VCL#61 40 Years of Vibration Assisted Molding

Abstract

In 1973, in the basement of an MIT laboratory started a journey which led to many innovations in the field of processing of plastics, using vibration to modify and enhance the properties of the molded products. First there was vibrated compression molding, which was described as Rheo-cooling, a method to simulate the effect of fast cooling rates across thick samples. Then came Rheomolding, pulsating melts as they were injected into molds, which was initially conceived to decrease melt viscosity and modify the filling flow pattern to obtain orientation or eliminate birefringence (in compact disks). Finally, the vibration was added to an extruder, cross-laterally to the flow direction, more like an added oscillation combined with pressure flow and extensional flow. This was called Rheo-Fluidification, an add-on to extruders capable of extruding melts at 50 to 100 oC below the normal processing temperature, a feature which appeared to be related to a decrease of viscosity due to “disentanglement”. In this review, we also discuss the underlying source of inspiration to these innovations, the quest for understanding the physics of interactions between the polymer chains under conditions of non-linear flow deformation. This quest led to question our understanding of entanglements and may lead to new innovations in the way plastics can be recycled and used as mechanical batteries, storing energy for future use.

Links to download VCL#61 (208 MB; 2h 39 min): inquire at newschoolpolymerphysics@gmail.com

Att: Dr. A. Beltzeki