Roller infusion by nip rollers is widely used in the infusion industry with broad applications, which is also adopted as one of the 7 steps of a newly developed manufacturing process for making fungal mycelium based biocomposites. One important technical issue related to infusion textile reinforcements for such biocomposites is how to predict and control the infusion fluid penetration depth, which directly affects the quality and performances of the preformed textile skins. Currently, the analytical relations between the modeling parameters and the final infusion penetration depth are still not well understood. Few studies have been performed on such topic and some of which used oversimplified assumptions. A new analytical model is developed in this paper and the infusion penetration curves are plotted based on certain input parameters including infusion speed, infusion fluid flow rate, and clamping forces of the two rollers, etc. The model calculated results are then validated by experiments that are performed with the same parameters. The measured parameters of prepared non-Newtonian starch-based natural glue are used both in the modeling and experiments and the results are close enough for model validation.
A new approach to manufacturing biocomposite sandwich structures is introduced. Materials used in the biocomposite are natural textile reinforcement, mycelium-bound agricultural waste as core, and bioresin. This paper focuses on three specific steps of the manufacturing process: filling pre-stamped textile shells with core mixture; allowing the core material to grow thereby binding reinforcement particles and textile skins into a unitized preform; and oven drying said preform to drive off moisture and inactivate the mycelium. Specific process details that are highlighted include design and thermoforming of growth trays, tray sterilization, filling trays with mycelium-inoculated substrates filling and allowing growth to occur, and finally conduction and convection drying/inactivation followed by grown parts conduction and convection drying. To study the new material's stiffness using different materials and under different processing conditions, specimen dimensions were based on ASTM D7250 and C393 standards. All dried samples were tested in flexure by three-point bending method to determine the stiffness and strength of the resin-less preforms and to identify optimal material combinations. INTRODUCTION Advanced polymer matrix composites (PMCs) are comprised of strong, rigid reinforcements (e.g., glass and carbon fibers) bonded together by durable polymers (e.g., epoxy, polyester, nylon) to form laminate skins, which can then be made into sandwich structures using lightweight cores (e.g. honeycomb, balsa). These materials provide significant benefits over conventional engineering materials (e.g., steel and
The manufacture and use of natural, textile-reinforced and shaped skins to replace rigid tooling for fungal mycelium-based, biocomposite sandwich structures are investigated. The motivation is a new manufacturing process proposed for such biocomposites that includes: cutting individual natural textile plies; impregnating multi-ply layups with natural glue conducive to mycelium growth; simultaneously forming, sterilizing and setting impregnated skins; filling formed skins with mycelium-laden agri-waste; allowing mycelium to colonize and bind together core substrate and skins into a unitized preform; high temperature drying that also inactivates fungus; and infusing skins with bioresin using resin transfer molding. Aspects of Steps 2-6 related to the preform shells are the particular focus of this paper. Three-point bending tests are performed on dry, natural glue-bonded, four-ply specimens in a full-factorial experimental design, and test results are analyzed statistically using ANOVA to assess process parameter effects and sensitivities along with environmental condition effects. New specimens are then made using the optimized process and tested for beam bending in creep within an environmental chamber that mimics the actual mycelium growth environment for three days. Two- and six-ply specimens loaded to provide identical maximum tensile stress in flexure are then tested, and useful conclusions are drawn based on all creep test results. Finally, preforms in the shape of a viable commercial product are filled with mycelium-inoculated substrate, grown and dried, and part quality is evaluated based on the amount of skin ingrowth and deviation of the measured shape from the desired shape.
Sustainable composites that use renewable materials and provide better end-of-life options are of great interest to industry. This paper describes an investigative study into high-production manufacturing approaches for a biocomposite material with these characteristics consisting of natural fiber reinforcement and agricultural waste cores bound together by a fungal mycelium matrix that grows in and around everything. Specific processes investigated include cutting of reinforcement plies (woven jute textile in this case), impregnating individual plies a temporary glue binder, stacking and forming laminates or 'skins', drying and sterilization of formed skins, and assembling all components that comprise a composite sandwich structure prior to the mycelium growth phase. Optimal processes are determined according to a number of metrics such as shortest cycle time, lowest cost, lowest energy consumption, and best product quality. The final manufacturing processes were selected based on the results of this comparative study.
This paper describes research related to manufacturing of composite parts and resin infusion
preforms with new materials based on a fungal mycelium-based binder developed and patented
by Ecovative Design, LLC (Green Island, NY). Mycelium, the vegetative part of a fungus, acts
like a natural, self-assembling glue that digests and binds securely to natural reinforcement
materials and agricultural byproducts with essentially no added energy. Laminate structures can
consist of natural reinforcement layers (e.g., jute textile, kenaf mat) bound by mycelium, while
sandwich structures have laminate skins and core made of agricultural byproducts (e.g., ground
corn stover) all bound with together with mycelium. These structures can be used as is or as
preforms for infusion with natural resin (e.g., epoxidized linseed oil) to significantly increase
strength and stiffness.
A new manufacturing system concept for mycelium-based biocomposite laminate and
sandwich structures is proposed. The process steps include: (1) cutting natural fiber
reinforcement in textile or mat form to the desired ply shape; (2) pre-impregnating each ply with
a natural glue; (3) using heated match tools to form, sterilize, and solidify flat stacks of
pre-impregnated plies into integral tooling; (4) filling integral tooling (thereby eliminating the
need for dedicated molds) with agricultural waste pre-colonized with mycelium; (5) allowing the
growing mycelium to bind together and grow into all constituent components under the right
conditions to form a completely unitized sandwich preform or part; (6) drying and inactivating
(killing) live mycelium in the mycelium-bound structure; and (7) infusing natural resin into the
reinforcement skins followed by resin curing if higher part stiffness is required. Proof of
concept and process optimization for Steps 1-3 is demonstrated for a shoe-shaped part in
preparation for production scale-up.
This study investigated mechanical properties of biocomposites developed from recycled polylactic acid (PLA) from packaging industry and treated cellulosic fibers from pulp and paper solid waste. Microwave and enzymatic treatments were used for extraction and surface modification of hydrophilic cellulosic fibers. Enzymatic treatment was specifically performed for activation of hydroxyl groups and improvement of adhesion between matrix and fibers including controlling the length of cellulosic fibers with size reduction of around 50% (142 and 127 μm for primary and mixed biosolids, respectively) as compared to microwave treatment. Microwave treatment produced cellulosic fibers of 293 and 341 μm, for primary and mixed biosolids, respectively. Mechanical properties of biocomposites with 2% (w/w) of treated cellulosic fibers (Young's Modulus 887.83 MPa with tensile strain at breakpoint of 7.22%, tensile stress at yield 41.35 MPa) was enhanced in comparison to the recycled PLA (Young's Modulus 644.47 ± 30.086 MPa with tensile strain at breakpoint of 6.01 ± 0.83%, tensile stress at yield of 29.49 ± 3.64 MPa). Scanning electron microscopy revealed size reduction of cellulosic fibers. X-ray diffraction and Fourier transform infrared spectroscopy confirmed strong mechanical properties of novel biocomposites.
Composite materials based on renewable agricultural and biomass feedstocks are increasingly utilized as these products significantly offset the use of fossil fuels and reduce greenhouse gas emissions in comparison with conventional petroleum- based materials. However, the inclusion of natural fibers in polymers introduces several challenges, such as excess water absorption and poor thermal properties, which need to be overcome to produce materials with comparable properties to the conventional composite materials. Instead of using rather expensive chemical and physical modification methods to eliminate these aforementioned challenges, a new trend of utilizing waste, residues, and process by-products in natural fiber-polymer composites (NFPCs) as additives or reinforcements may bring considerable enhancements in the properties of NFPCs in a sustainable and resilient manner. In this paper, the effects of waste materials, residues or process by-products of multiple types on NFPCs are critically reviewed and their potential as NFPC constituents is evaluated.
Abstract Natural fibres are increasingly used as reinforcements for thermoplastic composites. Additive manufacturing, also known as 3D printing, is a common material extrusion process using (bio)polymers reinforced with natural fibres. However, there is a lack of understanding of the effect of printing parameters on the mechanical properties involved in this new process, and more particularly in the case of Fused Deposition Modeling (FDM). Hygromorphic biocomposites represent a novel use of natural fibres for the production of original self-bending devices that actuate in a moisture gradient. By mimicking natural actuators and their bilayer microstructure adapted for seed dispersal, hygromorphic biocomposites take advantage of the hygro-elastic behaviour of natural fibres. The FDM of wood fibre reinforced biocomposites leads to mechanical properties that are strongly dependent on printing orientation (0 or 90°) due to fibre anisotropy. Mechanical properties depend also on printing width (overlapping of filaments), with a lower Young's modulus than in the compressed samples. Indeed, printed biocomposites have a microstructure with relatively high porosity (around 20%) that conjointly leads to damage mechanisms but also water absorption and swelling. The FDM of hygromorphic biocomposites enables a shift towards 4D printing since the material is able to evolve over time in response to an external stimulus. Typical microstructures achieved by printing could be used advantageously to produce biocomposites with a faster moisture-induced bending response compared to compressed samples.
Natural composites of biological matter such as mycological fungi offer several advantages, including freedom from oil feed-stocks, low cost production, and carbon capture and storage. These benefits make mycology materials carbon-neutral or even carbon-negative. Composite materials remain the material of choice for a wide variety of applications, but the high cost of raw materials and complex processing is opening a new avenue for sustainable composites. The vegetative part of fungi, called mycelium, provide a fast growing, safe and inert material as the matrix for a new generation of natural composites, which can serve as replacements for traditional polymeric materials for applications including insulation, packaging, and sandwich panels. As seen in nature, natural foams can provide acceptable mechanical properties, with the benefits of being lightweight, sustainable and inert. In this investigation mechanical testing was conducted to determine the mechanical behavior of a mycelium material, including its elastic and strength properties in tension and compression. As in synthetic polymeric foams the mycelium material exhibited a compressive strength almost three times the tensile strength. Its high specific compressive strength made it a sustainable option as the core of sandwich panels. The strength of the material was found to decrease with increasing moisture content of the material, suggesting that coatings to inhibit moisture diffusion would ensure consistency and performance.
Advanced composite materials made from non-renewable (synthetic) feed stocks are used in parts that require high specific stiffness and strength and also tailored properties. Bio-composite materials, although not currently able to provide the same level of performance as their synthetic counterparts, are improving as new constituent materials and manufacturing processes are developed. This paper describes an on-going collaboration between Rensselaer Polytechnic Institute and an innovative bio-materials company, Ecovative Design, LLC, to demonstrate and manufacture bio-composite laminate and sandwich parts made with mycelium-bound agricultural waste core material, natural textile reinforcement, and vegetable-oil based resins. Particular focus will be on the process whereby dry core and multi-layer textile skins are bound together with mycelium, into a preform that is then vacuum infused with thermally activated bioresin and cured in place.
The use of blends of recycled agricultural plastic and post-consumer high-density polyethylene from municipal solid wastes, as matrices for sustainable eco-composites, was investigated with the aim of boosting the use of recycled materials and reducing the waste plastic environmental impact. It was proposed that proper selection of blends of different waste plastics will allow the production of composites with optimized properties. The two plastics and their blends were characterized by using different spectroscopic techniques and thermal analysis, and measuring the flow curves. The eco-composites were obtained by compounding a selected blend of recycled agricultural plastic and post-consumer polyethylene with different proportions of coupling agent and waste cellulose fibers in a pilot-plant twin-screw extruder. The structure of the final materials and the role of the coupling agent were analyzed by using scanning electron microscopy. Finally, the novel eco-composites were compared to their counterparts without post-consumer polyethylene, revealing that the incorporation of polyethylene increases the strength and stiffness of the eco-composites, without compromising the impact strength. The incorporation of 40 wt% of polyethylene caused increases in moduli as high as 175% for the polymer and 47% for composites with 30% of fibers. The tensile strength increased up to 21% for the same composites. The decreases in processability caused by the incorporation of polyethylene can be corrected by increasing the coupling agent content. The improved balance between stiffness, strength and toughness without compromising processability can increase the recyclability of the polymer and cellulose wastes used in this work.
Sustainability, industrial ecology, eco-efficiency, and green chemistry are guiding the development of the next generation of materials, products, and processes. Biodegradable plastics and bio-based polymer products based on annually renewable agricultural and biomass feedstock can form the basis for a portfolio of sustainable, eco-efficient products that can compete and capture markets currently dominated by products based exclusively on petroleum feedstock. Natural/Biofiber composites (Bio-Composites) are emerging as a viable alternative to glass fiber reinforced composites especially in automotive and building product applications. The combination of biofibers such as kenaf, hemp, flax, jute, henequen, pineapple leaf fiber, and sisal with polymer matrices from both nonrenewable and renewable resources to produce composite materials that are competitive with synthetic composites requires special attention, i.e., biofiber–matrix interface and novel processing. Natural fiber–reinforced polypropylene composites have attained commercial attraction in automotive industries. Natural fiber—polypropylene or natural fiber—polyester composites are not sufficiently eco-friendly because of the petroleum-based source and the nonbiodegradable nature of the polymer matrix. Using natural fibers with polymers based on renewable resources will allow many environmental issues to be solved. By embedding biofibers with renewable resource–based biopolymers such as cellulosic plastics; polylactides; starch plastics; polyhydroxyalkanoates (bacterial polyesters); and soy-based plastics, the so-called green bio-composites are continuously being developed.
The influence of fiber treatment on the properties of biocomposites derived from grass fiber and soy based bioplastic was investigated with environmental scanning electron microscopy, thermal and mechanical properties measurements. Grass fibers were treated with alkali solution that reduced the inter-fibrillar region of the fiber by removing hemicellulose and lignin, which reduce the cementing force between fibrils. This led to a more homogenous dispersion of the biofiber in the matrix as well as increase in the aspect ratio of the fiber in the composite, resulting in an improvement in fiber reinforcement efficiency. This led to enhancement in mechanical properties including tensile and flexural properties as well as impact strength. Additionally, the alkali solution treatment increased the concentration of hydroxyl groups on the surface, which led to a better interaction between the fibers and the matrix.
Life cycle assessment is a technique to assess environmental aspects associated with a product or process by identifying energy, materials, and emissions over its life cycle. The energy analysis includes four stages of a life cycle: material production phase, manufacturing phase, use phase, and end-of-life phase. In this study, the life cycle energy of fiber-reinforced composites manufactured by using the pultrusion process was analyzed. For more widespread use of composites, it is critical to estimate how much energy is consumed during the lifetime of the composites compared to other materials. In particular, we evaluated a potential for composite materials to save energy in automotive applications. A hybrid model, which combines process analysis with economic input–output analysis, was used to capture both direct and indirect energy consumption of the pultrusion process in the material production and manufacturing stages.
Manufacturing of biocomposite sandwich structures using mycelium-bound cores and preforms
J Manuf Process
D F Walczyk
Jiang, L., Walczyk, D.F., McIntyre, G., Bucinell, R., 2017b. Manufacturing of biocomposite sandwich structures using mycelium-bound cores and preforms.
J. Manuf. Process. 28 (1), 50e59.
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