Novel wet laid nonwoven carbon fiber mats and their composites

In the wake of lightweight and specific strength, composite materials are increasingly used for few decades. In order to meet the industry production rates, a novel mixing method has been developed in this work that provides more control on fiber length and homogeneity in wet-laid (WL) carbon fiber (CF) mats. The WL process has been adopted from papermaking industries to produce non-woven CF fiber mats.This work investigates the production of CF mats in three main phases; (a) First, the mixing regime of the WL method is explored to optimize the process of fiber dispersion. Experimental and theoretical computational fluid dynamics (CFD) studies have been conducted to understand the different factors of the process, in order to obtain the most optimal time of production. Mats produced are imaged through the Back Light Scattering (BLS) technique and computationally analyzed using a Matlab generated code to determine the fiber density distribution through pixel counts and compare the improved results of the mixing method developed in this work to the traditional propeller mixing. Processing time was reduced by 60% to produce a mat on laboratory scale with optimal characteristics; (b) Second composites were made from mats produced by each of the two mixing methods presented in the first part of the work. An object oriented finite element analysis (OFF) investigated the isotropic nature of the composites. The mechanical properties of these composites were evaluated in tensile, flex and inter laminar shear (ILSS). Tensile data showed improvement in standard deviation between samples collected from plates made with mats produced through the innovated mixing method when comparing them to composites made with the mats produced through the traditional method; and (c) Third, the in-plane permeability of the mats was analyzed in respect to changes in the fiber length and mats grammage per square meter (gsm) and a link between local permeability in response to changes in complex geometries is investigated.The novel mixing method for fiber distribution in WL discussed in this work presents an innovation in composites production, leading to improved production rate of nonwoven CF mats, ease of production and reproducibility of composites

A Review of Recent Developments in Composites Made of Recycled Carbon Fiber Textiles

Carbon fiber recycling has garnered significant attention in recent years due to the large volume of manufacturing waste and upcoming end-of-life products that will enter the waste stream as the current generation of aircraft is retired from service. Recycled carbon fibers have been shown to retain most of their virgin mechanical properties, but their length is generally reduced such that continuous fiber laminates cannot be remade. As such, these fibers are typically used in low-performance applications including injection molding, extrusion/compression molding, and 3D printing that further degrade the fiber length and resulting composite properties. However, recent advances in the processing of long discontinuous fiber textiles have led to medium- to high-performance composites using recycled carbon fibers. This review paper describes the recent advances in recycled carbon fiber textile processing that have made these improvements possible. The techniques used to manufacture high-value polymer composites reinforced with discontinuous recycled carbon fiber are described. The resulting mechanical and multifunctional properties are also discussed to illustrate the advantages of these new textile-based recycled fiber composites over the prior art

Mechanical Response and Processability of Wet-Laid Recycled Carbon Fiber PE, PA66 and PET Thermoplastic Composites

The interest in recycled carbon fiber (rCF) is growing rapidly and the supply chain for these materials is gradually being established. However, the processing routes, material intermediates and properties of rCF composites are less understood for designers to adopt them into practice. This paper provides a practical pathway for rCFs in conjunction with low cost and, for the most part, commodity thermoplastic resins, namely polyethylene (PE), polyamide 66 (PA66) and polyethylene terephthalate (PET). Industrially relevant wet-laid (WL) process routes have been adopted to produce mats using two variants of WL mats, namely (a) high speed wet-laid inclined wire to produce broad good ‘roll’ forms and (b) 3DEPTM process patented by Materials Innovation Technologies (MIT)-recycled carbon fiber (RCF), now Carbon Conversions, which involves mixing fibers and water and depositing the fibers on a water-immersed mold. These are referred to as ‘sheet’ forms. The produced mats were evaluated for their processing into composites as ‘fully consolidated mats’ and ‘non-consolidated’ as-produced mats. Comprehensive mechanical data in terms of tensile strength, tensile modulus and impact toughness for rCF C/PE, C/PA66 and C/PET are presented. The work is of high value to sustainable composite designers and modelers