Spent Tea Leaves as Extender and Scavenger for Urea Formaldehyde-Bonded Plywood
Erlinda L. Mari, Juanito P. Jimenez, Jr.*, and Rebecca B. Lapuz
Forest Products Research and Development Institute,
Department of Science and Technology, College, Los Baños, Laguna 4031 Philippines
In lieu of wheat flour, spent tea leaves (STL) from the manufacture of tea-flavored drink was mixed with urea formaldehyde (UF) resin to produce an adhesive for 5-mm-thick plywood. Three glue mixes (GM1, GM2, and GM3) were formulated using three STL levels (3.4%, 6.8%, 10.2% by mass). GM1 had no catalyst and coconut shell flour/filler; GM2 had no catalyst but had a filler; while GM3 had a catalyst but no filler. The glue manufacturer’s recommended formulation was used for making the control plywood. All glue mixes were formulated with the same total resin solids. The effect of the STL on the various glue mixes was evaluated in terms of the plywood’s shear strength & wood failure (PNS ISO 12466-1:2016 & PNS ISO 12466-2:2016), and formaldehyde emission (PNS ISO 12460-4:2016). Results indicated that GM3, or complete replacement of wheat flour and coconut shell flour with STL both as extender and filler in the plywood glue mix, was the best formulation. It did not adversely affect the panel’s strength properties. Moreover, formaldehyde emission was significantly reduced by 36 to 60%.
Key words: extender, formaldehyde emission, plywood, shear strength, spent tea leaves
In the late-1970s, substituting tree foliage to wheat flour as extender in plywood and particleboard glue formulations was reported to obtain similar or even enhanced results compared to completely using wheat flour. This was attributed to the protein present in the tree foliage (Chow 1978). There was no mention of the formaldehyde scavenging activity of the tree foliage then. Formaldehyde was much later classified as carcinogenic to humans in a meeting in Lyon, France on 2-9 Jun 2004 by the International Agency for Research on Cancer – World Health Organization (IARC –WHO 2006). . . . . . read more
AOAC. 2005a. AOAC Official Methods of Analysis 18th ed. Number 930.05.
AOAC. 2005b. AOAC Official Methods of Analysis 18th ed. Number 978.04.
AOAC. 2005c. AOAC Official Methods of Analysis 18th ed. Number 978.10.
AYDIN I, DEMIRKIR C, COLAK S, COLAKOGLU G. 2017. Utilization of bark flours as additive in plywood manufacturing. Eur J Wood Prod 75: 63-69.
BUYUKSARI U, AYRILMIS N, AVCI E, KOC E. 2010. Evaluation of the physical, mechanical properties and formaldehyde emission of particleboard manufactured from waste stone pine (Pinus pinea L.) cones. Bioresource Technology 101(1): 255-259.
CHAN FD. 1996. Control of formaldehyde emission in plywood using giant ipil-ipil [Leucaena leucocephala (Lam.) de Wit] seed flour. FPRDI Journal 22(2): 15-19.
CHAN F, DIONGLAY MSP. 1996. Utilization of giant ipil-ipil [Leucaena leucocephala (Lam.) de Wit] seed flour as plywood glue extender. FPRDI Journal 22(2): 1-14.
CHOW S. 1978. Tree foliage extenders and fillers for wood adhesives. US Patent 4,082,903. Primary Class 428/514. Retrieved from http://www.freepatentsonline.com/4082903.pdf on 6 Mar 2013.
DUKE JA. 1983. Camellia sinensis (L.) Kuntze. Handbook of Energy Crops. Retrieved from http://www.hort.purdue.edu/newcrop/duke_energy/Camellia_sinensis.html. on 6 Mar 2014.
EVANGELISTA MPH. 2012. Evaluation of corn germ protein as an extender in plywood adhesives. Journal of Adhesion Science and Technology 27: 2075-82.
[IARC–WHO] International Agency for Research on Cancer – World Health Organization. 2006. IARC monographs on the evaluation of carcinogenic risks to humans. formaldehyde, 2-Butoxyethanol and 1-tert-Butoxypropan-2-ol. Vol. 88. Retrieved from http://monographs.iarc.fr/ENG/ Monographs/vol88/mono88.pdf. on 7 Apr 2014.
JIMENEZ JPJ, ESCOBIN RP, CONDA JM. 2015. Profile of wood species used in local and imported plywood and their bond performance. Philippine Forest Products Journal 6: 43-58.
HOFFMAN EA, FREY BL, SMITH LM and AUBLE DT. 2015. Formaldehyde crosslinking: A tool for the study of chromatin complexes. Journal of Biological Chemistry 290(44): 26404-11. American Society for Biochemistry and Molecular Biology, Inc. USA. Retrieved from http://www.jbc.org/content/290/44/26404.full.pdf on 20 Oct 2017.
NEMLI G, KIRCI H, TEMIZ A. 2004. Influence of impregnating wood particles with mimosa bark extract on some properties of particleboard. Industrial Crops and Products 20(3): 339-344.
PERVAIZ M, SAIN M. 2011. Protein extraction from secondary sludge of papermill wastewater and its utilization as a wood adhesive. BioResources 6(2): 961-970.
[PNS] Philippine National Standard. 2017. PNS 2103 Plywood – Formaldehyde emissions – Specification. Bureau of Philippine Standards, Department of Trade and Industry.
[PNS] Philippine National Standard. 2016a. PNS ISO 12460-4 Wood-based panels - Determination of formaldehyde release - Part 4: Desiccator method. Bureau of Philippine Standards, Department of Trade and Industry.
[PNS] Philippine National Standard. 2016b. PNS ISO 12466-1. Plywood - Bonding quality - Part 1: Test Methods. Bureau of Philippine Standards. Department of Trade and Industry.
[PNS] Philippine National Standard. 2016c. PNS ISO 12466-2. Plywood - Bonding quality -- Part 2: Requirements. Bureau of Philippine Standards. Department of Trade and Industry.
PIRAYESH H, KHANJANZADEH H, SALARI A. 2013. Effect of using walnut/almond shells on the physical, mechanical properties and formaldehyde emission of particleboard. Composites: Part B 45: 858-863.
ROBERTSON JE, ROBERTSON RR. 1977. Review of filler and extender quality evaluation. Forest Products Journal 27: 30-38.
SAS Analytics Pro. 2017. SAS Institute Inc. 100 SAS Campus Drive. Cary, NC 27513-2414, USA.
SELLERS TJ, MILLER GD, SMITH W. 2005. Tool wear properties of five extenders/fillers in adhesive mixes for plywood. Forest Products Journal 55(3): 27-31.
SHI J, LI J, FAN Y, MA H. 2006. Preparation and properties of waste particleboard. For. Stud. China 8(1): 41-45 DOI:10.1007/s11632-006-0008-5
Shimadzu Trapezium X (Version 1.4.2) [Computer software]. n/d. Retrieved from https://www.shimadzu.com/an/test/universal/trapeziumx.html