Elvin T. Choong

Effect of Silvicultural Practice and Wood Type on Loblolly Pine Particleboard and Medium Density Fiberboard Properties

Summary The objective of this study was to determine the effect of five different silvicultural strategies and wood type on mechanical and physical properties of loblolly pine (Pinus taeda L.) particleboard and fiberboard. The furnish was prepared in an unconventional manner from innerwood and outerwood veneer for each stand. Modulus of rupture (MOR) differences between the stands were insignificant for particleboard. Some significant modulus of elastisity (MOE) differences existed between the stands for particleboard and fiberboard. Differences between the wood types were minimal for each stand. Innerwood yielded higher mean MOR, MOE, and internal bond (IB) values than outerwood for most of the stands. The differences between the stand and wood types for 2 and 24 h thickness swell and 2 and 24h water adsorption were very minimal. This research has shown that innerwood can produce particleboard and fiberboard panels with very comparable mechanical and physical properties to outerwood. The effect of the silvicultural strategy (i. e., stand) was minimal for most properties.

Isolation and Characterization of Several Extractives in the Bark and Wood of Sweetgum

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Relationship of Longitudinal Permeability to Treatability of Wood

The permeabilities of sapwood and heartwood of twelve species representing different kinds of wood were determined using 1. water on never-dried/saturated and on previously-dried/resaturated specimens, and 2. nitrogen gas at mean pressure of 2.5 atm and at infinite pressure. Also, their effective permeabilities to water were determined. These specimens were subsequently treated with copper Sulfate, and their matched specimens with creosote. The sapwood showed much higher mean permeability and treatability values than the heartwood. The permeability to water was found to be much higher with specimens which had been previouslydried/resaturated than with those which had not been dried. High degrees of correlation between various permeability and treatability values were obtained. When the relationship between permeability and treatability was analysed by species group, higher correlations were obtained in the hardwoods than in the softwoods. Among the hardwoods, the semi-ring porous woods show no correlation, probably because they were all moderately permeable.

Ketahanan Tiang Listrik Bekas Pakai terhadap Kerusakan Biologis yang Dihubungkan dengan Sisa Kandungan Bahan Pengawet Kreosot didalamnya

Ketahanan kerusakan biologis tiang listrik bekas pakai dari kayu southern yellow pine yang diawetkan dengan kreosote, diteliti melalui percobaan simulasi kerusakan biologis (uji petak tanah) menggunakan jamur Neolentinus lepideus Fr., untuk menilai efektifitasnya terhadap kerusakan tersebut. Hal ini sehubungan dengan pemanfaatan tiang listrik dimaksud menjadi produk hasil olahan bermanfaat, seperti struktur kayu padat dan kayu majemuk. Temyata ketahanan kerusakan biologis tiang listrik baik yang telah berusia (masa pakai) 5 dan 25 tahun maupun yang masih baru diawetkan (segar) ada kaitannya dengan kandungan kreosotnya dan penyebarannya di dalam tiang tersebut. Selama masa pakai terjadi penurunan kandungan kreosot sedemikian rupa sehingga kandungan di bagian atas dan luar tiang tersebut lebih rendah dari pada bagian dalam atau bawahnya. Secara keseluruhan, kandungan kreosot dalam tiang listrik bermasa pakai 5 tahun lebilt rendah dari pada dalam tiang yang segar, tetapi lebih tinggi dan yang bermasa pakat 25 tahun. Pada kandungan kreosot di atas 14 persen, ketahanan kerusakan tiang listrik masih tinggi); akan tetapi di bawah 14 persen, ketahanannya menurun secara drastis. Oleh sebab itu, kadar kreosot 14 persen dianggap sebagai batas kritis. Selanjutnya kalau dihubungkan dengan batas kritis tersebut, ketahanau kerusakan biologis tiang listrtk bermasa pakai 5 tahun masih sebanding dengan tiang yang masih segar, sedangkan pada tiang bermasa pakai 25 tahun, terutama di bagian luamya ketahanannya jauh, jauh lebih rendah dan menvamai ketahanan kayu southern yellow pine yang tidak diawetkan. Lebih lanjut sekiranya dikaitkan dengan pemanfaatan kembali tiang bekas pakai tersebut menjadi produk hasil olahan kayu bermanfaat, nilai kandungan sisa kreosotnya perlu diperhatikan. Bagian dari tiang listrik berkandungan kreosot di alas 14 persen sesuat untuk struktur kayu padat guna pemakaian luar (udara terbuka). Untuk perakitan kayu majemuk, bagian tiang listrik berkandungan kreosot di atas 14 persen sebaiknya untuk bagian luar hasil perakitan tersebut, sedangkan bagian berkandungan kreosot di bawah 14 persen untuk bagian dalamnya.