Polymeric materials play a crucial role in modern ophthalmology and optometry and are widely used in contact lenses, intraocular lenses, and implants designed to replace damaged ocular tissues. Owing to their high optical transparency, biocompatibility, and tunable physicochemical properties, polymers have become the basis of numerous advanced medical devices for vision correction and ocular treatment. Although these materials are not subject to the biological aging processes characteristic of the natural crystalline lens, they may undergo structural and surface changes during long-term use as a result of exposure to ultraviolet radiation, oxidative stress, temperature fluctuations, and the ocular environment. These processes can affect the optical, mechanical, and functional properties of ophthalmic devices. This review presents current literature on the aging mechanisms of polymeric materials used in ophthalmic lenses, with particular emphasis on degradation factors, structural changes occurring within the materials, and their impact on durability, performance, and safety. The article is a continuation of a previous review devoted to the applications of polymeric materials in ophthalmology and optometry.
The effectiveness of layer-by-layer (LbL) surface modification in reducing the flammability of polylactide (PLA) composites was investigated. Alternating layers of chitosan and hydrophilic nanosilica were deposited onto the surfaces of neat PLA and PLA containing 5 wt.% hydrophobic nanosilica. The materials were characterized using SEM, EDS, DSC, TGA, MCC, LOI, and UL-94 tests. SEM observations revealed non-uniform coatings with local discontinuities and agglomerates. The LbL treatment did not significantly improve the thermal stability of the composites, while MCC results indicated only minor changes in combustion behavior. However, an increase in LOI values and improved UL-94 performance were observed for samples containing 10 and 15 bilayers. The results demonstrate that the investigated LbL system provides only limited enhancement of the flame resistance of PLA-based composites, with its effectiveness strongly dependent on coating uniformity and continuity. Further optimization of the deposition process and layer composition is required to achieve better flame-retardant effect.
Oxygen transmission rates (OTR) of commercially manufactured monolayer and multilayer polyethylene (PE) films used for food packaging were evaluated using ASTM D3985 method under local testing conditions. Monolayer PE films exhibited relatively high oxygen permeability, with OTR exceeding 200 cm³/m²·day, whereas multilayer PE films demonstrated substantially improved barrier performance, with OTR ranging from less than 0.036 to 63.496 cm³/m²·day. The results indicate that both the incorporation of barrier layers and the degree of polymer crystallinity play a significant role in reducing oxygen permeability. These findings highlight the importance of multilayer structures and crystalline morphology in enhancing and optimizing the oxygen barrier properties of polyethylene-based food packaging materials, thereby contributing to improved product preservation and extended shelf life.
This study investigated the effect of conductive carbon fillers on the electrical and mechanical properties of glass fiber-reinforced composites based on powdered epoxy resin. Carbon black and graphene were used as conductive fillers to modify the polymer matrix. The composites were manufactured using the Resin Powder Molding (RPM) technique with a hydraulic press. The effect of filler type and content on electrical resistivity, tensile strength, flexural strength, Rockwell hardness, and Charpy impact strength was assessed. The results showed that the incorporation of conductive carbon fillers significantly reduced the electrical resistivity of the composites while maintaining satisfactory mechanical properties. The effectiveness of the modification depended on both the type and loading of the conductive filler. These findings demonstrate that the functional performance of epoxy composites can be tailored through the appropriate selection of conductive carbon fillers, enabling the development of materials that combine enhanced electrical conductivity with good mechanical performance. Expanded graphite contained in the commercial epoxy resin formulation was maintained at a constant concentration in all composites and was not considered an experimental variable.
Short-chain carboxylic acids (SCCAs), particularly acetic acid, are important wastewater contaminants due to their high solubility and contribution to water acidification and increased chemical oxygen demand. In this study, quaternary ammonium functional polymers (QAFPs) were synthesized via a facile one-pot polymerization approach and evaluated as adsorbents for acetic acid removal. FT-IR, SEM, BET, and elemental analyses confirmed the successful incorporation of quaternary ammonium functionalities and the formation of a suitable adsorption structure. Batch adsorption experiments showed a maximum removal efficiency of 68.97% and an adsorption capacity of 2.299 mg/g under optimized conditions (60 mg/L, 60°C, 50 min). Isotherm analysis indicated that the Freundlich model best described the adsorption behavior, suggesting heterogeneous adsorption on energetically diverse sites. Kinetic data was best fitted by the pseudo-second-order model, highlighting the importance of adsorbate-adsorbent interactions in the adsorption process. The adsorbent also demonstrated practical applicability toward real bioethanol wastewater, achieving 44.7% removal efficiency without pretreatment. These results demonstrate the potential of one-pot-synthesized QAFPs as simple and scalable adsorbents for the removal of low-molecular-weight organic acids from wastewater.
