John Scheirs is a polymer research specialist with broad interests in polystyrenes and styrenic copolymers.  He is the principal consultant with ExcelPlas, a polymer consulting company.  John was born in 1965 in Melbourne and studies applied chemistry at the University of Melbourne.  He has worked on projects concerning the fracture, stress cracking, processing, characterization and recycling of styrenic polymers.  John has authored over 50 scientific papers, including 8 encyclopedia chapters, and a number of books on polymer analysis and polymer recycling. Professor Walter Kaminsky studied chemistry at the University of Hamburg. Since 1979 he has been a full professor for technical and macromolecular chemistry at the University of Hamburg. He supervises a group of 20 students and scientists in the field of metallocene/MAO catalysis and a group in the field of recycling of plastics and scrap tires by pyrolysis. He was President of the Gesellschaft Deutscher Chemiker (GDCh), Hamburg section, Dean of the faculty of chemistry at the University of Hamburg, Director of the Institute for Technical and Macromolecular Chemistry, and is a member of the GDCh, DECHEMA, Naturforscher und Ärzte, Verein deutscher Ingenieure, and American Chemical Society. He has published more than 200 papers/books and holds 20 patents. He has organized several international symposia in the field of olefin polymerization and pyrolysis of polymer wastes. He is advisor for authorities and companies in the fields of metallocene catalysts, polymerization of olefins, and recycling of plastics and environmental protection.