粉煤灰地聚合物砂浆的试验研究

粉煤灰基地聚合物是利用粉煤灰在碱激发剂溶液作用下形成的一种新型无机类陶瓷结构胶凝材料。通过抗折抗压强度指标研究不同模数碱激发剂对粉煤灰的激发效果以及三种高温养护条件对粉煤灰基地聚合物砂浆力学性能的影响规律。结果表明,碱硅酸盐激发剂溶液的激发作用显著,模数为1.5时效果最好;提高养护温度可以有效提高粉煤灰基地聚合物砂浆的早期强度。     

粉煤灰-矿渣基地质聚合物砂浆性能研究

运用正交试验探讨了Si/Al(A)、水玻璃模数(B)、外加剂(C)3个因素对粉煤灰-矿渣基地质聚合物砂浆扩展度、抗折强度和抗压强度性能的影响规律,最后进行了微观性能测试.结果 表明:砂浆扩展度可以达到175 mm,1d抗折强度和28 d抗折强度分别可以达到5.2 MPa和8.3 MPa,1d抗压强度和28 d抗压强度分别可以达到39.0 MPa和76.6 MPa.当Si/Al为1.49,模数为1,外加剂X添加量为3％时,砂浆扩展度、28 d抗折强度和28 d抗压强度三者性能最优,当Si/Al为1.49,模数为1.4,外加剂X添加量为1％时,砂浆1d抗折强度和1d抗压强度性能最优.     

基于正交及响应曲面设计的自燃煤矸石地质聚合物配体优化

为研究配体对自燃煤矸石-矿渣-粉煤灰地质聚合物活性的影响,以3d、28 d地质聚合物胶砂抗折和抗压强度为目标,首先以配体中激发剂品种、激发剂掺量和水玻璃模数为参数,进行的正交试验,根据正交试验结果确定的显著因素与水平范围,再进行二次响应曲面试验,通过对连续试验点进行优化分析,建立激发剂掺量、水玻璃模数与胶砂强度之间的回归方程,获得配体的最佳配合比.试验结果表明,激发剂品种是影响其活性的最显著因素,激发剂掺量及水玻璃模数对活性影响比较显著,建立的回归方程显著性好.以阜新新邱矿自燃煤矸石为主要原料配制的地质聚合物最佳配体配合比是:水玻璃:氢氧化钾为1∶1、激发剂掺量26.6％(占胶凝材料)、水玻璃模数1.0,此时地质聚合物28 d胶砂抗压强度达到65.13 MPa.     

粉煤灰-矿渣基矿物聚物的强度影响因素及机理分析

试验以三种不同化学成分的粉煤灰与矿渣组成二元胶凝体系,在碱硅酸盐激发下制备了粉煤灰-矿渣基矿物聚合物.研究了粉煤灰中CaO的含量、形态以及碱硅酸盐激发剂模数对所制备矿物聚合物抗压强度的影响规律,并结合NMR、XRD和SEM等微观测试手段分析了其作用机理.试验结果表明:粉煤灰中非晶态CaO含量越高,粉煤灰-矿渣基矿物聚合物的抗压强度越大;粉煤灰中晶态CaO含量高是导致后期强度倒缩的主要原因;随着碱硅酸盐激发剂模数的增大,粉煤灰-矿渣基矿物聚合物的抗压强度先增大后减小,当激发剂模数为1.2时,抗压强度最大.     

高掺量低碱度钢渣-脱硫石膏胶凝材料的制备

以钢渣和脱硫石膏工业废渣为主要原料,掺加适量的激发剂,制备出脱硫石膏基低碱度钢渣胶凝材料,并探讨了其制品应用形式。试验结果表明,钢渣∶脱硫石膏（质量比）=1∶1时,胶凝材料的凝结时间为初凝6 min、终凝9 min,2 h抗折强度2.21 MPa、抗压强度5.06 MPa,1 d抗折强度2.03 MPa、抗压强度4.7 MPa,而7 d抗折强度和抗压强度分别达到3.59 MPa和12.55 MPa。     

BP神经网络预测矿物聚合材料强度的影响因素

基于矿物聚合材料制备过程中激发剂和配料组成的多样性与复杂性,采用BP神经网络方法考察了影响矿物聚合材料强度的3个因素:激发剂NaOH溶液的浓度、配料中碱硅物质的量比和铝硅物质的量比.结果表明:BP神经网络可以准确地预测矿物聚合材料抗折强度和抗压强度(误差在10-2数量级);高碱激发下(COH-=12 mol/L),M2O/SiO2对抗压及抗折强度影响显著,预测M2O/SiO2=0.332,Al2O3/SiO2=0.441时制品的抗压强度达30.96 MPa,抗折强度高达9.33 MPa;SEM分析和MIP实验证明,提高激发剂NaOH溶液浓度和碱硅物质的量比更有利于形成内部结构完整、强度更高的矿物聚合材料.     

碱激发剂对铸造粉尘-粉煤灰基地质聚合物抗压强度的影响

以粉煤灰和铸造粉尘为主要原料,以KOH、NaOH、Na2SiO3、K2SiO3和水玻璃为碱激发剂,制备地质聚合物.研究了不同激发剂对铸造粉尘-粉煤灰基地质聚合物抗压强度的影响.结果表明:不同浓度的NaOH和KOH溶液的激发效果较差,制备的铸造粉尘-粉煤灰基地质聚合物的抗压强度较低.NaOH和KOH溶液与K2SiO3溶液混配复合激发剂可提高铸造粉尘-粉煤灰基地质聚合物的抗压强度.水玻璃溶液激发效果最好,随着水玻璃溶液模数的增加,铸造粉尘-粉煤灰基地质聚合物的抗压强度逐渐提高;当水玻璃模数为1.2时,铸造粉尘基地质聚合物28 d抗压强度达到最大,为21.4 MPa;继续增大水玻璃模数,铸造粉尘-粉煤灰基地质聚合物28 d抗压强度趋于下降.     

偏高岭土地质聚合物的制备及其抗压强度研究

在采用偏高岭土碱激发制备地质聚合物的基础上,优化配合比,为制备出早期强度较高的地质聚合物。以NaOH和水玻璃为复合碱激发剂,研究水玻璃模数、碱当量、液固比以及养护条件对偏高岭土地质聚合物抗压强度的影响。试验结果表明,偏高岭土130g、水玻璃模数1.0、碱当量11%、液固比0.31、标准养护时,制备的偏高岭土地质聚合物3d抗压强度最高,达到53.7MPa。另外,在初始液固比为0.31时,不同模数下的地质聚合物强度都达到最佳。本文为偏高岭土地质聚合物的制备提供了有效的借鉴。     

赤泥基发泡地质聚合物的性能研究

拜耳法赤泥含有较多赤铁矿且活性较低，一定程度上限制了其资源化利用。将拜耳法赤泥、矿渣微粉和粉煤灰以5∶3∶2的质量比混合，以水玻璃和氢氧化钠为碱激发剂，硬脂酸钙为稳泡剂，双氧水为发泡剂，制备发泡地质聚合物。通过调节碱激发剂模数，探究其对赤泥基发泡地质聚合物表观密度、强度以及微观结构的影响。结果表明，随着碱激发剂模数的增加，发泡地质聚合物的表观密度呈先增加后降低的趋势，抗压强度逐渐下降。当碱激发剂模数为1.4时，发泡地质聚合物的28 d表观密度最低，为195.86 kg/m³;28 d抗压强度达到最高值，为0.55 MPa,对应比强度为2 821.12 N·m/kg。这说明碱激发剂模数为1.4时发泡地质聚合物兼顾轻质与高强的性能。     

碱激发矿渣/粉煤灰胶凝材料力学性能研究

采用矿渣、粉煤灰为原料,液体水玻璃、固体水玻璃、固体NaOH为激发剂,研究Na_2O掺量、模数、粉煤灰掺量、萘系减水剂掺量对矿渣/粉煤灰胶凝材料胶砂强度、凝结时间的影响。结果表明:液体水玻璃最佳Na_2O掺量6%、模数1.00,28d抗压强度63.0MPa、抗折强度12.2MPa;固体水玻璃最佳Na_2O掺量4%、模数0.50,28d抗压强度20.5MPa、抗折强度6.3MPa;随着萘系减水剂掺量的增加,胶凝材料的凝结时间增加,萘系减水剂掺量1.5%的初凝时间362min、终凝时间392min、间隔30min,缓凝效果显著。     

Studies of physico–mechanical properties of wood and wood plastic composite (WPC)

An attempt has been made to improve the quality of low grade wood through radiation induced wood plastic composite (WPC) formation in order to use these low grade woods as substitutes for high grade wood. Six kinds of local woods of Bangladesh (simul, korai, mango, jack fruit, teak, and garjon) were investigated. Both soft and hard wood varieties of these were selected. Ten vinyl monomers were used for the WPC. Improvement in the quality of wood was ascertained by determining change in physico—mechanical properties of wood. These properties were tensile strength, Young's modulus, and dimensional stability. Among all the woods investigated, simuls exhibited the best performance for WPC formation. It was found that the tensile strength and Young's modulus of WPC increased about 1.6 and 1.5 times, respectively, as compared with the strength and modulus those of untreated wood.     

Fracture Strength of Polycrystalline Silicon Wafers for the Photovoltaic Industry

The fracture strength of polycrystalline silicon wafers has been investigated by means of twist and four-point bending tests. Under a twisting configuration, which generates high tensile stresses within the middle of the wafers, a unimodal distribution in strength is obtained. The characteristic strength and Weibull modulus are 131.0 MPa, and 14.4, respectively. Under a four-point bending configuration, which generates high stresses both at the surface and at the edges, an additive bimodal distribution is obtained. The first mode of the distribution has a characteristic strength of 76.0 MPa and a Weibull modulus of 1.6; the second mode has a characteristic strength of 161.2 MPa and a Weibull modulus of 11.5. Fractographic observations confirm that the first mode (lower strength) corresponds to wafers which failed from large edge chips (sizes up to 90 μm). Weibull analysis suggests that the second mode (higher strength) corresponds to wafers which failed from smaller surface chips (sizes up to 50 μm). The results obtained point to large edge chips as the most dangerous defects degrading the fracture strength of the wafers. This is of great relevance for the photovoltaic industry, as fracture of silicon wafers limits both the performance and lifetime of the solar cells, and production yields.     

促进剂ZBEC对天然胶乳胶膜的硫化及力学性能的影响

研究了二苄基二硫代氨基甲酸锌(ZBEC)、二乙基二硫代氨基甲酸锌(ZDC)以及氧化锌(ZnO)和硫化温度对天然胶乳配合胶膜的硫化及力学性能的影响。结果表明,随着促进剂ZBEC、ZDC、ZnO用量的增加和硫化温度的提高,天然胶乳配合胶膜的硫化速度显著提高,且与ZDC相比,ZBEC略快。当ZBEC用量从0.5份增加到1.5份时,定伸应力、拉伸强度、撕裂强度先增加后减小。当ZDC用量从0.5份增加到1.5份时,定伸应力、拉伸强度随之增大,撕裂强度先增大后减小。随硫化温度的提高,以ZBEC为促进剂的硫化体系及以ZDC为促进剂的硫化体系的硫化胶膜的定伸应力、拉伸强度及撕裂强度均先增大后减小。     

Tensile properties of ultrahigh strength PAN-based, ultrahigh modulus pitch-based and high ductility pitch-based carbon fibers

The tensile properties and fracture behavior of ultrahigh tensile strength PAN-based (T1000GB), ultrahigh modulus pitch-based (K13D) and high ductility pitch-based (XN-05) carbon fibers have been investigated. The statistical distributions of the tensile strength were characterized. The Weibull modulus for the T1000GB, K13D and XN-05 fibers were calculated to be 5.9, 4.2 and 7.9, respectively. The results clearly show that for PAN- and pitch-based carbon fibers, the Weibull modulus decreases with an increase in the tensile modulus and the mean tensile strength.     

过氧化物硫化聚醚型聚氨酯混炼橡胶力学性能的研究

研究了过氧化物过氧化二异丙苯（DCP）、双叔丁基过氧化异丙基苯（BIPB）和补强剂（炭黑或白炭黑）对聚醚型聚氨酯混炼橡胶力学性能的影响,讨论了DCP和补强剂用量变化及不同硫化条件对混炼橡胶力学性能的影响。结果表明,DCP硫化混炼胶定伸应力高,永久变形小;BIPB硫化混炼胶硬度和强度高;当DCP用量在1．6份时,混炼胶拉伸强度和撕裂强度最高;提高补强剂用量,混炼胶硬度和定伸应力增加,拉伸强度变化不明显,但永久变形变大。     

Effects of simulated clinical fabrication heat treatment and artificial weathering on the tensile testing of prosthetics/orthotics polymers

The tensile behavior was compared for five prosthetics/orthotics polymers: Durr-Plex (co-polyester), Polypropylene (polypropylene), Subortholen (polyethylene), Surlyn (ionomer), and Uvex (and cellulose acetate butyrate). Tensile properties, yield strength, and modulus of elasticity are related to a number of factors including composition and condition of polymers. The polymers were examined in the as-received and simulated clinical fabrication heat-treated conditions. The simulated clinical fabrication heat-treated specimens were subsequently treated to 2 weeks, 4 weeks, and 8 weeks of artificial weathering conditions, consisting of exposure to cycles of ultraviolet light and heated condensation. Tensile testing was performed on an Instron mechanical testing system, until fracture occurred. The ranges and respective rankings of yield strength and modulus of elasticity in tension were determined. Analysis of Variance (ANOVA) and post hoc Scheffé statistical analyses were performed for different polymers of the same treatment condition, and different treatment conditions of the same polymer. The analysis of variance (ANOVA) showed significant yield strength and modulus differences for the five polymers. The choice of material significantly influences the tensile properties for prosthetics/orthotics polymers. The Uvex polymer had the highest yield strength and elastic modulus, and the Surlyn polymer had the lowest yield strength and elastic modulus. The ranking trend was Uvex > Durr-Plex > polypropylene > Subortholen > Surlyn. © 1996 John Wiley & Sons, Inc.     

Studies of the Physico-Mechanical,Interfacial, and Degradation Properties of Jute Fabrics/Melamine Composites

Jute fabrics/melamine composites (20% fiber) were prepared by compression molding. Mechanical properties of the composites were evaluated. Mechanical properties of starch-treated jute/melamine composites, including tensile strength (31%), bending strength (29%), tensile modulus (23%), bending modulus (25%), impact strength (113%), and hardness (4%), inproved significantly over the untreated composite. Fracture surfaces of untreated and treated composites were studied by scanning electron microscopy (SEM) and supported poorer fiber matrix adhesion for the untreated composite than that of the treated composite. Water uptake and soil degradation tests of untreated and treated composites were also performed.     

The investigation of antistatic effects of 1-ethyl-2,3-dimethylimidazolium ethyl sulphate for acrylic-based polymer film

This study aims to produce a long-term antistatic acrylic-based film by incorporating ionic liquid (IL), 1-ethyl-2,3-dimethylimidazolium ethyl sulphate (EIL) into acrylic resin. After loading, characterisations of samples were conducted by mechanically, thermally and morphologically. In order to determine antistatic properties, surface resistivity of samples was measured by using at different time intervals. The results indicated that IL loaded polymers showed a good antistatic property for a long time. The effect of incorporation on tensile strength, tensile modulus, flexural strength and flexural modulus of polymer were also obtained. After loading process, tensile strength, tensile modulus, flexural strength and flexural modulus values decreased considerably. The decrement in tensile strength of polymer is much less than that in flexural strength. The effect of EIL incorporation into acrylic resin on thermal conductivity and surface wettability was also investigated. From scanning electron microscopy images, EIL particles in nano-size range were observed in polymer structure.     

Mechanical properties and morphology of polypropylene composites. Talc-filled,elastomer-modified polypropylene

The balance of impact strength and rigidity of polypropylene can be significantly improved by physical blending of the polypropylene with a talc filler and a variety of elastomer types. Unsaturated elastomers were found to be effective impact strength improvers in 70/15/15 percent PP/elastomer/talc composites, whereas saturated elastomers gave rise to a high stiffness of such compounds. This is attributed primarily to different tendencies of the elastomers to coat the filler surface. Studies on a wider range of compositions, using a butadienestyrene-butadiene (SBS) block copolymer and a ethylene-propylene-diene (EPDM) terpolymer as representatives of the two elastomer classes, indicated that at high stiffness levels (flexural modulus > 1.6 GN/m²), the composites with SBS show the best balance of properties, whereas at higher impact levels EPDM leads to a higher rigidity and impact strength. On the basis of morphological studies such differences can be explained qualitatively, in spite of the complex structure of these composites.     

Comparative Studies on the Mechanical,Degradation and Interfacial Properties between Jute and E-Glass Fiber-Reinforced PET Composites

Jute fiber mat (hessian cloth) reinforced PET-based composites (50% fiber by weight) and E-glass fiber matreinforced PET based composites (50% fiber by weight) were fabricated by compression molding and the mechanical properties tensile strength (TS), tensile modulus (TM), elongation at break (%), bending strength (BS), bending modulus (BM), impact strength (IS) and hardness (Shore-A) of the composites were evaluated and compared. The interfacial properties of the both composites were also compared. Water uptake test and soil degradation test were also investigated.