Fiberboards from Loblolly Refiner Groundwood: Effects of Gross Wood Characteristics and Board Density

The gross wood properties of specifit' gravit1, pro. portion of laIetv17ud, and g,.owtb rate affected the strengths of fib!',.boards in ten.rion ana benJinf.. dJ well dJ their dimC1lsiollaJ stabilit,Fa,. the refining conditions ana' formation procedures .rtudied, and after allowance for the effect of boar" specific g,.ar'it1' mo.rt ~opertie.r were improved b, usittg fiber refil,ed from "ense woo" having low 141""'00" content, BoAkDS FOil INSULATION AND STIlUCTUI.AL USES are being manulactured in increasing quantities. The coarse liber required for these products can be disk-refined lrom untreated wood chips. Since such liber is produced in essentially one mechanical operation, continuous control is required of the raw material as well as the relining process. Considerable research has been published concerning the effects ol reliner operation and boardlormation variables on the physical properties of fiberboards. Less well established are the independent effects ol wood quality. If these effects can be adequately defined, industrial operations may be able to apply the inlormation by isolating or selecting wood having the desired characteristics or by modifying the relining process in accordance with the characteristics ol the raw material. A broad program of research to establish interrdations between pulp quality, wood chemical composition, morphology of wood, board density, and the physical properties of fiberboards has been undertaken at the Southern Forest Experiment Station's utilization laboratory in Alexandria, ta. The ultimate objective is to develop criteria useful in predicting and controlling the board-making potential ol disk-relined fiber from loblolly pine (Pj,,*s talU L). This paper di$CU5Ses interrelationships between certain gross wood characteristics, board density, and the physical properties ol the boards. IThe author acknowledges the assistance 01 the Roy O. Martin Lumber Co., Alexandria, La.: R. A. Leask and J. Adams, Bauer Bros. Co., Springfield, Ohio: D. Bower, statistician, Southern Forest Experiment Station, New Orleans, La. Procedure A factorial experiment with four within-sample replications was designed with wood variables as follows: Specific gravity of unextracted .wood (ovendry weight and green volume )-Less than 0.49; more than 0.49. Growth r,ate--Less than 6 rings per inch; more than 6 rings per inch. Rings from the pith (Position in tree)-o to 10 rings (corewood); 11 to 20 rings (middle wood); 21 tt) 30 rings (outer wood). Held constant were: Specific refining energysingle refiner pass at 40 hp days! air-dry ton; refining consistency-20 percent; actual feedrate-21 tons of ovendry wood! day; refiner-Bauer Bros. #410, 40-inch, double-disk, 2'0 hp motors; chip sample size-~~ pounds. ovendry; refiner plate TW8 pope' w.. , ," at Set"o. 12-MechanJcol COft"'" lion-of the 21.. A.allol Meetla. of the ..,... Ptodudt a.-rch Society, Jllly 5, 1967 la Yoacou"" '.C., c...cIa. The pope' woe ..C8Md for pvWlcotiOft la No_Mr 1967. FOREST PRODUCTS JOURNAL Vol. 18, No.8 51 ., . r I .". '..co ,I I pattern-Bauer Bros. #40106; chip moisture content-l00 percent; rotational speed of plates-1200 rpm; dilution water temperature-130" 1". The study variables were selected to provide broad variation in gross wood characteristics. Sampling at three distances from the pith was chosen as a simple means of securing a range of morphological and chemical characteristics. Loblolly pine was used because of its moderate pitch level and its commercial importance in southern forests. A refining energy of 40 hp days! air-dry ton was selected (after trial runs) to achieve fiberization in the widely divergent wood types. Since the purpose of the study was to establish basic relationships, no attempt was made to optimize board properties by applying different refining energies or plate patterns. To maintain the energy at the selected