Advanced production control of thermoplastic vulcanizates

Kim Choo, Mehdi Sheikhzadeh, and Milana Trifkovic report on a study they have undertaken on advanced production control on thermoplastic vulcanizates.

Extrusion of blends of plastic and vulcanized rubber benefits from multivariable model-based predictive control.

Blending uncured ethylene propylene diene monomer (EPDM) rubber with polypropylene (PP) plastic produces thermoplastic polyolefin (commonly known as TPO), while blends of PP and dynamically vulcanized
EPDM rubber are referred to as thermoplastic vulcanizates (TPVs).1 Dynamic vulcanization is a reaction that involves curing agents and a plastic/rubber mixture in which elastomer crosslinking proceeds simultaneously with blending of the thermoplastic component.

In turn, this leads to changes in the morphological structure of PP/elastomer blends. One of the most practical ways to produce TPVs is by extrusion. Since dynamic vulcanization occurs during mixing, TPV manufacturing in an extruder is referred to as reactive extrusion.2 The extrusion process follows a standard setup, including a feeding section, a barrel and screw, and a head with a die for shaping. In the feeding section, the solid polymer is fed into the extruder through a hopper in the form of pellets or irregular small bits. The barrel wall is equipped with a number of electric heaters and liquid cooling channels, which melt and control the polymer’s temperature.

The full report including more graphis and further details can be downloaded here: Advanced production control of thermoplastic vulcanizates

The experimental results demonstrate that inferential control of influential variables through MPC maintains the product quality (crosslink density) within the desirable range.The research team will continue to work on optimizing product quality through better process control.

The results of this research is especially important for cockpit systems - not only in the automotive industry but also for aircrafts.