Effect of the Temperature on the Tensile Mechanical Behavior of Irradiated Linear Polyethylene

ENRIQUE M. VALLÉS; MARCELO D. FAILLA

JOURNAL OF APPLIED POLYMER SCIENCE

JOHN WILEY & SONS INC

Lugar: New York; Año: 2003 vol. 88 p. 1925 - 1935

0021-8995

The mechanical behavior of two
-irradiatedlinear polyethylenes was determined at 75 and 105°C undertensile stress. Each polymer was crystallized from the meltafter different thermal histories so that samples would beobtained with various degrees of crystallinity. Subsequently,they were irradiated in vacuo and at room temperature tototal doses ranging from 20 to 200 kGy. The initial crystallinity,dose level, and test temperature determined whetherthe samples displayed ductile, brittle, or transitional behavior.The yield stress decreased as the temperature increased.The value of the yield stress at a given temperature showeda tendency to increase with dose; this became more evidentas the initial crystallinity increased. The extensibility of ductilesamples, estimated from the draw ratio after break,decreased with the gel content. For ductile samples, thetemperature affected the values of this property when thegel fraction that developed in the samples was relativelylow. The effect of temperature became less noticeable whenthe gel reached values larger than 60%. The ultimate stress,normalized with the crosslinking density, correlated withthe draw ratio after break in a way that resembled the typeof relationship observed in other crosslinked systems