ABSTRACT
Polyethylene crystallizes from the molten state or solution when prevailing conditions make the crystalline state more stable than the disordered one. The processes by which polyethylene crystallizes reflect the properties of the disordered state from which the ordered phase condenses. Thus, for instance, levels of chain entanglement, molecular dimensions, and viscosity all play important roles. The factors affecting the structure of the disordered state are both intrinsic to the molecules and extrinsic to the surrounding conditions. The principal molecular factors are the molecular weight, molecular weight distribution, and concentration, type, and distribution of branches. External factors include temperature, pressure, shear, concentration of solution, and polymer-solvent interactions.
