Composite material reinforcement materials. Another important factor is the gross quantity of material to be produced. Large quantities can be used to justify high capital expenditures for rapid and automated manufacturing technology. Small production quantities are accommodated with lower capital expenditures but higher labour and tooling costs at a correspondingly slower rate. Many commercially produced composites use a polymer matrix material often called a resin solution. There are many different polymers available depending upon the starting raw ingredients. There are several broad categories, each with numerous variations. The most common are known as polyester, vinyl ester, epoxy, phenolic, polyimide, polyamide, polypropylene, PEEK,
Unusual types of gramophone records Ten-inch children's records were made as well, but the 7-inch size was more compatible with small hands. The 7-inch size was also used for flexi discs which were popular in Japan where they were known as sound-sheets and were often in traditional round format. In other areas, flexi discs were usually square and often included in a magazine (see Unusual materials and uses below). Numerous unusual diameters have been produced since the early 1900s ranging from 2 to 19.7 inches. Oddly shaped discs were also produced (see Unusually shaped discs below). The most common rotational speeds for gramophone records are