Because of the war, and the fact that the Japanese controlled the plantations, much work on synthetic substitutes began. Much of this work was done here at the University of Illinois. Several types of synthetic rubbers were made. For some purposes they are better than natural rubber, but, for others, not as good. In any case, use of natural rubber is greater today than at any time in the past.
Natural rubber is the best for airplane tires and is also important in radial tires.
Synthetic rubber is made from petroleum derivatives, which is a problem for the future. Another major future concern is that the rubber plants in Southeast Asia are susceptible to the fungal disease that decimates rubber production in South America. At some point the disease is bound to get there. That will cause major problems for the economies of several countries. Because of the problems of W. W. II, another approach was to search for new sources of rubber.