升效果,以CA-DEX-MP复合酶解物为乳液稳定剂制备乳液,优化稳定剂的添加剂量,并以原始MP和MP酶解物稳定的乳液为对照,评估乳液在不同环境刺激下的稳定性。结果表明,CA-DEX-MP酶解物添加量为3 wt.%时乳液具有较低的颗粒粒径(390.26 nm)、电位(-23.6 mV)和较高的界面蛋白吸附量(11.22 mg/mL),且均匀分布;流变性研究表明,该乳液体系显示出显著低于原始MP乳液的表观粘度,可有效避免乳液的相分离现象。3 wt.%CA-DEX-MP复合酶解物乳液在不同温度、酸碱、盐离子强度和28 d贮藏期下均表现出较优的稳定性,可实现乳液的稳定。最终结果表明,乳液稳定剂为3 wt.%CA-DEX-MP复合酶解物时,乳液拥有最高的稳定性。该研究可为肌原纤维蛋白在新型食品乳液稳定剂开发中的应用提供理论支撑和方法学指引。

复合二氧化钛的制备及在装饰原纸中的应用

采用乳液法制备二氧化钛(TiO_(2))/滑石粉复合填料,并将其应用在装饰原纸中。结合油包水型(W/O)乳液的拟三元相图,寻找合适的乳液体系,并利用响应曲面试验对TiO_(2)/滑石粉复合填料的制备工艺进行优化。结果表明,环己烷比正庚烷更适合作为油相,正丁醇的用量影响着乳液的稳定性;复合填料制备的最优工艺为:Tween80/正丁醇的质量比为1∶1,乳化剂/环己烷的质量比为4∶6,水/环己烷的质量比为1∶3,滑石粉/钛酸四丁酯(TBT)质量比为1∶4,在此条件下制备的复合填料加填在装饰原纸中,得到的不透明度为97.0%,白度为84.0%ISO。通过扫描电子显微镜(SEM)、X射线能谱仪(EDS)及X射线衍射(XRD)分析方法对复合填料进行表征,结果显示,滑石粉表面包覆了一层致密均匀的TiO_(2),其晶型结构为锐钛矿型。

氧化石墨烯辅助的超分子骨架膜用于水包油型纳米乳液的高效分离

制备可以同时高效且高通量地处理纳米乳液的超浸润材料仍然具有挑战。为此,本文提出了一种通过在超分子骨架纳米片上修饰氧化石墨烯以增强亲水性的策略。通过将两种具有片状形态的材料连续抽滤于商业基质上,可制备得到氧化石墨烯辅助的超分子骨架复合膜,并用于分离具有纳米尺寸液滴的水包油乳液。骨架一方面通过均匀的纳米孔拦截乳液中分散的微小液滴,另一方面也通过带负电的表面提供静电相互作用来驱动破乳过程发生。具有良好亲水性的氧化石墨烯赋予膜材料改善的亲水能力和水合层。该复合膜具有纳米级的截留尺寸、带负电的表面和水下疏油性,并且还获得了高的水通量和耐油污染性。基于尺寸筛分和破乳效应,该复合膜可有效地去除分散在水包油乳液中由非离子、阴离子和阳离子表面活性剂稳定的纳米油滴。特别是对于离子型乳液,在分离后动态光散射未检测出残留液滴。滤液中总有机碳含量小于10 ppm,对应着大于99.9%的分离效率,优于许多国家和组织的标准。在各种乳液的分离过程中,复合膜表现出较高的分离渗透性,约为原始骨架膜的3.5倍。此外,具有防污效果的复合膜获得了较高的通量回收率,通过简单的水洗处理即可实现5次具有稳定分离性能的循环。该复合膜在重复使用过程中没有组分损失,在150℃内具有热稳定性,并能抵抗腐蚀性化学环境。在本工作中,我们试图将具有不同结构特性和表面特性的两种组分结合,通过简单的方法制备复合膜,并在功能协同作用下实现水包油型纳米乳液的高性能分离。

基于水包稠油型乳状液黏度与稳定性的乳化剂配方研究

采用单因素实验法考察了一种稠油乳化剂配方中包括油酸钠(NaOA)、椰油酰胺丙基甜菜碱(CAB-35)、无机碱(Na_(2)CO_(3))、有机碱(三乙醇胺(TEOA))4种组分的配比和剂量。考察了乳化温度、含油率及Na^(+)和Ca^(2+)含量等指标对稠油乳状液流变性质和稳定性的影响,并采用响应曲面法优化上述指标后确定了乳化剂的配方。实验结果表明,表面活性剂与稠油的相互作用对乳状液的表观黏度具有显著影响;而表面活性剂与碱的相互作用则显著影响稳定性。优化的配方为:表面活性剂含量1.5%(w)(m(NaOA)∶m(CAB-35)=2∶1),碱含量0.4%(w)(m(Na_(2)CO_(3))∶m(TEOA)=1),乳化温度40℃,含油率为71%(w);乳状液的表观黏度为38.26 mPa·s,稳定性为90.28%。经济配方为:表面活性剂含量1.0%(w)(配比不变),碱含量0.2%(w)(配比不变),乳化温度40℃,含油率为75%(w);乳状液表观黏度为45.92 mPa·s,稳定性为87.01%。

含紫苏精油Pickering乳液活性膜的表征及其对冷鲜牛肉品质的影响

该研究以大豆分离蛋白(soy protein isolate, SPI)和壳聚糖纳米粒子(chitosan nanoparticles, CSNPs)为乳化剂制备负载紫苏精油(perilla essential oil, PEO)的Pickering乳液(SPI-CSNPs-PEO Pickering, SCEO),并测定了其粒径、Zeta电位和乳化指数,以进一步验证乳液的稳定性。结果表明,随着油相体积分数的增加,Pickering乳液的Zeta电位的绝对值和乳化指数增加,粒径减小。当油相体积分数为80%时粒径更小,乳滴分散均匀,体系更稳定。以细菌纤维素(bacterial cellulose, BC)和聚乙烯醇(polyvinyl alcohol, PVA)为基材,加入不同体积分数(1%、1.5%、2%、2.5%)的Pickering乳液制备BP/SCEO复合膜。红外光谱和扫描电镜结果显示,SCEO增加了膜表面的粗糙程度,与基膜之间形成氢键相互作用;差示扫描量热法分析表明,复合膜的热稳定性提高。此外,SCEO的加入降低了复合膜水蒸气透过率和拉伸强度而升高了断裂伸长率。其中,BP/SCEO3的性能最好。该方法在一定程度上降低了冷鲜牛肉的菌落总数,延缓了氧化酸败,并将其保质期延长了6 d。因此,负载PEO Pickering乳液的复合膜是一种很有前景的食品包装材料。

纳米复合聚丙烯酸酯乳液共聚浆料的制备与性能

采用纳米二氧化钛对聚丙烯酸酯乳液共聚浆料(NA)进行改性,制备了系列TiO_(2)/NA纳米复合聚丙烯酸酯乳液共聚浆料TNA,并对其性能进行了探讨。研究结果表明,在纳米TiO_(2)用量占NA浆料固含量不超过2.5%的范围内,NA浆料及TNA浆料的溶液均属于假塑性流体,且随着纳米TiO_(2)用量的增加,TNA浆料的乳胶粒子直径及其溶液表观粘度均呈递减趋势,而对涤棉(T/C:65/35)混纺纱线的粘附力则呈现先增加再降低的变化趋势;采用综合性能最优的TNA浆料溶液对13tex涤棉(T/C:65/35)混纺纱线上浆,在上浆率明显降低的情况下,TNA浆料的各项浆纱性能依然优于工厂实际浆纱生产配方。研究结果表明,TNA浆料具有调浆简单、上浆率低、浆纱性能优异与退浆废水易于治理的特点。

玉米醇溶蛋白-假酸浆子胶二元复合物的制备及在Pickering乳液中的应用

玉米醇溶蛋白(Zein)因其独特的自组装特性被广泛应用于食品功能性组分的荷载与递送。但由于其疏水性强,单一Zein基Pickering乳液的界面稳定性难以满足实际应用的需要,采用合适的多糖构建复合体系是改善其乳液稳定性的有效策略。本文采用复凝聚法制备了不同蛋白-多糖比例的假酸浆子胶(NPG)与Zein复合颗粒(NZPs),对其理化性质、结构及乳液特性进行了表征。结果表明,当NPG比例越大时,NZPs的表面润湿性越强,同时蛋白和多糖在静电作用力下形成的复合颗粒粒径尺寸越小且趋于均匀分布。NZPs的内源荧光光谱中对应特征峰的峰强分别与Zein和NPG的含量呈正比,NPG的复合影响了Zein中酪氨酸残基所处微环境的极性。傅里叶红外光谱(FT-IR)中峰位的移动以及新峰的生成表明蛋白-多糖中存在氢键作用以及新的化学键生成。NZPs基Pickering乳液的储能模量(G')大于损耗模量(G"),在Zein:NPG=1:1时二者均达到最大,形成的乳液体系结构最强。乳析指数(CI)结果显示,在不同pH和加热处理下,NZPs基Pickering乳液的稳定性普遍高于单一的Zein或NPG乳液。本研究为开发新型玉米醇溶蛋白-多糖复合体系及其高效稳定的Pickering乳液提供理论参考。

兼具高湿强度及长开放期EPI木材胶粘剂的制备与性能表征

首先分别制备了湿强度优异(6.4 MPa)但开放期较短(40 min),以及开放期较长(145 min)但湿强度偏低(3.8 MPa)的EPI木材胶粘剂用两款乳液(SAEP3和SAEP4),然后探索了两种乳液的配比对复合乳液胶粘剂性能的影响。研究结果表明:当两款乳液用量一样时,产生了协同效应,制得的乳液(SAEP5)胶粘剂开放期为100~120 min,湿强度达6.4 MPa。与同样条件下测试的市售SL6517胶粘剂相比,其开放期相当,湿强度高出SL6517胶粘剂(均值5.1 MPa)约25%。由此,成功制备兼具高湿强度及长开放期的EPI木材胶粘剂。