... nB is the number of bonds; N, Avogadro's number; l,, the length of the repeat unit; and V, the molar volume The theoretical brittle stress is then the number of bonds times the strength of an ... dependence of a polymer is strongly related to the entanglement molecular weight Above 2Me, the viscosity of the melt increases as the 3.4 power of the molecular weight In the glass, the mechanical ... can be calculated from only four basic molecular properties These are the molecular weight, van der Waals volume, length of the repeat unit, and the Tgof the polymer Since these properties are based...