Mechanical and Other Properties of WPC

In the 1980s, more attention has been increasingly paid to improving the physical properties, such as mechanical strength, stiffness, resistance to thermal deformation, and so forth, of the fiber-plastic composite products. It was recognized that moisture in cellulosic fiber leads to steam formation in the compounder and the extruder, increases porosity of the final product and decreases its density, accelerates the oxidation of the hot melt during processing, and makes the final product weaker and less durable. 

743 [47] discloses polyolefin-based resin compositions comprising newspaper sheets cut to small pieces (3-6 mm in size, 20-60% by weight of total composite, with 20-40% by weight given in the examples) and thermoplastic polymer such as low-density or HOPE or polypropylene. 

532 [48] describes a thermoplastic resin composition comprising PVC, an ABS resin, and a high amount of wood flour (up to 60% by weight, as given in the examples), pressed at 200°C (392° F) to obtain composite sheets. 

Pat No. 6,527,532 [50] (by Trex Company) discloses a method of making a wood-thermoplastic composite material, according to which the extruded profile is quenched in a nonoxidizing environment, such as water. 

Pat No. 6,578,368 [51] discloses a method for cooling extruded and molded cellulosic-polymer composites, among other plastics and plastic compositions the said method uses cryogenic fluid with a temperature below about 250° F, such as liquid oxygen, liquid nitrogen, liquid neon, liquid hydrogen, and liquid helium. 

---

Nanoflller mineral additives have not shown noticeable improvements in mechanical and other properties of WPC as yet, hence, they are not in commercial use in WPC materials. 

---