22G ANNUAL REPORT SMITHSONIAN INSTITUTION, 194 1 



scientific group, and transparent plastic belts and suspenders, shoes, 

 raincoats, and smocks topped the style and fashion group. In the 

 sporting goods, games, and toys classification, model boats, chess- 

 men, and harmonicas of exceptional interest were made of plastics. 

 The shipping, airplane, and automotive industries were all repre- 

 sented in the awards made in the transport group. Special listing 

 was given to the development of resin-bonded plywood, which has 

 expanded the market for this material to cover many outdoor ap- 

 plications, such as home construction, boats, concrete forms, outdoor 

 signs, airplanes, truck and bus bodies, farm silos, and refrigerator 

 cars. 



A consideration of the classification of plastics and of some de- 

 tails of each type will promote a better understanding of what 

 plastics are and why they can take on many important tasks. 



SCOPE OF THE PLASTICS INDUSTRY 



The dictionary definition of plastics as materials which are "readily 

 responsive to shaping influences" does not place a convenient limita- 

 tion upon this field. It implies, but does not state, that the material 

 should maintain its new form when the shaping influences are re- 

 moved. Even this more limited definition of a plastic would include 

 a great variety of materials — from the metals which are readily 

 shaped when heated to the solid rocks of the earth which exhibit 

 zones of flow at great depths because of the pressure of the overlying 

 mass. 



The modern plastics industry deals chiefly with moldable materials 

 manufactured from organic compounds, that is, combinations of 

 carbon with hydrogen, oxygen, nitrogen, and other elements. The 

 inorganic molding materials, such as concretes, cements, and ceramics, 

 and also rubber, an organic substance, are not generally included 

 within the scope of the plastics trade as it is known today, inasmuch 

 as the industries utilizing these materials are considerably older 

 and were already individually organized and developed prior to 

 the advent of the newer plastics. 



Classification on basis of chemical source. — The four principal 

 types of organic plastics are (1) synthetic resins, (2) natural resins, 

 (3) cellulose derivatives, and (4) protein substances. A brief de- 

 scription of each of these groups will serve to indicate to the reader 

 who is unacquainted with this field the essential characteristics of 

 each type and the distribution of the various commercial plastics 

 according to this classification. 



Synthetic resin plastics. — Public interest has probably centered 

 largely upon the synthetic resin plastics because of their multiplicity 

 and versatility. The chemist has been able to produce at will resin- 



