Multilayer interlocked woven fabrics: simulation of RTM mold filling operation with preform permeability properties

The simulation of resin flow during the resin transfer molding (RTM) process through multilayered textile fabric of known permeability and porosity has been attempted in this study. A simple three-dimensional computational fluid dynamics (CFD) simulation model has been developed and the results of the simulation are compared with the experimental RTM resin flow through multilayer interlocked woven structures. A multiphase simulation model is observed to reasonably predict the time for RTM mold filling. Fabric structural influence in terms of an Interlacement Index (I) has significant influence on the resin flow behaviour of the multilayered preform. A higher I of the preform means a longer time to fill the mold in both the experimental and simulated results. Images of the simulated flow front has been compared with the experimental results and it is observed that not only the mold filling time, but also the area of resin flow in the multilayer perform, is influenced by a fabric structural factor, I.(undefined

Influence of preform interlacement on the low velocity impact behavior of multilayer textile composites

Impact property of composite material is influenced not only by the type of fiber/matrix, but also by the woven structure of the reinforcement. Presence of 3D fibers in reinforcement is reported to enhance the performance of textile composites in an impact event. This article attempts to study the influence of interlacements in the multilayer woven interlocked 3D structures on the impact properties of the composite material reinforced with them. Low velocity impact testing was carried out on an instrumented drop weight impact tester to obtain loadelongation- time plots of the impact event. It has been observed that increased interlacement in the structure improves the impact resistance of the multilayer textile composites. Further, damage area maps have been developed to understand and analyze the interlacement effect on the impact behavior

Compression and permeability properties of multiaxial warp-knit preforms

Textile preform properties such as compression and permeability greatly influence the quality of the composite material and its performance, particularly those prepared by injection moulding techniques like resin transfer moulding (RTM). Directionally oriented warp-knit biaxial, triaxial and quadraxial glass fabrics have been studied for these preform properties. The preform compression properties were tested on the universal testing machine up to a maximum force of 250 N. The rate of test liquid flow through these preforms has been measured using the horizontalwicking test method. The permeability of these preforms has been analyzed based on the liquid flow-rate data. Fibre orientation and fibre volume fraction of the preforms are observed to be important factors influencing these preform properties

Soil-release behaviour of polyester fabrics after chemical modification with polyethylene glycol

The ease of cleaning the fibers depends, among other characteristics, on their hydrophilicity. Hydrophilic fibers are easy-wash materials but hydrophobic fibers are difficult to clean due to their higher water-repellent surfaces. This type of surfaces, like polyester (PET), produce an accumulation of electrostatic charges that adsorbs and retain dirt. Thus, the polyester soil-release properties can be increased by finishing processes that improve fiber hydrophilicity [1, 2]. In present study, PET fabric modification was described by using polyethylene glycol (PEG) and dimetilol dihidroxy ethylene urea chemically modified resin. Briefly, the modification process was carried out in two steps, one to hydrolyse the polyester and create hydroxyl and carboxylic acid groups on surface and the other to crosslink the PEG chains. The resulting materials were characterized by contact angle, DSC and FTIR- ATR methods. Additionally, the soil release behavior and mechanical properties of modified PET were evaluated. For the best process conditions, the resulted PET presented 0º contact angle, stain release grade of 5 and acceptable mechanical performance.Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136.info:eu-repo/semantics/publishedVersio

Tribological properties of the directionally oriented warp knit GFRP composites

Recently, directionally oriented warp knit structures have gained prominence as reinforcements in composite materials due to their superior isotropic behaviour compared to other types of textile reinforcements. In the present study, composites prepared from four types of directionally oriented warp knit glass preforms with three different thermoset resins have been considered for the tribological characterisation. The tribological tests have been conducted on a reciprocating sliding test rig with ball-on-plate configuration. The tests were conducted in dry (unlubricated) and wet (aqueous) conditions at a fixed applied load (100 N) by varying the sliding distance. E-glass warp knitted preforms were used for the study including biaxial, biaxial non-woven, triaxial and quadraxial fabrics. The matrices were three different thermoset resins namely polyester, vinyl ester and epoxy resin. 13 14 15 16 17 18 19 The main aim of the study was to identify a composite having the best tribological performance, with regard to types of preform and matrix resin. Moreover, the results obtained from the tests have been used to develop a wastage map for these composites, as a function of sliding distance and type of preform in order to have a clear understanding of the tribological process.Fundação para a Ciência e a Tecnologia (FCT

Modification of Poly(ethylene terephthalate) Fibre by Polymer Blending with Poly(butylene terephthalate) Fibre: Part I - Literature Review and Theoretical Predictions of Compatibility

177-180<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:"times="" roman";mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">Poly-blending of poly(ethylene terephthalate) with other polymers with a view to obtaining a compatible system is discussed. Poly(ethylene terephthalate )/poly(butylene terephthalate) is more compatible because of (i) a lesser difference in solubility parameter, (ii) a larger composition range for stability, and (iii) a closer DP in terms of reference volume, in comparison with the poly(ethylene terephthalate)/polyamide system.</span

Prediction of Viscosity for Blends of Nylop-6 with Different Molecular Weight Components

28-29<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:"times="" roman";mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">Of the various blending rules used for predicting the viscosity of polymer blends of different molecular weights, Hashin's lower bound rule has been found to predict viscosity closely matching with the experimental data in the case of blends of Nylon-6 samples of molecular weights 29,000 and 55,000.</span

Modification of poly( ethylene terephthalate) fibre by polymer blending with poly(butylene terephthalate) fibre: Part IV-deformation behaviour

59-62<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" "times="" new="" roman";mso-fareast-theme-font:minor-fareast;mso-hansi-theme-font:="" minor-latin;mso-bidi-font-family:"times="" roman";mso-ansi-language:en-us;="" mso-fareast-language:en-us;mso-bidi-language:ar-sa"="">The deformation behaviour of blended fibres prepared from poly(ethylene terephthalate) and 0-10% poly(butylene terephthalate) is influenced more by entanglement and phase segregation. Addition of 2-4% PBT improves the structural defects and modifies the properties due to higher entanglement as a result of strain induced crystallization. On the other hand, 94/6 PET/PBT fibre shows inferior properties, irrespective of the draw ratio used. 92/8 and 90/10 PET/PBT fibres show higher crystallinity as a result of phase segregation and nucleating effect of PBT.</span

Effect of compatibilizer on mechanical properties of chemically treated coir/polypropylene composite

155-162Composites of NaOH treated coir fibre and maleic anhydride functionalized polypropylene (MAHPP) with different formulations have been made by compression molding technique and the effect of compatibiliser on mechanical strength, flexural strength, and impact properties of the composites are measured and then compared with theoretically calculated values. It is observed that the tensile strength, tensile modulus, Izod impact strength and flexural strength of surface treated and MAPP coupling composite properties are enhanced significantly than the untreated one. This is due to better adhesion between fibre and matrix. This is also confirmed by SEM, interfacial shear strength or fibre pull-out tests and trans crystalline behavior of the composites constituents in the melt form

Modification of poly(ethylene terephthalate) fibre by polymer blending with poly(butylene terephthalate) fibre: Part VI-Annealing behaviour

100-103<span style="font-size:11.0pt;line-height:115%; font-family:" calibri","sans-serif";mso-ascii-theme-font:minor-latin;mso-fareast-font-family:="" calibri;mso-fareast-theme-font:minor-latin;mso-hansi-theme-font:minor-latin;="" mso-bidi-font-family:"times="" new="" roman";mso-ansi-language:en-us;mso-fareast-language:="" en-us;mso-bidi-language:ar-sa"="">The improvement in the properties of blended fibres prepared from poly(ethylene terephthalate) and 0-10% poly(butylene terephthalate) during annealing is influenced by chain entanglement and extent of phase segregation. The structural properties like crystallinity, birefringence and amorphous orientation of 98/2 PET/PBT blend fibre show minimum change due to chain entanglement resulting in better mechanical properties, 94/6 PET/PBT fibre shows maximum change in structural properties owing to phase segregation during annealing. The mechanical properties of 92/8 PET/PBT blend fibres deteriorate after annealing as a result of two-phase structure leading to higher incompatibility.</span