Glass fibers with clay nanocomposite coating: Improved barrier resistance in alkaline environment

Coatings made from neat vinyl ester and nanoclay reinforced vinyl ester composites are applied onto individual glass fibers as well as rovings to evaluate their barrier resistance against alkali and moisture attack. The fibers coated with clay nanocomposites present a significantly less damage caused by the diffusing alkali ions, giving rise to a much higher residual tensile strength after aging than the fibers without coating or those with a neat polymer coating. The static fatigue test performed on individual fibers verifies the advantage of using nanoclay composite to retard the corrosion process under the combined stress and alkaline environment. Similar beneficial effects of incorporating nanoclay on residual strength are identified for impregnated fiber bundles. The above observations confirm the excellent barrier characteristics of intercalated/exfoliated nanoclay in polymer that are applied in composite structures on both the microscopic and macroscopic scales.     

Tamarind Fruit Fiber and Glass Fiber Reinforced Polyester Composites

Polyester-based hybrid composites were developed by combining the tamarind fruit (Tf) and glass fibers into a polyester matrix. Hardness, impact strength, frictional coefficient, and chemical resistance of hybrid composites with and without alkali treatments were studied. Variation of the aforementioned mechanical properties and chemical resistance was studied with different fiber lengths, such as 1, 2, and 3 cm. A 9 vol% of the tamarind and glass fibers was reinforced into the polyester matrix. The aforementioned mechanical properties were optimally improved at 2-cm fiber length when compared with 1- and 3-cm fiber lengths. Chemical resistance was also significantly improved for all chemicals except toluene. A 3°C rise in decomposition temperature while a 2°C rise in glass transition temperature was observed from TGA and DSC micrograms, respectively.     

玻璃纤维网格布的耐碱性能及其对混凝土板双向受弯性能的影响

为了研究玻璃纤维网格布在混凝土板中的双向受力性能及钢纤维和纤维网格布混杂使用的增强效果,进行了耐碱试验和双向板受弯试验。探究了钢纤维和玻璃纤维网格布混杂替代传统钢筋网的可行性。结果表明,与中碱玻璃纤维相比,耐碱玻璃纤维的耐腐蚀性能更优越;掺入耐碱玻璃纤维网格布后,混凝土板的极限承载力提高了59%;钢纤维和玻璃纤维网格布的混杂使用表现出较好的正混杂效应,混凝土板的极限承载力和弯曲韧性明显提高,板的破坏形态由脆性破坏转变为延性破坏;可考虑用30 kg/m3钢纤维掺量的混杂钢纤维和耐碱玻璃纤维网格布增强混凝土板代替配筋率为0.2%的钢筋混凝土板。      

Effect of ZrO<Subscript>2</Subscript> on the alkali resistance and mechanical properties of basalt fibers

We have studied the effect of zirconia additions on the properties of basalt glasses and fibers. The solubility limit of ZrO₂ in basalt glasses is determined to be 7.1 wt %. Fibers produced from modified basalt glass contain both tetragonal and monoclinic zirconia. The highest ZrO₂ concentration in basalt fibers is 3.1 wt %. We have determined the fiber drawing temperature ranges and assessed the tensile strength and alkali resistance of the fibers. With increasing ZrO₂ content, the tensile strength of the fibers (d = 11−12 μm) decreases from 1.8 to 0.6 GPa. The addition of less than 3.1 wt % ZrO₂ increases the alkali resistance of the basalt fibers by 37%. The addition of more than 3.1 wt % ZrO₂ to the glass batch reduces the alkali resistance and tensilestrength of the basalt fibers.     

The effect of alkaline treatment on mechanical properties of kenaf fibers and their epoxy composites

In this work, kenaf fibers were pre-treated in a NaOH solution (6% in weight) at room temperature for two different periods (48 and 144 h). The chemical treatment of kenaf fibers for 48 h allowed to clean their surface removing each impurity whereas 144 h of immersion time had detrimental effect on the fibers surface and, consequently, on their mechanical properties.Untreated and NaOH treated kenaf fibers (i.e. for 48 h) were also used as reinforcing agent of epoxy resin composites. The effect of the stacking sequence (i.e. using unidirectional long fibers or randomly oriented short fibers) and the chemical treatment on the static mechanical properties was evaluated showing that the composites exhibit higher moduli in comparison to the neat resin. As regards the strength properties, only the composites reinforced with unidirectional layers show higher strength than the neat resin. Moreover, the alkali treatment increased the mechanical properties of the composites, due to the improvement of fiber–matrix compatibility.The dynamic mechanical analysis showed that the storage and the loss moduli are mainly influenced by the alkali treatment above the glass transition temperature. Moreover, the alkali treatment led to a notable reduction of tan δ peaks in addition to significant shifts of tan δ peaks to higher temperatures whereas the stacking sequence did not influence the trends of storage modulus, loss modulus and damping of the composites.     

Preparation of electrically conductive polyimide/silver composite fibers via in-situ surface treatment

Polyimide (PI)/silver composite fibers with high electrical conductivity were prepared via an in-situ surface treatment method. The following procedures were included: hydrolyzing the PI fibers in alkali solution, followed by silver ion loading through ion exchange in silver salt solution and finally reducing the silver ion-loaded PI fibers in ascorbic acid solution. The effects of alkali treatment and ion-exchange conditions on the surface morphology, electrical conductivity and mechanical properties of the final composite fibers were studied. Excellent surface electrical conductivity was achieved on PI fiber surface with an electrical resistance of about 10² Ω/cm. The mechanical properties of the PI composite fibers were essentially similar to those of the bare PI fiber.     

An exploratory study of GFRP rebar with ribs containing milled glass fibers

Surface deformations of GFRP rebars are important in developing mechanical anchorage. The mixture of epoxy resin and milled glass fibers is considered as an alternative for surface structure of GFRP rebar to enhance the bond with the concrete. In order to investigate the applicability of the surface structure, manufacturing, material tests, pullout tests and shear tests were conducted. The mixture was successfully applied and shaped onto the GFRP rebars when the milled fibers were mixed to be within 20–50 wt% of the mixture. The bond performance was enhanced by adding as much milled glass fibers as possible but up to a workable range. When the milled glass fiber content was 50%, the upper limit of mix ratio, bond strength to concrete was only 10% less than that of the ordinary steel rebar. In addition, under an accelerated alkalinity condition, the amounts of mixed milled glass fibers in surface deformations have a minor effect on the durability of the proposed GFRP rebar.     

玄武岩纤维和玻璃纤维的耐碱性及其网格布对混凝土双向板弯曲性能的影响

为了研究玄武岩纤维网格布和玻璃纤维网格布的耐碱腐蚀性及其对混凝土方板双向受弯性能的影响,进行了玄武岩纤维和高锆玻璃纤维的耐碱试验和其网格布增强混凝土双向板的弯曲性能试验。借鉴欧洲EFNARC标准,利用四边简支方板试验,对比分析了不同纤维网格布对混凝土方板的双向增强效应。结果表明,与玄武岩纤维相比,高锆玻璃纤维的耐碱腐蚀性更好。纤维网格布较高的双向受拉性能可改善混凝土双向板的内力和应力重分布能力,玄武岩纤维网格布和高锆玻璃纤维网格布使水泥双向板的受弯承载力分别提高了48%和59%,高锆玻璃纤维的双向增强作用优于玄武岩纤维。      

704胶胶结界面pH值对玻璃纤维复合铝箔动态模量的影响

采用均匀设计法,以盐酸和氢氧化钠为酸碱处理剂,制备pH值在1.90~13.70的玻璃纤维与铝箔表面。以704硅橡胶作为粘结剂,将处理过的玻璃纤维与铝箔在140℃热压60s制成玻璃纤维复合铝箔材料。用动态热机械性能测试仪(DMA)考察胶结界面pH值在30~400℃下,玻璃纤维复合铝箔动态模量随温度的变化情况。结果表明:当玻璃纤维界面pH值呈中性,铝箔界面pH值呈弱碱性时,复合材料的动态模量比其他胶结界面pH值都大;且随着温度的增加,其动态模量相应增加,并在200℃时达到最大值。扫描电镜(SEM)实验证明,在此条件下制备的复合材料胶结界面更为紧密,且玻璃纤维丝有部分嵌入铝箔表面层结构。     

The effect of alkaline and silane treatments on mechanical properties and breakage of sisal fibers and poly(lactic acid)/sisal fiber composites

The main goals of this work were to study the effect of different chemical treatments on sisal fiber bundles tensile properties as well as on tensile properties of composites based on poly(lactic acid) (PLA) matrix and sisal fibers. For this purpose, sisal fibers were treated with different chemical treatments. After treating sisal fibers the tensile strength values decreased respect to untreated fiber ones, especially when the combination of NaOH + silane treatment was used. Taking into account fiber tensile properties and fiber/PLA adhesion values, composites based on silane treated fibers would show the highest tensile strength value. However, composites based on alkali treated and NaOH + silane treated fibers showed the highest tensile strength values. Finally, experimental tensile strength values of composites were compared with those values obtained using micromechanical models.     

Structures and performances of simultaneous ultrasound and alkali treated oil palm empty fruit bunch fiber reinforced poly(lactic acid) composites

In this study composites were produced using extrusion followed by injection molding with alkali and ultrasound treated oil palm empty fruit bunch (EFB) fibers with poly(lactic acid). The fiber content, alkali solution concentration, exposing time and treatment temperature were optimized. The optimized EFB fibers were treated with hyper branched polyester solution. The composites were characterized by tensile testing, impact testing, scanning electron microscopy, thermogravimetric analysis, differential scanning calorimetry and Fourier transformation infra-red spectroscopy. A significant increase in mechanical and interfacial properties was found for composites due to simultaneous alkali and ultrasound treatment.     

Acid corrosion resistance and mechanism of E-glass fibers: boron factor

Acid corrosion and stress corrosion characteristics of E-glass fibers with and without boron (B₂O₃ or B) were carefully studied, using 1 N H₂SO₄ acid at 96 °C and room temperature, respectively. The effect of boron on glass resistance to the acid attack is elucidated in conjunction with structural roles of B, Al, and Ca in the glass. Scanning electron microscopy with energy dispersive spectrometer (SEM/EDS) characterization was performed on the selective fiber samples before and after the acid leaching. For high boron-containing fibers, the results showed the formation of alteration layer enriched in Si as a result of depletion of both Ca and Al. Chemical analysis of the high boron fibers before and after 24 h acid leaching and the solution after 24 h test further confirmed that B, Ca, and Al in the glass fibers preferentially dissolved in the acid solution. Glass fiber dissolution mechanisms were discussed with a proposal that acid corrosion attack in boron-containing E-glass is controlled by hydrolysis of aluminoborate complex species (less than 10 nm) separated from the silicate glass network, whereas the acid corrosion attack in boron-free E-glass is controlled by hydrolysis of the silicate network, where 4-coordinated aluminum in the network is locally charge compensated by Ca.     

稀土硼铝硅酸盐玻璃结构及其耐碱性研究

本文通过块体法测定了玻璃的化学稳定性,同时采用MAS NMR研究了玻璃的结构.通过比较玻璃化学腐蚀速率,研究了不同稀土浓度的B2O3-SiO2-Al2O3-Sm2O3体系玻璃的结构及其在碱溶液中的抗腐蚀能力,探讨其侵蚀机理与规律.结果表明:碱溶液对玻璃的侵蚀是通过OH-离子破坏骨架造成.玻璃体系中三维网络阴离子群增加越多,玻璃结构越牢固,玻璃的抗碱能力越强;此外,由于稀土离子具有较强的积聚能力,适当地提高稀土氧化物在玻璃体中浓度有利于提高玻璃的抗碱性能.     

Novel alkali-resistant porous glass prepared from a mother glass based on the SiO2-B2O3-RO-ZrO2 (R = Mg,Ca, Sr,Ba and Zn) system

The alkali-resistant porous glass was prepared from the Si0₂-B₂0₃-RO (R=Mg, Ca, Sr, Ba and Zn) system containing Zr0₂. The porous glass skeleton contained 2–3 mass% Zr0₂ and the alkali resistance was greatly improved over that of ordinary Vycor-type porous glass. Because of the high alkali resistance, the elimination of the colloidal Si0₂ and Zr0₂ gelated during the acid leaching of the phase-separated glass, was promoted and as a result, a very sharp pore-size distribution of porous glass was attained. In addition, the limit of the available pore size of porous glass was widely expanded.     

UV photopolymer materials and technique for making laser glass

A technique and the materials required for making laser glass are described. The technique includes cleaning glass plates, coating UV photopolymer materials onto the glass plates, attaching a master hologram to the plates, using exposure to UV light to cure the coating, screen printing, vacuum film depositing, and covering the plates with a protective coating. The UV photopolymer material is composed of a photoinitiator, a monomer, an oligomer, and other additives. The experimental results show that the laser-glass products have a high resistance to alkali, acid, heating, and UV irradiation.     

Polyamide-6/vegetal fiber composite prepared by extrusion and injection molding

The interest for the use of vegetal fibers as polymers reinforcement has recently increased because of their unique environmental and technological advantages. This work evaluated the use of Curauá fibers in polyamide-6 composites aiming at glass fiber replacement. Fiber content of 20, 30 or 40 wt% and fiber lengths of 0.1 or 10 mm were studied. Fibers were treated with N₂ plasma or washed with NaOH solution, to improve their adhesion to PA-6. Samples with 20 wt% of short or long fibers, with or without pre-treatment, were compounded in two different co-rotating intermeshing twin-screw extruders. These samples were submitted to mechanical and thermal tests. In conclusion, non-dried raw materials improved fiber/matrix interfacial adhesion. Tensile and flexural properties of this composite are better than unfilled, but lower than glass fiber reinforced polyamide-6. However, its impact resistance and heat deflection temperature are similar to the glass fiber reinforced polyamide-6 and its lower density, enable it to replace this latter in specific non-critical applications.     

Damage detection of glass fiber reinforced composites using embedded PVA–carbon nanotube (CNT) fibers

Polyvinyl alcohol–carbon nanotube (PVA–CNT) fibers were embedded in glass fiber reinforced plastic composites and used as strain sensors for damage monitoring of the composite. Sensing of the structural integrity of the composite was made by the in situ measurement of the electrical resistance of the embedded PVA–CNT fiber during the mechanical tests. The multi-functional materials were tested in tensile progressive damage accumulation (PDA) tests. These tests aimed to seek the electrical response of untreated and pre-stretched PVA–CNT fibers with known level of progressively induced damage to the composite. The advantages and disadvantages of each PVA–CNT fiber used as a sensor are analyzed; the electrical resistance readings of the PVA–CNT fibers were correlated with known parameters that express the induced damage of the composite.     

Improved properties of GRC composites using commercial E-glass fibers with new coatings

A study was carried out to evaluate the action of a new 15CaO-15BaO-20SiO₂-50TiO₂ coat on long-term durability of glass fiber reinforced cement. Compressive strength, flexural strength and drying shrinkage were measured. Significant improvement was observed and four reasons were given to explain it. The results testify further the effectiveness of the alkali resistance of the new coat.     

Comparative study of high temperature composites

Two classes of composite made using either ceramic matrix with high temperature fibers or carbon/carbon have been used for various applications that require high temperature resistance, over three decades. However, their use has been limited to special applications because of the high costs associated with fabrication. Typically the composites are cured at more than 1000°C, and in most instances the heating has also to be carried out in controlled environments. In addition, because of the high processing temperature, only certain type of expensive fibers can be used with the ceramic matrices. A recently developed inorganic matrix, called polysialate can be cured at temperatures less than 150°C, making it possible to use carbon and glass fibers. Composites made using carbon, glass and combinations of carbon and glass fibers have been tested in bending and tension. This paper presents the comparison of processing requirements and mechanical properties of carbon/carbon composites, ceramic matrix composites made with silicon carbide, silicon nitride and alumina fibers and carbon/polysialate composites. The results indicate that carbon/polysialate composite has mechanical properties comparable to both carbon/carbon and ceramic matrix composites at room and high temperatures. Since the polysialate composites are much less expensive, the authors believe that it has excellent potential for more applications in aerospace, automobile and naval structures.     

Effect of glass fiber hybridization on properties of sisal fiber–polypropylene composites

Natural fiber reinforced polymer composites became more attractive due to their light weight, high specific strength, and environmental concern. However, some limitations such as low modulus, poor moisture resistance were reported. This study aimed to investigate the effect of glass fiber hybridization on the physical properties of sisal–polypropylene composites. Polypropylene grafted with maleic anhydride (PP-g-MA) was used as a compatibilizer to enhance the compatibility between the fibers and polypropylene. Incorporating glass fiber into the sisal–polypropylene composites enhanced tensile, flexural, and impact strength without having significant effect on tensile and flexural moduli. In addition, adding glass fiber improved thermal properties and water resistance of the composites.