A Negative Index Nonagonal CSRR Metamaterial-Based Compact Flexible Planar Monopole Antenna for Ultrawideband Applications Using Viscose-Wool Felt

In this paper, a compact textile ultrawideband (UWB) planar monopole antenna loaded with a metamaterial unit cell array (MTMUCA) structure with epsilon-negative (ENG) and near-zero refractive index (NZRI) properties is proposed. The proposed MTMUCA was constructed based on a combination of a rectangular- and a nonagonal-shaped unit cell. The size of the antenna was 0.825 λ0 × 0.75 λ0 × 0.075 λ0, whereas each MTMUCA was sized at 0.312 λ0 × 0.312 λ0, with respect to a free space wavelength of 7.5 GHz. The antenna was fabricated using viscose-wool felt due to its strong metal–polymer adhesion. A naturally available polymer, wool, and a human-made polymer, viscose, that was derived from regenerated cellulose fiber were used in the manufacturing of the adopted viscose-wool felt. The MTMUCA exhibits the characteristics of ENG, with a bandwidth (BW) of 11.68 GHz and an NZRI BW of 8.5 GHz. The MTMUCA was incorporated on the planar monopole to behave as a shunt LC resonator, and its working principles were described using an equivalent circuit. The results indicate a 10 dB impedance fractional bandwidth of 142% (from 2.55 to 15 GHz) in simulations, and 138.84% (from 2.63 to 14.57 GHz) in measurements obtained by the textile UWB antenna. A peak realized gain of 4.84 dBi and 4.4 dBi was achieved in simulations and measurements, respectively. A satisfactory agreement between simulations and experiments was achieved, indicating the potential of the proposed negative index metamaterial-based antenna for microwave applications.

Basic research about corncob residue as Lyocell spinning material

Using the corncob residue as a new cheaper source material for Lyocell spinning technology. Chemical properties of the corncob residue after extraction of hemicellulose and lignin were investigated in this paper. It was found that the main composition of corncob residue is cellulose, accompanied by slight hemicellulose and very tiny amount of spinning insoluble components. Compared to wood pulp, corncob residue has a similar number-average molecular weight, a slightly larger weight-average molecular weight, a lower peak-relative molecular weight, and a larger polydispersity. All those properties suggest that this kind of corncob residue has big potential to be used as spinning material for regenerated cellulose fiber. A new type corncob residue made fiber was produced, using the Lyocell spinning technology. Mechanical properties of the corncob residue fiber were analyzed. The corncob residue fiber has a tensile strength value between that of viscose fiber and Lyocell fiber, indicating its good application prospects. However, the corncob residue fiber has a high crystallinity and the orientation value with large fiber linear density, suggesting that the spinning technology needs to be further improved.

Regenerated cellulose by the Lyocell process, a brief review of the process and properties

Lyocell fiber has emerged as an important class of regenerated cellulose that is produced based on the N-methyl morpholine-N-oxide (NMMO) dissolution method, and it has unique properties compared to viscose fiber. The NMMO technology provides a simple, resource-conserving, and environmentally friendly method for producing regenerated cellulose fiber. In this paper, the manufacturing process, environmental impact, and product quality of lyocell fiber are reviewed and compared with those of the conventional viscose fiber.