ABSTRACT
The average molecular weight (M) of a polymer is the product of the average number of repeat units or mers expressed as the degree of polymerization (DP) times the molecular weight for the repeating unit. This chapter explains the relationship between molecular weight and polymer physical properties. While a value of the threshold molecular weight value (TMWV) is essential for most practical applications, the additional cost of energy required for processing extremely high-polymer molecular weights is seldom justified. Certain mass spectral (MS) procedures allow the determination of the molecular weight or molecular mass of oligomeric to polymeric materials. In matrix-assisted laser desorption/ionization mass spectrometry (MALDI MS), the polymer is dissolved, along with a "matrix chemical", and the solution deposited onto a sample probe. Recently, MS combinations have been available, including the thermal gravimetric-mass spectrometry (TG-MS) combination developed by Carraher that allows the continuous characterization of evolved materials as a polymer undergoes controlled thermal degradation.
