Nitrocellulose optical properties

Most of over six million dentures produced annually in the USA are made of acrylics (PMMAs) that includes full dentures, partial dentures, teeth, denture reliners, fillings and miscellaneous uses. Plastics have been edging into the dental market for over a half century. Even before the introduction of acrylics to the dental profession in 1937, nitrocellulose, phenol-formaldehyde and vinyl plastics were used as denture base materials. Results, however, were not wholly satisfactory because these plastics did not have the proper requisites of dental plastics. Since then, PMMAs have kept their lead as the most useful dental plastics, although many new plastics have appeared and are still being tested. Predominance of PMMAs is not surprising, for they are reasonably strong, have exceptional optical properties, low water absorption and solubility, and excellent dimensional stability. Most denture base materials, therefore, contain PMMA as the main ingredient. 

Optical properties of nitrocellulose Electrical properties of nitrocellulose lateraturc... 

Like cellulose, nitrocellulose demonstrates optical anisotropy (double refraction) which is regarded as one of the facts confirming the microcrystalline structure of the substance. A relationship between this property of nitrocellulose and the nitrogen content has been discovered by Ambronn [127] who studied the double refraction of cellulose. Differences in the refractive index for rays of different wavelengths in two directions at right angle are of the order —0.50 x 10-3 to +2.8 x 10"3 (Table 60). 

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