Fibers

Stimuli-responsive textiles are a rapidly evolving class of functional fiber-based materials that sense and adapt to environmental triggers. Within these enabling technologies, hydrogels and microcapsules are very illustrative, as they offer complementary mechanisms for moisture management, controlled release, and adaptive performance. Hydrogels provide soft, water-rich polymer networks with modifiable swelling, permeability, and mechanics, while microcapsules offer protection and targeted delivery of active agents through engineered shell structures. When integrated into fibrous networks, they impart dynamic detection responses for moisture, temperature, pH, mechanical stress, light, and chemical or biological agents. This review critically examines progress in design, synthesis, and textile integration of hydrogel- and microcapsule-based systems, with emphasis on materials that exhibit stimuli-responsive behavior rather than passive or extended-release functionality. Strategies for incorporating bulk hydrogels, micro- and nanogels, and stimuli-responsive microcapsules into fibers, yarns, and fabrics are discussed in addition to applications such as smart apparel, medical and hygienic textiles, controlled drug delivery, antimicrobial fabrics, and adaptive filtration media. Existing challenges for durability, washability, response kinetics, scalability, and sustainability are highlighted, while future research directions are proposed to advance the development of robust and intelligent textile systems at the nexus of soft matter science and fiber engineering.

During use, the surface of textile fabrics is prone to wear, which can cause changes such as pilling. Pilling (entanglement of fibers) is primarily assessed using the standard visual method EN ISO 12945-4:2020, but it can also be quantitatively measured by instrumental methods with image analysis software. Due to non-uniform digital imaging conditions, such as variations in magnification and analyzed surface area, the assessed area is often inconsistent. As a result, the total percentage of the fabric specimen surface area covered with pills is often omitted. To ensure uniform digital imaging, an innovative apparatus was designed and constructed in this research and applied to woven fabrics made from 100% cotton, wool, viscose, polyamide 6.6, polyester, and acrylic fiber. Pilling in the fabric specimens was induced by rubbing with the Martindale pilling tester (EN ISO 12945-2:2020) using two different abradant materials, through predefined pilling rubs ranging from 125 to 30,000. Pilling assessment was conducted using both the visual method and the improved instrumental method, following established grading classes based on the total percentage of the fabric specimen surface area covered with pills. The research results highlight the importance of uniform digital imaging and digital grading, as these demonstrate the high comparability of pilling grades assigned by the standard visual method while providing better distinction between consecutive grades.

One of the most critical damage modes affecting the structural performance of traditional composite materials, and therefore their durability, is the occurrence of interlaminar cracks (delamination), which are prone to grow under different loading conditions. In this study, the feasibility of repairing carbon fiber reinforced polymer (CFRP) laminates using structural adhesives was experimentally investigated by evaluating the Mode I interlaminar fracture toughness. Two unidirectional AS4 CFRP systems were analyzed, manufactured with epoxy 8552 and epoxy 3501-6 matrix resins. Mode I delamination behavior was characterized using Double Cantilever Beam (DCB) specimens. Three commercial structural adhesives were used in the repair process: two epoxy-based systems, (Loctite^® EA 9460™, manufactured by Henkel adhesives (Düsseldorf, Germany), and Araldite^® 2015 manufactured by Huntsman Advanced Materials (The Woodlands, TX, USA) and one low-odor acrylic adhesive, 3M Scotch-Weld^® DP8810NS manufactured by 3M Company (St. Paul, MN, USA). Adhesive joints were applied to previously fractured specimens, and the results were compared with those obtained from baseline composite specimens. The results indicate that repaired joints based on the 8552 matrix exhibited higher strain energy release rate (G_Ic) values, approaching those of the original material. The 3501-6 system showed increased fiber bridging, contributing to higher apparent fracture toughness. Among the adhesives evaluated, the acrylic-based adhesive provided the highest delamination resistance for both composite systems.