Volume 13 Issue 3

The performance of short pineapple leaf fiber (PALF) reinforced tapioca biopolymer (TBP) composites were investigated, specifically the effect of fiber length and fiber composition on mechanical properties (tensile properties, flexural strength, and impact strength). Composite samples with different fiber lengths (< 0.50 mm, 0.51 mm to 1.00 mm, and 1.01 mm to 2.00 mm) and different fiber compositions (10%, 20%, 30%, and 40%) were prepared through crushing, sieving, internal mixing, compression molding, and machining processes. The combination of PALF and TBP enhanced the mechanical properties of composites with 30% as the optimum fiber content. However, the influence of different fiber lengths up to 2.00 mm provided no significant effect on producing maximum tensile properties. Good interfacial adhesion between PALF and TBP was evident from scanning electron microscopy analysis. Therefore, the combination of PALF and TBP has great potential as a renewable and biodegradable polymer. Moreover, PALF-TBP composites are expected to become alternatives to petroleum-based polymers.

Carbon black (CB) was used to fill the shell of wood high-density polyethylene (HDPE) composite to improve its antistatic properties and simultaneously maintain its mechanical properties. The conductivity analysis revealed that the percolation threshold of the CB in coextruded WPC was between 15% and 20%, and the surface resistivity of the sample containing 20% CB (CW-20) achieved the floor antistatic requirements of an electronic information system room and its support area according to GB/T 50174 (2017). The addition of CB into the shell of the coextruded WPC inhibited its crystallization. The mechanical properties of coextruded WPC were increased when the CB content was increased. The flexural strength, flexural modulus, and impact strength of the CW-20 sample were increased by 21.6%, 10.8%, and 26.1%, respectively. In addition, the dosage of CB in regular WPCs was 6.71 times as much as that of coextruded WPCs, which achieved similar antistatic and mechanical properties of the two structural WPCs. These results demonstrated that the low CB filled shell of HDPE composite exhibited a large reduction in its surface resistivity and a significant enhancement in its mechanical properties, which expands the application of coextruded WPCs in flammable and explosive uses while also improving the antistatic and mechanical properties.

Pine oleoresin is an important industrial resource, used widely in pharmaceuticals, cosmetics, and insecticides. To reveal the function of 1-deoxy-D-xylulose 5-phosphate synthase (DXS) in oleoresin biosynthesis in Simao pine, three complete cDNAs of DXS genes were obtained, of lengths 2223 bp (PkDXS1), 2217 bp (PkDXS2), and 2142 bp (PkDXS3). Phylogenetic analysis showed that PkDXS1 belonged to DXS type 1, and both PkDXS2 and PkDXS3 belonged to DXS type 2. Functional complementation experiments indicated that the three PkDXS genes had DXS protein function. Real-time PCR detection showed that physical wounding slightly influenced the gene expression of PkDXS1 and strongly influenced the gene expression of PkDXS2 and PkDXS3. The gene expressions of PkDXS3 in high-oleoresin-yield individuals were higher than their gene expressions in low-oleoresin-yield individuals. This result implied that the gene expressions of DXS regulated the oleoresin yields in different individuals of Simao pine. These results will provide information to help reveal the mechanisms of high-oleoresin-yield of Simao pine in the future.

Correlations were determined between the thermal degradation behaviors of ball-milled Miscanthus plants and their enzymatic digestibilities. Overall, thermal degradation temperatures of Miscanthus giganteus were higher than those of M. sinensis. The differential thermogravimetric (DTG) curve of M. giganteus had a characteristic shoulder peak near 292 °C as opposed to that of M. sinensis. The thermal degradation temperatures of both ball-milled samples decreased with increased ball-milling time, although the composition was not changed by ball milling. Remarkable changes in the DTG curves of M. sinensis and M. giganteus occurred with ball milling for more than 60 min and 120 min, respectively. These thermal degradation results were similar to the results for physicochemical pretreatments and enzymatic digestibilities. The thermal decomposition temperatures of both ball-milled samples at 20% weight loss were most negatively correlated with the enzymatic digestibilities with a value of approximately -1.0.

Composites made from annual plants, such as winter rapeseed, can be used as an alternative to wood-based composites because of their ecological character, low price, as well as physical and mechanical properties. The goal of this study was to prepare such boards and evaluate their properties. Unmodified material and chemically and hydrothermally modified rapeseed particles glued by powder polyester glue were used. The characteristics measured were the internal bonding, swelling and moisture uptake over time, and surface soundness. The results showed that modification of the raw material influenced the properties of the resulting composites. The highest swelling values were exhibited by the boards with particles that were alkaline-modified. Boards made from hydrothermally modified particles achieved the highest strengths compared with the commercially produced boards. The alkaline modification of the particles resulted in a stronger adhesive bond between the particle and adhesive. During the internal bonding test, the boards made from the alkaline-modified particles exhibited cohesive failures in the particles. Therefore, the modification of the particles increased the mechanical properties of the boards, but the physical properties deteriorated.

Much research has been carried out to improve the wettability and to overcome the low adhesion of tire rubber for use in developing new building materials, such as wood-cement panels. Corona surface treatment (air plasma) of rubber particles was used in this study with various application times to improve adhesion and the interface between the particles and the cementitious matrix. Another aspect evaluated in this study was the partial replacement of wood particles by tire rubber waste in wood-cement panels. The particulate rubber residue was subjected to various corona application times to determine the most suitable treatment; the samples showed the most desirable qualities after 20 min of air plasma treatment. Then, panels were produced using Pinus oocarpa particles associated with various contents of tire rubber after corona treatment. Overall, after 20 min of air plasma treatment, the wettability and adhesion properties of tire rubber waste improved. The use of 5% rubber to replace pine wood in wood-cement panels led to a substantial improvement in the physical-mechanical properties evaluated, making its production feasible and promoting the reuse of a material harmful to the environment.

Market globalization, with its accompanying higher living standards, food availability, and sedentary jobs noticeably affects the eating habits and lifestyles of people. Therefore, the body weight of populations is increasing globally. These changes must be taken into account when various everyday items (furniture, clothes, and shoes) are designed. Population-based studies dealing with measuring the height and body weight of adult male populations were analyzed (body mass index categories: 25 kg/m² to < 30 kg/m² (overweight), > 30 kg/m² (obese), > 35 kg/m² (severely obese)). Because of the analysis of anthropometric parameters in Central Europe, especially Slovakia, it is necessary to produce chairs with two weight categories for the common population (normal weight up to 110 kg) and a population with a higher weight. The aim of this research was to investigate the effect of the body weight of users on the load capacity and dimensions of structural elements of chairs. Following the static analysis of the load-carrying capacity of several chair types, it was calculated that the only suitable construction type for users with a higher weight is the construction with stretchers. The cross-section of the leg space and side rail increased by 20% and 25%, respectively, in the case of a 150-kg user and tenon dimensions of 10 mm × 60 mm × 30 mm.

This study investigated the dyeing methods (soaking and vacuum-pressure), types of dye (direct dye and reactive dye), and dyeing parameters (dye concentration, dyeing time, and temperature) in the veneer dyeing process for Eucalyptus globulus grown on plantations in Australia. The dyed veneers were assessed in two ways: dye penetration, which was determined using ImageJ software, and visual veneer grading for identifying any damage (curves or cracks). Veneers with different moisture content (MC) levels were used and were called green veneer (80% ± 5% MC) and dried veneer (12% MC). The study showed that the reactive dye Procion Brown P2RN at a concentration of 2% resulted in a significantly higher dye penetration than the other dyes. Soaking was not recommended as the dyeing method for this species because the dyed samples were severely damaged by the pre-treatments and high temperatures. A dye penetration of 100% was achieved when using the vacuum-pressure method with a dyeing time of 120 min, a pressure of 1000 kPa, and the addition of 20 g/L of sodium chloride. The results of this study can be applied in further research on the veneer dyeing process for this species.

Combustion characteristics of cattle manure (CM) and pulverized coal blends under oxy-fuel atmosphere were considered. Factors such as the furnace temperature, O2 concentration, and blending ratio were analyzed. The experiment under non-isothermal and isothermal conditions were used to study effects of the heating rate. Blended CM can improve the combustion characteristics of pulverized coal. However, a difference exists between the increase of the blending ratio of CM with Shanxi bituminous coal (SX) and Xiaolongtan lignite coal (XLT) under various O2 concentration conditions. More attention should be paid to the blending ratio > 50%. CM and coal co-firing affected by the furnace temperature had a close association with its characteristics. Inhibition was found in most conditions, and the trend of interaction between CM and coal under the non-isothermal and isothermal condition was consistent. These experiments provided information for the utilization of livestock and poultry manure and pulverized coal blends in the oxy-fuel atmosphere.

Polyester/kenaf composites reinforced with zinc oxide nanoparticles (ZnO NPs) were fabricated. The nanoparticle treatment had a noticeable effect on the mechanical properties of the composites. Kenaf treatments with five different concentrations 1%, 2%, 3%, 4%, and 5% were performed. The mechanical analysis showed an increased flexural strength stability and break elongation in the functionalized ZnO NPs-treated kenaf polyester resin composites. The polymer nanocomposites with 2% ZnO NPs had stable mechanical properties with moderate elastic properties compared with the remaining ZnO NPs systems. The mechanical properties of the composites that contained different layers of kenaf mat demonstrated positive influence on the polymer nanocomposites. The material increased in stiffness with an increase in layers from 1 to 5. The results of weathering confirmed the stability of the polymer nanocomposites with increased stability. The 2% nanoparticle coating with a 5-layer kenaf layer revealed no remarkable changes in the mechanical degradation throughout the 6-month weathering period. The results of the mechanical properties tests suggested that a 2% ZnO NPs concentration with five kenaf layers had the highest moisture resistance, thus; the ZnO NPs acted as a water repellent agent.