Tensile Mechanical Behavior of Linear High-Density Polyethylenes Modified With Organic Peroxide

CLAUDIO J. PÉREZ; GUILLERMO A. CASSANO; ENRIQUE M. VALLÉS; LIDIA M. QUINZANI; MARCELO D. FAILLA

POLYMER ENGINEERING AND SCIENCE

JOHN WILEY & SONS INC

Lugar: New York; Año: 2003 vol. 43 p. 1624 - 1633

0032-3888

weights and vinyl contents was modified without altering their thermoplastic characterusing an organic peroxide. Chain linking was the main chemical event that occurredduring the modification process. Samples of these polymers were crystallizedfrom the melt, generating materials with different morphologies. Two crystallizationprocedures were followed: slow cooling and quenching. The density and crystallinityof the polymers were found to be slightly dependent on the molecular structures generatedby the modification process. Tensile tests were performed at room temperatureto evaluate the mechanical behavior of the polymers. The mechanical responseof some of the slowly cooled samples changed from brittle to ductile when increasingconcentrations of peroxide were added to the formulation. All the quenchedsamples displayed ductile behavior. The elastic modulus and yield stress werefound to increase linearly with the crystallinity of the polymers independently of themolecular structure generated by the modification process. The molecular weight ofthe modified polymers appears to be the main structural property that influencesthe draw ratio after break and the ultimate tensile stress of the samples. The drawratio diminishes, while the ultimate tensile stress increases with the molecularweight of the polymers, irrespective of the evolution of other molecular parameters