Properties of red maple laminated veneer lumber impregnated with waterborne micronized and two soluble copper formulations

ABSTRACT

Certain important quality parameters of red maple (Acer rubrum) laminated veneer lumber (LVL) impregnated with three waterborne formulations: copper azole (CA-B), micronized copper azole (MicroCA or MCA) and alkaline copper quaternary (ACQ-D) bonded with phenol formaldehyde or cross-linked polyvinyl acetate (XPVAc) adhesives were evaluated. Pre-dipping of veneers before LVL production and two post-manufacturing procedures, viz., vacuum-pressure and post-dipping of LVL, were applied. Maximum copper retention in pre-dip-treated, vacuum-pressure and post-dip-treated LVL was 1.4, 9.7 and 1.7 kg/m³, respectively. Copper retention in MCA-treated LVL was relatively lower than soluble formulations. Various physical, mechanical and bonding properties of treated LVL such as density, water absorption, swelling, flexural properties, hardness, tensile shear strength, delamination and wood failure (%) were studied and compared with untreated LVL. Little to negligible deleterious effect was observed on properties of LVL due to these chemical treatments. Analysis of variance results showed that most of properties of red maple LVL were not significantly different compared with those of untreated LVL. Therefore, vacuum-pressure impregnation process can be used to treat the red maple LVL with novel micronized copper formulations for increasing the service life of such products against biodegradation without affecting techno-mechanical quality parameters.

KEYWORDS:

• LVL
• phenol formaldehyde
• cross-linked PVAc
• micronized copper azole
• alkaline copper quaternary
• tensile shear strength

Acknowledgements

We also acknowledge Biewer Lumber, Lansing for providing the XRF instrument; Georgia-Pacific Chemicals LLC for PF adhesive; Osmose Holding Inc., and PhibroWood for supplying the stock solutions of preservatives used in the present study.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

Authors acknowledge the financial support from USDA-CSREES Eastern Hardwood Utilization program in the Department of Forestry, Michigan State University, East Lansing, USA.