Use of Longitudinal Vibration and Visual Characteristics to Predict Mechanical Properties of No. 2 Southern Pine 2 × 8 and 2 × 10 Lumber

The objective of this study was to evaluate the accuracy of single MOE and MOR and combined mechanical properties with visual characteristics to improve the prediction of 2 x 8 and 2 x 10 No. @ southern pine lumber. This study evaluated the following variables: nondestructive tests, knots (knot diameter ratio [KDR] and knot area ratio), density, and mechanical properties (stiffness [MOE] and strength [MOR]). A total of 486 pieces were used, and linear regression models were constructed using stepwise selects to determine the best variables to estimate the MOE and MOR of southern pine lumber. The best single predictor for MOE and MOR was dynamic MOE (dMOE) followed by density. Among the two knot measurement methods used, the KDR best predicted stiffness and strength. For predicting the MOE, the variables dMOE, density, and KDR. The results showed that the addition of knot measurements to the models is able to improve the prediction of mechanical properties

Low VOC drying of lumber and wood panel products. Progress report number 6

Twenty five Southern pine boards were machined into 2 x 4 inch pieces. Next, the 8 foot boards were cut in half into matched pairs. One of the two was irradiated with RF, while the other served as a control. Both sets were dried under a conventional temperature-time based schedule. Results and conclusions are: RF pretreatment of lumber does not affect strength; the amount of pinene lost into the headspace during low-VOC RF-treatment of wood approximately corresponds to the amount of material lost from the wood; virtually all the pinene can be removed from the low-VOC reactor with steam, suggesting that pinene can be collected when the small amount of steam released during low-headspace treatment is condensed; temperature and moisture loss profiles for particle at 105 C has been modeled using experimental data at 130 C and 160 C; the VOC-temperature curve from dried particle shows a break at about 156 C, the boiling point of {alpha}-pinene, demonstrating that pinene boil-off occurs beyond this threshold; VOC release from dry particle has been successfully modeled; the transport of VOC from sapwood to the atmosphere for pine is faster than the corresponding movement from heartwood to sapwood; and seasonal variations in pine extractives are small

Low VOC drying of lumber and wood panel products. Progress report No. 8

This study was initiated by an Institute of Paper Science and Technology finding that heating softwood in a low-headspace environment removed much of the VOCs without removing the water. This offered the possibility of removing VOCs from wet wood, capturing them as a product, and then drying the VOC-depleted wood conventionally with little or no VOC controls. Two means of low-headspace heating were explored: steam and radiofrequency (RF). It was found in the previous year, that while both steam and RF were able to drive out VOCs, steam was impracticably slow for lumber. Hence the effect of RF or microwave on wood was the principal focus of the work reported here. Finally, in order to understand the mechanism of VOC release, the transport of the VOCs in wood was studied, together with the seasonal effects that influence VOC concentration in trees

Furnish type and mat density effects on temperature and vapor pressure of wood-based panels during hot pressing

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