The paper presents preliminary results on the relationships of the longitudinal modulus of elasticity (E) in bending, based on ISO Standard 3349 tests on small, clear specimens, and some basic characteristics of Finnish Scots pine (Pinus sylvestris L.) wood. A manual image analysis method – quantitative stereological counting – was introduced and applied for the investigations of wood structure.
The main results were consistent with those from the prior research. The range of E was 9.7 to 19.1 GPa. Increase in especially fibre density index (R2 = 0.95), weight density and specific gravity (R2 = 0.90), Runkel’s ratio, coefficient of cell rigidity and number of growth rings per cross-sectional unit area, but also in latewood percentage (R2 = 0.58) resulted in an increase in E. Increase in growth ring width, particularly in the width of the late wood section within a ring (R2 = 0.63 to 0.90) had a reverse effect. Cell wall thickness did not show any clear effect. Except for tracheid diameter, the relationships were stronger for the variables determined in the tangential than in the radial wood direction.
Quantitative stereological counting has been used to some degree in the Finnish wood research. The procedure is technically feasible and easy to use. A large sample of counting areas is frequently needed to obtain accurate mean results for the size and distribution of the features. Because the actual analysis points are located at a fixed distance from each other, the method is not in principle well suited for wood with a regular and simple structure, as Scots pine. However, the good correlations between E and some characteristics obtained with stereological counting did not support this misgiving.
The PDF includes an abstract in Finnish.