2.7 covering Materials Various kind

2.7 covering Materials
Various kinds of coverings are used for each method because each method has its own
specific characteristics (see Fig .2.2). In the descriptions that follow and differences between
production methods and detailed characteristic structures, such as low and high density and
linear low density, are not mentioned, because durability and economic aspects are beyond
the scope of this book.
There are mainly two ways to classify films. One is based On their components and
production method, and the other is based on their physical properties such as reflectivity
and permeability. In the classification based on the use components, the such of abbreviations
is popular. PVC (Polyvinyl chloride) and PE (Polyethylene) films are two predominant films
used for almost all methods. Others are EVA (Ethylene vinyl acetate), EVOR (Polyethylene vinyl alcohol), PP (Polypropylene), PETP (Polyethylene telephtalate), FRP (Fiber reinforced plastic), FRA (Fiber reinforced acrylic), PMMA (Polymethyl methacrylate) and PC (Polycarbonate).