Cell Structure

Simplified structure of the cell wall showing orientation of microfibrils in each of the major wall layers

from The Science and Technology of Civil Engineering Materials, J.F. Young, et al., Prentice Hall, 1998. from Wood: Nature's Cellular, Polymeric Fibre-Composite, J.M. Dinwoodie, The Institute of Metals, 1989, p. 13.

The Tree Collection @ Molecular Expressions

Jeff Thomas, 2010

 

Composition of cell wall of wood

Material Structure Approx. wt %
Fibres Cellulose (C6H10O5)n Crystalline 45
Matrix Lignin Amorphous 20
Hemicellulose Semi-crystalline 20
Water Dissolved in the matrix 10
Extractives Dissolved in the matrix 5

from Engineering Materials 2: An Introduction to Microstructures, Processing and Design, M.F. Ashby & D.R.H. Jones, Pergamon, 1994, p. 258.

 

Cellulose molecule - a linear polymer of glucose units

Cellulose is the primary component of the cell wall.  Furthermore, it is the single most abundant organic chemical in nature.  It is one of the few natural compounds that retain the same structure regardless of whether its source is wood, cotton, grass, or a host of other plants.  Structurally cellulose is the simplest of the cell wall components -- a linear polymer of glucose units.  Biosynthetic polymerization is such that the basic polymeric unit of two combined glucose constituents is "stretched" to almost its maximum dimension.  The number of glucose units in a cellulose molecule (degree of polymerization) ranges from a few to as many as 15,000, depending on its location within the cell wall.

from Mechanics of Wood and Wood Composites, J. Bodig & B.A. Jayne, Krieger Publishing, 1993, p. 5.

 

Properties of some fibers and matrices

Materials Density Modulus Strength
ρ (Mg m-3) E (GPa) σf (MPa)
Fibers Carbon, Type 1 1.95 390 2200
Carbon, Type 2 1.75 250 2700
Cellulose fibers 1.61 60 1200
Glass (E-glass) 2.56 76 1400-2500
Kevlar 1.45 125 2760
Matrices Epoxies 1.2-1.4 2.1-5.5 40-85
Polyesters 1.1-1.4 1.3-4.5 45-85

 

Description of wood 8

  • multicomponent
  • hygroscopic
  • anisotropic
  • inhomogeneous
  • discontinuous
  • inelastic
  • fibrous
  • porous
  • biodegradable
  • renewable
 from Mechanics of Wood and Wood Composites,
J. Bodig & B.A. Jayne, Krieger Publishing, 1993, 
pp. vii, 5, 291, 297, 299, 305.

 

Softwood Hardwood
  • Larger, longer cells
  • Water transported by cells
  • Contains large-diameter vessels
  • Water transported by these vessels

 

Yellow Pine
Koch, P. 1972a. Utilization of the southern pines. I. The raw material. USDA Forest Service Agricultural Handbook No. 420. 733 pp.
Koch, P. 1972b. Utilization of the southern pines. II. The raw material. USDA Forest Service Agricultural Handbook No. 420. 926 pp.
 


www.ci.chi.il.us/PlanAndDevelop/ChgoFacts/Climate.html
 

White Ash
 

White Oak