urophylla (n = 54) Property AD+MFA (b) KS 0.17 TS 0.28 T/R 0.17 CS 0.53 (**) MOE 0.67 (**) MOR 0.61 (**) (a) n = number of samples from 18 trees (three trees x three clones in a hybrid); AD = air-dry density; MFA = microfibril angle of [S.sub.2] layer in wood fibers; RS and TS = radial and tangential shrinkages per 1 percent change in moisture content, respectively; T/R = ratio of tangential shrinkage to radial shrinkage
; CS = compressive strength parallel to grain; MOE = modulus of elasticity; MOR = modulus of rupture; (*), (**) = significantly different at 5 and 1 percent levels, respectively.
The study objective is to identify the differences in morphological characteristics (percentages of sapwood, heartwood, bark, and pith and pit eccentricity), physical properties (green density; specific gravity; volumetric, tangential and radial shrinkage
; and moisture content) and mechanical properties (module of elasticity and modulus of rupture in bending, parallel compression, Janka harness, parallel and perpendicular tension and shear stress) of wood from 7-year-old trees in two populations with the same provenance of Cedrela odorata growing in an agroforestry system with Theobroma cacao (cacao).
It is worth noting that the radial shrinkage
of Mo-Cu composites is always higher than the axial shrinkage.
It also reduces radial shrinkage
, enabling cycle-time reductions in extrusion blow molding and injection molding of some parts.
Notice that equations of strains and stresses for restraint hydrate process of the ring are also able to be used in the case of uniform radial shrinkage
by reforming the constitutive equation for uniform shrinkage:
The molar ratios between the precursors (MR/FA, MR/Cat, W/MR or H/FA, H/Cat, methanol/H) were optimized, taking into account the final density, the preparation time and the radial shrinkage
Before and after the drying, the bulk gels were measured and their radial shrinkage
and density were calculated.
Percent radial shrinkage
(given in negative values) was calculated for 10 min time steps by relating the total radial shrinkage
(digital gauge, accuracy 1 [micro]m) to the total coupling pressure decrease.
Even quarter-sawn boards (radial shrinkage
) move significantly across the grain (Figure 8).
wood expands and contracts with changing humidity levels, while mortar does not." White cedar has the lowest coefficient of expansion and contraction ("radial shrinkage
"), at 2.2%, of any of the common woods.
Since it's the radial shrinkage
that is going across the width of the board, quarter-sawn boards also shrink less in width than flat-sawn boards.
Nevertheless, in the nodal area, the bent vascular bundle can enhance the resistance to radial shrinkage
. Razak et al.