1. Overview of Wood-Plastic Composites and Uses

A composite material is made by combining two or more materials to give a unique combination of properties. The above definition is generic and can include metal alloys, plastics, minerals, and wood. Fiber-reinforced composite materials differ from the above materials in that the constituent materials are different at the molecular level and are mechanically separable. In bulk form, the constituent materials work together but remain in their original forms. The final properties of composite materials are better than constituent material properties.

The concept of composites was not invented by human beings; it is found in nature. An example is wood, which is a composite of cellulose fibers in a matrix of natural glue called lignin. The shell of invertebrates, such as snails and oysters, is an example of a composite. Such shells are stronger and tougher than man-made advanced composites. Scientists have found that the fibers taken from a spider’s web are stronger than synthetic fibers. In Korea, India, Greece, and other countries, husks or straws mixed with clay have been used to build houses for several 100 years. Mixing husk or sawdust in a clay is an example of a particulate composite and mixing straws in clay is an example of a short fiber composite. These reinforcements are done to improve performance.