جستجوی مقالات مرتبط با کلیدواژه "پالونیا" در نشریات گروه "صنایع چوب و کاغذ"

One of the disadvantages of recycled fibers is the significant loss of mechanical strength of the paper due to the decrease in the bond between the fibers. The objective of this study was to investigate the effect of adding paulownia nano-wood on the improvement of pulp from old corrugated containers (OCC). Therefore, in this study, with the aim of preserving the mechanical properties of paper, a nano wood-cationic starch system was used. The pulp was prepared from OCC collected and after refining and obtaining a flow rate of 380 ± 20 ml, different amounts of nano-wood (1, 2, and 3%) and cationic starch (0.5, 1, and 1.5%) was added to it. Finally, standard hand sheet papers were made from these treatments, and their physical and mechanical properties were measured according to the TAPPI standards. The results showed that the density and air permeability increase with the addition of cation-starch nano-wood in the paper. Also, the results showed that there is a significant difference with 95% confidence between different treatments in terms of mechanical strength. The highest values of burst resistance index (2.173 kPa / g), crush resistance in ring mode (177.4 N), and air passage resistance (36.9 s) belonged to S3N 1.5 treatment. It can be concluded that the use of larger amounts of nano-wood with the help of cationic starch as retention aids improves the final paper strengths.

Present research was conducted investigate to physical (water absorption and volumetric swelling) and mechanical properties (MOE، MOR، Compression strength parallel to the grain and hardness) of Paulownia fortunei impregnated with Nano-zinc Oxide with size range from 10 to 80 nm. Specimens were impregnated with a 5000 ppm aqueous suspension of nano-zinc oxide، at 2. 5 bars in a pressure vessel for 20 minutes. Results showed that modulus of rupture (MOR)، modulus of elasticity (MOE) and compression strength parallel to the grain were significantly increased in impregnated specimens. The only mechanical property decreased by nanoparticle-impregnation was hardness. Highest water absorbtion and volumetric swelling took place during first 8 hours of soaking period. Results of the analysis of variance showed that the impregnation of wood with nano-zinc oxide was positive and significantly affected water absorption and volumetric swelling of Paulownia fortunei.

In this paper effect of static densification of treated paulownia on relationship between strength properties and density was investigated. Specimens were steamed at 130 and 170oc and immediately were compressed to 35% and 45% of their original thickness in radial direction. Mechanical properties such as bending strength, brinell surface hardness and compression strength in axial and radial direction were determined for non-densified and densified wood. Indexes of density, strength, quality and strength potential were calculated to study the relationship between strength and density. The results show that the density index and strength index and also strengths significantly increased with increase in densification but strength potential indexes decreased. Steam treatment at 130oc had a slight positive effect on the strengths and strength potential indexes as effect of softening the wood but the strength potential indexes and strengths decreased due to treatment of wood at 170oc. Generally, strength potential indexes of all tested mechanical properties show that strength of densified paulownia was lower compared to what had expected for non-densified paulownia from increasing density, which in turn demonstrate the cell walls were negatively affected by compression. Axial compression strength and brinell hardness were slightly affected by densification.