PROPERTIES AND USES OF CELL WALLS 



95 



The highest elastic moduli among common materials are found 

 in metals, alloys, and glasses. The low values among those recorded 

 apply to various synthetic fibers and plastics. Save for wool, the 

 natural fibers listed are appreciably more resistant to reversible 

 deformation, than synthetics, with flax and ramie approaching 

 the range for glasses and aluminum. The intermediate range 

 contains the two important non-metallic structural materials, 

 wood and concrete. 



Table 1. Mechanical Properties of Wood and Other Materials 



1 kg/mm2 = ca. 1400 lb/in*. 



In contrast to the reversible deformation expressed by Young's 

 modulus, tensile strength measures maximum tensile stress at 

 the breaking point. It is, therefore, the ratio of force at breakage to 

 initial cross-section, again F/a. 



By this measure, wood is a comparatively weak material 

 (although it approaches aluminum in some cases), whereas the 



