Jurkka Kuusipalo. (2001). Plastic coating of plywood using extrusion technique. Silva Fennica vol. 35 no. 1 article id 607. https://doi.org/10.14214/sf.607

Keywords: plywood; thermoplastics; polymer; polyethylene; polypropylene; extrusion coating; adhesion

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The target was to study and develop industrially suitable methods to apply thermoplastic coatings on plywood. Typically, wear and climatic resistance for wooden sheets, such as chip board and plywood, is achieved by thermosetting resin coating (e.g. phenol-formaldehyde). However, economical and environmental issues are driving towards thermoplastic coatings (e.g. polyethylene) in such products. Several technologies, such as film gluing and laminating, have been introduced, but the costs and processing are limiting factors. This study concentrates on direct coating of plywood with extruded molten plastic film, in other words extrusion coating of plywood. This technique provides fast coating process and cheap raw materials. In the study it was found that extrusion coating of plywood is difficult. The high heat energy of the molten plastic causes moisture evaporation of the top veneer, and the only possible escape direction of the evaporated moisture is through the plastic, which causes bubbling in the plastic coating. Another disadvantage of the plywood is its rigidity, which limits the development of the process. In this work, a new technique was applied for coating the flexible veneers with typical extrusion coating equipment, where the escape of the evaporated moisture was possible through the top veneer to the atmosphere. Another main issue was to reach sufficient adhesion between plastic and plywood. Target was achieved using either monolayer polyethylene (PE-LD) or 2-layer polypropylene/adhesion polymer plastic coatings.

Kuusipalo, Tampere University of Technology, Institute of Paper Converting, Korkeakoulunkatu 4 C, P.O. Box 541, FIN-33720 Tampere, Finland E-mail: jurkka@cc.tut.fi

Category : Research note

article id 23050, category Research note

Anne Carolina, Rita K. Sari, Deded S. Nawawi, Effendi T. Bahtiar, Dai Kusumoto. (2024). Mechanical-chemical induction of balsam from Liquidambar excelsa trees. Silva Fennica vol. 58 no. 2 article id 23050. https://doi.org/10.14214/sf.23050

Keywords: Liquidambar excelsa; balsam; ethylene; methyl jasmonate; sustainable tapping

Highlights: The combination of mechanical and chemical induction on Rasamala branches offers an easy and efficient method for balsam exudation; Balsam exudation is chemically stimulated by methyl jasmonate and ethephon; Stimulant concentration increased the amount of balsam exuded in a dose-dependent manner.

Abstract | Full text in HTML | Full text in PDF | Author Info

Rasamala (Liquidambar excelsa (Noronha) Oken) is an endemic plant in Indonesia. Apart from its use as wood, Rasamala also produces an exudate, known as balsam. Rasamala balsam has the potential to be a substitute for other true balsams derived from Altingiaceae, namely Storax. However, local communities have not used Rasamala balsam to its full potential owing to a lack of knowledge about the tapping method and processing. Therefore, an easy and efficient induction method for plant exudates is required to boost productivity. The use of exogenous hormones as stimulants and less damaging tapping techniques for plant stems requires further investigation. In this study, mechanical and chemical inductions were conducted using 0.1%, 1%, 2%, 5%, and 10% (w/w) methyl jasmonate and ethephon as stimuli. These chemical compounds were applied to young twigs without incision (TW), by incision (TI), to branches perforated with an electric bore (BB), and by incision (BI). After exogenous application for 21 days, Rasamala balsam exuded in all induction techniques, except for the TW treatment. BI treatment showed the highest effective induction, as indicated by the highest balsam exudation. Furthermore, methyl jasmonate was a better chemical stimulant than ethephon. In addition, the induced balsam Rasamala exudate showed a physical characteristic of a clear, thick, sticky colorless to white liquid with a distinctive balsamic odor.

Carolina, Department of Forest Products, Faculty of Forestry and Environment, IPB University, Jl. Lingkar Kampus IPB Dramaga, Bogor, 16680, Indonesia https://orcid.org/0000-0002-2129-8665 E-mail: a_caroline@apps.ipb.ac.id
Sari, Department of Forest Products, Faculty of Forestry and Environment, IPB University, Jl. Lingkar Kampus IPB Dramaga, Bogor, 16680, Indonesia https://orcid.org/0000-0001-5377-1384 E-mail: rita_kartikasari@apps.ipb.ac.id
Nawawi, Department of Forest Products, Faculty of Forestry and Environment, IPB University, Jl. Lingkar Kampus IPB Dramaga, Bogor, 16680, Indonesia https://orcid.org/0000-0001-8367-0349 E-mail: dnawawi@apps.ipb.ac.id
Bahtiar, Department of Forest Products, Faculty of Forestry and Environment, IPB University, Jl. Lingkar Kampus IPB Dramaga, Bogor, 16680, Indonesia https://orcid.org/0000-0003-0003-5855 E-mail: bahtiar_et@apps.ipb.ac.id
Kusumoto, The University of Tokyo Chiba Forest, Graduate School of Agricultural and Life Sciences, The University of Tokyo, 770 Amatsu, Kamogawa, Chiba 299-5503, Japan https://orcid.org/0000-0002-4250-2469 E-mail: kusumoto@uf.a.u-tokyo.ac.jp

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