Volume 11 Issue 4

The geometrical limits of the deep drawing process of paper to advanced shapes are not known. This report examines the technological limits of convex elements of the base shape in relation to the drawing height and shows the material behavior in the bottom radius of 3D shapes with regard to special material properties. In the bottom radius, non-compressed wrinkles occurred due to the in-plane compression, but wrinkles were reduced by an increased blank holder force or tool temperatures and improved extensibility or in-plane compressive strain. The forming ratio during deep drawing (drawing height related to base diameter) was increased to a value of more than 1 by a blank holder force, which increased with the drawing height such that the initial blank holder force was reduced concurrently. Straight sections in the base shape reduced the risk for ruptures in the edge radii of rectangular shapes, producing a forming ratio in these radii of 2.5. The forming ratio was further supported by a pattern of creasing lines at the blanks with a radial orientation and a number near the expected maximum number of wrinkles. The spring-back at rectangular shapes mainly depended on the drawing height and edge radius.

Chusquea quila or “quila”, is one of the most abundant lesser-known species from Chile, and for many years it has created problems for farmers in the southern part of this country. In this study, it was examined as a promising resource for high-tech materials. The chemical and physical properties were determined by ASTM standards. The extractives, ash content, lignin, and alpha-cellulose were 4.55%, 2.17%, 13.78%, and 54.65%, respectively. The higher heating value and basic density obtained were 5,106 kcal/kg and 290 kg/m3, respectively. The moisture content was studied during four seasons and found to be the highest in winter (73%). Regarding the nanomechanical profiles, hardness varied from 0.16 GPa in the cortex to 0.21 GPa in the nodule. The average elastic modulus in the nodule and internode was 12.5 GPa, while in the cortex it was 7.45 GPa. Considering the high cellulose content and structural features of the lignocellulosic matrix, it could be possible to extract cellulose fibers for commercial use and crude lignin for testing new applications. Thus, the entire quila structure is a potential biomass resource.

Effects of treatment duration and clamping during heat treatment were evaluated relative to the color and physical and mechanical properties of okan wood. Sapwood and heartwood boards from okan wood were treated with and without clamping for 1 to 4 h at 180 °C. Changes in color were mostly due to a reduction in lightness (L*) and yellow/blue chromaticity (b*). These values decreased more for longer treatment durations. Red/green chromaticity (a*) was not affected by the treatment duration. Weight loss and volume shrinkage increased with increased treatment duration. Density only slightly decreased because of a balanced reduction in weight and volume. Clamping during treatment prevented surfaces from having direct contact with the heated air, which resulted in lower weight loss and volume shrinkage than in the samples treated without clamping. Heat-treated wood absorbed less water than the control group, as suggested by the lower equilibrium moisture content and water absorption. Furthermore, the heartwood absorbed less water than the sapwood. An evaluation of the mechanical properties showed a reduction in both the modulus of rupture and modulus of elasticity after heat treatment. Clamping minimized strength reduction in both sapwood and heartwood, particularly for 1 and 2 h heat treatments.

Torrefaction is a thermochemical pretreatment method for improving fuel characteristics of biomass. The process is conducted between 200 and 300 °C under inert atmosphere. The relatively low process temperature of torrefaction makes the use of solar energy suitable with low costs. In this study, solid olive mill residue (SOMR) was used to test the feasibility of using solar energy in the torrefaction process. SOMR is an agricultural waste obtained from olive oil extraction, and it is mainly produced in the Mediterranean region, which has high solar energy potential. In this study, the torrefaction of SOMR was conducted by concentrating solar energy with a parabolic dish concentrator, at 250 °C for 10 min. The fuel properties of solar torrefaction products were compared with raw SOMR. Solar torrefaction yielded a deoxygenated solid fuel with increased carbon content and higher heating value (HHV), similar to torrefaction.

Esterase is an important enzyme for ester hydrolysis or synthesis. Its activity, however, has not been accurately ascertained due to a lack of accurate protocols. In this study, the isosbestic point of p-nitrophenol was found and used as the marker for its activity. The methodology avoided decomposition of the substrate, chromophore agents, and pH changes. The esterase activity was determined accurately and rapidly in a complex solution. In this protocol system, organic solvents were used for dissolving substrates, which influenced activity determination to some extent. Among the solvents tested, methanol exerted the least inhibitory influence. The results indicated that this modified method has potential to be applied for esterase activity determination on a large scale and in real time.

The influence of repeated cycles of injection molding on some mechanical and thermal properties of wood plastic composites (WPCs) was investigated. Pine wood flour (50 wt%) was mixed with HDPE (50 wt%) containing compatibilizing agent (MAPE, 3 wt%) in a co-rotating twin-screw extruder. The test specimens were produced by injection molding from the pellets dried to the moisture content (MC) of 1%. After the mechanical properties of the WPC test specimens were determined, the failed specimens were subsequently pelletized. These pellets were stored and dried for 4 to 6 h until the repeated injection was molded. These processes were repeated seven times. The results revealed that the flexural strength of WPCs increased by about 5.26% from the original granules to the third injection cycle, but further increments in the number of cycles decreased the flexural strength. The tensile strength and tensile modulus of the WPC specimens increased until the third cycle of injection molding while they tended to decrease after the third injection cycle.

Poplar wood is commonly used for many purposes due to its easy machinability, low density, uniform light colour, and relatively low cost. Here, vacuum thermal treatment is proposed for upgrading veneers in the manufacturing of plywood panels with resulting reduced hygroscopicity, improved durability, and dimensional stability. Thirty-eight batch processes with different treatment conditions (temperature ranging from 150 to 240 °C, time from 0.5 to 22.5 h and pressure from 100 to 1000 mbar) were performed to characterize the influence of process parameters on the product properties. Samples were characterized considering their appearance (colour) and their physical (mass loss and equilibrium moisture content), mechanical (bending strength), and chemical (investigated with near infrared spectroscopy (NIR)) properties. The darkening of poplar veneers and the reduction of mechanical strength were observed with increased treatment time and intensity. Mass loss closely correlated with colour change, resulting from chemical changes in wood components. Principal component analysis (PCA) and partial least squares (PLS) were used for evaluation of near infrared spectral data. Both were correlated with several technical properties, and thus NIR allowed the simultaneous prediction of several of these properties. Both colour change and NIR could be used to optimize the thermal treatment of poplar veneers at the industrial scale and for real-time statistical process control.

The use of a hardwood lignosulfonate (HLS) precursor along with electrospinning technology was studied to produce HLS-based carbon fibers. The production of the fibers helped to determine the appropriate processing parameters in the HLS carbon fiber production process. The processing parameters examined were the heating rate (POR) and the treatment temperature (POT) in the preoxidation process; the heating rate (C₁R) and the treatment temperature (C₁T) were in the low-temperature carbonization phase; and the carbonization temperature (C₂T) and temperature holding period (C₂t) were in the high-temperature carbonization phase. The results revealed that preoxidation with a POR of 1 °C/min and a POT of 250 °C generated favorable properties, particularly enhancing the fiber mat integrity and the fiber carbon content. The designed two-phase carbonization process was found to be satisfactory in increasing carbon fiber yields and enhancing fiber mat integrity. A C₁R value of 1 °C/min and C₁T of 400 °C facilitated favorable properties in the produced carbon fibers. Furthermore, a prolonged C₂t increased the fiber carbon content but reduced the carbon fiber yield. The highest fiber carbon content occurred with a C₂t of 3 h and a C₂T of 1200 °C.