Application of Ultrasonics to the Characterization of Composites: A Method for the Determination of Polyethylene Density
Polyethylene (PE) is the most fundamental plastic, scientifically because of its simple structure and commercially because of its low cost and interesting balance of properties. Basically, the structure is that of long chains of -[CH2 — CH2]- units. Actually, the details of the structure, such as the average chain length, or molecular weight and the distribution thereof, the presence of side groups (branching), etc. can be adjusted by controlling the polymerization process. This allows to fabricate different grades of polyethylene, which in turn, have specific properties. The spectrum of applications for PE is extremely broad: packaging (from garbage bags to milk pouches), household construction (from plumbing to water vapor insulation), general facilities (from gaz tubing, electrical insulation to chemical containers), automotive industry (car bumpers to gazoline tanks, wear plates, gears and bearings). In order to take advantage of the versatile character of PE, it is of primary importance for the producer and also for the processor to have means and methods of characterizing the material in a representative manner.
KeywordsShear Velocity Volume Content Average Chain Length Crystalline Lamella Wear Plate
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