Effects of Closure Phase on Vertical Density Profile of Fiberboard

Abstract:

Studying the vertical density profile (VDP) forming progress of fiberboard helps understand and improve the hot-pressing technology. The presented work aims to investigate the effects of coreline temperature and thickness curve on VDP by changing hot-pressing curve and moisture content of mat. In doing so, it was hoped to study the VDP forming progress and manufacture “Steep-Flat” VDP and “Flat” VDP fiberboard. The results indicated that Closure phase of traditional hot-pressing curve failed to alter shape of mat thickness curve which control the shape of VDP. The mat manufactured by traditional hot-pressing curve was “Steep” VDP and could not manufacture “Steep-Flat” VDP and “Flat” VDP; Closure phase of “high-low-high” hot-pressing curve could be separated into rapid compression stage, thickness expansion stage, and second compression stage. The density of surface layer formed at rapid compression stage and decided by first high-pressure. The density gradient between surface layer and core layer formed at thickness expansion stage and decided by expansion time. The density of surface layer formed at rapid compression stage and decided by second high-pressure. The “Steep-Flat” VDP and the “Flat” VDP could manufactured by modulated moisture content of mat, first high-pressure, expansion time, second high-pressure.

• Periodical: Advanced Materials Research (Volumes 163-167)
• Pages: 2770-2775
• DOI: https://doi.org/10.4028/www.scientific.net/AMR.163-167.2770
• Online since: December 2010
• Authors: Yang Zhang, Zhi Ming Yu
• Keywords: Closure Phase, Fiberboard, Mat Thickness Curve, Vertical Density Profile

References

[1] Kelly MW (1977) Critical literature review of relationship between processing parameters and physical properties of particleboard. Gen. Tech. Rep. FPL-10. USDA Forest Serv., Forest Prod. Lab., Madison. WI.

[2] Winistorfer PM, Moschler WW, Wang S, DePaula E, Bledsoe BL (2000) Fundamentals of vertical density profile formation in wood composites. Part 1. In-situ density measurement of the consolidation process. Wood and Fiber Science 32: 209-219.

[3] Wang SQ, Winistorfer PM (2000) Fundamentals of vertical density profile formation in Wood Composites. Part 2. Methodology of vertical density formation under dynamic conditions. Wood and Fiber Science 32: 220–238.

[4] Wang SQ, Winistorfer PM (2001) Step-closing pressing of medium density fiberboard Part1 Influences on the vertical density profile. Holz als Roh-und Werkstoff 59: 19–26.

DOI: 10.1007/s001070050466

[5] Wang S Q, Winistorfer PM. (2004) Fundamentals of vertical density profile formation in wood composites. Part3. MDF density formation during hot-pressing. Wood and Fiber Science 36: 17–25.

[6] Zhang Y, Yu ZM (2009) Forecasting model of MOR of fiberboard. Journal of Beijing Forestry University 31 (1): 127–130.

[7] Zhang Y, Yu ZM (2009) Study on fiberboard VDP forming progress in hot-pressing process. Journal of.

[8] Beijing Forestry University 31(3) : 129–134.

[9] Zhang Y, Yu ZM (2009). Effects of hot-pressing parameters on vertical density profile of MDF. Journal of Beijing Forestry University 31(4) : 118–122.