Formation of Structure of Highly Filled UHMWPE Composites under Conditions of Intensive Mechanical Activation for Radiation Protective Materials

Abstract

The structural changes of the ultrahigh molecular weight polyethylene (UHMWPE) filled by 70 wt.% of the ultradisperse mechanocomposites Fe/M (M = HfC (12 об.%), TiC (26 об.%), TiB2 (27 об.%), B4C (51 об.%)) and activated by the treatment in the spherical ball mill, as well as when compacting of the filled mechanically activated polymer powder by hot pressing were studied by FTIR spectroscopy. It was shown that no significant changes occur in the molecular structure of unfilled UHMWPE during mechanical treatment with a low dose of mechanical energy (Dа ≤ 0.84 kJ/g). The change of the shape of powder particles is associated with the segmental mobility of macromolecules. The introduction of the filler leads to the formation of the interphase zone “polymer–filler” with a branched polymer structure. The degree of crystallinity (χ) of mechanically activated filled polymer powders with a dose Dа = 0.21 kJ/g is decreased relative to the mechanically activated unfilled UHMWPE with a dose Dа = 0.84 kJ/g from 44 to 25–40 vol.% depending on the nature of the filler. The oxidative destruction of the polymer during mechanical activation does not occur. The degree of crystallinity of UHMWPE of filled mechanically activated powders is increased to χ = 35–45 vol.% after hot pressing, but this value is 1.6 times lower than for the compacted unfilled UHMWPE. During hot pressing, the insignificant oxidation of the polymer occurs.

Keywords

• mechanical activation
• mechanocomposites
• ultrahigh molecular weight polyethylene
• filled polymers