The mechanical and thermal properties of epoxy were significantly enhanced modified by H20-g-PDI.

No abstract

In this study, microcrystalline cellulose fibers (MCFs) derived from sisal were treated with a hyperbranched aromatic polyamide (HBAP). The modified sisal fibers were used to produce composites with epoxy resins.Firstly the MCFs were treated with a silane coupling agent, then a HBAP was grown on the modified surface.The HBAP-MCFs were used to reinforce epoxy resins. The HBAP-MCF/epoxy composites were studied by Fourier transform infrared spectroscopy (FT-IR), scanning electron microscopy (SEM), thermal gravimetric analysis (TGA), dynamic mechanical analysis (DMA), and mechanical properties analysis. The results show that the HBAP-MCFs enhanced the thermal and mechanical properties of the epoxy resin. For instance, the impact strength, tensile strength, Young's modulus and toughness of the HBAP-MCF/epoxy composites with 2.0 wt% HBAP-MCFs were 32.1 kJ m À2 , 59.4 MPa, 695 MPa, and 4.37 MJ m À3 . These values represent improvements of 83.4%, 34.7%, 25%, and 178.3%, respectively, compared to a neat epoxy resin. Moreover, the addition of HBAP-MCFs produced composites with higher thermal degradation temperatures and glass transition temperatures. The HBAP-MCF swere effective in improving the thermal and mechanical properties due to a strong affinity between the fillers and the matrix.

In this report, we synthesized a new kind of liquid-crystal perylenebisimide polyurethane (LCPBI).Noncovalently functionalized reduced graphene oxide (RGO) with LCPBI was prepared via p-p stacking interactions. The noncovalently functionalized graphene nanosheets (LCPBI/RGO) were used to improve the thermal properties of epoxy composites, with modified Al 2 O 3 nanoparticles (Al 2 O 3 -APS) which were grafted with a silane coupling agent . We demonstrated that the thermal conductivity of the epoxy composites could be improved by hybrid LCPBI/RGO and Al 2 O 3 -APS fillers. For instance, the thermal conductivity of the epoxy composite with 30 wt% Al 2 O 3 -APS and 0.3 wt% LCPBI/RGO was 0.329 W m À1 K À1 , increased by 105.6% compared to that of the pure epoxy (0.16 W m À1 K À1 ). Meanwhile the glass transition temperature and storage modulus of epoxy composites with increasing hybrid fillers was improved, as well as the a-relaxation apparent activation energy.

In this study, the nanocomposites are prepared which used polyamide 6 (PA6) composite as matrix, melamine cyanurate (MCA) as fire retardant and attapulgite (AT) as synergistic agent. The mathematical model between MCA content, AT content, and limited oxygen index (LOI) is established by multiple linear regression fitting. The polymer materials are characterized using Fourier transform infrared spectroscopy, X-ray diffraction, Thermogravimetric Analysis, and scanning electron microscopy. Through response surface methodology, the important variables (polymerization time, the content of MCA, and the content of AT) affecting the mechanical strength of composites are modeled. Results demonstrate that when the t is 0.6 h, the AT content is 6.2%, and the MCA content is 11.5%, the mechanical properties of the PA6/MCA/AT composite are up to 44.81 MPa, and the sample passes the UL-94 V-0 flammability rating, and the LOI reaches 27.9%. Therefore, polymers with highly effective flame retardancy and optimal mechanical properties are prepared.