The Effects of Boric Acid on Fiberboard Properties Made from Wood/Secondary Fiber Mixtures: Part 1. Utilization of Recycled Newsprint Paper Fibers

Abstract

It was realized that both boric acid (BA) and secondary fibers (S) from recycled newsprint papers had negative impact on thickness swelling (TS) properties of boards in water. The highest TS value of 48% was observed in both type boards that produced only from 100% secondary fibers. However, the highest Modulus of Elasticity (MOE) values of 1783 MPa was found, A4 experimental boards that produced from 60/40 (W/S) proportion with 5.0% boric acid content (type1) whereas the highest MOE values of 970 MPA was found, A2a experimental boards that produced from 80/20 (W/S) proportion with 10% boric acid content (type2). It is clear that increasing secondary fiber content impact on lowering MOE values in some level. But except of the boards of A10 and A10a which produced only from recycled newsprint papers (secondary fibers) with both type, all other boards have higher MOE values than standard value of 600 MPa. The highest Internal Bond (IB) mean value of 0.18 MPa was obtained with board of A1 following by A3 (type1). However, the highest IB values of 0.16 MPA was found A1a experimental boards that produced from 90/10 (W/S) proportion with 10% boric acid content (type2). The lowest thermal conductive was realized for both type boards at 10/90 (W/S) fiber proportion with 0.15 W/mK and 0.22 W/mK, respectively. However, the results indicate that heat conductivity values decrease (improved) as secondary fiber content increase in board’s structure. This is very important findings considering improving heat insulation properties of boards. Hence, secondary fibers from recycled newsprint papers had positive impact against heat conductivity properties of boards.