Recyclable Epoxy Research Articles

Low-cost manufacturing and recycling of advanced biocomposites

ABSTRACTIn 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.

Hybrid biobased recyclable epoxy composites for mass production

Hybrid flax/carbon composites were studied in this artcle. The matrix used was developed using a sustainable green epoxy monomer cured by a novel cleavable amine. The combination of cleavable amine with green epoxy monomers led to a fully recyclable composite. The laminates were manufactured by using High Pressure Resin Transfer Molding with injection cycles down to 25 sec and cure cycles of 8 min at 120°C, followed by postcuring at 120°C for 1 h. The effect of the stacking sequence of the laminates was analyzed in terms of the tensile, flexural, and impact properties. A chemical recycling was also performed and the mechanical properties of the recovered thermoplastic measured. POLYM. COMPOS., 39:E2217–E2225, 2018. © 2017 Society of Plastics Engineers

Hybrid composites manufactured by resin infusion with a fully recyclable bioepoxy resin

Abstract Bioepoxy based monomers were formulated with a cure inhibitor and a cleavable amine to obtain a recyclable epoxy system suitable for resin infusion at room temperature. Hybrid flax/carbon fiber layup were used. Tensile, flexural and dynamo-mechanical properties for the composites were studied. The cured laminates were chemically recycled obtaining from the epoxy matrix a thermoplastic. The recycled was processed by fused deposition modelling (FDM) and injection molding after mixing with short kenaf fibers.

Epoxy Matrices Modified by Green Additives for Recyclable Materials.

Epoxy-based thermosets are one of the most popular matrix materials in many industries, and significant environmental benefits can be obtained by developing a recyclable variant of this widely utilized material. Incorporation of a bio-based disulfide additive within a commercial epoxy system leads to a cross-linked material that can be fractionated under mild and environmentally benign conditions. The material has been analyzed by FTIR and solid-state NMR. Furthermore, modified epoxy matrices with low additive concentrations are demonstrated to have similar mechanical and thermal properties compared to commercially available benchmarks. Thus, additive formulation and fractionation based on green chemistry principles have been demonstrated, and a recyclable epoxy matrix has been developed.

Thermo-reversible MWCNTs/epoxy polymer for use in self-healing and recyclable epoxy adhesive

A self-healing and recyclable carbon tube/epoxy adhesive was prepared by epoxy monomer with Diels-Alder (DA) bonds, diethylenetriamine and polyethyleneimine modified multi-wall carbon nanotubes (MWCNTs). The self-healing and recyclable ability was attained by thermally reversible Diels-Alder reaction between furan and maleimide in the epoxy monomer. By controlling the molar ratio of furfuryl glycidyl ether and 4,4′-methylenebis(N-phenylmaleimide), the glass transition temperature and mechanical properties of MWCNTs/epoxy adhesives were varied. The self-healing properties of MWCNTs/epoxy polymers were evaluated by lap shear experiment and the results showed that the MWCNTs/epoxy adhesives exhibited enhanced mechanical properties and excellent self-healing ability under heat stimulus. The healing efficiency was related to the molecule mobility and the conversion of DA reaction between furan and maleimide. The MWCNTs/epoxy adhesives also displayed excellent recyclable ability by transforming into soluble polymer under heating. These materials offer a wide range of possibilities to produce materials with healing and recyclable ability and have the potential to bring great benefits to our daily lives by enhancing the safety, performance, and lifetime of products.

Hot Solvent Extraction Method for Recycle Epoxy Resin in Waste Printed Circuit Board with Polyethylene Glycol

Waste printed circuit board (WPCB) from waste electrical and electronic equipment (e-waste) can be recycled a precious metal part while a non-metal part was burned or landfilled, which normally generated toxic substance of organic component to environment. The research work aimed to recycle epoxy resin by hot solvent chemical extraction. Polyethylene glycol 400 (PEG400) and ethylene glycol (EG), at 180°C, were mainly using as solvent and sodium hydroxide (NaOH) as a catalyst. Extraction method was reflux technique. The thermogravimetric analysis (TGA), Specific viscosity, and Fourier transform infrared spectroscopy (FT-IR) methods were investigated and discussed. The TGA result showed that the organic composition was 40.73%wt. The maximum of percent yield was 97.89% at non-metal WPCB/PEG, equal to 0.05 g/ml. Moreover, the extracted product presented a functional group close to virgin epoxy resin according to the peak of FT-IR data. The recycled epoxy resin could be formed well on specimen by virgin epoxy resin and hardener filled with 50% recycled extraction product.

Structure property relationships of biobased n-alkyl bisferulate epoxy resins

In this work, a series of bio-based chemically recyclable epoxy resins were synthesized from n-alkyl bisferulate esters that do not activate human estrogen receptor alpha (ERα).

Insight into the role of potassium hydroxide for accelerating the degradation of anhydride-cured epoxy resin in subcritical methanol

Degradation of methyl-1,2-cyclohexanedicarboxylic anhydride (MeHHPA)-cured epoxy resin in subcritical methanol in the presence of potassium hydroxide (KOH) was studied. The degraded products of epoxy resin were first separated using vacuum distillation, extraction and preparative high-performance liquid chromatography (HPLC) and then characterized by HPLC, electrospray ionization mass spectrometry (ESI-MS), 1H and 13C nuclear magnetic resonance (NMR). The effects of temperature and KOH on the kinetic behavior of degradation and the product distribution were examined. The temperature for the complete degradation of epoxy resin decreased greatly after adding a small amount of KOH. Transesterification was the dominant mechanism of degradation of epoxy resin. Reaction between KOH and epoxy resin and transetherification mechanism were also proposed. KOH improved the reaction mainly as a catalyst with consumption of methanol but contributed little to the reaction as a reagent. The bending properties of recycled epoxy resin with degraded products obtained at different KOH concentrations were also examined.

The Effect of Coarse Particle Size on the Properties of Recycled Copper-Filled Epoxy Composites

The effect of coarse particle size of recycled copper filled epoxy composites on mechanical, electrical, thermal and physical properties was investigated. The recycled copper was collected as a waste from the milling machine and ground into a coarse (300-400 µm) particle size. The recycled copper filled epoxy composite was fabricated using a mechanical stirrer. The effect of volume fraction of recycled copper of the epoxy composites was also studied based on the flexural properties, coefficient of thermal analysis (CTE), electrical conductivity, hardness and density. Incorporation of recycled copper decreased the CTE of the composites. The flexural properties, electrical conductivity, hardness and density of the composites increased with increasing volume fraction and filler loading.

Chemical recycling of carbon fiber reinforced plastic using supercritical methanol

Advanced chemical recycling of carbon fiber reinforced plastic (CFRP) was developed using supercritical methanol. In this method, the thermosetting epoxy resin in CFRP was converted to a thermoplastic resin by the selective decomposition of the bridged structure by supercritical methanol at 270°C and 8MPa for 90min and the resin dissolved in supercritical methanol. On the other hand, the carbon fiber was fully recovered from CFRP without the plastic component and it had no thermal damage. The bridged structure in the epoxy resin could be formed again by adding a cross-linker to the recovered thermoplastic resin and the thermosetting resin was reproduced. This was the first attempt on the recycling of thermosetting epoxy resin. However, in order to maintain the strength of the recycled epoxy resin to that of virgin epoxy resin, the proper ratio of the recovered thermoplastic resin to virgin epoxy resin was determined. The recovered carbon fiber from CFRP maintained the shape of the plain fabric and the reduction of the tensile strength was less than 9% compared with the virgin one. The recovered carbon fiber could be used to make a recycled CFRP with epoxy resin and cross-linker, the strength of which was close to that of virgin CFRP.

Novel Method for Recycle Epoxy Resin from Waste Printed Circuit Board

This research was aimed to study and develop a method for recycle epoxy resin from waste printed circuit board by hot solvent methods and DMSO/NaOH catalytic extraction method. It was found that the pressure tank system, sub set of hot solvent method, variable as following; pressure of 15 bar, temperature of 80 °C, reaction time for 6 h and ethyl acetate solvent presented maximum yield 50.46 %, while DMSO/NaOH catalytic system at 145 °C for 5 h was found maximum yield of 42.97 %. Recycled epoxy resin, the final product from hot solvent and DMSO/NaOH catalytic were showed similarly clear orange-yellow high viscosity. Comparatively, DMSO/NaOH system showed slightly darker color than that of hot solvent system. Functional group at 3000-2850, 1480-1540 and 1020-1040 cm-1, characterized from Fourier transform infrared spectroscopy (FT-IR), indicated that the both product were alkane, aromatic, and phenyl-O-C group, respectively. It could be confirmed that the beneficial functional group of recycled epoxy resin was appeared as a new epoxy resin.

Porous Pavers: Effects of the Recycled Aggregate Size on Drainage Properties

Pervious pavers allow water to percolate through the pavement surface. One of its functions is to reduce runoff. This research studies the possible usage of recycled aggregates as the main base material for pervious pavers. Recycled aggregates are produced by crushing waste concrete and mixing with a non-cement, epoxy binder to produce a pervious pavement. The samples were tested for permeability, porosity and compressive strength. The effects of using recycled aggregates and epoxy binders on the mechanical and physical properties are examined. Mixed proportions of several sizes of recycled aggregates were carried out in order to identify its drainage properties. The permeability test indicated an outstanding result which is 10 times more permeable compared to previous studies. A high porosity was also recorded, up to 2 times more porous than conventional pervious pavers bound with cement. Also, the result of the compressive strength of pervious pavers bound with epoxy binders has shown enough strength for light usage purposes. It can be concluded that the construction of pervious pavers using recycled aggregates with epoxy binders is suitable for pedestrian and light traffic usage.

Degradable and chemically recyclable epoxy resins containing acetal linkages: Synthesis, properties, and application for carbon fiber‐reinforced plastics

AbstractFour sorts of epoxy resins containing degradable acetal linkages were synthesized by the reaction of bisphenol A (BA) or cresol novolak (CN) resin with vinyl ethers containing a glycidyl group [4‐vinlyoxybutyl glycidyl ether (VBGE) and cyclohexane dimethanol vinyl glycidyl ether (CHDMVG)] and cured with known typical amine‐curing agents. The thermal and mechanical properties of the cured resins were investigated. Among the four cured epoxy resins, the CN‐CHDMVG resin (derived from CN and CHDMVE) exhibited relatively high glass transition temperature (Tg = ca. 110 °C). The treatment of these cured epoxy resins with aqueous HCl in tetrahydrofuran (THF) at room temperature for 12 h generated BA and CN as degradation main products in high yield. Carbon fiber‐reinforced plastics (CFRPs) were prepared by heating the laminated prepreg sheets with BA‐CHDMVG (derived from BA and CHDMVE) and CN‐CHDMVG, in which strands of carbon fibers are impregnated with the epoxy resins containing conventional curing agents and curing accelerators. The obtained CFRPs showed good appearance and underwent smooth breakdown with the aqueous acid treatment in THF at room temperature for 24 h to produce strands of carbon fiber without damaging their surface conditions and tensile strength. © 2012 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2012

Corrosion Behavior of Recycled Epoxy Resin Filled with Ground Resin in Alkaline Environment

Corrosion Behavior of Recycled Epoxy Resin Filled with Ground Resin in Alkaline Environment