The effect of lamina configuration and compaction pressure on mechanical properties of laminated gigantochloa apus composites

This study aims to investigate the mechanical properties of bamboo apus (gigantochloa apus) as a natural reinforced composite material. Bamboo’s laminates of gigantochloa apus were used as reinforcement on the epoxy resin matrix. The parameters examined in this study are the configuration of lamina and compaction pressure. Laminate configuration varies in the number, thickness and direction of the lamina. Compaction pressures of 1.5 MPa, 2 MPa, and 2.5 MPa were used to fabricate the Laminated Bamboo Composites (LBCs). The stem of bamboo with a length of 400 mm was split to obtain bamboo lamina with a size of 400×20 mm. The thickness of bamboo lamina is varied between 1 mm, 1.5 mm, and 2 mm. The bamboo lamina is then preserved by watering it with a preservative solution in the form of 2.5 % sodium tetraborate solution and dried in an oven until the water content reaches 10 %. LBCs were made with a hand lay-up method. After the LBCs were molded, they were pressed with 3 variations of dies compaction 1.5 MPa, 2 MPa and 2.5 MPa. The tensile and bending tests were carried out on the LBCs. Tensile testing is performed in accordance with ASTM standard D3039 and the bending tests were conducted based on ASTM standard D7264. The results show that at each compaction pressure, the highest tensile and bending strength was achieved by LBCs with a thickness of 1 mm of bamboo lamina and 7 layers of bamboo laminates. The LBC with thinner bamboo lamina reinforcement and more layers has the highest tensile strength and bending strength, even it has a lower mass fraction. The LBCs with laminates oriented 0° exhibited greater tensile and bending strengths than the LBCs with laminates structured –45°/+45° and 0°/90°. The LBCs with the 0° laminates direction is matrix fracture followed by lamina fracture. In the 0°/90° direction, matrix fracture is followed by delamination in the 90° and 0° laminates direction. Delamination and lamina clefting were observed in LBCs with laminates oriented +45°/–45°.

The Filtration Efficiency of Single-Layer Textiles for Respiratory protection

Due to the increasing number of corona cases and the face mask industry's associated bottleneck, this work focuses on the various single-layer textiles used as cloth masks. The purpose of this work is to test ten different single-layer textiles for their suitability as face masks. All tests in this work were carried out based on the ASTM F2299 and the new ASTM Standard for barrier masks (3502-21). The new standard offers a more precisely defined test protocol and is consistent with how respirators are tested. The results show that only one of the ten textiles tested meets the ASTM requirements for a barrier mask. We also include data for ASTM F2299 and report the results for unneutralized challenge particles at various face velocities for the same single-layer textiles. These results are different from those of the ASTM 3502 because the particle size and the procedure used are different. Under ASTM 3502, the resistance values ​​are significantly higher, and the efficiency values ​​are significantly lower than those reported by using the ASTM F2299.

PENGARUH PERSENTASE PEREKAT TAPIOKA TERHADAP KARAKTERISTIK BRIKET ARANG TEMPURUNG KELAPA

Tapioka flour as an adhesive for coconut shell charcoal briquettes can affect the characteristics of charcoal briquettes consisting of physical and chemical properties. The purpose of this study was to determine the physical properties of coconut shell charcoal briquettes in several adhesive percentages. The method used was a completely randomized design pattern and in this study there was only one factor (factor = coconut shell charcoal and tapioca adhesive/starch), as many as 5 treatments with 3 replicatins = 15 samples to be tested. Charakteristics of coconut shell charcoal briquettes that meet ASTM standard : water content that entered ASTM standard (Max 6%) in treatment A2 (95% coconut shell charcoal + 5% tapioca adhesive), the best density is found in treatment A3 (90% coconut shell charcoal + 10% tapioca adhesive)and enter ASTM standard(1.0-1.2 g / cm3), ash content that falls within the ASTM standard (Max 18%) in treatment A3(90% coconut shell charcoal + 10% tapioca adhesive), flying substancs that comply with ASTM standard (19-28%) in treatment A3 (90% charcoal coconut shell + 10% tapioca adhesive), bonded carbon content which is included in the ASTM standard (at least 58%) in treatment A2 (95% coconut shell charcoal + 5% tapioca adhesive),and the best heating value is found in the treatment A3 ( 90% coconut shell charcoal + 10% tapioca adhesive) which falls within the ASTM standard (4000-6500 cal / g). The results of this study indicate that the percentage of tapioca adhesive can affect the characteristics of coconut shell charcoal briquetess.Keywords: Percentage of tapioca adhesive; Charcoal briquettes; Coconut shell

The effect of natural fillers on the marine biodegradation behaviour of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV)

Worldwide, improper disposal of plastics is instigating environmental initiatives to combat plastics accumulation of in the environment and the world’s oceans. Poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) biocomposites with Miscanthus (Misc) fibres and distillers’ dried grains with solubles (DDGS) were studied to ascertain if natural fibres and proteinaceous fillers can improve polyhydroxyalkanoate marine biodegradability. Using ASTM standard D7991-15, the biodegradation of PHBV, PHBV with Misc (15 and 25 wt%) and PHBV with DDGS (15 and 25 wt%) was performed in a simulated marine environment for the first time, as indicated by a literature survey. PHBV/Misc (85/15) and (75/25) biocomposites showed 15 and 25% more biodegradation compared to PHBV, respectively. Proteinaceous PHBV/DDGS (85/15) and (75/25) biocomposites showed 17 and 40% more biodegradation compared to PHBV, respectively. Furthermore, PHBV/Misc (75/25) and PHBV/DDGS (75/25) biocomposites were marine biodegraded in 412 and 295 days, respectively. In conclusion, proteinaceous fillers (DDGS) biocomposites have better marine biodegradability than miscanthus.

Characterizing Additively Manufactured Metals From a Novel Laser Wire Metal Deposition Process

Several tests were conducted on 316 stainless steel, and 17-4 PH stainless steel to understand the effect of additive manufacturing on their mechanical properties in general. The samples were produced via a custom-built laser wire metal deposition, with variable laser power of 3600W for 316 stainless, and 4000W for 17-4 PH, but all other printing parameters were kept same. Four different tests, Tensile, Rockwell hardness, Charpy impact, and optical microscopy were carried out to establish the material properties and surface characterization. Through our assessment, it was found that the properties of the laser-printed samples can be greatly varied by printing in an inert atmosphere, while the printing orientation and post-print heat treatment process also play a dominant role in determining the properties. This research showed that the properties of additively manufactured 316 stainless, and 17-4 PH have fared well when compared to ASTM standard values for annealed metals. Details of the results are presented. Inspecting the 316 stainless, the metal strength and hardness were high while being printed in x orientation, while the metal was much more ductile when printed in y orientation. The 316 stainless micro-structure contained no porosity or no anomalies from the samples tested. The results of 17-4 stainless samples matched the ASTM standard values for strength and hardness. But with Charpy impact tests, the results seemed slightly ductile as the values were slightly lower than the threshold. That brittle nature could have been a result of porosity that was visible under microscope. But the porosity levels decreased tremendously when the sample was once again printed in an inert environment. The results of this research have helped us understand the intricate nature of 316 and 17-4 PH stainless steels while being additively printed. The beneficial research experience of participating undergraduate students in collaboration with industry is a special feature of this project.

Low cost 3D printed clamps for external fixator for developing countries: a biomechanical study

Background External fixation is a mainstream limb reconstruction technique, most often used after a traumatic injury. Due to the high rates of trauma in developing countries, external fixation devices are often utilized for immediate fracture stabilization and soft tissue repair. Proper external fixation treatment too often still fails to be adopted in these regions due to the high cost and trauma complexity. A novel, inexpensive, unilateral fixator was constructed using 3D printed clamps and other readily available supporting components. ASTM standard F1541 tests were used to assess the biomechanical properties of this novel external fixator. Methods Applicable sections of ASTM standard F1541 were used to determine the biomechanical properties of the novel external fixator. 3D printed clamps modeled using SolidWorks and printed with chopped carbon fibers using a fuse deposition modeling (FDM) based 3D printer by Markforged (Boston, MA) were used. This study included 3 different testing configurations: axial compression, anterior-posterior (AP) bending, and medial-lateral (ML) bending. Using the novel unilateral fixator with 3D printed clamps previously sterilized by autoclave, an input load was applied at a rate of 20 N/s, starting at 0 N via a hydraulic MTS tester Model 359. Force and deformation data were collected at a sampling rate of 30 Hz. There was a load limit of 750 N, or until there was a maximum vertical deformation of 6 mm. Also, 4 key dimensions of the 3D printed clamps were measured pre and post autoclave: diameter, width, height and length. Results The novel external fixator had axial compression, AP and ML bending rigidities of 246.12 N/mm (σ = 8.87 N/mm), 35.98 N/mm (σ = 2.11 N/mm) and 39.60 N/mm (σ =2.60 N/mm), respectively. The 3D printed clamps shrunk unproportionally due to the autoclaving process, with the diameter, width, height and length dimensions shrinking by 2.6%, 0.2%, 1.7% and 0.3%, respectively. Conclusion Overall, the biomechanical properties of the novel fixator with 3D printed clamps assessed in this study were comparable to external fixators that are currently being used in clinical settings. While the biomechanics were comparable, the low cost and readily available components of this design meets the need for low cost external fixators in developing countries that current clinical options could not satisfy. However, further verification and validation routines to determine efficacy and safety must be conducted before this novel fixator can be clinically deployed. Also, the material composition allowed for the clamps to maintain the appropriate shape with minimal dimensional shrinkage that can be accounted for in clamp design.

Potential of Chrozophora tinctoria Seed Oil as a Biodiesel Resource

Biodiesel is a renewable fuel that has been widely used in recent years. There are various resources used as biodiesel feedstocks, including animal fats, waste oils, and vegetable oils. In the present study, Chrozophora tinctoria seed oil is introduced as a new biodiesel feedstock. C. tinctoria is a weed and non-edible plant. So, the primary cost of this resource is very low, and hence it can be considered as a biodiesel source. This plant can also grow in most weather conditions. In the present study, the research team tried to produce biodiesel from C. tinctoria seeds through a transesterification reaction. To intensify the transesterification reaction, an ultrasonic device was used. In order to perform the transesterification reaction, potassium hydroxide was used as a catalyst. Important parameters, such as the reaction temperature, reaction time, molar ratio of methanol, and concentration of the catalyst, were adjusted. Based on the adjusted conditions, a biodiesel yield of 84% was attained. The properties of the C. tinctoria biodiesel was compared with the American Society for Testing and Materials (ASTM) standard. The results show the properties of a biodiesel: the density, kinematic viscosity, pour point, flash point, cloud point, and acid number are 0.868 g/cm3, 3.74 mPa, −7 °C, 169 °C, 4 °C, and 0.43 mg, respectively. The specification properties of C. tinctoria biodiesel can thus pass the requirement of the ASTM standard. So, C. tinctoria seed oil can be used as a suitable fuel source instead of petroleum-derived fuels.