Ammonium nitrate surface is extremely hygroscopic, due to high energy on its surface which increases the potential of the molecules to absorb moisture from the surrounding environment. Ammonium nitrate particles were modified using second coating process with myristic acid in the different amount. The hygroscopicity was tested for ammonium nitrate with and without coating. Fourier transform infrared (FTIR) and scanning electron microscopy (SEM) were used to characterize the surface of coated and uncoated ammonium nitrate. Meanwhile, the method determined mass ratio of coating layer was improved to achieve more accuracy. In addition, focused ion beam technique was used to determine the thickness of coating layer. The results indicated that by using second coating modification method of surfactant adsorption, the anti-hygroscopicity performance of coated samples was significantly improved. The result showed that the decline of the absorption moisture rate was 40.57%, and the mass ratio of the coating layer was 1.42%. These results suggest that the second coating process employed could provide the well fundamental for the further anti-hygroscopic surface modification of ammonium nitrate particles coated by surfactants.
As electronic technology swiftly progresses, conventional epoxy resins can no longer fully meet the demands of copper-clad laminates (CCLs). To develop an epoxy resin exhibiting superior thermal performance, low dielectric properties, and reduced moisture absorption, low-molecular-weight TMBPA-MPPO-2OH was successfully synthesized using TMBPA and DMP as comonomers. The molecular structure of TMBPA-MPPO-2OH was comprehensively characterized by FT-IR and 1 H NMR spectroscopy. Subsequently, the synthesized monomer was employed to modify epoxy resin E51 in combination with 4,4′-diaminodiphenylmethane (DDM). Modified epoxy resin composites (E51/DDM/TMBPA-MPPO-2OH) were prepared through a casting method, with TMBPA-MPPO-2OH and E51 mixed in varying mass ratios. The effects of TMBPA-MPPO-2OH incorporation on both the curing kinetics and final characteristics of the modified epoxy resin systems were systematically investigated. Results showed that E51/DDM/TMBPA-MPPO-2OH composites possessed a high glass transition temperature (T g = 178.77 ~ 194.16°C), along with excellent thermal stability (T d5% = 355 ~ 360°C) and flexural strength (67.31 ~ 75.28 MPa). Additionally, the inclusion of TMBPA-MPPO-2OH reduced the dielectric constant, dielectric loss tangent, and moisture absorption rate of E51/DDM/TMBPA-MPPO-2OH. When the TMBPA-MPPO-2OH content was 20 wt%, the dielectric constant (10 MHz, 3.2), dielectric loss (10 MHz, 0.015), and moisture absorption rate (1.7%) of E51/DDM/TMBPA-MPPO-2OH showed reductions of 16%, 58%, and 32%, respectively, compared to the pure epoxy resin.
Four carbon fiber reinforced epoxy resin composites (CFRPs), CF/EP, CF-COOH-EP, CF-COOH/MXene/EP and CF-CONH-MXene-EP, were prepared and subjected to hydrothermal aging experiments at 55 °C. The changes in structure and mechanical property of these CFRPs, having different interface, before and after the aging were investigated to explore the influence of interface structure on hydrothermal aging of CFRPs. CF-COOH-EP has the highest moisture absorption because of a large number of hydrophilic groups in the interface. The Mxene nanosheets help reduce the moisture absorption rate and equilibrium moisture absorption of CFRPs CF-COOH/MXene/EP and CF-CONH-MXene-EP is similar to that of CF/EP. The aging results in decreases of storage modulus and temperature at maximum tan δ, but the different interface structures show little influence on them. The inter-laminar shear strength (ILSS) presents a fast decline in the early aging and a gradual decrease at the following stage. The interface structure has an influence on the hydrothermal aging of the CFRPs and results in different ILSS changes. Among the four CFRPs, CF-COOH-EP presents the fastest hydrothermal aging corresponding the lowest ILSS retention rate and CF-CONH-MXene-EP keeps the highest ILSS after aging exhibiting the highest reliability.
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