Mechanically strong, thermostable, and flame-retardant composites enabled by Brown paper made from bamboo

We design a facile strategy to manufacture a high-performance composite of polyvinyl chloride (PVC) made from brown paper and PVC film. Brown paper with little fiber damage is prepared using bamboo pulping via a moderate method, and a high content of lignin enhances the lipophilicity of the fibers. The "layer-network" porous paper provides "green" framework support. When hot and cold pressing of the stacks of paper sheets and PVC films is performed, PVC resin fills the pores of the framework support, and then, strong mechanical interlocking structures are established, similar to the vastly distributed microscale "mortise riveting". Then, a dense and lightweight paper/PVC composite is produced. The composite exhibits strong mechanical properties in terms of tensile strength (132.65 MPa), flexural strength (183.45 MPa), flexural modulus (10.44 GPa), and internal bonding strength (2.6 MPa), with good thermal stability and flame resistance. The strength is 5- to 10-fold that of commercial artificial boards, substantially surpassing that of bamboo, PVC, and other PVC composite resin profiles. Additionally, PVC replaces adhesives that contain or release formaldehyde, and a high percentage (>60 wt%) of green cellulose fibers is used. The simple technology directly uses existing manufacturing methods of papermaking, film stretching, and press laminating systems. Therefore, the high-performance paper/PVC composite is environmentally sustainable and more cost-effective than PVC composites prepared with other fillers. The new materials have great potential prospects for the development of high-strength materials and the implementation of carbon neutrality in prefabricated houses, furniture, vehicles, ships, containers, and color steel plates.