For supplying information not obtainable by the usual methods, the microscope is useful and often essential; not only will it disclose details which would otherwise be unseen, but by its unique methods of examination measurements of certain properties of materials can be readily secured which are not otherwise obtainable. When one considers the value of the microscope to the rubber industry specifically, the study of the size of particles is usually the first and frequently the only application which comes to mind, although other uses have been suggested and described. The present paper not only describes the importance of the microscope in determining particle size and shape, but also covers its applications in the solution of other problems which ordinarily are not considered to lie in the field of microscopy. [Chamot describes many interesting applications in different industries which indicate the unusual capabilities of microscopic methods.] In a well-organized industrial laboratory, the microscope is used to supplement and aid other methods for examination of raw materials, control of factory processing, correlation of physical properties with service performance, and solution of factory difficulties. The specific examples cited in this paper represent uses which have originated in connection with the manufacture of rubber goods, but they serve also to illustrate methods applicable to problems of the same type originating in other industries.
THE possibility of seeing pigment particles in a rubber stock has always been a desire of rubber chemists. There has been a natural belief that if the particles in rubber could actually be observed with a microscope more could be learned about their action and properties. The main difficulty in attaining this end lies in the preparation of sufficiently thin sections. For clear observation of highly loaded gas-black stocks the sections must be less than 1 micron thick. For bright-field work with light-colored or colorless pigments, such as litharge and zinc oxide, the sections may be somewhat thicker. However, if the examination is to be made with dark-field illumination the sections for even the colorless pigments must again be very thin. Several methods have been proposed and utilized for making thin sections, and the names of Dannenberg (2), Depew (3), Green (4), Grenquist (5), Hauser (7), Moore (11), Pohle (9), Ruby (3), Spear (11), and Walton (12) are identified with the skilful manipulation which is necessary for achieving the desired result. There have been many other workers in this field, including Weber (13), Breuil (1), Loewen (8), Regnaud (10), and Hardman (6). The method to be described was developed in this laboratory in 1926. It has been used continually since that time and has proved valuable in the study of rubber compounds and pigments. While it bears a slight similarity to some of the other methods, it has certain unique and distinct advantages of its own.
scite is a Brooklyn-based organization that helps researchers better discover and understand research articles through Smart Citations–citations that display the context of the citation and describe whether the article provides supporting or contrasting evidence. scite is used by students and researchers from around the world and is funded in part by the National Science Foundation and the National Institute on Drug Abuse of the National Institutes of Health.