Nyoman Wistara

The properties of red meranti wood (Shorea leprosula Miq) from stand with thinning and shade free gap treatments

Abstract Selective cutting and line planting silvicultural system has been carried out in natural forest to increase the growth rate of red meranti (Shorea leprosula Miq.). Even though high growth rate has been understood tend to decrease certain basic properties of wood; however measurement of the basic properties specifically done on the red meranti resulted from thinning and shade free gap treatment has been lacking. In the present research, measurement of the basic properties of red meranti resulted from thinning and shade free gap treatment was done. It was found that thinning and increasing shade free gap increased the diameter of tree, longitudinal shrinkage, fiber diameter, lumen diameter, sapwood extractives, and ash content. On the other hand, these treatment decreased heartwood proportion, crown coverage, specific gravity, wood density, mechanical properties, radial and tangential shrinkage, fiber length, cell wall thickness and heartwood extractives. Lignin, holocellulose, α-cellulose and hemicelluloses were not significantly influenced by the treatments. Overall, thinning and increasing shade free gap tended to reduce the quality of wood.

Characterization of cellulose nanocrystal with cellulose II polymorph from primary sludge and its application to PVA nanocomposites

AbstractCellulose nanocrystals with cellulose II polymorph (CNC-II) were obtained from primary sludge fiber (PSF) in a pulp and paper mill by sulfuric acid hydrolysis after purification to remove inorganic materials and lignin. The CNC-IIs obtained were applied as reinforcing fillers for polyvinyl alcohol (PVA). Characterization of CNC-IIs was performed using FTIR spectroscopy and X-ray diffraction. The morphology, conductivity, and tensile properties of CNC-IIs-reinforced PVA nanocomposites were also investigated. Purification treatment effectively reduced non-cellulosic material in the sludge, increasing the cellulose content from 39.87 to 76.34%. The conductivity and tensile properties of the PVA/CNC-II nanocomposite was better than those of neat PVA and PVA/PSF composite.

KAJIAN STRUKTUR ARANG-PIROLISIS, ARANG-HIDRO DAN KARBON AKTIF DARI KAYU Acacia mangium Willd. MENGGUNAKAN DIFRAKSI SINAR-X

Kegunaan karbon aktif sangat luas dan penting untuk beragam aplikasi. Arang-hidro dari biomassa yang dibuat melalui proses karbonisasi hidrotermal merupakan prekursor alternatif terhadap prekursor konvensional untuk pembuatan karbon aktif yang selama ini banyak menggunakan arang dari proses pirolisis (prekursor konvensional). Tulisan ini menganalisa struktur kristalin arang-pirolisis dan arang-hidro suhu 200 ?C dan 300 ?C serta produk karbon aktif menggunakan difraksi sinar-X (XRD). Hasil penelitian menunjukkan bahwa indeks kematangan dan tingkat aromatisasi karbon dari prekursor (baik konvensional atau alternatif) meningkat setelah diaktivasi; jarak antar lapisan graphene (d002) semakin kecil, sementara itu derajat kristalinitas, jumlah, tinggi dan lebar lapisan aromatik semakin besar. Arang-hidro memiliki derajat kristalinitas, indeks kematangan dan tingkat aromatisasi lebih rendah dari arang pirolisis suhu 300?C dengan kandungan bahan mudah menguap lebih tinggi. Keduanya telah membentuk struktur karbon bersifat amorf. Karbon aktif dari arang-hidro suhu 300?C menghasilkan daya jerap iodin tertinggi. Analisis XRD terhadap arang-pirolisis dan arang-hidro suhu rendah dapat memprediksi porositas karbon aktif yang dihasilkan.