Recycling of engineering thermosets is extremely difficult for conventional techniques due to their crosslinked networks. In this study, we demonstrated a new recycling approach for anhydride‐cured engineering epoxy. After soaking the epoxy networks in alcohol solvent mixed with transesterification catalyst, both solvent and catalyst molecules diffused inside, broke the ester bonds on the chain backbone through bond exchange reactions, and eventually decomposed the networks. The ester covalent bonds would be reformed as evaporating the solvent, and the dissolved polymer solution was re‐polymerized into near‐identical networks. When compared with existing recycling approaches, the proposed one is advantageous for its low cost, zero pollution, low temperature (160°C), and ambient pressure during operation. Epoxy networks with different amount of anhydride cross‐linkers were synthesized, and the influences of solvent choice, network stoichiometry, and crosslinking density on the recycling rate were studied. Specifically, the dissolution rate of epoxy samples was evaluated by their weight loss in two types of alcohol solvents, and the re‐polymerization rate was evaluated by the increment of solution viscosity and network modulus. Thermomechanical properties of recycled epoxy were compared with those of native samples. Finally, the dissolution and re‐polymerization cycles were performed for multiple times to investigate the repeatability. POLYM. ENG. SCI., 59:E111–E119, 2019. © 2018 Society of Plastics Engineers

No abstract

The influence of the porosity on the static mechanical strength of the carbon fiber fabric reinforced epoxy composites laminates was investigated. The tensile, compressive, bending, and interlaminar strength test on the CFRP laminates with porosity of 0.33% and 1.50% were conducted and simulated by a finite element analysis model. The article proposes the failure criterion of the static mechanical strength of the fabric fiber reinforced composites based on the improved Hashin failure criterion that is suitable for the undirectional composite laminates. The basic composite strength parameters are used to evaluate the mechanical properties of CFRP laminates with different porosities. A finite element analysis model is established by using software ABAQUS TM combined with the sudden stiffness degradation model. The experiment results show that the tensile, compressive, bending, and interlaminar strength decrease with the increasing porosities. The tensile, compressive, bending, and interlaminar strength of the fabric carbon fiber reinforced epoxy composites laminates are simulated accurately by the finite element model. POLYM. COMPOS.,

No abstract

No abstract