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Traditional epoxy resin materials are widely used in coatings, composite materials, electronic packaging materials, etc. They are usually made of unsustainable fossil resources and cannot be recycled under mild conditions. Degradable thermosetting resins with dynamic covalent structure provide a potential solution to this conflict. In this paper, using biomass energy vanillin, m-xylylenediamine and 1, 6-hexanediamine as raw materials, two dynamic imine bond curing agents were synthesized, and then cured with DGEBA to prepare two bio-based imine epoxy vitrimers. The thermal and mechanical properties of two imine epoxy vitrimers were studied and compared in detail. Results showed that the two types of polymers exhibit excellent thermal stability and solvent resistance. At the same time, the tensile strength, modulus and elongation at break were comparable to or even better than those of conventional bisphenol A epoxy resin. In addition, due to the hydrolysis of the dynamic imine bonds, vitrimers had degradable characteristic, and its degradation also exhibited temperature, solvent and acidity dependence. More importantly, the recyclable carbon fiber reinforced polymer composites made of these two vitrimers could be completely degraded under weak acid conditions, and the nondestructive recycling of carbon fiber composites could be realized. We envision that this vitrimers with simple process, excellent comprehensive properties and degradability will make it a potential candidate for applications in sustainable structural materials. [ABSTRACT FROM AUTHOR]

In this paper, (3-mercaptopropyl)trimethoxysilane (MPTS)- and copper-coated carbon fiber (M-Cu-CF) was obtained by electroless plating method. The M-Cu-CF was evaluated by FTIR, XRD, TGA, and SEM. It was found that the MPTS and Cu were coated on the fiber surface successfully. The M-Cu-CF was utilized as a conductive filler in silicone rubber (SR) for thermal and electrical conductivity applications and exhibited good dispersion and compatibility with the matrix. The effect of M-Cu-CF content on the thermal conductivity and volume resistivity of silicone rubber composites was investigated. The results showed that the thermal conductivity of the M-Cu-CF/SR composites reached 1.99 W (m K) with only 4.0 wt% filler loading, approximately 2.10 times higher than that of raw-CF/SR composites at the same loading. And with the increase of M-Cu-CF loading, the least volume resistivity of M-Cu-CF/SR composites was 3.5 × 10 Ω cm. [ABSTRACT FROM AUTHOR]

This paper presents an extensive set of measurements from complementary surface analysis techniques performed for characterizing deuterium retention in carbon fiber composite SepcarbNB31 subsequently to a deuterium beam exposition: adsorption isotherm measurements and Hg porosimetry to characterize the porous network, coupled deuterium beam exposure and in situ µ-NRA analysis to follow the dynamics of the penetration of the retained deuterium in the material, TEM and Raman microscopy to investigate the change in the material structure induced by ion irradiation, and finally TPD to estimate the respective proportion of deuterium retained in the surface layer and in the bulk material. The parameters extracted from this set of characterizations are introduced in a 2D Monte Carlo model which couples the propagation of deuterium and eroded carbon atoms in a network of rectilinear pores and plasma-surface interaction parameters from the SRIM code. The simulations reproduce satisfactorily the main features of the measured deuterium concentration profile and behavior of the retained deuterium amount with incident fluence, validating the physical picture of deuterium retention in CFC as due to the simultaneous implantation of the incident ions in the few 10-nm-depth layer the closest to the surface and penetration of atoms deeper in the material (several tens of microns) through the pore network. [ABSTRACT FROM AUTHOR]

Compaction of the preforms to a desired fiber volume fraction in liquid composite molding has a significant influence on the subsequent injection process and mechanical properties of the final composites. Hence, knowledge of the compaction of the fabric preforms is important for improving the composite product quality and developing the mold filling simulation. In this paper, the compaction behavior of four types of carbon non-crimp fabrics (NCFs) was experimentally studied. The investigation of compaction behavior included the influence of number of cyclic compaction, number of layers, stitching pattern, compaction speed, and the lubrication (wet states). The results show that the compaction curves tend to be stable and repeatable with an elastic deformation from the third cycle. Other factors affecting the compaction behavior can be explained by the nesting effect, considering the special structure of the NCFs. Gaps between fiber tows created by the stitches may provide room for the adjacent fibers to embed or nest in. Meanwhile, the relaxation of the preforms after compaction was discussed in terms of the energy dissipation. The results elucidate that the lubrication and compaction speed have no significant effect on the compaction process, but exhibit influence on the relaxation. Finally, the microstructural observation of the laminates backs up the experimental analysis and highlights the deformation of fibers at the tow gaps. The change of the internal parameters, including the shape and dimensions of the tows and the gaps, with the compaction degree was statistically studied. It also provides geometrical parameters for establishing predictive models of carbon NCFs with different compaction degrees. [ABSTRACT FROM AUTHOR]