Polymer nanocomposites based on graphite nanoplatelets (GNPs): a review on thermal-electrical conductivity,mechanical and barrier properties

Journal of Materials Science - In this paper, graphite nanoplatelets (GNPs)-based polymer nanocomposites were reviewed. This review mainly discusses various synthesis techniques for making graphite...     

Dimensional stability of multiaxis 3D-woven carbon preforms

Multiaxis 3D-woven carbon preforms are fabricated using prototyped multiaxis weaving. The fabricated preform has structural instability at thickness. For this reason, the structural parameter and processing parameters were evaluated to make uniform preform and to understand the preform-process relations. The important process parameters are identified and described to enhance the preform and unit cell architecture. Also, preform structural parameters are analyzed in terms of fiber cross-section and fiber tow size, bias angle, and fiber waviness. The useful recommendation is also to make uniform multiaxis 3D-woven preform for composites.     

Developments of Multi-nanostitched 3D Carbon/epoxy Nanocomposites: Tensile/shear and Interlaminar Properties

Applied Composite Materials - Mechanical properties such as tensile, shear and interlaminar shear of multi-nanostitched three dimensional (3D) carbon/epoxy composites were studied. Introducing the...     

Warp and weft directional tensile properties of multistitched biaxial woven E-glass/polyester composites

The objective of this research work was to understand the warp and weft directional tensile properties of the two-dimensional multistitched multilayer E-glass/polyester woven composites. The warp and weft directional specific tensile strength and modulus of unstitched structure were higher than those of multistitched structures as stitching caused minor warp and weft yarn filament breakages. Contrarily, the specific tensile strains of unstitched structure were slightly lower than those of all multistitched structures. The stitching yarn type, the number of stitching directions, and the stitching density generally influenced the warp and weft directional tensile properties of multistitched E-glass/polyester woven composites. The failure of warp and weft directional multistitched woven E-glass/polyester composite structures was matrix breakages, and partial and complete yarn breakages in their surfaces. They had a local delamination in their cross-sections and the delamination did not propagate to the large areas due to multidirectional stitching. Also, the failure was confined at a narrow area and resulted in the catastrophic fiber breakages. The warp and weft directional specific damaged areas of multistitched structures, in particular four-directional stitching, were significantly lower than those of the unstitched structures. This indicated that the multistitching made the structures better damage-tolerance materials.     

Multiaxis three‐dimensional circular woven preforms – “radial crossing weaving” and “radial in–out weaving”: preliminary investigation of feasibility of weaving and methods

The aim of the study is to develop new preform structures and processes to use in the technical textile and composite industries. Multiaxis and orthogonal three‐dimensional (3D) circular woven preforms and weaving methods have been developed. The multiaxis structure has five yarn sets as (±)bias, axial, circumferential, and radial yarns whereas the orthogonal structure has three yarn sets, axial, circumferential, and radial yarns. Two weaving methods, radial crossing and radial in–out weaving were introduced to form the structures. An experimental rig was constructed to evaluate the methods. Basic process and structure parameters have been identified. The preliminary studies showed that the multiaxis 3D circular woven preforms and methods seemed feasible.     

Properties of yarn pull-out in para-aramid fabric structure and analysis by statistical model

The aim of this study is to analyze and determine the pull-out properties of para-aramid woven fabrics. Para-aramid Kevlar29® and Kevlar129® woven fabrics were used to conduct the pull-out tests. They have high and low fabric densities. A yarn pull-out fixture was developed to test various fabric sample dimensions. Data generated from single and multiple yarn pull-out tests in various dimensions of Kevlar29® and Kevlar129® woven fabrics included fabric pull-out forces, yarn crimp extensions in the fabrics and fabric displacements. The regression model showed that yarn pull-out forces depend on fabric density, fabric sample dimensions and the number of pulled ends in the fabric. Yarn crimp extensions depend on the crimp ratios of the fabric and fabric density. Fabric displacements depend on fabric sample dimensions and the number of pulled yarns.     

Fracture Toughness (Mode-I) of Para-Aramid/Phenolic Nano Preform Composites

The mode-I interlaminar toughness properties of nanostitched para-aramid/phenolic multiwall carbon nanotube composites were studied. The toughness strength of the stitched and stitched/nano composites demonstrated 40 fold and 38 fold (beam theory) increases compared to the base composites, respectively. It was found that stitching yarn type, especially prepreg para-aramid stitching yarn, was effective. On the other hand, the initiation and propagation of the G_IC values for stitched and stitched/nano composites were considerably deviated due to strengthening mechanism of the para-aramid stitch yarn in the transverse direction of the composite. The fracture toughness resistance to arrest crack propagation in the stitched/nano composite was mainly due to through-the-thickness stitching fiber bridging and pull-out, and was also due to warp and weft directional fiber bridging and multiwall carbon nanotubes. The results demonstrated that mainly stitching and some extent the nanotubes arrested the crack growth. Therefore, the stitched/nano and especially stitched para-aramid/phenolic composites showed a better damage resistance performance.     

Analysis and tensile characterization of flocked fabric after rubbing

In this study, the tensile properties of flocked fabric after rubbing were studied. A statistical method was used to analyze the generated data. For this purpose, woven fabric was used as a substrate and an acrylic adhesive was applied on this substrate to hold the polyamide flock fibers forming flocked fabrics. A rubbing test was applied in dry and wet forms to the flocked fabrics before and after washing. The tensile properties of these rubbed flocked fabrics were determined. The regression models developed in this study explain the relationship between rubbing and the tensile strength of the flocked fabrics. The results from this experiment could be used in the development of flocked fabric as seat covers for the automotive industry. The warp tensile strength of a flocked fabric is generally higher than its weft tensile strength due to its higher substrate density in the warp direction. Also, the weft tensile elongation of a flocked fabric is generally higher than its warp tensile elongation due to its higher crimp ratio in the weft direction. When the stroke number increases, the warp and weft directional tensile strength and the elongation of a flocked fabric generally decrease. In addition, the stroke number of a flocked fabric before and after washing is low in its wet form compared to the dry form. The main reason is that the acrylic adhesive has poor wet properties. Results from the regression models were compared with the measured values. It was concluded that the method used in this study could be a viable and reliable tool.