Investigation on Aesthetic and Water Permeability of Surface Protective Material under Accelerated Weathering

In this paper, experiments were conducted on the effects of aesthetic and durability of three representative surface protective material under accelerated weathering test for 5000 h. First, the adaptability of the surface protective material coating to the substrate was proven by examining the aesthetic properties and the water permeability of the building materials. Second, the pollutant resistance of the surface protective material coating to artificial stain was assessed using xenon-arc light. The result shows that the appearance of the silane types did not change significantly, and the water permeability was improved. In addition, the silicate types did not improve water permeability and the surface color was changed. Fluor- resin types effectively improved the water permeability, but the surface color became dark. Sample measurements showed changes in the average width of the contamination after weathering, with an increase after spray cleaning and ultrasonic cleaning. However, it was observed that after washing the pollution average width of all specimens due to weathering at 5000 h was almost as much or smaller than the initial value.

Optical Investigation of PVA/PbTiO3 Composite for UV-Protective Approach Applications

Samples of a new-fangled polymer of poly (Vinyl Alcohol) (PVA) doped with various concentrations of Lead (II) Titanate (PbTiO3, PT) were prepared using the casting method. The prepared samples were identified by Attenuated Total Reflection–Fourier Transform Infrared (ATR-FTIR). Peaks characteristic of PVA at 3280, 2917, 1690, 1425, 1324, 1081, and 839 cm−1 appeared; a peak indicating the presence of PbTiO3 also appeared at 713 cm−1. The interaction between PVA and PbTiO3 was confirmed by observing the change in IR absorption intensity. Optical properties in the UV-Vis range were investigated using an Ultraviolet Visible technique (UV-Vis). An enhancement in absorption capacity by the increasing PbTiO3 concentration was observed. Optical properties such as band gap energy, Urbach energy, and extinction coefficient indicate that addition of PbTiO3 into the PVA polymer induced variance in internal states by increasing the ratio of PbTiO3. Obtaining a UV-protective material derived from a PVA/PbTiO3 composite is the aim of this paper.

Preparation and Ballistic Performance of a Multi-Layer Armor System Composed of Kevlar/Polyurea Composites and Shear Thickening Fluid (STF)-Filled Paper Honeycomb Panels

In this study, the ballistic performance of armors composed of a polyurea elastomer/Kevlar fabric composite and a shear thickening fluid (STF) structure was investigated. The polyurea used was a reaction product of aromatic diphenylmethane isocyanate (A agent) and amine-terminated polyether resin (B agent). The A and B agents were diluted, mixed and brushed onto Kevlar fabric. After the reaction of A and B agents was complete, the polyurea/Kevlar composite was formed. STF structure was prepared through pouring the STF into a honeycomb paper panel. The ballistic tests were conducted with reference to NIJ 0101.06 Ballistic Test Specification Class II and Class IIIA, using 9 mm FMJ and 44 magnum bullets. The ballistic test results reveal that polyurea/Kevlar fabric composites offer better impact resistance than conventional Kevlar fabrics and a 2 mm STF structure could replace approximately 10 layers of Kevlar in a ballistic resistant layer. Our results also showed that a high-strength composite laminate using the best polyurea/Kevlar plates combined with the STF structure was more than 17% lighter and thinner than the conventional Kevlar laminate, indicating that the high-strength protective material developed in this study is superior to the traditional protective materials.

Thermodynamic Study of Fire-Protective Material

The paper considers the material for the protective coating of building structures made of wood. The possibility of chemical processes occurring in the material leading to its expansion has been studied. The coefficient of expansion of the material when heated is practically established. It has been established that the material can swell, both under the influence of flame and when the temperature rises at a low speed. Swelling coefficient at the same time it reaches 8. The temperature range of swelling is 150–250 С, which is confirmed by thermodynamic calculations and experimentally. The temperature at which the material begins to swell is lower than the temperature of thermal destruction of wood.

Zeolitic Imidazolate Frameworks (ZIF-8) for Biomedical Applications: A Review

: Beyond being an excellent protective material for bioentities, zeolitic imidazolate frameworks (ZIF-8) have advanced several applications, including biomedical applications. The straightforward synthesis of ZIF-8 at mild conditions improved the biomineralization of several biomolecules, e.g., protein, peptides, carbohydrate, and biological cells, such as viruses and bacterial cells. Bioinspiration of ZIF-8 enhanced and improved the material's applications for biomedicine. This review article summarized the recent achievements of ZIF-8 for biomedical applications, such as cancer therapy, antimicrobial, biosensing, and biocatalysis. ZIF8-based materials advanced cancer therapy via drug delivery of chemotherapeutic drugs, photothermal therapy (PTT), photodynamic therapy (PDT), hemodynamic therapy (CDT), gene therapy, and starvation therapy. Antibacterial agent encapsulated ZIF-8 exhibited superior biological activity compared to the free antibacterial agents. ZIF-8 based materials enhanced the selectivity and sensitivity for analytes' biosensing, ensuring their potential for electronic devices. Biocatalysis of enzyme encapsulated ZIF-8 offered high catalytic performance with robust properties for recycling. ZIF-8 acts as a protective host for enzymes, proteins, and drugs from degradation induced due to temperature, solvents, and proteolytic agents. The first part of the review discussed the structure, chemistry, and bioinspiration of ZIF-8. The second part reviewed the biomedical applications of ZIF-8. The potential risks and current challenges of using ZIF-8 for biomedical applications were also reviewed.

Fish-inspired flexible protective material systems with anisotropic bending stiffness

Biological structures integrate morphometry (shape-based rules) with materials design to maximize organism survival. The exoskeleton of the armored fish, Polypterus senegalus, balances flexibility with protection from predatory and territorial threats. Material properties of the exoskeleton are known; however, the geometric design rules underlying its anisotropic flexibility are uncharacterized. Here, we show how scale shape, articulation, and composite architecture produce anisotropic mechanics using bio-inspired, multi-material 3D-printed prototypes. Passive loading (draping) shows that compliant connections between the scales contribute to mechanical anisotropy. Simulated and experimental active loading (bending) show orientation-dependent stiffness ranging over orders of magnitude, including ‘mechanical invisibility’ of the scales where they do not add stiffness to the exoskeleton. The results illustrate how morphometry provides a powerful tool to tune flexibility in composite architectures independent of varying constituent materials composition. We anticipate that introducing morphometric design strategies will enable flexible, protective systems tuned to complex shapes and functions.

Ultrahigh Ballistic Resistance of Twisted Bilayer Graphene

Graphene is a good candidate for protective material owing to its extremely high stiffness and high strength-to-weight ratio. However, the impact performance of twisted bilayer graphene is still obscure. Herein we have investigated the ballistic resistance capacity of twisted bilayer graphene compared to that of AA-stacked bilayer graphene using molecular dynamic simulations. The energy propagation processes are identical, while the ballistic resistance capacity of the twisted bilayer graphene is almost two times larger than the AA-bilayer graphene. The enhanced capacity of the twisted bilayer graphene is assumed to be caused by the mismatch between the two sheets of graphene, which results in earlier fracture of the first graphene layer and reduces the possibility of penetration.