ABSOLUTE MOLECULAR WEIGHT DISTRIBUTION OF NITROCELLULOSE

Abstract

Being one of the oldest known polymers, nitrocellulose has been the subject of study for over a century. It was initially used solely for military purposes; however, since the end of World War I its usage has expanded into the fiber and coatings industries where it has been a mainstay to the present day [1, 2]. General interest in the molecular weight characterization of nitrocellulose may be classified into two categories. The firstand more obvious reason for the relevance of this parameter is that the molecular weight and molecular weight distribution profoundly influence the properties of the product and affect the processability of the material, For instance, the molecular weight (hence, the viscosity of this material) is one of the most important factors that needs to be considered in the determination of the nonvolatile content in lacquers [21]. The second reason is that it is a soluble derivative of cellulose, for which direct molecular weight determination is problematic due to solubility difficulties. Thus, nitrocellulose, barring degradation during nitration, has been utilized as a practical means of indirectly arriving at the molecular weight distribution of the starting cellulose. Very closely tied with this second interest is the focus on the conformation of nitrocelluloses with different degrees of substitution. This piece of information has been a major source of questions related to the methodology of calibration when gel permeation chromatography (GPC) was chosen for molecular weight determination.