Mechanical properties and size stability of wheat straw and recycled LDPE composites coupled by waterborne coupling agents

In this study, two novel coupling agents (CAs) were used for manufacturing wheat straw (WS)/recycled low density polyethylene (LDPE) composites, one being waterborne polyacrylate latex (PAL), the other being blend prepared from polymethylene polyphenylene isocyanate (PAPI) and the PAL. The effects of the PAL components, the ratio of PAPI/PAL, the loaded content of the CA composed of PAPI and PAL, and the ratio of WS/recycled LDPE on the mechanical properties and thickness swelling stability of the composites were investigated. The PAL could improve composite quality, while the CA composed of PAPI and optimized PAL resulted in a more significant improvement. As the loaded content of the CA with PAPI/PAL of 30/70 was 4.5 wt%, the composite behaved the maximum internal bonding (IB) strength and the IB strength after soaked in boiling water for 2 h (2 h WIB). IB strength were significantly enhanced with WS content ranging from 90 to 40 wt%.