Showing papers in "Appita Journal in 2016"

Processing and characterisation of polyhydroxyalkanoate (PHA)-based wood plastic composites: effect of non-reactive additives

Abstract: This investigation aims to develop an optimised biodegradable wood plastic composite formulation through inclusion of a nucleating agent (boron nitride, BN) and an inorganic filler (talc) in Pinus radiata wood flour/ poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) composites. Mechanical tests of the prototype composites showed that the addition of 1 wt% boron nitride did not influence the final tensile properties of the composites. However, addition of 10 wt% of talc resulted in a 44% increase in tensile modulus and a 14% increase in tensile strength. The addition of talc produced a less pronounced effect on stiffness when the process was scaled up to pilot scale. Differential scanning calorimetry (DSC) analyses demonstrated the nucleating effect of BN. The inclusion of 1 wt% of BN led to an increase in crystallisation temperature and in the observed rate of crystallisation of PHBV, as evidenced by the shorter time required for complete crystallisation.

Optimisation of froth flotation for removal of wood extractives in paper manufacture

Abstract: A laboratory scale froth flotation batch process has been optimised for removal of wood extractives from Pinus radiata thermo-mechanical pulp (TMP) process water. This has provided insight into the mechanism of flotation and has potential for application in industry. The study involved optimisation of surfactant type and concentration, flotation time, airflow, impeller speed, pH, temperature and ionic strength. Maximum wood extractive removal was achieved by flotation with the addition of 80 mg/L of the cationic surfactant dodecyltrimethylammonium bromide (DoTAB) at pH 5.0 and 60 oC for 20 min with an air flow of 4.5 L/min and impeller speed of 1300 rpm. Under these conditions the removal efficiency of total extractives was close to 95%. Process water treated in this way would be suitable for recirculation in a pulp or paper mill and would result in significant reduction in problems caused by accumulation of wood extractives.