![Sample our Physical Sciences journals, sign in here to start your FREE access for 14 days]({"type":"image" , "src" : "/sda/110819/TOC-Subject-Sample-2021-Physical-Sciences.jpg"})
Abstract
Many normally ductile semi-crystalline polymers, such as polyamide-6 (or 6,6) (Nylon), high density polyethylene (HDPE), and isotactic polypropylene (iPP) are known to be brittle under impact loading.
Some general principles for improvement of toughness of semi-crystalline polymers that rely on the reduction of plastic resistance of the cavitated matrix are presented. As typical cases, the mechanisms of the dramatic toughness jumps achievable in both Nylon and HDPE through the incorporation of either flexible rubbery particles or rigid CaCO3 particles are discussed. In both cases these result in the establishment of a material component of reduced plastic resistance in the form of a layer of oriented crystallization of well-defined thickness around the particles. The toughness jumps occur when the average interparticle ligament thickness is reduced below a critical value, specific to the particular polymer, and the component of reduced plastic resistance percolates through the structure.
ACKNOWLEDGMENTS
The author is especially grateful to Profs. Ali S. Argon and Robert E. Cohen (MIT, Cambridge, MA) for much encouragement and numerous stimulating discussions and for plenty of other collaboration during the stay at MIT. Special thanks are also due to Dr. Mark Weinberg (Du Pont Co.) for supplying blend samples and help in their characterization, and to Dr. T. Kowalewski (Washington University, St. Louis, MO) for support on AFM observations. The author also gratefully acknowledges discussions with Dr. Orhun Muratoglu (Massachusetts General Hospital, Boston, MA).