Jobs in aeronautics also pay less than other engineering jobs, which may be why nearly half of engineers who major in aeronautics work in another industry, according to data from the American Institute of Aeronautics and Astronautics. Two other factors will influence the number of aeronautics job opportunities.
The basic binding materials in plastic are resins, which undergoes polymerization and condensation reactions during the preparation of plastic. There are two types of plastics, thermoplastics and thermoset plastics. Examples of thermoplastics include polythene (PE), polypropylene (PP), polyvinyl chloride (PVC), polytyrene (PS), nylons, and polytetrofluoro ethylene (PTFE or Teflon). Examples of thermoset plastics include phenolic resins, amino resins, polyester resins, silicon resins, epoxy resins, and polyurethanes. This handbook discusses the types, properties, uses, and advantages of thermoset plastics.
 The properties of a particular plastic depend on what the polymer chains look like, how they are bonded to each other, and which additives have been introduced.  There are two groups of plastics: Thermoplastics, which melt when heated and can be remolded easily.Thermosets, which can't melt or be remolded.ne of the most common is the plastic grocery bag. Polyethylene is made from just ethylene monomers-but it's also possible to create polymers from two or more different monomers. You can make hundreds of different polymers depending on which monomers and catalysts you use.