粉煤灰基矿聚物材料的研究进展

论述了粉煤灰基矿聚物其特殊的三维网络结构及其具有类似于水泥、陶瓷的优良性能。系统评述了国内外粉煤灰基矿聚物的研究现状、反应过程及其机理。     

聚吡咯及其复合材料的研究进展

介绍了聚吡咯及其纳米复合材料的最新研究进展,综述了聚吡咯的聚合机理、制备方法、应用范围等,同时也介绍了聚吡咯复合材料的主要类别及应用领域,最后对聚吡咯及其复合材料的发展前景进行了展望。     

聚氯乙烯/偏高岭土基地聚物复合材料的制备和性能

采用聚氯乙烯(PVC)树脂与处于地聚合初期凝胶阶段的偏高岭土基地聚物混合、熔融加工的方法制备了PVC/偏高岭土基地聚物复合材料,研究地聚物含量对PVC复合材料加工塑化、力学性能、热性能及断面形貌的影响。发现少量地聚物(如≤8%(wt))的引入可促进PVC树脂的塑化,地聚物分散尺寸较小,在基体中分散较均匀,并与PVC基体有良好的界面结合,可有效发挥地聚物刚性粒子对PVC的增强增韧作用,复合材料有较好的力学性能,其中以4%(wt)的地聚物含量为最佳,其材料的抗冲击强度达到了9.16 kJ?m?2,比纯PVC材料提高了约40%。当地聚物含量过高时,PVC树脂塑化困难,地聚物分散尺寸增大,与PVC基体界面作用减弱,导致复合材料拉伸强度和韧性的下降。随着地聚物含量的增加,PVC复合材料抵抗热变形的能力增加,维卡软化温度升高。     

中国专利

正一种纳米协同膨胀阻燃增韧聚丙烯共混物复合材料及其制备方法本发明公开的纳米协同膨胀阻燃增韧聚丙烯共混物复合材料的组成为:聚丙烯71 phr、辛烯-乙烯嵌段共聚物20 phr、改性膨胀型阻燃剂23 phr、有机改性蒙脱土2 phr、马来酸酐接枝聚丙烯1~11 phr。本发明加工工艺简单,所制复合材料具有良好的阻燃及增韧性能。与纯聚丙烯相比,复合材料的热释放速率峰值、烟气释放速率明显降低,而且材料的冲击强度提高。     

聚噻吩纳米复合材料的制备及测试方法

介绍了聚噻吩及其纳米复合材料的合成方法,综述了聚噻吩纳米复合材料的测试方法及应用领域,并对聚噻吩纳米复合材料的发展进行了展望。     

中国塑料专利

优异抗刮伤特性的聚丙烯树脂组合物；聚烯烃／纳米碳酸钙预分散母粒的制备方法;聚醋瓶及其制备方法;热塑性树脂／氢氧化镁高性能阻燃复合材料;一种竹粉-高密度聚乙烯复合材料;基于聚酰胺和／或聚醋基质的组合物     

硅系阻燃剂阻燃PC及PC/ABS复合材料研究进展

综述硅系阻燃剂阻燃聚碳酸酯(PC)及PC/丙烯腈-丁二烯-苯乙烯塑料(ABS)复合材料的机理,以及无机硅、有机硅氧烷类、聚倍半硅氧烷及其衍生物、有机/无机杂化硅材料、带有双螺环磷酸酯和磷杂菲的硅系阻燃剂等在PC及PC/ABS复合材料中的应用进展。指出硅系阻燃剂是PC及PC/ABS复合材料用阻燃剂的发展趋势。     

原位聚合法制备PVC/地聚物复合材料

通过偶联改性偏高岭土基地聚物存在下的氯乙烯原位悬浮聚合制备聚氯乙烯(PVC)/地聚物复合树脂,研究了地聚物加入方式与用量、复合分散剂组成对复合树脂颗粒特性和理化性质的影响,同时分析了PVC/地聚物复合材料的力学和热性能.结果表明,地聚物添加量质量分数不大于4％时,采用倒加料聚合工艺和聚乙烯醇/羟丙基甲基纤维复合分散体系,可聚合得到粒径分布较窄、理化指标符合国标要求的PVC复合树脂.随着地聚物添加量的增大,PVC/地聚物复合材料的抗冲击强度、拉伸强度和断裂伸长率先增大后减小.与未添加地聚物的PVC材料相比,地聚物质量分数为3％的PVC复合材料的抗冲击强度和拉伸强度分别提高56％和14％.地聚物对PVC热分解脱除HCl过程有抑制作用,能提高PVC的分解温度,同时地聚物的加入可提高PVC耐热形变温度.     

金属及其化合物填充聚合物PTC材料的研究进展

某些有机高分了聚全物可与导电材料形成PTC复合材料。评述了用金属系分散体作导电材料填充聚合物形成聚合物基PTC复合材料时所用金属系物质的种类、用量等对复合材料PTC强度的影响及其导电机理。认为在聚合物／碳系分散体构成的二元体系中添加合适的金属系分散体组成三元复合材料时,可望得到性能优良的PTC复合材料。     

可生物降解聚合物的发泡技术研究进展

介绍了可生物降解聚合物的发泡技术进展,包括聚乳酸、聚己内酯、二元醇二元羧酸脂肪族聚酯、聚乙烯醇等及其共混物、纳米复合材料等的发泡技术,涉及了超临界二氧化碳发泡技术、化学发泡剂发泡技术等。     

Hybrid thermoplastic composites using ceramic reinforcements

Abstract

Polyethylene-based and polypropylene-based composites, incorporating silica nanoparticles and geopolymers, were prepared by melt compounding. Scanning electron microscope (SEM) images indicate that the silica nanoparticles do not distribute uniformly as fine particles in the matrix, but are unevenly distributed as clusters. As a result, the tensile properties of those composites are inferior to those of the matrix polymer. A novel concept of in situ formation of a reinforcing phase has been investigated as a method of resolving that problem. The reinforcing elements are microcrystalline phases developed during melt processing of mixtures of geopolymer precursors with polyethylene or polypropylene. Preliminary tensile test data on injection moulded specimens show some improvement in mechanical properties of both geopolymer–polyethylene and geopolymer–polypropylene composites relative to the matrix polymers. Scanning electron micrographs clearly show the presence in the composites of a nanoscale acicular crystalline structure that is thought to act as a fibre-like reinforcement.     

Improving compressive strength of fly ash-based geopolymer composites by basalt fibers addition

In this study, ASTM Class C fly ash used as an alumino-silicate source was activated by metal alkali and cured at low temperature. Basalt fibers which have excellent physical and mechanical properties were added to fly ash-based geopolymers for 10–30% solid content to act as a reinforced material, and its influence on the compressive strength of geopolymer composites has been investigated. XRD study of synthesized geopolymers showed an amorphous phase of geopolymeric gel in the 2θ region of 23°–38° including calcium-silicate-hydrate (C-S-H) phase, some crystalline phases of magnesioferrite, and un-reacted quartz. The microstructure investigation illustrated fly ash particles and basalt fibers were embedded in a dense alumino-silicate matrix, though there was some un-reacted phase occurred. The compressive strength of fly ash-based geopolymer matrix without basalt fibers added samples aged 28 days was 35 MPa which significantly increased 37% when the 10 wt%. basalt fibers were added. However, the addition of basalt fibers from 15 to 30 wt% has not shown a major improvement in compressive strength. In addition, it was found that the compressive strength was strong relevant to the Ca/Si ratio and the C-S-H phase in the geopolymer matrix as high compressive strength was found in the samples with high Ca/Si ratio. It is suggested that basalt fibers are one of the potential candidates as reinforcements for geopolymer composites development.     

Synthesis and thermal behavior of inorganic–organic hybrid geopolymer composites

Inorganic geopolymer potassium aluminosilicate was prepared at room temperature by the reaction of kaolin, potassium silicate, and potassium hydroxide solution and was dispersed in situ into an epoxy matrix by various proportions to fabricate novel inorganic–organic hybrid geopolymer composites. The formation of inorganic geopolymer with respect to time was monitored by X‐ray diffraction and FT‐IR analysis and confirmed that 30 min is required to complete the geopolymerization. When geopolymers were properly mixed at different ratios with organic polymers such as epoxy and cured, these hybrid polymers exhibit significant thermal stability. Pure kaolin was also incorporated into the epoxy matrix to compare the change in chemical and thermal properties. Cone calorimetry results showed about 27% decreased in rate of heat release (RHR) on addition of 20% pure kaolin. However, about 57% of RHR was decreased on addition of only 20% geopolymer. Evaluation of CO₂ and CO were found to be minimum 2.0 and 0.7 kg/kg, respectively, for hybrid geopolymer composites compared to very high yield for epoxy at 3.5 kg/kg after 200 s of ignition. The current study shows that due to the high thermal stability of hybrid geopolymer composites, the novel hybrid geopolymer composites have the ability to be potential candidates to use in practical application where fire is of great concern. © 2005 Wiley Periodicals, Inc. J Appl Polym Sci 96: 112–121, 2005     

High-flexural-strength of geopolymer composites with self-assembled nanofiber networks

Natural-fiber-reinforced geopolymer composites are environmentally friendly materials that have garnered considerable attention. In practice, the drying shrinkage and uneven dispersion of fibers in geopolymers result in low flexural strength, which limits the use of large-scale composites. In this study, high-flexural strength geopolymer composites with self-assembled nanofiber networks were hybridized using in situ polymerization. Composites with different fiber contents were evaluated via morphology and mechanical strength assessments. A mixed nanofiber and geopolymer solution was created to achieve uniform dispersion, and then the geopolymers were optimized at the nanoscale level using a bottom-up approach to achieve self-assembled nanofiber networks with good interfacial bonding. Due to the water retention properties of the nanofibers and subsequent gel material, the networks facilitated internal curing of the geopolymers, thus preventing drying shrinkage. This ultimately reduced the weight loss and increased the density of the composites. In addition, high flexural strength properties were observed in composites with a fiber content of 0.5%, due to the combination of fiber reinforcement and porosity. Thus, this work introduces new considerations for geopolymer applications.     

Geopolymer reinforced with E‐glass leno weaves

This study explores the viability of fiberglass‐geopolymer composites as an intermediate temperature structural ceramic composite. E‐glass fibers are cheap, readily available, resistant to heat, electricity and chemical attack. Geopolymers are refractory and can be processed at room temperature. However, pure geopolymers have low tensile strength and fracture toughness, as is typical of ceramics. In this work, tensile and flexure properties of metakaolin‐based sodium and potassium geopolymers reinforced with E‐glass leno weaves were measured and the data was analyzed by Weibull statistics. The average tensile and flexural strengths for sodium geopolymer reinforced with E‐glass leno weaves were 39.3 ± 7.2 MPa and 25.6 ± 4.8 MPa, respectively. For potassium geopolymer reinforced with E‐glass leno weaves, the average tensile and flexural strengths were 40.7 ± 9.9 MPa and 15.9 ± 4.0 MPa, respectively. The composites were heat treated for one hour at two temperatures, 300°C and 550°C and their flexure properties were studied at room temperatures. The average flexural strengths for sodium geopolymer reinforced with E‐glass leno weaves were reduced to 6.6 ± 1.0 MPa after heat treatment at 300°C, and 1.2 ± 0.3 MPa after heat treatment at 550°C, respectively. For potassium geopolymer reinforced with E‐glass leno weaves, the average flexural strengths were 6.1 ± 1.5 MPa and 1.3 ± 0.3 MPa after heat treatment at 300°C and 550°C, respectively. SEM and EDS were performed to observe the fiber‐matrix interface. XRD was done to check if the geopolymer was amorphous as expected.     

Comparative performance of geopolymers made with metakaolin and fly ash after exposure to elevated temperatures

This paper presents the results of a study on the effect of elevated temperatures on geopolymers manufactured using metakaolin and fly ash of various mixture proportions. Both types of geopolymers (metakaolin and fly ash) were synthesized with sodium silicate and potassium hydroxide solutions.

The strength of the fly ash-based geopolymer increased after exposure to elevated temperatures (800 °C). However, the strength of the corresponding metakaolin-based geopolymer decreased after similar exposure. Both types of geopolymers were subjected to thermogravimetric, scanning electron microscopy and mercury intrusion porosimetry tests. The paper concludes that the fly ash-based geopolymers have large numbers of small pores which facilitate the escape of moisture when heated, thus causing minimal damage to the geopolymer matrix. On the other hand, metakaolin geopolymers do not possess such pore distribution structures. The strength increase in fly ash geopolymers is also partly attributed to the sintering reactions of un-reacted fly ash particles.     

碱激发地质聚合物固化软土的研究进展

软土地基处理是工程界公认的有较高风险的工程领域,传统软土固化中大量使用硅酸盐水泥,不仅消耗自然资源,还会对环境产生不良影响,使用环境友好型碱激发地质聚合物替代传统硅酸盐水泥越来越受到国内外学者的重视。论文基于国内外已有研究成果,从碱激发地质聚合物固化土发展历史、碱激发地质聚合物种类、碱激发地质聚合物反应机理、碱激发地质聚合物固化土力学特性和各类性能等方面进行研究进展的综述分析,重点谈论地质聚合物处理软土的力学特性,并对不同碱激发地质聚合物在软土地基加固中抗渗性能、抗冻融性能、抗腐蚀性能等进行分析,对碱激发地质聚合物在软土地基加固中的应用进行系统梳理和展望,以期引导和提升碱激发地质聚合物在软土地基加固中的应用,实现我国地基加固可持续发展。     

SiC fiber reinforced geopolymer composites,part 2: Continuous SiC fiber

In this paper, unidirectional SiC fiber (SiC_f) reinforced geopolymer composites (SiC_f/geopolymer) were prepared and effects of fiber contents on the microstructure and mechanical properties of the composites in different directions were investigated. The XRD results showed that addition of SiC_f retarded geopolymerization process of geopolymer matrix by weakening the typical amorphous hump. SiC_f in all the composites were well infiltrated by geopolymer matrix, but microcracks which were perpendicular to the fiber axial direction were noted in the interface area due to the thermal shrinkage of matrix during the curing process. With the increases in fiber contents, although Young's modulus of the composites increased continuously, flexural strength, fracture toughness and work of fracture increased at first, reached their peak values and then decreased. And when fiber content was 20 vol%, the composites showed the highest flexural strength, fracture toughness and work of fracture, which were 14.2, 15.2 and 81.6 times as high as those of pristine geopolymer, respectively, indicating significant strengthening and toughening effects from SiC_f. Meanwhile, SiC_f/geopolymer composites failed in different failure modes in the different directions, i.e., tensile failure mode in the x direction (in-plane and perpendicular to the fiber axial direction) and shear failure mode in the z direction (laminate lay-up direction).     

Synthesis and characteristics of fly ash and bottom ash based geopolymers–A comparative study

The research was carried out to develop geopolymers mortars and concrete from fly ash and bottom ash and compare the characteristics deriving from either of these products. The mortars were produced by mixing the ashes with sodium silicate and sodium hydroxide as activator solution. After curing and drying, the bulk density, apparent density and porosity, of geopolymer samples were evaluated. The microstructure, phase composition and thermal behavior of geopolymer samples were characterized by scanning electron microscopy, XRD and TGA-DTA analysis respectively. FTIR analysis revealed higher degree of reaction in bottom ash based geopolymer. Mechanical characterization shows, geopolymer processed from fly ash having a compressive strength 61.4 MPa and Young's modulus of 2.9 GPa, whereas bottom ash geopolymer shows a compressive strength up to 55.2 MPa and Young's modulus of 2.8 GPa. The mechanical characterization depicts that bottom ash geopolymers are almost equally viable as fly ash geopolymer. Thermal conductivity analysis reveals that fly ash geopolymer shows lower thermal conductivity of 0.58 W/mK compared to bottom ash geopolymer 0.85 W/mK.     

Influence of modified multi-walled carbon nanotubes on the mechanical behavior and toughening mechanism of an environmentally friendly granulated blast furnace slag-based geopolymer matrix

This study aimed to investigate the mechanical behavior of an environmentally friendly granulated blast furnace slag-based geopolymer matrix reinforced with modified multi-walled carbon nanotubes (MWCNTs). The modified MWCNTs were obtained using a modification method combining nitric acid and sulfuric acid and were then dispersed using sodium dodecylsulfate (SDS) as a dispersant. Two types and three concentrations of MWCNTs were mixed directly into the aqueous solution, sonicated, and then mechanically mixed with waste granulated blast furnace slag to form the geopolymer matrix. Raman and Fourier transform infrared (FT-IR) spectroscopy were used to evaluate the ordered structure and crystallization degree of the modified MWCNTs. Then, the dispersity of the modified MWCNTs was characterized using transmission electron microscopy (TEM). The compressive and bending strengths were measured to evaluate the mechanical behavior of specimens. Moreover, the polycondensation products, polycondensation degree, pore structure, and microscopic morphology of the geopolymer matrix were analyzed using X-ray diffraction (XRD), FT-IR spectroscopy, nuclear magnetic resonance (NMR), mercury intrusion porosimetry (MIP), and field emission scanning electron microscopy with energy dispersive X-ray spectroscopy (FESEM-EDS). The experimental results showed that the incorporation of 0.1% functionalized MWCNTs had an optimal influence on the fluidity and mechanical behavior. The slump diameters of geopolymers with 0.1% functionalized MWCNTs with and without SDS were increased by 16.3% and 23.5%, respectively, compared with the reference geopolymer matrix. For geopolymer matrix samples at a curing age of 28 d, the compressive strength of geopolymers with 0.1% functionalized MWCNTs with and without SDS were increased by 16.3% and 17.6%, respectively. For the bending strength, the corresponding increases were 17.6% and 18.7%, respectively. It was found that functionalized MWCNTs could increase the degree of polycondensation, leading to a more traditional amorphous N-A-S-H phase, a finer C–S–H phase, more Q⁴ (2Al) and Q⁴ (3Al), and lower porosity. In addition, the propagation of micro-cracks in the geopolymers was inhibited by the incorporation of functionalized MWCNTs.