ABSTRACT The present study considered the effect of nanosilica levels on the thermal, flammability, and morphological properties of nanocomposites made of wood flour and recycled polystyrene. To do so, the recycled polystyrene (50%), wood flour (50%), nanosilica (four levels of nanosilica; 0, 2, 4 and 6 phc (parts per hundred compounds)), and maleic anhydride, grafted with polypropylene (at a constant level of 3 phc) were mixed by a twin-screw extruder; then standard experimental samples were made using a hand pressing method. Next, the thermal and flammability properties were measured. The results showed that increasing of nanosilica content to 6 phc by weight increased thermogravimetric analysis (TGA) of nanocomposites; in addition, the limited oxygen index increased. Moreover, scanning electron microscopy (SEM) indicated that an increasing of nanosilica increased compatibility so that better link and adherence was observed among the fiber and matrix material.

Abstract Hornbeam wood (Carpinus betulus) is a native species from Iran and covers 33% of the commercial volume of Iranian woods. Surface quality of solid wood products is one of the most important properties influencing further manufacturing processes such as finishing or strength of adhesive joint. Wood surface roughness is affected by growth condition. The objective of this study was to evaluate effect of altitude index (400 m, 800 m and 1200 m) on the surface roughness of sanded hornbeam wood (C. Betulus). Surface characteristics of sanded specimens of hornbeam wood were made employing a stylus profilmeter. Average roughness (Ra), mean peak-to-valley height (Rz), root-mean square deviation of the profile (Rq), core roughness depth (Rk), reduced peak height (Rpk), and reduced valley depth (Rvk) roughness parameters were used to determine surface characteristics of the test pieces. Significant statistical differences were found among altitude indexes in reduced valley depth parameter and wood oven-dried density, but not for the other variables. This variable did not have significantly effect on other surface roughness parameters in hornbeam wood. The low altitude had a rougher surface than intermediate and high altitudes. There is no relationship between surface roughness parameter and wood oven-dried density.

Resumen La especie Carpinus betulus (‘hornbeam’) es una especie nativa de Irán y cubre 33% del volumen comercial de las maderas de este país. La calidad de la superficie de productos de madera sólida de ‘hornbeam’ es una de sus propiedades más importantes, que afecta los procesos de manufactura tales como acabados o resistencia de las uniones con adhesivos. La rugosidad de la superficie de la madera se ve afectada por las condiciones de crecimiento del árbol. El objetivo de este estudio fue evaluar el efecto del índice de altitud (400 m, 800 m y 1200 m) en la rugosidad de la superficie de madera de ‘hornbeam’ lijada. Las características de la superficie de muestras de madera de ‘hornbeam’ lijadas se midieron con un equipo llamado medidor de perfiles de contacto “Contact stylus profilmeter” PGK. Las características de la superficie de las muestras medidas fueron: rugosidad promedio (Ra), altura promedio cresta a valle (Rz), desviación media de los cuadrados medios de la rugosidad (Rq), profundidad de la rugosidad del núcleo (Rk), altura de la cresta reducida (Rpk) y profundidad del valle reducida (Rvk). Se encontraron diferencias estadísticas significativas entre los índices de altitud para la variable profundidad de valle reducida y para la densidad de la madera secada en estufa, pero no para el resto de las variables. Esta variable no tuvo un efecto significativo en los parámetros de rugosidad de la madera de ‘hornbeam’. La madera de altitudes bajas tuvo una superficie más rugosa que las altitudes intermedia y alta. No hay relación entre la rugosidad y la densidad de la madera secada en estufa.

Abstract: This study considered the effect of nanomagnesium oxide on the mechanical and flammability features of composites made of wood flour and high-density polyethylene. A sample of wood flour was made from the mixture of hardwoods and high density polyethylene with the weight ratio of 50%. Maleic anhydride was added as a compatibilizer (2 phc), and nanomagnesium oxide was applied at 6 levels (0, 1, 2, 3, 4, 5 phc). These materials were mixed, and samples were prepared with determined sizes by injection molding machine. The samples were subjected to flexural tests to examine the mechanical features, and to study flammability strength, various tests were conducted with a cone calorimeter, including the amount of char residue, total smoke production, time to ignition, and heat release rate, according to ASTM E1354-92 (1992). The addition of up to 3 phc nanomagnesium oxide increased flexural strength and modulus, but further additions decreased these values. The addition of 5 phc nanomagnesium oxide increased the char residue and ignition time, and it decreased the heat release rate, total smoke production, and burning rate. Scanning electron microscopy and energy dispersive X-ray (EDX) analysis indicated the improper transmittance of nanomagnesium oxide and accumulations in the samples.

Abstract: The aim of this research was to investigate the effects of longitudinal position (stem height) and heart-sapwood on density, modulus of elasticity (MOE) and modulus of rupture (MOR) in bending for Persian silk wood (Albizzia julibrissin). Five normal trees were selected from the Guilan region, Iran. Samples for testing were prepared at four stem height levels (5%, 25%, 50% and 75% of total stem height) in both positions along radial direction (heartwood and sapwood). Analysis of variance results (Anova) indicated that the effects of longitudinal position (stem height) and heartwood-sapwood on the wood density, MOE and MOR were significant. The mean of wood density, MOE and MOR along longitudinal position from base to top decreased with height. The mean of wood density, MOR and MOE in sapwood are lower compared to the corresponding values for heartwood. The relationship between wood density and mechanical strength properties were analyzed by regression models. A positive correlation was found between wood density with MOE and MOR in both heartwood and sapwood.

Resumen: El objeto de esta onvestigación fue estudiar los efectos de la posición en dirección longitudinal (altura del tronco) y del duramen y la albura sobre la densidad, el módulo de elasticidad (MOE) y el módulo de ruptura (MOR) en flexión para la madera de 'seda' persa (Albizzia julibrissin). Se recolectaron cinco árboles representativos de la región de Guilan, Irán. Se elaboraron especímenes para prueba a cuatro niveles de la altura del árbol (5%, 25%, 50% y 75% de la altura total del tronco) en ambos tipos de madera en la dirección radial (duramen y albura). Los resultados de los análisis de varianza (Andeva) indicaron que los efectos de la ubicación longitudinal (altura del árbol) y duramen y albura sobre la densidad de la madera, el MOE y el MOR fueron significativos. Los valores promedio de la densidad, MOE y MOR a lo largo de la posición longitudinal de la base a la copa disminuyeron con la altura. Los valores promedio de la densidad, MOR y MOE en albura son menores comparados con los del duramen. La relación entre la densidad de la madera y las propiedades mecánicas se analizaron por medio de modelos de regresión. Se encontró una correlación positive entre la densidad de la madera con MOE y MOR tanto en duramen como en albura.

Persian Ironwood (Parrotia persica (DC) CA Meyer) is native species from Iran and covers 10,54% of the commercial volume. Its wood structure and its chemical composition are affected by growth conditions. The aim of the study was to assess the variation of mineral content (Ni, Fe, Cu, Zn, Pb, Cd), wood density and chemical properties (cellulose, lignin, ash and extractive) of ironwood in relation to altitude above sea level (100, 500 and 700 meter) and pith distance within stem (near to pith and bark and middle point). In addition was investigate the relationship between mineral content with oven-dried density and chemical properties. Results showed that Cd, Cu, Fe, Ni and Zn content (except Pb concentration) increased by increasing of altitude and decreased along radial position within stem from the pith to the bark. Lignin, ash and extractive content increased by increasing altitudes from 100 to 700 meter while cellulose decreased. Radial position had not significant impact on the chemical properties. There are significant relationships between mineral content-chemical properties and between mineral content-wood density (except Cu - density). Forward stepwise regression showed that ash and lignin content had important role on the variation of all of mineral content except on Cd.

Plum (Prunus domestica) is one of the most widespread species of fruit trees in Asia and South-East Europe. There are large quantities of fruit wood trees without suitable usage in world. The aim of this research was to examine biometrical and chemical properties of the plum wood and its application in the pulp and paper industry. Five normal plum trees were randomly selected from Shahriyar province, Iran. A log cut down at stem (breast height) and branch for each of trees. The pith parts of cross-section were removed to examine the chemical (according to the TAPPI standard) and biometrical properties (according to the Franklin method). Results indicated that there were significant differences between stem and branch samples in fiber diameter and lumen diameter. Types of wood (branch and stem) had not significant differences on the chemical properties and fiber length, cell wall thickness and morphological properties. Among all of studied properties, the lignin, cellulose, fiber diameter, fiber lumen diameter, cell wall thickness and flexibility coefficient in branch wood is higher than stem wood. Although Runkel and flexibility coefficients of stem and branch fibers are lower than the accepted standard, but because of closing amount of lignin, extractive composition and fiber length to hardwood species, it can solve some of the problems of the lack of raw materials for paper production.

The effect of residual lignin content on the mechanical strength and water absorption of kraft pulp/polypropylene composites was studied. To meet this objective, hornbeam wood chips were converted to kraft pulp at three different alkalinities (15, 20, and 25%) and three different cooking times (60, 90, and 120 min). The residual lignin contents of these pulps were determined according to the TAPPI standard. Kraft pulp was mixed with polypropylene (PP) at 50% weight ratios. The amount of maleic anhydride (MAPP) coupling agent was fixed at 4 per hundred compounds (phc) for all formulations. The results indicated that the lignin residual content decreased with increasing cooking time and alkalinity in kraft pulp. Also, it was found that tensile strength, tensile modulus, flexural strength, and flexural modulus were increased by increasing the alkalinity and cooking time; however, the notched impact strength and water absorption decreased. Overall, decreasing the lignin content had a positive impact on the flexural and tensile properties and had a negative effect on the notched impact strength.