Glass Filaments Research Articles

Characterization of the dynamic friction of woven fabrics: Experimental methods and benchmark results

A benchmark exercise was conducted to compare various friction test set-ups with respect to the measured coefficients of friction. The friction was determined between Twintex®PP, a fabric of commingled yarns of glass and polypropylene filaments, and a metal surface. The same material was supplied to all benchmark participants and the test conditions were prescribed, making the used set-up the most important variable among the laboratories. Tests at ambient temperature as well as tests above the melting point of polypropylene are part of the benchmark, in order to determine both the dry and hydrodynamic friction characteristics. The dependency on sliding velocity, average pressure and temperature was investigated. Systematic differences are observed between the measurements obtained by the different set-ups, which are discussed and related to design characteristics of the devices. The values obtained in this benchmark are comparable and may serve as a reference to evaluate other friction set-ups. The paper concludes with guidelines for the design of a friction tester.

The Design and Weaving of Glass Filament Spacer Fabric

Glass filament reinforced composite materials have become an indispensable material in national economic construction. The main purpose of this project is to produce the spacer fabric adopting glass filament through changing weaving process. First glass filaments were treated with epoxy resin to prevent from its low bending rigidity. Second ground warps and binding warps were separately warped and double warp beams were used in the weaving. At the shed crossing point the height of heald frames was different between the top layer and down layer warps, then the drafting sequence of the top layer of warps, the down layer of warps and binding warps were adjusted. The cotton yarns were chosen as the selvage warps which have good wear resistance and uniform tension. The long and short beat–up method was used. Eventually 3cm thickness of glass filament spacer fabric is achieved. It is hoped that this work will provide meaningful help to the development of glass filament spacer fabric.

Calculation of the Loads on Composite Materials Formed by Winding

To make composites reinforced with differently structured windings of glass filaments, the stresses in the filaments of the finished composite are calculated theoretically with allowance for the type of winding that is used. The mutual locations of the filaments within the volume of the composite that is being formed need to be taken into account when calculating the stresses in them. The number of filaments in the composite and extent to which the winding’s structure is closed should be calculated prior to calculating the stresses.

Skin irritation to glass wool or continuous glass filaments as observed by a patch test among human Japanese volunteers.

Glass wool and continuous glass filaments have been used in industry. We examined the irritability of those among Japanese. A patch test was performed on 43 volunteers for the followings: glass wool for non-residential use with and without a urea-modified phenolic resin binder, that for residential use with and without the binder, and continuous glass filaments with diameters of 4, 7, 9, and 13 µm. Materials were applied to an upper arm of each volunteer for 24 h. The skin was observed at 1 and 24 h after the removal. At 1 h after removal, slight erythema was observed on the skin of a woman after the exposure to glass wool for residential use without the binder. Erythema was observed on the skin of another woman at 1 h after a 24-h exposure to glass wool for non-residential use without the binder. There were no reactions at 24 h after the removal. The low reactions in the patch test suggested that the irritability caused by glass wool, irrespective of a resin component, could be induced mechanically, and that the irritability caused by continuous glass filaments with resin could be slight and either mechanical or chemical.

Intrinsic Safety Factors for Glass & Carbon Fibre Composite Filament Wound Structures

The determination of intrinsic safety factors for glass and carbon fibre unidirectional composites and filament wound internally pressurised structures, is described. In such structures the fibres are placed on geodesic paths and the pressure induces tensile forces in them. The fibres ensure the strength of the composite and must break for it to fail. Failure is seen in such structures, to depend mainly on the accumulation of fibre breaks. These are initially randomly distributed but become critical when clusters of breaks develop. Long term behaviour of carbon fibre composites is controlled by the viscoelastic relaxation of the matrix around breaks, which can lead to further delayed fibre breaks. Failure in glass fibre structures can additionally be induced by stress corrosion of the glass fibres. This process does not seem to occur with carbon fibres and as the latter are increasingly used in critical structures emphasis is given to them. Until the development of clusters of fibre breaks, in a filament wound structure, no macroscopic changes in the composite behaviour are evident so that failure occurs in a sudden death manner. Multi-scale simulation, taking into account the characteristics of the composite components and scaling up their behaviour under load, accurately describes the overall behaviour of the composite structure. This approach not only allows the behaviour to be described, as a function of time, but also calculates the scatter which will occur in the behaviour of the structure. This allows the intrinsic safety factors of the composite structure to be quantified.

Processing and flexural properties of surface reinforced flat pressed WPC panels

While extrusion and injection molding are the common technologies to produce wood-plastic composites (WPC), pressing may be an alternative, particularly when flat products are striven for. In this study, flat pressed WPC panels were surface-reinforced by two different types of thermoplastic face layers to improve flexural properties. The two face materials applied were a commingled fabric made of glass and polypropylene filaments (TWINTEX®) and a glass fabric reinforced polypropylene laminate (S-TEX®). Combination of face layers and WPC panels was achieved in a single and a two stage flat pressing process. Besides studying the effects of reinforcing material and number of process stages, the influence on flexural properties of the reinforced panels was identified. Unreinforced WPC panels were tested for comparison. The reinforced WPC panels exhibited greatly improved flexural properties, with MOE (MOR) values up to nearly 10,000 N/mm² (90 N/mm²).

Comparison of tensile properties of co-woven-knitted and multi-layered biaxial weft-knitted fabric reinforced composites

The co-woven-knitted (CWK) fabric and multi-layered biaxial weft-knitted (MBWK) fabric were produced using glass filaments as warp and weft inserted yarns and high tenacity polyester as stitched yarns. Vacuum Assisted Resin Transfer Molding process was used to produce the two composites. Tensile tests were carried out in the course, wale and slanting directions of the composites, respectively. Specific stress-strain curves and failure modes of the two composites were investigated and compared. Results reveal that tensile strengths and elastic moduli of the two composites in the course and wale directions are better than those in the bias direction. All the composite samples fracture in the brittle damage mode. Furthermore, the buckling due to different inserted ways of the warp and weft yarns has a few influences on the tensile properties of the two composites. This research may lay a foundation for the establishment of the process windows for the co-woven-knitted reinforced composites.

Preservation of telescopic bonding upon aging of bundled glass filaments by treatments with nano-particles

The potential for enhancing the durability performance of AR-glass — cement composites by means of incorporation of nano-particles in between the filaments in the yarn was studied. The paper presents the results of bond studies to characterize the nature of pull-out and the potential of preservation of the telescopic mode of failure. The yarn–cement matrix bond was found to decline upon aging and relations between this decline and reduction in the tensile strength of the composite could be established. The incorporation of nano-particles into the yarn by impregnation with a slurry containing these nano-particles could provide an effective means for a drastic improvement in the aging performance of AR-glass textile reinforced composites. Complete preservation upon aging of the pull-out characteristics could be obtained only when inducing an effect which is in addition to the physical presence of the nano-particles between the filaments.

Mechanical behaviour of carbon and glass filament yarns under high temperatures for composite applications

Fibre composites made with high-performance fibres composed of carbon and glass are used in numerous technical applications due to their physical and chemical properties, which are valued for their high strength capabilities. Also in the construction field, textile fibres are gaining importance as reinforcements for concrete and are being coated to improve their bonding performance. Under thermal loads, these yarns show structural alterations in their mechanical properties. The following paper is concerned with experimental investigations of the strength and elasticity of commonly used textile fibres under high temperatures with the goal of specifying the materials’ parameters relative to thermal conditions.

Capturing the effect of initial concentrations on the drying kinetics of high solids milk using reaction engineering approach

Many industries practice trial and error method to achieve optimum process conditions for desired powdered product quality in the event of fluctuations in the feed concentration, which happens more often than not and leads to wastage in product, time and energy. This paper presents the thermal-moisture drying histories for skim milk droplets from 37 to 43 wt%, in order to study the effects of initial solids variation on drying kinetics. The changes in droplet temperature, diameter and moisture content during drying were directly obtained using a glass filament single droplet drying technique. The experimental data were interpreted using the reaction engineering approach, an activation energy-based model where drying is dependent on vapour density gradient at the material–air interface. It was shown that the drying profile was sensitive to the initial solid content of droplet at this range of concentrations, since attempts to apply a single master activation energy curve to describe drying kinetics yielded less accurate predictions. The model’s predictions were validated experimentally for both moisture content and temperature profiles during drying. The proposed approach enables drying histories of high solids milk to be modelled more accurately and could potentially assist in evaluating process design for high solids milk drying.

Ultrabroad supercontinuum generation through filamentation in tellurite glass

Although soft glass such as tellurite or chalcogenide glass is transparent in the range of 3–6 μm, fiber made of it is difficult to generate as a supercontinuum (SC) to that range because of the high loss, the wavelength limit of the pump source, and the challenges in light-coupling. To circumvent these problems, we developed an SC light source by using tellurite bulk glass through filamentation. For this scheme, the optical path length in the glass is very short due to the adopted high pump power, so the negative influence of material loss is reduced greatly. The light-coupling is straightforward, and the coupling efficiency is high. The bulk glass for SC generation is cheap, and can be fabricated easily. We have shown that under suitable pump conditions, the SC generation by filamentation can cover from visible to 6 μm. It is the broadest SC generation by tellurite (including glass and fiber). For suitable pump conditions, the glass was free of optical breakdown. If the interface reflections were deducted, the SC conversion efficiency was 87%; the SC conversion efficiency was stable. To the best of our knowledge, this is the first report on filamentation in tellurite glass which has a comparatively small bandgap.

Single Droplet Drying Technique to Study Drying Kinetics Measurement and Particle Functionality: A Review

Advances in the study of the rate processes in spray drying have helped improve product quality. Single droplet drying (SDD) is an established method for monitoring the drying kinetics and morphological changes of an isolated droplet under a controlled drying environment, mimicking the droplet convective drying process in spray drying. To enhance particle quality requires understanding of both the particle formation process and knowledge of how different particle properties are affected by the drying conditions used. The latest development in the SDD technique enables evaluation of these aspects by incorporating a dissolution test in the drying experiment. The experiment is realized by attaching a solvent droplet to a dried/semi-dried single particle in situ and then video-recording the resultant morphological changes. Some of the particle (e.g., crystallinity) properties obtained under different drying conditions can be modelled using the measured droplet drying kinetics. This paper reviews the applications of SDD experiments in measuring the drying kinetics and monitoring the droplet morphological changes during drying. Some examples of extending the glass filament SDD technique to examine particle functionalities are discussed. SDD experiments are shown to be a powerful tool for particle engineering due to its ability to study both the external convective transport process of a single droplet and to understand the different particle functionalities of the resultant single dried particle.

Study on the Performance of Woven Basalt Filament Diaphragm Fabric

The tensile properties of basalt filament were measured and compared with these of E-glass fiber. The plain basalt filament fabric (PBFF), twill basalt filament fabric (TBFF) and plain glass filament fabric (PGFF) that woven by the CSW-03 loom under the same fabric density were used to make diaphragm preforms. Thermoplastic acrylic resin was chosen to coat on the diaphragm preforms using Werner Mathis AG LTF97885 coating machine when the coating thickness is 0.1mm, curing time is 30min. Tensile test was carried out on the diaphragm performs and coating diaphragm by 3380Instron advanced testing machine. Effect of curing temperature (<200°C) on tensile properties of diaphragm materials was investigated. The coating PBFF and the coating TBFF were compared to analysis the effect of organization structures on the elastic modulus. The results indicated that the best elastic modulus of diaphragm materials was achieved when the curing temperature was 120°C. PBFF is more suitable for diaphragm materials than PGFF and TBFF. The proposed curing temperature for making diaphragm with different elastic modulus ranges from 100°C to 140°C.

Glass Fiber‐Reinforced Composites: From Formulation to Application

Glass fiber‐reinforced composite materials are attractive because their properties can be tailored to meet the specific needs of a variety of applications. The mechanical and thermal properties of a composite generally follow the rule of mixtures. As glass fiber is the major component at 70–75% by weight (50–60% by volume), selection of the correct glass product is critical. Glass fiber reinforcement is available in many forms, including continuous rovings, chopped fibers, fabrics, and nonwoven mats. In addition to form, selection of a reinforcement product involves choosing a glass type, chemistry on the glass (sizing) filament diameter, and tex. Glass formulation or type governs mechanical, thermal, and corrosion properties, whereas sizing protects the glass during handling and gives compatibility with the resin system. Filament diameter and strand tex are chosen to balance physical properties and manufacturing efficiency. A significant amount of tensile strength, up to 50%, may be lost from a pristine single filament to a multi‐filament roving. To minimize this degradation, the utmost care and consistency must be exercised in the fiber forming process. This, coupled with selection of a high‐performance glass formulation, enables use of composites in highly demanding applications, such as pressure vessels and ballistic armor.

Early prediction of the failure of textile-reinforced thermoplastic composites using hybrid yarns

In this study, the manufacturing of core-sheath hybrid yarns consisting of steel fibres and glass filament yarn (GFY) using a friction spinning technique and their usability for failure prediction in composites is reported. With the DREF-2000 friction spinning technique, it is possible to manufacture hybrid yarns having a core-sheath structure. Steel fibres are used as the sheath and the GFY is used as the core of the yarns. These hybrid yarns are embedded between two layers of glass/polypropylene (GF/PP)-based knitted fabric composites. By varying the steel fibre content, it is possible to adjust the initial resistance as well as the sensitivity of the hybrid yarns to measure the interphase strain in the thermoplastic-based knit composite during tensile loading. The hybrid yarns with lower steel fibre content are found to be more sensitive in the prediction of the early damage in the composite. By performing a quasi-static and gradual increase of loading during the tensile tests, it is possible to identify the critical load for the composite. The before mentioned hybrid yarns show their suitability for the structural health monitoring and the potential to be integrated into thermoplastic-based composites by textile processing.

Effect of nanoclay particles on mold‐filling performance in composites made via resin infusion process

AbstractThis study investigates the effect of 3 and 5 wt% nanoclay (Cloisite 30B) addition on mold filling time and performance of continuous glass filament mat reinforced unsaturated polyester (UP) resin composites made by vacuum infusion process. X‐ray diffraction and transmission electron microscopy analysis as well as viscosity change in liquid state resin confirmed intercalation and exfoliation of the nanoclay in the resin system. The result shows mold filling time increase of 3 and 2.4 times for the samples containing 3 and 5 wt% nanoclay, respectively, compared with nanoclay‐free sample. This increase in mold filling time is directly attributed to the increase in resin viscosity. Filtration of nanoclay particles were observed in the resin flow direction. Result showed 8 and 14% filtration of nanoclay in flow direction for the samples with 3 and 5 wt% nanoclay content, respectively. Nanoclay containing specimens prepared from near resin entry port area showed relatively higher flexural and tensile modulus and as well as strength compared to specimens prepared from area close to vacuum port area. The result showed best performance for 3 wt% nanoclay containing specimen. However, impact strength decreased about 6.1 and 10.8% for 3 and 5% nanoclay, respectively. POLYM. COMPOS., 2012. © 2012 Society of Plastics Engineers

Product stewardship and science: Safe manufacture and use of fiber glass

This paper describes a proactive product stewardship program for glass fibers. That effort included epidemiological studies of workers, establishment of stringent workplace exposure limits, liaison with customers on safe use of products and, most importantly, a research program to evaluate the safety of existing glass fiber products and guide development of new even safer products. Chronic inhalation exposure bioassays were conducted with rodents and hamsters. Amosite and crocidolite asbestos produced respiratory tract cancers as did exposure to “biopersistent” synthetic vitreous fibers. “less biopersistent” glass fibers did not cause respiratory tract cancers. Corollary studies demonstrated the role of slow fiber dissolution rates and biopersistence in cancer induction. These results guided development of safer glass fiber products and have been used in Europe to regulate fibers and by IARC and NTP in classifying fibers. IARC concluded special purpose fibers and refractory ceramic fibers are “possibly carcinogenic to humans” and insulation glass wool, continuous glass filament, rock wool and slag wool are “not classifiable as to their carcinogenicity to human.” The NTP’s 12th report on carcinogens lists “Certain Glass Wool Fibers (Inhalable)” as “reasonably anticipated to be a human carcinogen.” “Certain” in the descriptor refers to “biopersistent” glass fibers and excludes “less biopersistent” glass fibers.

A Process For Treating Woven Glass Cloth

Woven fiberglass cloths are by far the most common reinforcement material used in PCBs. The glass yarns are coated with silane-based coupling agents designed to improve the interfacial adhesion between the glass filaments and the resin matrix. Poor glass surface wetting and weak adhesion of the resin to the yarn are the major root causes for a number of PCB failure mechanisms. Time-of-Flight Secondary Ion Mass Spectrometry (ToF-SIMS) was utilized in order to garner a better understanding of the observed poor glass surface wetting and weak adhesion of the resin to the yarn following standard thermolysis processes during preparation of the glass cloth. A solvent-based process was demonstrated to yield excellent retention of the glass cloth physical properties while simultaneously providing a clean glass surface for bonding of the coupling agent. ToF-SIMS verified the presence of silane at the cloth surface. The results were used to derive recommendations for the glass cloth suppliers in order to improve the efficiency of their silanation process.

Flat-knitted innovative three-dimensional spacer fabrics: a competitive solution for lightweight composite applications

Flat-knitted spacer fabrics offer a strong potential for complex shape preforms, which could be used to manufacture composites with reduced waste and shorter production times. A reinforced spacer fabric made of individual surface layers and joined with connecting layers shows improved mechanical properties for lightweight applications, such as textile-based sandwich preforms. We report the development of flat-knitted multi-layered innovative three-dimensional (3D) spacer fabrics from hybrid yarns consisting of glass and polypropylene filaments. Moreover, for structural health monitoring of composites, sensor networks could be created into a 3D spacer fabric structure in a single processing step through innovative integration of functional yarns.

Quantitative measurement of filament ruptures of a multi-filament AR-glass yarn embedded in concrete

This paper presents a new digital image analysis method for quantitative and online measurement of filament ruptures of a multi-filament AR-glass yarn embedded in concrete during pullout loading. The proposed method was developed based on an existing test method for determination of filament ruptures occurring during the loading called failure investigation using light transmitting (FILT) property test, which uses light transmitting property of AR-glass fibers. Artificial light is exposed on the glass filaments from one side of the specimen. On the opposite side, a charge-coupled device (CCD) camera with an optical microscope records the lighted filament cross-sections in the yarn. To detect filament ruptures during pullout loading, the light intensity time history of every individual filament of the yarn was investigated by a digital image analysis method. The number of broken filaments was also investigated by acoustic emission (AE) analysis simultaneously and the results were compared. Test results showed that the light transmitting property of AR-glass can be used to identify filament ruptures and it is possible to determine the failure of the filaments during pullout in the cross-section quantitatively by the improved FILT test.