Study on the Flexural and Water Absorption Properties of Mixed Office Wastepaper/Recycled-PP Composites

How to use the waste printing and packaging materials such as wastepaper, and waste plastic effectively has received considerable attention from the printing and packaging industry in recent years. In this paper, mixed office wastepaper (MOW) and recycled polypropylene (rPP) were used as the main raw materials to product composite materials by hot press molding process. The composition and morphology of MOW fiber, flexural properties, water absorption, and interfacial properties of composites were analyzed. The results found that MOW fiber mainly included cellulose, hemicelluloses, inks, and a certain amount of CaCO3 filler, which can be used as reinforcement for wood-plastic composites (WPC). The maximum flexural strength (FS) of the composite with 30 wt% fibers increased by 65 % compared to rPP. The flexural modulus (FM) increased with the increasing of the fiber loading. With the increasing of the fiber content and the immersion time, the water absorption of the composites increased gradually. The water absorption rate tended to stability after soaking 150 h. The FS of the composites filled by 35 wt% MOW fibers decreased 14 % approximately after soaking two weeks. Scanning electron microscopy (SEM) found that when the MOW fiber content was 30 %, the composites had good interfacial performance.