2889 



.6 



.8 .9 1.0 



DENSITY (G/CM^) 



I.I 



1.2 



Figure 23-108. — Modulus of elasticity in bending as related to density of eight types of 

 commercially manufactured medium-density fiberboard. Horizontal lines indicate 

 density gradient from board surface (right end of line) to board center (left end). 

 (Drawing from Suchsland et al. 1978.) 



Table 23-17. — Property requirements of thick medium-density fiberboard in 

 two thickness classes (U.S. Department of Commerce 1980) 



Thickness class 



13/16-inch and 7/8-inch and 



Property thinner thicker 



Modulus of rupture, psi 3,000 2,800 



Modulus of elasticity, psi 300,000 250,000 



Internal bond strength, psi 



(tensile strength perpendicular 



to surface) 90 80 



Linear expansion, percent' 0.30^ 0.30 



Screwholding strength, pounds 



Face 325 300 



Edge 275 225 



'Between 50- and 90-percent relative humidities. 



^For boards Ys-inch thick or less (nominal), the maximum linear expansion value is 0.35 percent. 



