In this study, green composites were prepared using natural rubber (NR) as the matrix and the sisal microcrystalline cellulose (MCC) as the filler. Three modifying agents oleic acid (OA), γ-aminopropyltriethoxylsilane (KH550), and bis-γ-(triethoxysilylpropyl)-tetrasulfide (Si69) were individually tested to modify the MCC to improve the interfacial compatibility of the NR and MCC. Combined with modern instrumental analysis technology and molecular dynamics simulation, the reinforcing effect and microscopic mechanism of modified MCC on NR were analyzed. The structure-activity relationship of NR and MCC composites was further revealed, and the interaction between the two components was clarified. At the same time, the reinforcing and compatibilizing effect of three kinds of modified MCC in NR matrix were also revealed. The results showed that the properties of NR/Mod-MCC composites were better than those of NR/MCC composites, where NR/OA-MCC presented the highest tensile strength, followed by NR/Si69-MCC. In addition, NR/Si69-MCC exhibited higher elongation at break and NR/KH550-MCC exhibited higher vulcanization characteristics. Molecular model systems were constructed through molecular dynamics simulation to investigate the interactions between the three modified cellulose molecules and the NR molecules.OA-cellulose has a better interaction with NR than KH550-cellulose and Si69-cellulose, The simulation results were consistent with the experimental results.

Graphite is a thermally conductive filler. However, when dispersed into high density poly(ethylene) (HDPE) resin, graphite particles tend to agglomerate and requires a compatibilizer to achieve desired thermal/physical properties. In this study, oleic acid (OA), a bio‐based additive and polyethylene‐polyamines (PEPA) were used to synthesize a new compatibilizer, PEPA‐g‐OA, containing numerous NR2 groups. The experimental results showed that PEPA‐g‐OA can significantly improve the compatibility between graphite particles and the HDPE matrix due to uniform dispersion of graphite in the HDPE matrix. When the graphite content was 25 wt%, the thermal conductivity of the composite recorded 1.2 W m−1 K−1 (three times that of neat HDPE) and the volume resistivity was 1.8 × 109 Ω cm, indicating excellent electrical insulation. Compared to the composites with no graphite content, the properties of the composites with 25 wt% graphite content exhibited narrower melting and crystallization peaks, more stable mechanical properties, and higher ultraviolet aging resistance. Synthesized new bio‐based compatibilizer and thermally conductive and electrically insulating composites developed in this study can be useful in different industrial fields for the preparation of the next generation composites.

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The fabrication of composites of two or more materials with different polarities requires the use of compatibilisers to improve interface properties. However, most compatibilisers used for industrial production are derived from the cracking products of petroleum, which is a limited resource susceptible to price fluctuations and pollutes the environment. In this study, a new compatibiliser derived from renewable plant‐oil‐based products, ESO–G–OA, was designed and synthesized using epoxy soybean oil, oleic acid, and glycerol. Scanning electron microscopy results showed that ESO–G–OA can effectively improve the dispersion of CaCO3 in a recycled high‐density polyethylene (reHDPE) matrix and reduce the interfacial gap between the two phases. The analysis of the mechanical properties showed that the ESO–G–OA‐modified composite has higher tensile and impact strength than unmodified samples. The ESO–G–OA modification improved the thermal stability and melt flow of the composite and reduced the energy consumption during processing. Moreover, the excellent compatibility of ESO–G–OA can improve the comprehensive properties of CaCO3/reHDPE composites, compensating for the performance reduction caused by the multiple processing steps necessary to obtain reHDPE. This confirmed that ESO–G–OA has promising application prospects in the production of composites requiring compatibilisers.

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