Solid State Phenomena Vol. 386

Abstract: Epoxidized natural rubber (ENR) has attracted significant attention due to its outstanding properties, such as mechanical properties and oil resistance. In particular, the development of self-healing properties without external stimuli in ENR has been an important challenge. In this study, the self-healing ENR composites were successfully developed by incorporating microcrystalline cellulose (MCC) as a reinforcing agent and borax as a dynamic cross-linker. The addition of borax resulted in the formation of dynamic borate-ester bonding and hydrogen bonding, enhancing the mechanical properties and self-healing ability of the composites. Structural analysis confirmed good compatibility between borax and MCC. The borax-grafted MCC reinforced ENR composite with 5 wt% borax achieved significant improvements, with self-healing efficiencies reaching 99% in Young’s modulus, 96% in tensile strength, 84% in elongation at break, and 76% in tensile energy after self-healing time 24 h at room temperature, without external stimuli. These results demonstrated the potential of ENR-based composites for sustainable and self-healing rubber applications.

Abstract: Traditional handmade bamboo paper is a commonly used material for the restoration of ancient books and the printing of classic texts. This study discussed the ageing behavior of handmade bamboo paper under dry thermal ageing conditions. The filter paper composed of cellulose serves as a reference example. The results showed that the mechanical properties of bamboo paper containing lignin remained stable for a certain period of time before declining when the pH was less than 7. While the mechanical properties of the filter paper immediately decreased when the pH falls below 7.0. Pore structure analysis indicated that bamboo paper undergoes substantial structural changes in the early stages of aging, with an increase in specific surface area and pore volume, and a decrease in average pore size. These changes then stabilize over time. This may be attributed to the fact that hemicellulose and lignin help maintain the overall integrity of the bamboo paper fibers.The study provides a scientific basis for understanding bamboo paper ageing mechanisms and offers references for preserving historical documents.

Abstract: In the field of natural fiber-reinforced composites, hybridization of fibers is commonly used to improve the composite’s properties further. Traditionally, this involves the incorporation of secondary fibers to compensate for the limitations of the primary reinforcing material. Recently, the integration of nanomaterials has emerged as a promising approach for hybrid composite fabrication. In this study, Multi-Walled Carbon Nanotubes (MWCNTs) were incorporated into the nito fiber-reinforced epoxy composite for further improvement of the composite’s properties. MWCNTs, when uniformly dispersed, serve as effective nanoreinforcements capable of improving both mechanical strength and thermal behavior. The incorporation of 0.10 wt% MWCNTs resulted in improved impact strength compared to both unreinforced epoxy and nito fiber-reinforced composites. The hybridized composites also exhibited higher peak temperature and overall thermal stability. Water contact angle measurements also indicated enhanced hydrophobicity upon MWCNT addition. However, excessive loading of MWCNTs led to agglomeration and subsequent deterioration of composite performance. These findings highlight the potential of MWCNTs as multifunctional nanofillers in natural fiber-based hybrid composites, offering improved impact resistance, thermal stability, and moisture resistance. Such hybrid systems expand the applicability of natural fiber composites to demanding sectors such as automotive interiors, construction materials, and consumer goods, where improved durability and environmental resistance are critical.

Abstract: This study aimed to present a method for measuring the mechanical strength and electrical chargeretention properties of fibers containing nano-sized oxide particles, which have become widely usedin recent years, and to clarify the fundamental physical properties of these fibers. There have beenfew studies measuring the mechanical and electrical properties of composite fibers containing nanosizedoxide particles. Polyester fibers containing SiO2 and ZrO2 nanoparticles were fabricated usingindustrial techniques to clarify the effect of particle introduction on strength. Furthermore, theelectrostatic charge properties of fibers containing these particles, which act as insulators, weremeasured, revealing that mechanical strength and electrical charge retention properties are mutuallyexclusive parameters. Increasing the nanoparticle content decreased mechanical strength, butprolonged the charge half-life and improved electrostatic retention. Furthermore, it was shown thatthis phenomenon can be represented using an equivalent circuit model of a resistor and a capacitor.

Abstract: The Philippines is facing environmental challenges due to the increasing plastic waste and crop residues. To address this issue and enhance the country's economy while ensuring sustainability, research and the effective development of waste utilization strategies are paramount. This study focuses on the fabrication, characterization, and testing of fiber-polymer composites using corn cob pith particles and recycled polypropylene. Corn cob pith particles (CCP) at varying filler loadings (5, 10, and 15 wt.%), recycled polypropylene (RPP), and maleic anhydride grafted polypropylene (MAPP) were combined using a single screw extruder. As a result, the incorporation of CCP particles demonstrated a significant increase in flexural strength, flexural modulus, and tensile modulus with highest values reaching 21.88 MPa, 437.19 MPa, and 239.61 MPa, respectively. The significant increase in flexural strength and flexural modulus was observed at 10% loading, for tensile modulus it was at 15% loading. On the other hand, tensile decreased with the lowest value of 19.24 MPa at 15% loading. Moreover, the composites exhibited better thermal stability than RPP. Furthermore, the FTIR peaks located at1033 cm⁻¹ and 3340 cm⁻¹ confirm the incorporation of CCP particles into the RPP matrix. Overall, adding CCP particles to RPP, using a compatibilizer, enhanced the stiffness and rigidity of the composite, as well as its fiber-polymer adhesion. Industries can utilize the composite in applications requiring stiffness and rigidity.

Abstract: Paper-based cultural heritage is highly sensitive to cleaning processes, requiring materials that are mechanically safe, precisely applicable, and capable of preserving fiber and surface integrity. Conventional poly (vinyl alcohol) (PVA) hydrogels often exhibit poor dimensional stability, leading to spreading outside the targeted treatment area, and high tackiness, which can damage paper surfaces. This study presents an optimized PVA-based hydrogel incorporating cellulose nanofibers (CNF) and tartaric acid (TA), with polyethylene glycol (PEG) as a plasticizer and borax as a crosslinker. The effects of different compositions and gelation methods on viscoelasticity, swelling, and water release were investigated. The abundant hydroxyl groups of CNF enhanced solvent absorption, increased swelling capacity, reduced tackiness, and improved the storage modulus of the hydrogel, while TA improved dimensional stability and PEG balanced stiffness with controlled water release. The formulation containing 4 wt% PVA, 0.3% CNF, 25% TA, 10% borax, and 1% PEG exhibited superior performance, with a storage modulus within the suitable range for cleaning (1,000–20,000 Pa), moderate swelling, low tackiness, and no residue on paper. These results highlight the contribution of nanoscale technology to hydrogel design and demonstrate the potential of the developed material as a safe and effective cleaning system for paper conservation.

Abstract: Nickel-Aluminium Bronze is a copper alloy with excellent corrosion resistance in marine environments. However, there are also applications of NAB in freshwater and corrosion phenomena have been observed in such cases. To explore the effect of microstructure on the corrosion behaviour, heat treatments were applied to NAB samples, which were corrosion tested in electrolytes with a composition typical for freshwater. Depending on the presence of bicarbonate, sulfate, and chloride, different kinds of corrosion attack were observed. The mayor effect lies in minimization of the β-phase amount and increasing the portion of a- and κ-phases. Corrosion promoted by sulfate is the major hazard in fresh water, while the passivating effect of bicarbonate supports localization of the attack. Chloride plays an ambivalent role; it promotes the corrosion attack but limits the progressively penetrating evolution of localized corrosion. Since the composition of freshwater has a stronger impact on the corrosion phenomena of the NAB alloy, the influence of the heat treatments is not clearly evident. Compared to seawater, heat treatments have a lesser effect on the corrosion behaviour in freshwater.

Abstract: The aim of the experimental work was to propose innovative procedures for the formation of renovation layers, to determine suitable material, modify the microgeometry and surface topography of new and renovated shaped parts of moulds for high-pressure casting of aluminium alloys. It has been designed and validated under laboratory and operational conditions a method of modifying the surface of the mould parts of moulds for casting aluminium alloys by forming stochastic texture by low energy laser in combination with duplex PVD coatings on the surfaces of mould parts in contact with the aluminium alloy melt. It has been verified the contact angle measurement methodology for determining the number of spurs by separation lubricant on the surface of the new or refurbished mould part before the first casting cycle. For the formation of the renovation layers, the additive materials were verified Dievar, Dratec, UTPA 702. A TruDisk 4002 solid-state disk laser with BEO D70 focusing optics was used for winding.

Abstract: Al₂O₃-SiC-C (ASC) lining bricks for pouring ladle used in pre-treating molten (desulfurization) iron and molten iron ladles, which offer advantages such as high oxidation resistance, strong resistance to slag corrosion, good thermal shock resistance, and excellent resistance to mechanical wear and abrasion, have been investigated. It is expected that the combination of these new techniques will improve the energy and economic efficiency of the steel industry while also contributing to the decarbonization of both the refractory and steel industries. Additionally, the developed technology is expected to be applicable to other energy-intensive industries, such as cement, glass, pulp and paper, and non-ferrous metal processing. Investigating used samples is crucial for reducing wear on both ALKO60A and ALKO66ASC linings. The microstructures of laboratory prepared samples were analyzed using OLM, XRD, and SEM/EDS techniques. It is expected the formation of phases with low melting points, along with spinel solid solutions in the matrix and calcium di-aluminate near the alumina aggregates.