Research Projects

Konrad Mulrennan


Soft sensor modelling of a Polylactide (PLA) twin screw melt extrusion process

Polylactide is a biodegradable polymer which is currently of research interest across a multitude of industries including medical devices, food packaging and waste packaging. However, all of these industries face challenges in melt processing of Polylactide due to its poor thermal stability which is influenced by processing temperatures and shearing. The characterization of the processed products takes place offline in laboratory environments. This can result in the manufacturer completing full production runs while having no knowledge on whether the product is in or out of specification. As a result, typical scrap rates of a Polylactide medical grade product can be up to 25-30%. The aims of this project is to enhance the process control of melt processing of PLA and develop soft sensor models which can indicate changes in key end product material properties – which are currently assessed offline – in real time using available system data. The ability to predict these properties from processing data would prove a significant advancement in the development of PLA products. These models will act as novel inline indicators as to whether products will be in or out of specification. This will reduce manufacturing costs and minimize waste as well as accurately predict future performance and behavior of products. This work aims to eliminate many of the issues faced by manufacturers in developing products by increasing the speed to production while eliminating high scrap rates associated with the development of the products created from these biopolymers.


Konrad Mulrennan, Darren Whitaker, Elina Talvitie, Inari Lyyra, Tuija Annala, Minna Kellomäki, Marion McAfee. Development of a soft sensor to predict the molecular weight of Polylactide (PLA) in a melt extrusion process. Presented at the 22nd annual Bioengineering in Ireland conference, Salthill, Ireland, 2016.

Konrad Mulrennan, Darren A. Whitaker, Fraser Buchanan, Mark Billham and Marion McAfee. The determination of optimal processing conditions for PLA and PLA/CaCO3 in twin screw extrusion using DoE and multivariate analysis. Presented at The 8th European Symposium on Biopolymers, Rome, Italy, 2015.

Konrad Mulrennan, Fraser Buchanan and Marion McAfee. Modelling and Control of Bioresorbable Polymer Processing. Presented at the 20th annual Bioengineering in Ireland conference, Limerick, Ireland, 2014.

Darren A. Whitaker, Konrad Mulrennan, Inari Lyyra, Elina Talvitie, Minna Kellomaki and Marion McAfee. In-situ monitoring of thermal degradation during melt processing of PLA. Presented at The 8th European Symposium on Biopolymers, Rome, Italy, 2015.

Darren A. Whitaker, Konrad Mulrennan, Fraser Buchanan, Domhnall Lennon, Mark Billham and Marion McAfee. Inline monitoring of the degradation of bioresorbable polymers for the medical device industry. Presented at 15th Annual Research Conference, Sligo Regional Hospital, Sligo, Ireland, 2014.


Polymer Processing Research Centre, Queens University Belfast
Scaffdex Oy, Finland
Applied Polymer Technology Gateway, Athlone Institute of Technology
Department of Life Sciences, Institute of Technology Sligo