Broadly speaking,
Broadly speaking,
composite materials include all structures composed of two components. Composites with polymers as the matrix contain at least one kind of high molecular resin and another filler. For example, plastic composites filled with glass fibers, due to the interaction between the resin and the interface, show a surprising increase in strength, and are therefore called reinforced plastics, commonly known as glass fiber reinforced plastic. Synthetic fibers such as carbon fiber and boron, and even metal wires can also be used as fillers for reinforced plastics. In addition to fibers, fillers can also have other forms and compositions, such asdery calcium carbonate, metal oxides, silica, asbestos, etc. According to the type and form of the filler, composites can have special properties. The of the composition, structure, properties and processing of composites has formed an independent composite material edge discipline in the field of materials science, and has achieved rapid development in theory and practice. Composite packaging materials are somewhat different from the above-mentioned reinforced plastic composites. Composite packaging materials are a multi-layer structure formed by combining several different base materials through technologies such as lamination, extrusion coating, and co-extrusion, in order to meet the requirements of transportation, storage, sales, etc for packaging functions and the special requirements of certain products. Of course, from a broad perspective, this multi-layer structure also belongs to the category of composites. For, the previous fried potato chips were packaged in paper bags, and had to be sold immediately after production, because moisture would make it soft, oxygen would make it sour and the oil in the potato chips would seep into the packaging paper. Wax paper was once used to improve the moisture resistance of packaging paper, which was the first-layer structure. However, the improvement of a single base material is very limited. Today, fried potato chips and countless other foods can be transported over long distances and stored months, because the packaging formed by the multi-layer structure can effectively play the functions of dustproof, stainproof, gas barrier, fragrance preservation, transparency (or openess), ultraviolet resistance, decoration, printing, and easy mechanical processing and sealing. Many modern packaging technologies, such as vacuum packaging, gas replacement packaging, packaging deoxidizer sealed in, packaging of dried food, aseptic filling packaging, steaming packaging, and liquid hot filling packaging, are closely related to the development application of composite packaging materials. The development of new multi-functional composite materials and their packaging technology is an important direction for the development of modern packaging engineering disciplines
