Physical properties of handsheets derived from Coi (Streblus asper Lour.) pulp fiber as papermaking material traced from ancient times

There have been recent attempts to revive the traditional production of handmade paper from the bark of the Coi (Streblus asper Lour.) tree in Thailand. A sheet sample of Coi handmade paper, made from the traditional production, was collected and examined microscopically for the first time. Film-like material and cubic calcium particles were found on the sheet sample surface, which is consistent with the results of the authors’ previous research. Meanwhile, handsheets derived from Coi pulp fiber, freshly made in the laboratory, demonstrated a low air permeance and brightness with high opacity due to the film-like material and cubic calcium particles. With a high felting power of Coi pulp fiber coupled with a possible strengthening role of the film-like material, both the beaten and unbeaten fibers were used to form handsheets with high strength. Some potential aspects of Coi pulp fiber suitable for creating a unique Thai banknote paper have been demonstrated, for which further studies are suggested.

Modeling of formation ring sheet sample from aluminum alloy by elastic medium stamping

The forming process in tank with elastic structure of ring sheet sample from aluminum alloy D16AM with flanges on internal and external sides was modulated. The numerical modulation by using the module “explicit dynamics” of the “ANSYS” software package was performed. The features of modeling the quasi static problem of forming a sheet part by using the elastic medium was described. The simulation results are compared with experimental data obtained in previous studies of the authors. The possibility of using the “explicit dynamics” module of the “ANSYS” software package for modeling the forming of sheet parts by an elastic medium has been confirmed. Calculations of the required press force for stamping ring sheet samples made of D16AM alloy with an elastic medium showed good convergence with experimental data.

Fast, Nondestructive, and Broadband Dielectric Characterization for Polymer Sheets

We propose a compact nearfield scheme for fast and broadband dielectric characterization in the microwave region. An open-type circular probe operated in the high-purity TE01 mode was developed, showing a strongly confined fringing field at the open end. This fringing field directly probed the freestanding sheet sample, and the overall reflection was measured. Without sample-loading processes, both of the system assembling time and the risk of sample damage can be significantly reduced. In addition, the nearfield measurement substantially simplifies the calibration and the retrieval theory, facilitating the development of easy-to-integrate and easy-to-calibrate dielectric characterization technique. The dielectric properties of more than ten polymers were characterized from 30 GHz to 40 GHz. We believe that this work fulfills the requirement of the fast diagnostic in the industrial manufactures and also provides valuable high-frequency dielectric information for the designs of 5G devices.

A study on some properties of thin biocomposites made from unbeaten wood and non-wood pulps

A number of thin biomaterials were prepared via a wet formation method from seven different unbeaten plant fibers without using any chemical additives. It is noted that sheets made with short fibers (Flax-B: 0.32 mm and Straw-UB: 0.36 mm) and high fine content (Flax-B: 9.77% and Straw-UB: 10.64%) showed higher tensile index values (Flax-B: 27 Nm/g and Straw-UB: 25 Nm/g) than those made from long fibers. Despite having the longest fibers (1.11 mm) in studied samples, the tensile index values of sheet sample made from Pine-S-UB was just 12 Nm/g, which is just half of short-fibered (0.36 mm) straw sheets. Air permeability of sheets made from Pine-S-UB and Straw-UB were 5322 and 917 ml/min, respectively. Densities of the same sheets in the same order were 493 and 539 kg/m3. It is concluded that long cellulose fibers actually produce bulky materials with limited interfiber contacting areas, while short ones give biocomposites with higher density values indicating a firmly compacted internal structure in the case of utilizing plant fibers without beating and refining. Results would be usable when producing biocomposites from plant fibers via wet formation followed by various resins and polymer moldings.

Simulation Analysis of the Tensile Process on Sheet Sample

Stress-strain is commonly used in engineering; however the real stress-strain is more used in the test and exploitation of new product. ANSYS finite element software is adopted in this study, stress-strain of the tensile sample of the sheet in different stage is calculated under the 10mm displacement load, stress-strain curve is obtained, and the engineering and the real stress-strain are analyzed. The results show that simulation data are in accordance with the measured ones, the error is less than 3%, which proves that the model is the rational.