Effects of different interfacial modifiers on the properties of digital printing waste paper fiber/nanocrystalline cellulose/poly(lactic acid) composites

Abstract Digital printing waste paper fiber/nanocrystalline cellulose/poly(lactic acid) composites, modified through γ‐methacryloxy propyl trimethoxy silane (KH570), isopropyl tri(dioctylpyrophosphate) titanate, sodium hydroxide, polyethylene glycol 6000 (PEG6000), and a composite silane coupling agent (KH570/PEG6000), were fabricated by melt blending and injection molding, and the effects of different modifiers on the properties of composites were studied. The results show that the mechanical properties of the modified composites were improved, and the best flexural strength, tensile strength, and impact strength were obtained by PEG6000, KH570/PEG6000, and KH570, respectively. Thermogravimetric analysis showed that the thermal decomposition performance of the composites treated by KH570 was relatively superior. Differential scanning calorimetry analysis demonstrated that the melting enthalpy and crystallinity of the modified material increased, while the cold crystallization temperature decreased. After modification, both water absorption and degradation showed a decreasing trend, especially KH570/PEG6000. Under the action of several modifiers, the diffusion coefficient, thermodynamic solubility, and permeability of composites were reduced to varying degrees. Furthermore, scanning electron microscopy demonstrated that interfacial adhesion and composite compatibility were improved with significantly fewer and smaller pores, as well as a fuzzy boundary among the three phases.