Kinematics, Dynamics, Crystallization, and Thermal Characteristics and Their Relationship to Physical Properties of Blown Film

Understanding the physics relating to the development of blown film physical properties is potentially very important to both the industrial and academic practitioner. This chapter focuses on many of the processes that affect the development of physical properties during production of semicrystalline polymer such as polyethylene (PE) film. The physical properties of PE are frozen into the film as a result of physical crosslinks developed during crystallization. The crystallization of low-density polyethylene is investigated as received from the polymer producer and relative to the influence of a small amount (less than 6%) of high-density PE added to the asreceived resin as a nucleation agent. The process was evaluated by the use of simultaneous online SALS (small angle light scattering) and IR (infrared) temperature measurements to study structure development as influenced by nucleation during tubular blown film extrusion of LLDPE. As the concentration of the nucleation aid HDPE was increased, the observed scattering intensity decreased.