Improving Tearing Resistance of Leather - Part 2 Prevention and Treatment of Low Tearing Strength in the Tannery

An appropriate tear strength is one of the main properties that concern customers and it is also a significant source of claims. The authors make a review of the production process, focusing on each step that can either damage the natural strength of collagen fibers or improve them, and therefore, the leather. The aim of this work, divided in Part 1 and 2, is to transfer field tannery experiences collected over 40 years of activity in different tanneries, to colleagues that are looking for world class leather production. Part 1 has been published in JALCA, 116 (12), 2021.

Improving Tearing Resistance of Leather - Part 1 Prevention and Treatment of Low Tearing Strength in the Tannery

An appropriate tear strength is one of the main properties that concern customers and it is also a significant source of claims. The authors make a review of the production process, focusing on each step that can either damage the natural strength of collagen fibers or improve them and therefore, the leather. Although the authors’ experience is in bovine hides, the general concepts presented in this paper may be applied to other types of hides and skins. The aim of this work is to transfer field tannery experiences collected over 40 years of activity in different tanneries, to colleagues that are looking for world class leather production.

Mechanical and Dynamic Mechanical Analysis of PBO Paper-based Composites

Poly ( p-phenylene benzoisoxazole; PBO) paper is a potential raw material for use in honeycomb sandwich composites in the aerospace industry, which are able to sustain high temperatures exceeding 300°C. This work presents a wet-forming method of making PBO paper, consisting of PBO chopped fibers. The paper was impregnated with phenolic resin to simulate honeycomb wall material. The structure and mechanical and dynamic mechanical properties of the raw and impregnated paper were characterized. The performance of PBO paper was tested against p-aramid paper. The comparative results showed the tensile strength of PBO raw paper was 2.17 kN/m, which was slightly worse than p-aramid raw paper: 2.66 kN/m. After impregnation, the tensile strength of the PBO paper was 13.93 kN/m due to the increase in the number of bonding points—better than p-aramid paper: 7.99 kN/m. The tearing resistance value for PBO raw paper versus p-aramid raw paper was 3252 mN against 845 mN. The morphology of the torn samples in the impregnated paper revealed higher levels of PBO fiber pullout than p-aramid fiber, therefore the tearing resistance value was 6000 mN for PBO impregnated paper, which was again superior to p-aramid impregnated paper: 675 mN. The PBO paper also showed higher storage modulus than p-aramid paper after impregnation. Experimental studies showed that PBO paper could be used in load-bearing structures and in honeycomb components where high resistance to deformation and thermal stability is necessary.

Optimization of Bolted Connection in Steel Corbel Attach to RC Column of MRT Viaduct

MRT is one of the backbones of a city’s public transportation system, capable of carrying large crowds. The use of a portal frame in the design of an MRT train station has raised significant concerns about how the portal frame’s load will be supported by the extended structure element known as a corbel. A corbel is a protruding structural element that supports weights like primary beams and girders. Engineers must then decide how to properly bolt the steel corbel structure to the concrete pier segment or columns. Generally, most corbel structure designs were constructed of concrete; however, in this study corbel design was made of steel so that the steel portal frame could rest on the corbel structure, allowing for more usable area on the platform, such as kiosks and other amenities. Optimization of end plate thickness and beam web thickness is carried out. Manual calculations are used in addition to FEA modeling to examine the bolt’s deflection, shear, bearing, tension, slip, and block tearing resistance. When using Eurocode, all three loadings, transverse force, vertical force, and transverse moment, produce values that are 10% lower than the British Standard. As a result, designers can optimize their designs using Eurocode.

CC(T) Specimen Load-Bearing Capacity Related to Yield Strength and Upper-Shelf Charpy-V Energy

The load-bearing capacity of a CC(T) specimen (Center-Cracked Tension) in the ductile fracture regime is usually controlled by plastic collapse. If the material’s tearing resistance is sufficiently low, the load-bearing capacity can drop below the plastic collapse value. Here, a recently developed simple fracture mechanics-based Charpy-V impact energy criterion for plastic collapse was used to provide a best estimate assessment of the CC(T) specimen load-bearing capacity.

Fabrication of Paper Sheets Coatings Based on Chitosan/Bacterial Nanocellulose/ZnO with Enhanced Antibacterial and Mechanical Properties

Here, we designed paper sheets coated with chitosan, bacterial cellulose (nanofibers), and ZnO with boosted antibacterial and mechanical activity. We investigated the compositions, with ZnO exhibiting two different sizes/shapes: (1) rods and (2) irregular sphere-like particles. The proposed processing of bacterial cellulose resulted in the formation of nanofibers. Antimicrobial behavior was tested using E. coli ATCC® 25922™ following the ASTM E2149-13a standard. The mechanical properties of the paper sheets were measured by comparing tearing resistance, tensile strength, and bursting strength according to the ISO 5270 standard. The results showed an increased antibacterial response (assigned to the combination of chitosan and ZnO, independent of its shape and size) and boosted mechanical properties. Therefore, the proposed composition is an interesting multifunctional mixture for coatings in food packaging applications.