Morphology and structure of hemp fibre after bioscouring.

ABSTRACT

Bioscouring of hemp (Cannabis Sativa L) using pectate lyase (EC 4.2.2.2), Scourzyme L, was performed at 55 degrees C and pH 8.5 in a nonagitated system. The enzyme concentration, treatment time and substrate concentration were varied to obtain the kinetic constants, K(m) and V(m). Greater enzyme concentration and a longer treatment improved the removal of the low methoxy pectin component as indicated by UV spectroscopy. Removal of pectate caused no crystalline transformation in the fibres, except for a slight decline in the crystallinity order index analysed by Fourier Transform infrared spectroscopy and wide angle X-ray diffraction. This corresponded well with the single fibre bundle tensile mechanical properties test. Smooth surfaces and separated fibres observed using SEM images were evidence of successful treatment, supported by weight loss at low temperature of a pectic substance. After treatment, the pectin substance was no longer observed during thermogravimetry. An increase in surface area and pore size after scouring were further evidence of modification.