Properties Of Glass Fiber Reinforced Composites Research Articles

Evaluation of mechanical properties of glass fiber-reinforced composites depending on length and structural anisotropy

Recently, as the size of liquid natural gas (LNG) carriers has dramatically increased, applied force in the LNG Cargo Containment System (CCS) has also increased. However, the existing E-glass fiber-reinforced composite, which plays an important role to prevent accident as secondary barrier induced LNG leakage, has remained unchanged. In case of in-situ length of the composite in membrane type of MARK-III LNG CCS, it is continuously installed as a prolonged structure by using automatic bonding machine (ABM). From this point of view, it should be considered that the length effect of the mechanical properties to represent an infinitely long distance for structural reliability. Fracture strength of a brittle material, such as glass fiber components, is generally not constant because of the variable quantity and distribution of imperfections throughout the composites. In this study, 2-parameters of Weibull distribution were derived to standardize the widely dispersed fracture strengths under the quasi-static tensile test condition. As a result of the experiments by length, the standardized failure strength associated with scale parameter (63.2% probability of failure over all the repeated tests) in the Weibull distribution increases until it reaches a specific length at 250 mm, at which point it stops rising and converges to a constant value. This tendency indicates that material properties at the specific length will be reliable for mechanical evaluation of the composites under the infinitely prolonged condition.

The Effects of Some Phosphorus-Containing Fire Retardants on the Properties of Glass Fibre-Reinforced Composite Laminates Made from Blends of Unsaturated Polyester and Phenolic Resins

This study investigated the effects of phosphorus fire retardants (FRs) in matrices from co-cured blends of an unsaturated polyester (UP) with inherently fire-retardant phenolic resoles (PH) on the mechanical and flammability properties of resultant glass fibre-reinforced composites. Three different phenolic resoles with UP have been used: (i) an ethanol soluble (PH-S), (ii) an epoxy-functionalised (PH-Ep), and (iii) an allyl-functionalised resin (PH-Al) with two different phosphorus FRs: resorcinol bis (diphenyl phosphate) (RDP) and 9,10-dihydro-9-oxa-10-phosphaphenanthrene-10-oxide (DOPO). The flammabilities of the resultant composites were evaluated using cone calorimetry and the UL-94 test. Cone calorimetric results showed reductions in peak heat release rate (PHRR) and total heat released (THR) as expected compared to those of UP and respective UP/PH composite laminates without FRs. UL-94 tests results showed that while all composites had HB rating, FR containing samples self-extinguished after removal of the flame. The mechanical properties of the composites were evaluated using flexural, tensile and impact tests. All FRs reduced the mechanical properties, and the reduction in mechanical properties was more severe in UP/PH-S (least compatible blends) composites with FRs than in UP/PH-Al (most compatible blends) composites with FRs. Amongst the different composites, those from UP/PH-Al with DOPO showed the best fire retardancy with little deterioration of mechanical performance.

Mechanical Performance of Knitted Hollow Composites from Recycled Cotton and Glass Fibers for Packaging Applications

This research deals with the development of knitted hollow composites from recycled cotton fibers (RCF) and glass fibers (GF). These knitted hollow composites can be used for packaging of heavy weight products and components in aircrafts, marine crafts, automobiles, civil infrastructure, etc. They can also be used in medical prosthesis or in sports equipment. Glass fiber-based hollow composites can be used as an alternative to steel or wooden construction materials for interior applications. Developed composite samples were subjected to hardness, compression, flexural, and impact testing. Recycled cotton fiber, which is a waste material from industrial processes, was chosen as an ecofriendly alternative to cardboard-based packaging material. The desired mechanical performance of knitted hollow composites was achieved by changing the tube diameter and/or thickness. Glass fiber-reinforced knitted hollow composites were compared with RC fiber composites. They exhibited substantially higher compression strength as compared to cotton fiber-reinforced composites based on the fiber tensile strength. However, RC fiber-reinforced hollow composites showed higher compression modulus as compared to glass fiber-based composites due to much lower deformation during compression loading. Compression strength of both RCF- and GF-reinforced hollow composites decreases with increasing tube diameter. The RCF-based hollow composites were further compared with double-layered cardboard packaging material of similar thickness. It was observed that cotton-fiber-reinforced composites show higher compression strength, as well as compression modulus, as compared to the cardboard material of similar thickness. No brittle failure was observed during the flexural test, and samples with smaller tube diameter exhibited higher stiffness. The flexural properties of glass fiber-reinforced composites were compared with RCF composites. It was observed that GF composites exhibit superior flexural properties as compared to the cotton fiber-based samples. Flexural strength of RC fiber-reinforced hollow composites was also compared to that of cardboard packaging material. The composites from recycled cotton fibers showed substantially higher flexural stiffness as compared to double-layered cardboard material. Impact energy absorption was measured for GF and RCF composites, as well as cardboard material. All GF-reinforced composites exhibited higher absorption of impact energy as compared to RCF-based samples. Significant increase in absorption of impact energy was achieved by the specimens with higher tube thickness in the case of both types of reinforcing fibers. By comparing the impact performance of cotton fiber-based composites with cardboard packaging material, it was observed that the RC fiber-based hollow composites absorb much higher impact energy as compared to the cardboard-based packaging material. The current paper summarizes a comparative analysis of mechanical performance in the case of glass fiber-reinforced hollow composites vis-à-vis recycled cotton fiber-reinforced hollow composites. The use of recycled fibers is a positive step in the direction of ecofriendly materials and waste utilization. Their performance is compared with commercial packaging material for a possible replacement and reducing burden on the environment.

Fabrication and Properties of Glass Fiber-Reinforced Composites Using Polyimide Prepregs with Inorganic Nanofillers

Numerous studies have addressed the utilization of polyimide (PI) and silica for improving the properties of hybrid composites. However, the applicability of polyhedral oligomeric silsesquioxanes (POSSs) has not been elucidated. Herein, inorganic nanoparticles containing poly(amic acid)s (PAAs) were synthesized; further, glass fibers (GFs) were impregnated with PAA solutions to obtain PAA prepregs. PI-based fiber-reinforced composites were manufactured with the prepregs by using the hand lay-up technique. The morphology and the thermal, mechanical, and dielectric properties of the composites with inorganic nanoparticles were analyzed to investigate the effects of inorganic additives. The addition of inorganic particles were observed to primarily improve the properties of the PI-based fiber-reinforced composites as compared to those of the neat PI composites. While this improvement was limited in the case of the addition of POSSs owing to the aggregation and a poor interaction with the PI matrix, silica-containing composites exhibited superior thermal, mechanical, and particularly dielectric properties as compared to those of the composites containing POSSs; this was because of the increase in the dispersion of silica nanoparticles that was caused by a silane coupling agent (SCA). The results obtained in this study can be utilized for applications pertaining to the design of PI composites with high mechanical strengths, enhanced thermal stabilities, and low dielectric constants.

The effect of graphene presence in flame retarded epoxy resin matrix on the mechanical and flammability properties of glass fiber-reinforced composites

The effect of adding graphene in epoxy containing either an additive (MP) or reactive-type (DOPO) flame retardant on the thermal, mechanical and flammability properties of glass fiber-reinforced epoxy composites was investigated using thermal analysis; flexural, impact, tensile tests; cone calorimetry and UL-94 techniques. The addition of MP or DOPO to epoxy had a thermal destabilization effect below 400°C, but led to higher char yield at higher temperatures. The inclusion of 10wt% flame retardants slightly decreased the mechanical behavior, which was attributed to the poor interfacial interactions in case of MP or the decreased cross-linking density in case of DOPO flame retarded resin. The additional graphene presence increased flexural and impact properties, but slightly decreased tensile performance. Adding graphene further decreased the PHRR, THR and burning rate due to its good barrier effect. The improved fire retardancy was mainly attributed to the reduced release of the combustible gas products.

Influence of silane coupling agents on the surface energetics of glass fibers and mechanical interfacial properties of glass fiber-reinforced composites

The effect of various silane coupling agents on glass fiber surfaces has been studied in terms of the surface energetics of fibers and the mechanical interfacial properties of composites. γ-Methacryloxypropyltrimethoxysilane (MPS), γ-aminopropyltriethoxysilane (APS), and γ-glycidoxypropyltrimethoxysilane (GPS) were used for the surface treatment of glass fibers. From contact angle measurements based on the wicking rate of a test liquid, it was observed that silane treatment of glass fiber led to an increase in the surface free energy, mainly due to the increase of its specific (or polar) component. Also, for the glass fiber-reinforced unsaturated polyester matrix system, a constant linear relationship was observed in both the interlaminar shear strength (ILSS) and the critical stress intensity factor (KIC) with the specific component, γS SP, of the surface free energy. This shows that the hydrogen bonding, which is one of the specific components of the surface free energy, between the glass fibers and coupling agents plays an important role in improving the degree of adhesion at the interfaces of composites.