Setting kinetics and mechanical properties of flax fibre reinforced glass ionomer restorative materials

Regardless of the excellent properties of glass ionomer cements,their poor mechanical properties limit their applications to non-load bearing areas.This study aimed to investigate the effect of incorporated short,chopped and randomly distributed flax fibers（0,0.5,1,2.5,5 and 25 wt%） on setting reaction kinetics,and mechanical and morphological properties of glass ionomer cements.Addition of flax fibers did not significantly affect the setting reaction extent.According to their content,flax fibers increased the compressive（from 148 to 250 MPa） and flexure strength（from 20 to 42 MPa）.They also changed the brittle behavior of glass ionomer cements to a plastic one.They significantly reduced the compressive（from 3 to 1.3 GPa） and flexure modulus（from 19 to 14 GPa）.Accordingly,flax fiber-modified glass ionomer cements could be potentially used in high-stress bearing areas.

Analysis of Mechanical Properties of Injection Molded Short Glass Fibre (SGF)/Calcite/ABS Composites

Acrylonitrile-butadiene-Styrene (ABS), with and without calcium carbonate (calcite) particles,was used as the matrix for reinforcement with as-received short-glass fibres (were originallytreated by the manufacturer) and sized short-glass fibres with two amino-silane coupling agents.The calcite particle content is 0, 11.7 and 23.5 vol. pct for the matrices. The glass fiber contentis 0, 10 and 15 vol. pct. The matrix materials and corresponding composites were compoundedusing a twin screw extruder and dumbbell-shaped tensile bars were prepared with an injectionmolding process. The tensile and flexural properties as well as the unnotched and notchedCharpy impact energies of short glass fibre/calcite/ABS composites were studied in this paper.The effects of fibres, fibre surface treatments and particles on these mechanical properties ofthe composites were discussed in detail. An importarit information was obtained, which is thatthe tensile and flexural strengths of hybrid SGF/calcite/ABS composites are the same as thoseof corresponding fibre composites when the ratio of the interfacial adhesion strength betweenparticles and matrix to that between fibres and matrix is higher than certain value. otherwise theformer are lower than the latter.

The Influence of Additions in the Use of Glass Fibre Reinforced Cement as a Construction Material

Although in recent years glass fibre reinforced cement (GRC) has been used in buildings and infrastructure, its application in structural elements has been somewhat restricted due to the worsening of its mechanical properties with ageing and the limited data available related with its fracture energy. With the aim of developing existing knowledge of GRC, the fracture energy in an in-plane and out-of-plane direction of the panel has been obtained. Three types of GRC with different formulations have been tested. The results showed that the fracture energy of a GRC with a 25% addition of a pozzolanic admixture is 40% and 8% higher than a standard GRC in, respectively, in-plane and out-of-plane directions. Similarly, an addition of 25% of thermal-treated kaolin to a standard GRC increases its fracture energy up to 490% and 400%, to the corresponding orientation. The use of digital image correlation (DIC) in the fracture test analysis has permitted a description of the damaging patterns and explanation of the behaviours identified in the fracture tests performed. The multi-cracking process that appears explains the higher fracture energy found in the GRC with an addition of 25% of the aforementioned thermal-treated kaolin. The analysis performed by means of DIC and the results obtained showed GRC with an addition of 25% of thermal-treated kaolin to be the most suitable formulation for possible future structural applications with a short life span in horizontal and vertical elements.

Influence of an Optimized Fibre Coating on Interfacial and Mechanical Properties of Glass Fibre/Polypropylene Composites

The influence of pretreatment of fibre on interfacial and mechanical properties of glass fibre/ polypropylene composites was investigated. Firstly, the glass fibres were coated with the blends of m-IPP (maleic anhydride grafting isotatic polypropylene ) and m-APP ( maleic anhydride grafting amorphous polypropylene) in different, ratios. Secondly, the interfaced reaction of the coated composites was analysed by FTIR, which shows that the interfacial chemical reaction between m-IPP/m-APP in the fibre coating and the fibre surface- bound coupling agent is in existence. Thirdly, the microstructure of the coated composites wax studied by SEM. The results indicate that the coating treatment is effective on improving interfacial adhesion of the, fibre-matrix and the right amount of m-APP added to the coal impels the plastic deformation surrounding the point of cracks , which makes cracks turn to region and prevents from further interface debonding. Lastly, the mechanical properties were evaluated by measurement, of the flexural strength and impact strength of the composites. It was found that, the flexural strength and impact strength of the composites with coating fibre are higher than those of uncoating fibre composite. The results of these investigations draw the conclusion that the pretreatment of fibre with m-IPP/m-APP blends can form an optimize interlayer between the fibre and the PP matrix, which improves both the strength and lough-ness of the composites.

Glass Fibre Reinforced Concrete Rebound Optimization

Glass fibre reinforced concrete placement technique generates losses due to rebound effects of the already sprayed concrete particles.Rebounded concrete amount cause a significant difference between the initial mix design and emplaced mix compositions.Apart from the structural differences,it comes with a cost increase which was resulted by the splashed concrete amount.Many factors such as viscosity and quantity of mixes dominate this rebound amount in sprayed glass fibre reinforced concrete applications depending on production technologies and processes;however,this research focuses on the spray distance and the angle of the spray gun which mainly effects the rebound amount in glass fibre reinforced concrete production.This paper aims to understand the required angle and distance for glass fibre reinforced concrete mixes having on-site plastic viscosity values.Glass fibre reinforced mixtures were also modelled with a finite element method based software and,the analysis results were compared with production line results.Results of the analysis and on-site studies showed a decisive correlation between,discharge distance,discharge angle and the viscosity of the concrete.

Hybrid Composites of Phosphate Glass Fibre/Nano-Hydroxyapatite/Polylactide: Effects of Nano-Hydroxyapatite on Mechanical Properties and Degradation Behaviour

Hydroxyapatite/polylactide (HA/PLA) composites have been intensively investigated for their potential as biodegradable fixation devices to heal bone fractures. However, most of these composites failed to achieve a bone-mimicking level of mechanical properties, which is an essential demand of the targeted application. In this study, the nano-hydroxyapatite/polylactide composites were used as the matrix and continuous phosphate glass fibres (PGF) served as the major reinforcement to obtain the nano-HA/PGF/PLA hybrid composites. While the PGF volume fraction remained constant (25%), the nano-HA content (in weight) varied from 0% to 20%. As nano-HA loading increased, the flexural modulus of the composites increased from 8.70 ± 0.35 GPa to 14.97 ± 1.30 GPa, and the flexural strengths were enhanced from 236.31 ± 10.83 MPa to 310.55 ± 22.88 MPa. However, it is found that the degradation rates are higher with more nano-HA loaded. Enhanced water absorption ability, as well as increased voids in the composites is possible reasons for the accelerated degradation of composites with higher nano-HA loading. The hybrid composites possess mechanical properties that are superior to most of the HA/PLA composites in previous research while maintaining the biodegradability. With a proper loading of nano-HA in composites of 10 weight percent, the composites are also found with improved mechanical properties without catastrophic degradation. The composites developed in this study have great potential as biodegradable bone fixation device with enhanced load-bearing ability as confirmed and superior bioactivity as anticipated.

Evaluating the Structural Integrity of Fibreglass for the Manufacture of Headgears

A composite material is made up of two phases, the matrix, and the reinforcing materials. The reinforcing material is embedded over matrix material. The reinforcing material works to make the matrix material harder. A fibreglass reinforced composite was developed using E-glass fibre reinforcement and epoxy resin matrix. The composites were produced using the hand lay-up technique with varying fibre percentage of 9%, 13% and 25% by weight percentage of fibreglass mat at orientations of 0°, 15°, 45°, and 90° chosen at random. A 13% by weight percentage of chopped mat was also developed for purpose of comparison. The fabricated composites were subjected to tensile test, flexural test, impact test, punch shear test and hardness test to ascertain the appropriate fibre contents and orientation that is optimum for the manufacture of headgears. Analysis of Variance was carried out to determine level of significance and percentage contribution of the parameters. The results show that both fibre orientation and percentage of fibre content reinforcement of have significant influence on the strength and fracture energy of the composite .The fibre orientation has a higher impact on the strength of the composite (79.74%) while the percentage of fibre reinforcement has a lesser impact on the tensile strength of the composite (20.26%). However, the fibre orientation has a lesser impact on the fracture energy of the composite (24.54%) while the percentage of fibre reinforcement has a higher impact on the fracture energy of the composite (75.46%) The result from this study shows that the increase in fibre content increases flexural strength and impact toughness of the fibreglass reinforced composite. A fibre orientation of 90° and fibre reinforcement of 25% wt. was determined to be optimally suitable for the manufacture of headgears.

Thermo-Stamping Process of Glass and Carbon-Fibre Reinforced Polymer Composites

In this work, manufacturing tools for thermoplastic (TP) composites have been developed. The chosen process involves the stacking alternately of oriented dry fabrics and TP films and does not use semi-products in order to reduce material costs. This study was specifically directed towards optimizing the impregnation of continuous glass and carbon fibres reinforcing two TP amorphous matrices, the polyphenylsulfone (PPSU) and polyetherimide (PEI), to obtain semi-finished products employed for aeronautical structures. The impregnation quality of inter and intra-yarns is analyzed and validated by optical and scanning micrographic observations conducted with an optical and a Scanning Electron Microscopies (SEM), respectively. The study showed that besides the process parameters and porosity distribution in the core of warp yarns, the impregnation quality depends on the surface properties of constituents. Desizing treatment has been carried out to improve the wettability of fibres by the TP matrices.

Axial Tensile Testing of Single Fibres

The mechanical and damage properties of single fibres used in fibrous composite have gained tremendous importance in recent years. These properties are used in determination of effective properties of composites by micromechanics. These are also used in the micromechanical damage modeling. Further, these properties are used as an indicator of the excellence of product by manufacturers. In the present study the axial tensile modulus, ultimate strength and failure strain of single fibres are determined for carbon and glass fibres. ASTM D3379-75 standard is followed and a number of fibers are tested for statistical analysis. The axial tensile moduli measured are 246.7 GPa and 93.3 GPa, respectively and strength are 3031.6 MPa and 2035.9 MPa, respectively for carbon and glass fibres. Further, the respective axial tensile failure strains are 0.0137 and 0.0224. The error in the measurement of axial modulus is below 8% while for axial tensile strength is below 1%.

FIBRE REINFORCED COMPOSITES BASED ON NOVEL BLEND MATRICES

A series of glass fibre reinforced composites based on novel blend matrices were fabricated us-ing reaction injection moulding （RIM） processing.The blends were made of sub-sequentialinterpenetrating polymer networks of acrylic-polyurea or acrylic-copoly（urea-isocyanurate）.Themechanical and thermal properties were characterized by tensile test and dynamic mechanical ana-lysis.The fracture data from single edge notch bend tests were analysed using fracture mechanicsfor the composites to give KIC and GIC.The correlation between reaction kinetics and morphologyof the blend and the composite properties were discussed.The investigations showed that the novelblends have good bonding property on glass fibre,thus good processability in RIM,and the re-suited composites have good mechanical and thermal properties.

Assessing Mechanical Properties of Natural Fibre Reinforced Composites for Engineering Applications

Mechanical properties of ukam, banana, sisal, coconut, hemp and e-glass fibre reinforced laminates were evaluated to assess the possibility of using it as new material in engineering applications. Samples were fabricated by the hand lay-up process (30:70 fibre and matrix ratio by weight) and the properties evaluated using the INSTRON material testing system. The mechanical properties were tested and showed that glass laminate has the maximum tensile strength of 63 MPa, bending strength of 0.5 MPa, compressive strength of 37.75 MPa and the impact strength of 17.82 J/m2. The ukam plant fibre laminate has the maximum tensile strength of 16.25 MPa and the impact strength of 9.8J/m among the natural fibres;the sisal laminate has the maximum compressive strength of 42 MPa and maximum bending strength of 0.0036 MPa among the natural fibres. Results indicated that natural fibres are of interest for low-cost engineering applications and can compete with artificial glass fibres (E-glass fibre) when a high stiffness per unit weight is desirable. Results also indicated that future research towards significant improvements in tensile and impact strength of these types of composites should focus on the optimisation of fibre strength rather than interfacial bond strength.

新型GFRP-钢屈曲约束支撑设计与受力性能分析

为发展轻质、耐腐蚀的屈曲约束支撑,以玻璃纤维(GFRP)拉挤型材和缠绕工艺构造支撑约束构件,H型钢为内芯,提出一种新型GFRP-钢屈曲约束支撑.通过理论分析与数值模拟,探究了支撑内芯的屈曲模态发展规律;结合GFRP的各向异性和层合板结构特性,建立了GFRP约束构件的设计参数计算公式;分析了支撑间厚比、翼缘和腹板宽厚比及纤维角度对GFRP约束构件与内芯相互作用特征的影响规律,并给出了合理取值;通过算例分析,验证了该设计方法的可靠性.结果表明:H型钢内芯依次发生翼缘局部屈曲、绕弱轴整体屈曲、腹板局部屈曲和绕强轴整体屈曲,且整体屈曲模态较低,而局部屈曲模态较高;间厚比和宽厚比均会影响内芯的屈曲模态发展,进而改变约束构件的受力状态,间厚比宜为0.125 0~0.50,宽厚比宜小于6.29;GFRP约束构件主应力方向接近45°,为充分发挥纤维纵向承载能力,纤维宜按45°相互垂直交叉布置.

APP-MCA-CFA三元复配阻燃体系改性环氧树脂基玻璃纤维复合材料及性能研究

首次以聚磷酸铵(APP)为酸源和主阻燃剂,以高氮含量的三聚氰胺氰尿酸盐(MCA)为气源,以大分子型三嗪成炭剂(CFA)为炭源,组成APP-MCA-CFA三元复配阻燃剂体系。将其用于环氧树脂体系的阻燃改性,通过极限氧指数(LOI)、垂直燃烧等级、锥形量热、扫描电镜(SEM)、热失重分析(TG)和动态力学分析(DMA)等实验分析了它们之间的协同效应。结果表明:与单独使用APP阻燃剂相比,三元复配阻燃剂体系(20%APP-5%MCA-5%CFA,均为质量分数)表现出显著的协同阻燃效应,LOI值提升至62.0%,热释放速率峰值(PHRR)降低至401kW/m^(2),总热释放量(THR)下降至37.3MW/m^(2)。成炭分析结果表明,APP-MCA-CFA三元复配阻燃剂体系的引入使环氧树脂在高温下形成孔洞直径约5μm的形貌均一且规整的微米级膨胀炭层。DMA实验表明MCA和CFA可以通过粒子表面的胺基参与环氧固化反应,提高环氧固化交联密度,在一定程度抵消APP阻燃剂粉体加入导致的环氧机械性能下降。APP-MCA-CFA三元复配阻燃体系可用于环氧树脂基玻璃纤维复合材料的阻燃改性,垂直燃烧等级提升至UL-94 V0级,LOI值提升至66.3%。该研究为开发综合性能优异的阻燃环氧树脂基复合体系提供了一种简单易行的途径。

玻纤网覆盖下不同外墙保温材料火灾行为研究

为探究玻璃纤维网对热固性、热塑性外墙保温材料燃烧性能的影响,采用锥型量热仪进行燃烧实验研究,并对燃烧产生的各项参数进行分析。结果表明,玻璃纤维网会增大保温板材的点燃时间、热释放速率、生烟速率等相关参数。热固性材料的部分火灾行为受玻璃纤维网的影响较为明显,但在引燃性和火灾传播性能方面所受影响较小。热塑性材料中,玻璃纤维网对于XPS的引燃性、释热性、火灾传播性能及EPS的生烟性影响较大。玻璃纤维网使PUF、EPS的火灾增长指数小幅度降低,有抑制火焰蔓延的作用。

玻璃纤维/环氧树脂/不锈钢网复合材料性能研究

为研究金属网厚度、金属网粒度、上层预浸料厚度和铺层角度对复合材料力学性能的影响。制备了1.8 mm厚度的9组玻璃纤维/环氧树脂/不锈钢网复合材料,对其进行正交试验仿真分析,并与试验结果对比。结果表明:仿真与试验的最大偏差为4.36%,证明仿真结果可靠。当金属网厚度为0.4 mm,粒度为590μm,上层预浸料厚度为0.9 mm,铺层角度为0°时力学性能最优。

PP复合材料的性能研究

通过添加改性碳酸钙、POE、玻璃纤维、碳纤维研究其对PP复合材料性能的影响。研究表明:随着改性CaCO3含量的逐渐增加,PP复合材料的拉伸强度和冲击强度呈先增后减的趋势,改性CaCO3添加量为2%(wt.)时,拉伸强度为23.7MPa,冲击强度为17kJ·m^(-2);随着POE添加量的增加,复合材料的拉伸强度和弯曲模量降低,冲击强度增大,当POE添加量超过17%(wt.)时,冲击强度增幅减缓,综合力学性能及经济性,确定POE的添加量为17%~20%(wt.);添加玻璃纤维后,复合材料的拉伸强度、弯曲模量是增加的,冲击强度明显下降,但当玻璃纤维添加量为10%(wt.)以上,复合材料的拉伸强度和弯曲模量是逐渐增大的,冲击强度明显下降。通过复合材料冲击断面SEM表征发现:断面粗糙,有较多的片状结构,部分可见明显的“拉丝”形态,是典型的韧性断裂特征;玻璃纤维和碳纤维集束在树脂基体中随机取向分布,形成了足够的骨架网络,起到增强增韧作用。

无碱玻璃熔体表面张力的研究与应用

基于玻璃熔体表面张力测试技术,研究玻璃纤维行业中,典型无碱配方玻璃(E玻璃)在高温液体状态下(即玻璃液)的熔体表面张力。在此基础上,结合无碱玻璃熔体的粘度性能,对其应用进行探究。结果表明:玻璃纤维行业中,CaO-B_(2)O_(3)-SiO_(2)-Al_(2)O_(3)无碱玻璃,在1200~1500℃时,熔体的表面张力随着温度的升高而增大,有着近似线性的关系;等质量分数的B2O3替代CaO时,无碱玻璃熔体的表面张力减小,同时对温度的变化也更加敏感;对于玻璃纤维用典型无碱玻璃,其熔体可纺性指标k(表面张力γ与黏度η的比值)在2.4~10.4 mm/s范围内。

玻璃纤维短切纱质量影响因素探索

为提高玻璃纤维短切纱产品质量,采用控制变量法从玻纤原丝质量、生产设备和人员控制3个方面开展实验,以翻包毛羽量作为短切纱质量评价标准,探究不同方面对产品质量的影响。通过研究,提高玻璃纤维短切纱产品质量需要:在合理范围内保证纱团含水,提高可燃物含量,及时更换刀片、清理除尘器,采用小孔径筛网,控制升温保障产品烘制充分。

退役风机叶片的回收方法分析探讨

本文对退役风机叶片的回收方法进行了调研分析。对风机叶片的回收技术进行了阐述,主要包括填埋、焚烧、直接重复利用、水泥窑协同处理、机械回收、热回收(热解法、流化床法和微波法)和化学回收。对各回收技术的技术现状进行分析探讨,目前具有商业化潜力的仅有机械回收法和热解法。

玻璃纤维和膨胀剂增强混凝土轴压性能试验研究

海水海砂混凝土的开发与应用可有效降低生产混凝土的自然资源利用,从而保护生态环境。添加玻璃纤维和膨胀剂可以通过控制裂纹发展和降低孔隙率来提高混凝土的韧性和密实度。本文以玻璃纤维和膨胀剂掺量为控制变量,设计了7组混凝土配合比,对玻璃纤维和膨胀剂增强海水海砂混凝土的轴压性能进行了研究。研究发现,混凝土的破坏形态与玻璃纤维和膨胀剂掺量相关性较大。玻璃纤维和膨胀剂的掺入能提高海水海砂混凝土的抗压强度,提升幅度在4%~7%之间。此外,玻璃纤维和膨胀剂的掺入对海水海砂混凝土的弹性模量没有明显的影响。