Process Optimization through Designed Experiments to Achieve Consistency in Output Color of a Compounded Plastic Grade

ABSTRACT

Plastics compounders need to understand the relationship between process variables and output color and know the optimal process conditions to achieve consistency in output. Such a relationship and optimal processing conditions are investigated for a polycarbonate resin-based plastic grade using a Box-Behnken design of response surface. This study analyzes and discusses the results of designed experiments and highlights individual and combined influences on output color of three process parameters: temperature, screw speed, and feed rate. Experimental results verify the fitness of the statistical model employed. This study suggests five sets of processing conditions ensuring consistency in output color of the plastic grade.

KEYWORDS:

• CIELab 1976
• color pigments
• design of experiments
• design robustness
• injection molding
• POE
• spectrophotometer
• statistical methods
• twin-screw extruder

ACKNOWLEDGMENTS

The authors acknowledge the staff at SABIC IP Cobourg Plant, Canada for their help with the experimentation and data collection.

FUNDING

The authors wish to acknowledge financial support provided by SABIC IP and NSERC.

ABOUT THE AUTHORS

Shahid Ahmed is a Ph.D. candidate in mechanical engineering at University of Ontario Institute of Technology. He is a recipient of NSERC graduate research award. His current area of research is investigation of various scientific reasons that cause color processing mismatch issues in compounded plastics. Main focus during his research has been to optimize processing conditions so as to achieve consistency in plastics coloration. In his investigation, he has successfully employed techniques such as statistical methods, material characterization, and numerical simulation of compounding process.

Jamal Al-Sadi is a Ph.D. candidate in mechanical engineering at University of Ontario Institute of Technology. His current area of research is investigation of various scientific reasons that cause color processing mismatch issues in compounded plastics. In his research he has successfully employed techniques such as design of experiments, datamining, and rheological characterization of materials.

Usman Saeed is a lecturer and post-doctoral fellow at University of Ontario Institute of Technology. He received his Ph.D. degree in materials science from University of Vienna, Germany. His area of research is related to development of composites.

Ghaus Rizvi is an associate professor at University of Ontario Institute of Technology. He received his Ph.D. degree in mechanical engineering from University of Toronto. His current area of research is related to wood-plastics composites, compounding of plastics, and making of glass fibers by electro spinning technique.

Daniel Ross is a graduate in engineering physics from McMaster University and is a certified project management professional (PMP). He is associated with SABIC Innovative Plastics since 2003. His current assignment at SABIC Innovative Plastics Cobourg Plant Canada is Asset Operations Leader. He is one of the key coordinators for SABIC-UOIT collaboration project funded by both NSERC and SABIC.

Richard Clarke is a senior extrusion specialist for cast polypropylene (CPP) product line at SABIC Innovative Plastics Cobourg Plant Canada. His assistance and guidance was the success key for UOIT grad students in planning and execution of their experimentation.

James Price is an imminent color expert at SABIC Innovative Plastics, Cobourg Plant, Canada. He was a great help in gathering color data of various investigated plastics grades, and in executing experimentation.