free or very low voids composites even in large or complicated moulds

 In this process, the preform is laid into the mould in a dry form without any resin, and then enclosed by a specific stack of bagging materials (such as peel ply, infusion mesh and bagging film) before being subjected to vacuum pressure using a vacuum pump. Once all the air has been removed or vacuumed from the bag and the preform has been fully compressed, resin is introduced to the preform through a pipe known as spiral tube meteor shower tonight new jersey, then resin infuses through the preform under the vacuum pressure. After 166 A. H. Hassanin et al. the resin has completely infused through the preform, the supply of resin is closed, and the composite is left to cure under vacuum pressure. Figure 4 shows a schematic diagram of VARTM and VARTM consumable tools. The use of VARTM with natural fibers is not very popular. However, flax and hemp fibers were used in nonwoven and woven forms as reinforcement to epoxy and soybean oil resins (O’Donnell et al. 2004; Rayyaan et al. 2019). 

Main Advantages (Strong 2008; Advani and Hsiao 2012; Netcomposites 2019) • Much lower tooling cost compare to RTM, due to one side of the tool being a vacuum bag, and traditional metal mould in the other side • Fabrication of large parts • Flexibility, where standard wet lay-up tools may be able to be modified for this process. • Cored structures can be produced in one operation. Main disadvantages (Strong 2008; Advani and Hsiao 2012; Netcomposites 2019) • Surface quality is not as good as RTM • Complex compared to other methods • Low viscosity resins must be used which significantly affect mechanical properties • Dry spot areas can be formed • Some elements of this process are covered by patents (SCRIMP). 2.5 Filament Winding This process is mainly used for creating tubular components that are hollow and have circular or oval cross section, such as pipes and tanks. Yarns are passed through a resin bath then the impregnated yarns are wound onto a mandrel as shown in Fig skin exfoliating shower sponge. 5. Yarns orientations can be controlled by the traverse feeding mechanism, in conjunction with the speed of rotation of the mandrel. Filament winding is mostly used for producing pipes especially for petroleum industry and pressure vessels. The use of filament winding technique with natural fibers was very limited in the literature. However, some researchers investigated the potential of using natural fibers in composite fabrication using this technique. Lehtiniemi et al. (2011) used flax yarn as reinforcement in composites; however, the flax fibers lacked adhesion compared to tubes reinforced with glass fibers. Another attempt was made by Mahdi et al. (2002). They used epoxy resin reinforced with oil palm frond fibers. Also, kenaf fibers was used with unsaturated polyester (Misri et al. 2016). Overall, it’s important to optimize the process parameters in filament winding for making natural fiber reinforced composites for use in light weight tubular applications (Salit et al. 2015). Main Advantages (Strong 2008; Advani and Hsiao 2012; Netcomposites 2019) • The process is very fast and can be automated easily, therefore it is economical technique Date Palm Fiber Composite Fabrication Techniques 167 Fig. 4 a Schematic diagram of resin infusion technique (Matsuzaki et al. 2011). b VARTM process setup (Hassanin et al. 2016). c VARTM consumables and tools 168 A. H. Hassanin et al. Fig. 5 Filaments winding technique (Balasubramanian et al. 2018) • Labor intensive, usually one labor per each machine • 

Fiber cost is minimized since there is no secondary process to manufacturing preforms • Resin content can be controlled by metering the resin onto each fiber tow through nips or dies • Void content can be very low navy body puff, depending on the tension on the filament and speed of winding • Structural properties of produced composites are very good since straight fibers can be laid in a complex pattern to match the applied loads. Main disadvantages (Strong 2008; Advani and Hsiao 2012; Netcomposites 2019) • Convex shaped components cannot be manufactured by filament winding • Fiber cannot easily be laid along the length of a component • Mandrel costs for large components can be high • The external surface finish of the component is not high quality because it is not moulded • Low viscosity resins should be used which affect the mechanical properties • Health and safety considerations of resins because the process is carried out in open moulds mini body puff. 2.6 Compression Moulding Compression moulding is the most popular technique used in fabrication of poly- meric composites bath sponge natural. There are two types of compression moulding; cold compression moulding and hot compression moulding. In compression moulding process, two matched metal moulds (flat or shaped) are used to fabricate composite products as shown in Fig. 6. Compression moulding could be further classified into two cate- Date Palm Fiber Composite Fabrication Techniques 169 Fig. 6 Compression moulding process gories; Sheet Moulding Compound (SMC) and Bulk Moulding Compound (BMC). In BMC the resin is mixed with the reinforcement. The BMC material has a dough- like appearance. On the other hand, in SMC the resin and fibers are not mixed together, but rather supplied in the form of sheets. In SMC the composite has a sand- wich structure with an alternative layers of reinforcements and resin (Strong 2008). In compression moulding, one plate is stationary while the other plate is movable. Preform and matrix are placed in between the two moulds then heat and pressure is applied as required for composite for a specific period of time shower sponge singapore. In case of ther- moplastic matrix heat will be required to melt the matrix and let it flow through the preform. For thermoset matrix curing of the composite may take place either at room temperature or at some elevated temperature (Advani and Hsiao 2012). As mentioned earlier, compression moulding is one of the most extensively used technique in the literature.

 Therefore, there is a large amount of research made on the possibility of using natural fibers with compression moulding. Date palm leaflet fibers were used as reinforcement to epoxy resin using compression moulding (Sbiai et al. 2008). Also, mesh fibers were mixed with a starch based resin then compressed to form the final composite (Ali and Alabdulkarem 2017). Midrib fibers were also used as reinforcement to thermoplastic matrices such as HDPE and LDPE (Mahdavi et al. 2010; Mirmehdi et al. 2014). Sisal fiber composites and thermoset or thermoplastic matrix have been manufactured using compression moulding. Sisal was used in woven and the nonwoven forms. The most commonly used matrix materials with sisal fibers were epoxy and unsaturated polyester (Lu et al. 2003; Jiang et al. 2009; Kejariwal and Keerthi Gowda 2017; Sathishkumar et al. 2017; Senthilkumar et al. 2017; Yorseng et al. 2020). Bamboo and coir fiber composites were manufactured using compression moulding with starch based resins or epoxy resin (Ochi 2006; Mulinari et al. 2011; Romli et al. 2012; Keerthi Gowda et al. 2016; Abdullah et al. 2020). Moreover, coir fibers were used with polypropylene as a matrix (Lai et al. 2005; Mir et al. 2013; Arya et al. 2015). As for jute fibers, they were used in plain 170 A. H. Hassanin et al. woven and unidirectional forms with PLA and starch based resin respectively.

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