Low-cost manufacturing and recycling of advanced biocomposites

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In this paper, the capabilities of Specialized Elastomeric Tooling for Resin Infusion, a low-cost and low-energy autoclaving alternative for consolidating and curing resin-infused thermoset composite parts, are expanded to biobased composites. Specifically, multiple flat laminate parts (10-ply stack of woven cellulose fiber with a high bio-content, recyclable epoxy resin matrix) are infused with bioresin, consolidated between a temperature-controlled rigid tool and matching rubber-faced tool specially engineered to provide uniform pressure under load, and then thermally cured in place. As expected, parts made using this process are thinner, have higher stiffness and strength, and have fewer surface voids as consolidation pressure is increased. Experimental results reported include resin infusion observations, part thickness, surface roughness, microscopy, tensile strength/modulus, and flexural strength/modulus. Following consolidation and curing, the recyclability of the cellulose textile is assessed by dissolving the commercially available bioresin in a dilute acetic acid bath to create a recyclable thermoplastic.

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... Food packaging requirements are based on the type of food that is packed, as varying materials are needed to fulfill different requirements (Bugnicourt et al. 2013). However, it is also worthy to note that Garofalo et al. (2018) has stated in their report that biocomposites materials applications have difficulties penetrating the market. Two of the three main obstacles revealed are cost related: (1) material cost, and (2) manufacturing cost (and time). ...
The biodegradability of a material has been an important measure in packaging design. Green biocomposites, which are made of natural fiber and biopolymer matrix, are promising alternative materials in single-use packaging to replace conventional materials. Selection of the most suitable natural fiber for reinforcement in green biocomposites is an initial attempt towards reducing resources depletion and packaging waste dumping. A selection system of analytic hierarchy process (AHP)-based method is proposed. Food packaging materials’ requirements and production factors are the basis of selecting 13 vital characteristics of natural fibers as the selection criteria. Nine natural fibers were assessed based on data gathered from recent literature. From the results, ijuk obtained the highest priority score (14%). Whilst, sisal had the lowest rank with a score of 8.8%. Sensitivity analysis was then performed to further validate the results, and ijuk remained at the top rank in four out of the six scenarios tested. It was concluded that ijuk is the most suitable natural fiber for reinforcement in green biocomposites for food packaging design. Nonetheless, for future development, more comprehensive selection criteria, such as fiber specific properties, fiber processing, and fibre treatment, are suggested to be included in the framework for more comprehensive results.
... Vacuum infusion, a well known and widely used process for impregnating dry fiber preforms with resin using differential pressure, was combined with the PFL process to successfully impregnate dry fiber preforms and then consolidate and thermally cure flat carbon fiber/epoxy [26] and cellulose textile/epoxy [27] laminate parts. This research showed that PFL was not limited to just prepreg layups. ...
This paper describes the application of a new manufacturing process for low-cost and rapid consolidation and curing of advanced thermoset composites that avoids the use of expensive prepreg, autoclaving, and thermally induced curing. The process, called VIPE, uses a novel tooling design that combines vacuum infusion (VI) of a dry preform with resin, a rigidly backed pressure focusing layer (P) made of an elastomer to consolidate the wet preform with uniform pressure, and high-energy electron beam curing (E). A VIPE tool is engineered and fabricated to manufacture 3D laminate bicycle seats composed of woven carbon fiber textile and an electron beam-curable epoxy acrylate. Details of the tooling design discussed include computational fluid dynamics (CFD) simulation of the vacuum infusion, iterative structural finite element analysis (FEA) to synthesize the pressure focusing layer (PFL), structural FEA to design the top mold made of a composite sandwich structure for electron beam transparency, and Monte Carlo electron absorption simulations to specify the e-beam energy level. Ten parts are fabricated using the matched tool (bottom aluminum mold covered with silicone layer and top mold with carbon/epoxy skins separated by foam core) after the dry textile preform contained within is infused with resin, the tool halves are clamped under load, and a 3.0 MeV e-beam machine bombards the tool for less than 1 min. Part thickness, part stiffness, surface roughness, and fiber and void volume fractions measurements show that aerospace quality parts with low cycle times are achievable, although there is high variability due to the small number of replicates and need for process optimization.
... Based on the conventional cohesive pressures used for advanced compounds and the resin supplier's recommended healing guidelines, SET is one of several alternative processes for integrating / modifying thermoset and thermoplastic manufacturing systems under one temperature, high pressure and temperature conditions. [38].The fiber-matrix interface plays an important role in determining the mechanical properties of the composite material. Creating compounds Therefore, increase the mechanical properties, The statistical design of experiments based on the eligibility method to obtain integrated results between parameters will vary between factor levels. ...
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Recycling is a manufacturing process. In a production process that is not recycled, a natural Resources (trees, iron ore, bauxite ore, Such as silica) has been Sustainable Manufacturing, life cycle assessment, Additive manufacturing, powder recycling, polymer composites Extracted, processed, made into consumer goods that can be sold, Consumed then discarded Usually landscape or combustion facility Significant facing the waste / recycling industry There are security challenges. Chemical exposure in them, Flammable dust explosions, mechanical safety hazards And powerful equipment with moving parts Include exposure. Recycling is a production process. Pause for a moment and read that first sentence again. It's the center of any recycling project, but not about recycling Not often seen in debate either. At its center, Recycling is the filling or waste of our production and consumption land Is to make it more durable than management. If your only goal is to get things off the ground, It’s stinging and recycling. Why recycling is better than garbage We often fail to remember. Recycling is not good because it fills the land Worse. Recycling is good because recycling is good. In a non-recyclable production process, a natural resource (Wood, iron ore, bauxite ore, silica, etc.) As consumer goods that can be extracted, processed, produced and marketed Consumed, then discarded - usually landscaping or combustion facility Recycling is the same production process.
... Two of the three main obstacles are cost related issues: (1) the material cost, and (2) the manufacturing cost (and time). Another major constraint is the sustainability of obtaining the raw material, and its recyclability (Garofalo et al. 2018). ...
Starch is a natural polymer and eligible for short-term, single-use food packaging applications. Nevertheless, different starches have different features and properties determined by their botanical plant origins. This paper presents an approach that combines Shannon’s entropy and the Analytic Hierarchy Process method to aid the selection process of starch as matrix in green biocomposites for takeout food packaging design. The proposed selection system ranks alternative starches in terms of the key design elements, i.e. strength, barrier property, weight, and cost. Shannon’s entropy established corresponding weight values for the indicators selected. Six starches: wheat, maize, potato, cassava, sago, and rice were appraised using gathered data from the literature to determine their suitability as a more sustainable option. This study found that sago starch obtained the highest priority score of 26.8%, followed by rice starch (20.2%). Sensitivity analysis was then carried out to further verify the results; sago starch was at the top rank for five of six different scenarios tested. The results showed that sago starch is the starch that can best satisfy the design requirements. Despite the results attained, the selection framework used could be enhanced with a more comprehensive attributes assessment and extensive dataset.
The capabilities of specialized elastomeric tooling (SET), a low-cost and low-energy autoclave alternative for consolidating and curing thermoset and thermoplastic composite parts made of "prepreg" material, are expanded to allow vacuum infusion of dry fiber preforms through a simple demonstration project. In this case, SET was designed to allow vacuum infusion of a flat five-ply, woven carbon fiber preform with epoxy resin, consolidate under uniform pressure in a press, and thermally cure while still under load. As expected, parts made using this process were thinner, showed slight increases in stiffness and strength, and had less surface voids as consolidation pressure was increased. Curing temperature/time has no significant effect on part quality. This expanded SET process was further characterized through a full-factorial set of experiments with replicates and quality metrics measured, such as stiffness, strength, surface roughness, and composite volume fractions. Future work will include the design and fabrication of tooling for a realistic part shape.
A detailed overview of Resin transfer molding (RTM) and Vacuum infusion molding (VIP) Infusion Processing Technologies has been discussed. Advantages of RTM are that they have best tolerance control, better surface finish gel and low pressure infusion operation. Disadvantages of RTM are that the tooling costs are high for large production runs, mold filling software is limited and perform and reinforcement alignment in mold is critical. RTM is developed from urethane technology, the resin are injected into matched mold under pressure. VIP also known as Vacuum-Assisted RTM, Vacuum pulls liquid resin into perform and single-sided tool is normally used. Other comparisons are also made between the RTM and VIP processes such as the comparison between RTM or VIP process Parameter.
Specialized elastomeric tooling (SET) is a patented process that can replace autoclaving for consolidating and curing advanced thermoset and thermoplastic composite parts. The process mimics autoclave conditions of uniform pressure and temperature by clamping an uncured laminate or sandwich structure with known force between a temperature-controlled lower tool and an engineered, rubber-faced upper tool. Several published studies involving small-to medium-sized parts have shown that SET provides equal or better quality, but at fraction of the energy, waste, and capital and consumable costs. The elastomer of choice for the upper tool is a castable, platinum-catalyzed silicone rubber because of its high working temperature, high tear strength, and negligible shrinkage. To date, there is limited understanding about the properties of silicone rubber subjected to high temperature and compression for long periods of time over multiple cycles. This paper discusses recent work that characterizes silicone rubber under these conditions for design and simulation purposes. Compression testing performed per ASTM-D575 exhibited linear behavior at 125 °C (typical processing temperature for epoxy resins), whereas tensile testing (per ASTM-D412) at the same temperature exhibited strain softening. To show the repeated effect of compression on rubber properties (i.e., mimic multiple loading cycles on rubber mask) at typical process temperature (125 °C) and pressure, a fatigue testing apparatus was custom designed and fabricated. Over repeated cycles between 0 and 1.35 MPa (typical consolidation pressure for advanced composites), silicone rubber exhibited slight hysteresis and a minor stiffening effect that appears to plateau at a particular modulus. Static and kinetic frictional coefficients, also used in modeling, between silicone rubber and several materials commonly used in SET ranged from 0.5 to 2.4 (per ASTM-D1984). Finally, pressure injection and in-line mixing of uncured rubber resulted in significantly less entrained air bubbles (and resulting surface defects in contact with composite part) than the current standard practice of hand mixing. Results are applicable to both SET and any advanced composite forming or curing/consolidation processes involving rubber-faced tools.
Thermal press curing (TPC) is an alternative process to autoclaving for consolidating and curing thermoset and thermoplastic prepreg composite parts by pressing them between a heated "curing mold" and a customized rubber-faced "base mold" that are engineered to provide uniform temperature and pressure conditions. A study was performed with a kayak paddle part made from eight plies of woven carbon/epoxy prepreg material and formed by double diaphragm forming (DDF). The study expounds on the narrow body of TPC knowledge around three main objectives: (1) to experimentally compare TPC cured parts to a benchmark autoclave process using a realistic part shape with fine geometrical details, (2) to evaluate the necessity of vacuum bagging of TPC cured parts, and (3) to characterize the robustness/sensitivities of pressure application during the TPC process by varying both the total pressure applied to the base mold and the location the hydraulic press ram applied pressure to the base mold. Maximum temperature and pressure variations around the target levels over the entire clamped tool surface were measured as 5.0 degrees C and 5.5%, respectively, both of which were well within the manufacturer's recommendations. The TPC part had fewer defects, was generally thinner, and had a higher fiber volume fraction than a comparable autoclaved part. Little difference was observed between the TPC parts made with and without vacuum bagging. Parts with too little pressure (90%) resulted in more thickness variation and defects than too much pressure (110%). Finally, TPC parts exhibit some thickness variation, as expected, when ram force is applied off the center of pressure (COP).
Over the years, several modifications of the more standard liquid molding processes such as SRIM and RTM have been proposed. Among them the Compression Resin Transfer Molding (CRTM) presents great interest. In that process, like in RTM, the fiber preform is preplaced in a mold and then a liquid resin is injected. In CRTM however, the mold is kept slightly open during the resin injection. Once the necessary amount of resin is injected, the final closing is done and the resin filled the entire cavity. The main advantage of this technique is to reduce the necessary injection pressure and to ease the molding of parts with high fiber. In this paper, results are reported for two series of plaque molding experiments. In all cases filling time and pressure distribution in the cavity were recorded. In the first series, vinyl ester resin was injected in a slightly open cavity where a thermoformed glass fiber preform had been placed. In this case, an open gap was present on the top of the preform which eased considerably the filling. The mold was then closed to final part thickness. In this case, the resin injection time was extremely short and most filling and wetting time was elevated to the final closing of the cavity. In the second set of experiments continuous strand glass fiber mat was used. Because of their nature, the layers of glass mat completely filled in partially closed cavity. As opposed to the previous experiments, in this case, the cavity was closed during the resin injection. The closing time was chosen in such a way that filling and closing occur simultaneously. Since the reinforcement permeability is reduced during injection, the filling rate was much slower at the end. The data gathered with these experiments could also be used to validate the modeling of foamed core parts molding when resin pressure crushes the core.
Lightweight vehicles for energy savings encourages the use of composites in the new generation of vehicles. The compression resin transfer molding process (CRTM) is a novel variation of liquid composite molding (LCM) which offers fast manufacturing cycle for net-shape complex parts with excellent performance, ideal for the automotive industry. The process combines features of resin transfer molding (RTM) and compression molding. The process stages are identified and compared to other LCM processes to take advantage of existing simulation tools. A numerical model that simulates the resin flow in this process is proposed. Several first-order analyses are developed to estimate important process parameters to simplify modeling. Finally, this approach is used to model and simulate the process and is applied to a complex automotive part (the Automotive Composites Consortium B-pillar) with qualitative experimental validation.
An alternative process to autoclaving, called Thermal Press Curing (TPC), is proposed, whereby an uncured composite laminate is pressed between a heated curing mold and customized rubber-faced mold that are designed to provide uniform temperature and pressure conditions. TPC was demonstrated by designing a complex 3-D ‘benchmark’ part shape, applying a simple computational algorithm to derive the required tool shapes, and fabricating the tooling. A comparative study was performed involving the benchmark part made from four plies of woven carbon/epoxy prepreg material. Identical laminates were pre-formed by double diaphragm forming and then cured and consolidated by autoclaving, Quickstep, and TPC using standard industry practice. Results of the study indicate that the TPC part is of similar quality as compared to those made by autoclaving and Quickstep, but, more importantly, requiring significantly less energy and resource consumption, lower cost (capital and recurring), and less preparation and cycle time.
Curing and consolidating thermoset composite laminates and sandwich structures typically involves vacuum bagging an uncured and formed layup over a thin-walled mold, placing it in an autoclave, and subjecting the entire unit to temperature, vacuum, and pressure cycles as prescribed by the manufacturer. Autoclaving is generally considered the major bottleneck in manufacturing advanced composite parts because of high capital and consumable costs, energy usage, waste generated, and process scalability. A new curing and consolidation process called “thermal press curing” is presented and demonstrated as an alternative to autoclaving. The process involves compressing a composite laminate between a special mold set––a heated metal mold and a matching rubber-covered mold made of an insulative material––designed to provide uniform temperature and pressure over the metal mold surface, that is, mimic the process conditions provided by an autoclave. The thermal press curing process is demonstrated for the first time using a mold set for a simple two-dimensional axisymmetric shape. An aluminum curing mold with embedded electric resistance cartridge heaters is heuristically designed to provide uniform temperature in operation across the mold surface within 1°C of the target value (177°C). With the mold set compressing an eight-ply carbon/epoxy composite workpiece and well insulated on all sides, the power draw is at least one to two orders of magnitude less than a comparable autoclaving operation. The potential to significantly improve pressure uniformity from the compressed rubber mask is shown by changing the mask shape. Even without an optimized rubber layer shape and thickness, the eight-ply composite part was successfully cured. Finally, a plan for future work is described.
Recylable by design: a chemical approach to recyclable epoxy composites
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Growth opportunities in global composites industry
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