Volume 15 Issue 3

Paperboards of thickness 0.6 cm with densities of 0.8, 0.9, and 1.0 g/cm3 were produced from waste papers mixed with cement and kaolin. Printing and corrugated waste papers were employed in the proportions of 50.0/25.0/25.0, 50.0/37.5/12.5, and 50.0/12.5/37.5 (paper/cement/kaolin), respectively. The dimensional and strength properties of the boards were investigated. The values obtained range from 0.40 to 0.94 g/cm3, 51.19 to 68.10%, 0.14 to 3.10%, 0.01 to 1.69 Nmm-2, and 119.98 to 567.32 Nmm-2 for observing the density, water absorption, thickness swelling, modulus of rupture, and modulus of elasticity, respectively. The board of proportion 25/25 of kaolin/cement was densest with high strength. As the nominal density and kaolin content were increased from 12.5 to 37.5%, an increase was observed in density and strength properties. Similarly, as the proportion of kaolin and cement content were increased, the rate of moisture uptake to cavity decreased. This study shows that boards from printing papers were more dimensionally stable than corrugated papers. It revealed that printing papers could be better raw material for manufacture paperboard than corrugated papers. Information provided in this study could be used as a guideline for the manufacture of paperboard reinforced with kaolin as an additional constituent for quality improvement.

This research aimed to elucidate the effect of black and non-black filler systems on the cure characteristics and mechanical properties of butyl reclaimed rubber (BRR). In this study, BRR800 was the BRR investigated. Since reclaimed rubber is not entirely 100% rubber, actually being a mixture of rubber, carbon black, oil, zinc oxide, stearic acid and other compounding ingredients used in the original compounds, the reclaimed rubber content in each system was fixed at 161 parts per hundred (pphr). Each mixture was mixed using a two-roll mill. The fillers used in this study were carbon black and calcium carbonate. The Mooney viscosity, cure characteristics, crosslink density, and mechanical properties, such as hardness, abrasion resistance, compression set, tear strength, rebound resilience, and the tensile properties of the vulcanizates were investigated. The results showed that the Mooney viscosity of BRR800 filled with carbon black was increased effectively and had a faster curing time and higher crosslink density than BRR filled with calcium carbonate. In addition, except for compression set and elongation at break, the mechanical properties of BRR800 with a black filler system were higher than those of BRR800 with a non-black filler system.

Polyurethane foam is one of the most versatile construction insulation materials because of its low density, high mechanical properties, and low thermal conductivity. This study examined biobased rigid polyurethane foam composites from apricot stone shells, which are lignocellulosic residues. The apricot stone shells were liquefied with a PEG-400 (polyethylene glycol-400) and glycerin mixture in the presence of sulfuric acid catalyst at 140 to 160 °C for 120 min. Rigid polyurethane-type foam composites from the reaction were successfully prepared with different chemical components. Biobased polyurethane-type foam composites were successfully produced from the liquefied apricot stone shells. The FTIR spectra of liquefaction products confirmed successful liquefaction of products and that they are sources of hydroxyl groups. The liquefaction yield (81.6 to 96.7%), hydroxyl number (133.5 to 204.8 mg KOH per g), the highest elemental analysis amount (C, H, N, S, O) (62.08, 6.32, 6.12, 0.13, and 25.35%), and density (0.0280 to 0.0482 g per cm3) of the rigid polyurethane foam composites were comparable to foams made from commercial RPUF composites.

The procedure for the liquefaction of apricot stone shells was reported in Part 1. Part 2 of this work determines the morphological, mechanical, and thermal properties of the bio-based rigid polyurethane foam composites (RPUFc). In this study, the thermal conductivity, compressive strength, compressive modulus, thermogravimetric analysis, flammability tests (horizontal burning and limited oxygen index (LOI)) in the flame retardants), and scanning electron microscope (SEM) (cell diameter in the SEM) tests of the RPUFc were performed and compared with control samples. The results showed the thermal conductivity (0.0342 to 0.0362 mW/mK), compressive strength (10.5 to 14.9 kPa), compressive modulus (179.9 to 180.3 kPa), decomposition and residue in the thermogravimetric analysis (230 to 491 °C, 15.31 to 21.61%), UL-94 and LOI in the flame retardants (539.5 to 591.1 mm/min, 17.8 to 18.5%), and cell diameter in the SEM (50.6 to 347.5 μm) of RPUFc attained from liquefied biomass. The results were similar to those of foams obtained from industrial RPUFs, and demonstrated that bio-based RPUFc obtained from liquefied apricot stone shells could be used as a reinforcement filler in the preparation of RPUFs, specifically in construction and insulation materials. Moreover, liquefied apricot stone shell products have potential to be fabricated into rigid polyurethane foam composites.

Biomass resources in nature produce a large amount of waste resources (agricultural residues, wood waste, etc.) during agricultural and forestry production processes. Therefore, the effective utilization of these solid biomass waste resources has attracted widespread interest. In this paper, a pulsed discharge plasma technology was used to perform catalytic liquefaction experiments on solid biomass sawdust at room temperature and atmospheric pressure, and the reaction parameters such as the solid:liquid ratio, liquefaction solvent ratio, and catalyst ratio were optimized. The results showed that the plasma technology achieved a higher liquefaction yield; the optimized reaction parameters were: a solid:liquid ratio of 1:23.4, a liquefaction solvent polyethylene glycol (PEG) / glycerol (GL) ratio of 25:15 (V:V), and an acid volume fraction of 0.188%. In addition, the characteristics of the products of the liquefaction reaction were analyzed and discussed. The liquid products were mainly composed of small molecules. The experiment established that the liquefaction of solid sawdust by high-voltage pulsed discharge plasma can be an effective technical method.

In an effort to reduce negative feedback resulting from temperature fluctuations, house floors are commonly laid with laminate flooring. The aim of this study was to study the thermal insulation properties and adhesion strength of the water-based insulation paint mixed with hollow glass spheres and applied onto the laminate flooring. The objective was to determine whether a prepared insulation paint mixture can be used instead of backing paper. For this purpose, two different laminate flooring samples were used. In the first case, the upper surface of the sample was coated with decorative paper and the lining surface was coated with backing paper. The upper surface of the second sample was coated with decorative paper and the lining surface was not coated with backing paper. Then, insulation paint mixture was applied 2, 4, or 6 times to the lining surfaces of both groups, and experimental results were obtained. As the number of layers was increased, the insulation mixture applied to the lining surfaces of the test samples was found to contribute positively to thermal insulation and adhesion resistance of specimens.

The ballistic impact behavior of oil empty fruit bunch fiber reinforced bio-composites was studied. Epoxy and polyester resins were used as the main material and were evaluated as a matrix to determine their capability. The ballistic test was performed using a 9 mm handgun and a jacketed hollow point round. A model based on kinematics and dynamics was used to calculate the decrease in velocity of the projectile with a constant deceleration. The energy lost during the impact was calculated based on the theory of kinetic energy. The epoxy bio-composite was able to hold a projectile more successfully than the polyester bio-composite at a certain penetration depth. The curve of the decrease in velocity for both of the resins was exponentially distributed. An 18% epoxy bio-composite was able to more successfully stop the projectile at a penetrative depth of 2.14 mm and was able to absorb all the kinetic energy generated (408 J).

The surface roughness of pine, beech, and oak wood cut in the abrasive water jet (AWJ) system was evaluated for different processing parameters. Wood specimens were prepared in thicknesses of 18, 36, and 54 mm in both tangential and radial directions. Then the specimens were cut, applying three different feed speeds (50, 100, and 200 mm/min), three different abrasive flow rates (200, 300, and 450 g/min), and two different cutting liquid pressures (300 and 380 MPa) with the AWJ system. The Ra and Rz roughness values were higher in the tangential cut for pine and oak specimens and in the radial cut for beech wood. Roughness values increased in all specimens with increases in the AWJ feed speed and the wood thickness. In contrast, with increased amounts of abrasive, Ra and Rz values of the specimens decreased and surface smoothness tended to increase. Roughness values of pine and oak specimens generally decreased due to the increase in liquid pressure. However, an increase in the roughness of the beech specimens was determined. As a result, the feed speed and wood thickness were the most influential parameters on the roughness of specimens. In contrast, the cutting direction and liquid pressure showed less importance on the roughness.

An approach combining maps of wood morphology and digital image correlation was developed to investigate the drying of Eucalyptus nitens wood. Maps of morphological features (vessel and ray distribution) and cell cross-section dimensions were acquired by confocal laser scanning microscopy. Shrinkage maps were generated using digital image correlation. There were statistically significant correlations between shrinkage/collapse and wood morphology at two levels. Firstly, there were positional relationships, with for example, both radial and tangential shrinkage increasing with increasing distance from vessel elements. Secondly, there were dimensional relationships, such as, cells with large perimeters (relative to their wall thickness) on average showing greater shrinkage. Generally, the positional relationships dominated the dimensional relationships. Detailed analysis over large areas allows for a fuller analysis of the interrelationship between wood morphology and drying shrinkage and collapse.

The development of a formaldehyde-free wood-based panel is a major research direction in the wood-based material industry. Previous research has demonstrated that nitric acid activated fibers and coupling agents could be utilized to manufacture formaldehyde-free medium-density fiberboards. Herein, based on the chemical characteristics of wood, nitric acid and tannin were applied in formaldehyde-free particleboard, featuring suitable mechanical properties and water absorption resistance. The results of modulus of rupture (MOR), surface bonding strength, internal bonding strength, and 2 h moisture thickness swelling (TS) of formaldehyde-free particleboard (that was synthesized at optimal conditions and satisfied the China National Standards GB/T 4897 (2015) and GB/T 17657 (2013)) are discussed. The investigation of the technological conditions on bond performance showed that when the particleboard was bonded with the conditions of 20/80 nitric acid/particles mass proportion, 50% tannin concentration, and 135 °C temperature, the MOR, surface bonding strength, inner bonding strength, and 2 h TS were better than that of the particles with urea formaldehyde resin adhesive. The synthesis mechanism was studied by both Fourier transform infrared spectroscopy and wide-angle X-ray diffraction, and the chemical composition indicated polycondensation of furfural and tannin, and hydrogen bonding of hydroxyl groups as the reaction mechanism between nitric activation and the tannin coupling agent.