Characteristics of undeinked, alkaline deinked, and neutral deinked old newspaper fibers reinforced recycled polypropylene composites

The properties of old newspaper fibers (ONPF) reinforced recycled polypropylene (rPP) composites (ONPF/rPP) have been studied. The effect of alkaline and neutral deinking treatments of ONPF was investigated. The tensile and flexural strength of ONPF/rPP composites were significantly improved when compared to the neat rPP. Composites from neutral deinked fibers showed slightly better mechanical strength than that reinforced by alkaline deinked fibers. The effect of the ONPF deinking treatment on the water absorption of the composites was notable. Thermogravimetric analysis revealed that deinked ONPF/rPP composites had lower thermal stability. Differential scanning calorimetry showed deinking treatment reduced the degree of crystallinity of composites as compared to the undeinked composites. X‐ray diffraction was used to characterize the crystallization structures of composites. Scanning electron microscopy micrographs of 20 wt% ONPF/rPP composites showed well fiber dispersion in the matrix. Interfacial adhesion was decreased in the deinked samples due to removal of ink particles. POLYM. COMPOS., 39:3537–3544, 2018. © 2017 Society of Plastics Engineers