Dielectric study of surface modification of linear low density polyethylene treated with chromic acid and sodium carbonate

Abstract

The relative permittivity (<img src='/image/spc_char/italics_e.gif' border=0>') and dielectric loss (<img src='/image/spc_char/italics_e.gif' border=0>'') of linear low density polyethylene (LLDPE) sample of 60 μm thickness treated successively with a highly oxidizing environment like chromic acid of normality N/5 to N/30 for time duration of 0.5 to 12 hr and sodium carbonate for 24 hr are measured using GRA 650A impedance bridge over 100 Hz to 10 kHz range at 303.16±1K. The N/10 chromic acid treated sample exhibited increase in values of e¢ (from 3.2 to 4.3) and e¢¢ (from 0.48 to 0.75) relative to the virgin sample at 300 Hz while the rest of the samples recorded reduction. But these chromic acid treated LLDPE samples being further treated with N/10 sodium carbonate (Na₂CO₃), exhibit change in <img src='/image/spc_char/italics_e.gif' border=0>' and <img src='/image/spc_char/italics_e.gif' border=0>'' values in as much as those for N/10 chromic acid treated sample drops while that of N/15 chromic acid treated sample increases significantly. This indicates intense polarization penetrating to reasonable depth of the surface of the material. The higher value of <img src='/image/spc_char/italics_e.gif' border=0>' and <img src='/image/spc_char/italics_e.gif' border=0>'' in N/10 chromic acid treated sample may be due to intra-molecular three-dimensional network of H-bonding between PE-COOH species. Attempt is made to explain these features.