Thomas Gries’s research while affiliated with RWTH Aachen University and other places

Firefighter protective clothing is composed of multiple layers, each serving distinct functions. The outer layer shields the user from fire, chemicals, cuts, body fluids, and water, while also permitting water vapour to escape. The middle membrane layer acts as a thermal and moisture barrier, preventing heat and liquid penetration but allowing vapour diffusion. The inner layer enhances thermal protection and wearer comfort. A nationwide German survey and risk analysis with different fire brigades identified a need for enhanced comfort, reduced physiological heat load, and improved protection against stabs and cuts. Enhanced tear resistance is one proposed method for increased stab and cut protection. Wearer comfort parameters include water vapour permeability, breathability, air permeability, efficient cooling and increased breathability of the protective clothing are crucial for comfort. Sweat is diffused through the jacket due to differing water vapour partial pressures inside and outside the jacket. Enhancing air permeability of the outer layer and reducing the water vapour transmission resistance across the entire layer structure improve cooling by lowering the external water vapour partial pressure, thus facilitating better sweat transport and heat dissipation. To increase breathability and stab- and cut protection, different fabric weaves for the outer layer of a firefighter´s jacket are produced and compared with each other. The Honeycomb and the Huck-a-back fabric achieve better properties than Twill 2/2 fabric used as standard.

Carbon fibers (CF) are characterized by their excellent mechanical properties and low specific weight. However, due to the high production costs of CF, the application areas of this material are highly limited. A more cost‐effective production of CF through the use of N 2 ‐pretreatment can further increase the spread in mass markets. In the research presented, the influence of fiber stretching on the properties of pretreated Polyacrylonitrile (PAN)‐fibers as well as the resulting carbon fibers is investigated on continuous scale. The investigations show that the fibers can be stretched much more (> 10%) during N 2 ‐pretreatment than in air atmosphere without impairing the mechanical properties of resulting CF. With increasing stretching ratio, the E‐modulus and tensile strength of the pretreated fibers are increasing while the elongation remains on a similar level as the reference carbon fibers. Using this effect, a more efficient stabilization process has been developed in which the first of four stabilizations zones has been skipped. This method ensures high acceptance by the industry, as the process parameters of the other three remaining stabilization zones are untouched. As a result, the thermal conversion time of CF has been reduced by 20% while the mechanical properties of the CF are maintained.

Tissue engineering (TE) aims to provide personalized solutions for tissue loss caused by trauma, tumors, or congenital defects. While traditional methods like autologous and homologous tissue transplants face challenges such as donor shortages and risk of donor site morbidity, TE provides a viable alternative using scaffolds, cells, and biologically active molecules. Textiles represent a promising scaffold option for both in-vitro and in-situ TE applications. Textile engineering is a broad field and can be divided into fiber-based textiles and yarn-based textiles. In fiber-based textiles the textile fabric is produced in the same step as the fibers (e.g. non-wovens, electrospun mats and 3D-printed). For yarn-based textiles, yarns are produced from fibers or filaments first and then, a textile fabric is produced (e.g. woven, weft-knitted, warp-knitted and braided fabrics). The selection of textile scaffold technology depends on the target tissue, mechanical requirements, and fabrication methods, with each approach offering distinct advantages. Braided scaffolds, with their high tensile strength, are ideal for load-bearing tissues like tendons and ligaments, while their ability to form stable hollow lumens makes them suitable for vascular applications. Weaving, weft-, and warp-knitting provide tunable structural properties, with warp-knitting offering the greatest design flexibility. Spacer fabrics enable complex 3D architecture, benefiting applications such as skin grafts and multilayered tissues. Electrospinning, though highly effective in mimicking the ECM, is structurally limited. The complex interactions between materials, fiber properties, and textile technologies allows for scaffolds with a wide range of morphological and mechanical characteristics (e.g., tensile strength of woven textiles ranging from 0.64 to 180.4 N/mm²). With in-depth knowledge, textiles can be tailored to obtain specific mechanical properties as accurately as possible and aid the formation of functional tissue. However, as textile structures inherently differ from biological tissues, careful optimization is required to enhance cell behavior, mechanical performance, and clinical applicability. This review is intended for TE experts interested in using textiles as scaffolds and provides a detailed analysis of the available options, their characteristics and known applications. For this, first the major fiber formation methods are introduced, then subsequent used automated textile technologies are presented, highlighting their strengths and limitations. Finally, we analyze how these textile and fiber structures are utilized in TE, organized by the use of textiles in TE across major organ systems, including the nervous, skin, cardiovascular, respiratory, urinary, digestive, and musculoskeletal systems.

This study aims to optimize the thermo-mechanical properties and shape-memory effect of twisted nanofibrous yarns featuring a core–shell structure for potential integration into thermo-responsive smart textiles via conventional processing methods, such as weaving and knitting. Twisted shape-memory polyurethane (SMPU) yarns were fabricated utilizing a double-nozzle electrospinning device, and the effects of twist amount and core–shell configuration on their structural, mechanical, and shape-memory properties were examined. Morphological analysis confirmed the production of uniform yarns with twist angles ranging from 7 to 21°, while differential scanning calorimetry (DSC) thermograms indicated a transition temperature of approximately 44 °C. Increased levels of twist resulted in a significant rise in maximum stress, approximately 36%, alongside an enhancement in Young’s modulus of about 30%, with elongation at break values within the range of 140% to 180%. The thermo-mechanical behavior was assessed at 50% and 100% strain over three cycles, demonstrating improved shape fixity and recovery with increased twist levels. Although exhibiting lower mechanical strength, core–shell yarns displayed comparable shape-memory performance to their single counterparts. These findings contribute valuable insights into the optimization of electrospun yarn structures for enhanced shape-memory functionality in the context of smart textiles.

While the integration of fibers in concrete is not novel, the application and use of continuous fabric-like textiles represent a more recent development. Carbon-based textiles stand out for their superior mechanical properties, demonstrating high strength and durability when combined with cementitious matrices. Coatings applications in multifilament yarn textile reinforcements are crucial to enhance adhesion and facilitate effective stress transfer between the fabric and the cementitious matrix, ensuring long-term durability and structural integrity for the Textile Reinforced Concrete (TRC). Although epoxy resin is commonly employed as it results in excellent TRC mechanical performance, its hydrophobic nature poses challenges in achieving strong chemical adhesion, potentially leading to issues such as delamination between the textile reinforcement and the matrix. In this context, water-dispersed epoxy emerges as a promising alternative, mitigating hydrophobicity and enhancing chemical adhesion, thus improving the overall integrity of the composite. Continued research on the use of this alternative coating at a material level regarding their suitability for a structural application remains to be investigated. Thus, this study aims to assess the impact of a water-dispersed epoxy resin compared to a commercially available epoxy resin on the mechanical behavior of carbon TRC through direct tensile tests. The evaluation focuses on the assessment of its viability for future practical applications.

The textile field is diverse and encompasses products intended for technical and non-technical applications. The product diversity in the textile domain has led to various product development approaches. This paper describes a product development method for textile products that is generally applicable. In the so-called Textile Development (TED)-Method, the textile surface manufacturing process is determined in the product development process. In this way, it is possible to develop in an open, target-oriented way and independent of an existing supplier or machine park. By using correlation matrices, a broad design field is considered and specific solutions are extrapolated that lead to the desired product without lengthy iteration series. Thus, the TED-Method additionally represents a resource-saving product development without renouncing a broad design field. Three different development examples of the TED-Method are presented, thus demonstrating the open and comprehensive use of the method

Flame retardants are commonly used to reduce fire risk in various products and environments, including textiles. While many of these additives contain harmful substances, efforts are underway to reduce their usage. Current research aims to minimize flame-retardant quantities and enhance durability against external factors. This involves utilizing anchor peptides or material-binding peptides (MBPs), which are versatile molecules that bind strongly to surfaces like textiles. MBPs can be equipped with functional molecules, e.g., flame-retardant additives, by chemical or enzymatic bioconjugation. In this research, biohybrid flame retardants and an adapted finishing process are developed. Specifically, biobased adhesion promoters, the so-called MBPs, are used to finish textiles with flame-retardant additives. To date, there is no finishing process for treating textiles with MBPs and so a laboratory-scale finishing process based on foulard was developed. Necessary parameters, such as the take-off speed or the contact pressure of the squeezing rollers, are determined experimentally. In order to develop an adapted finishing process, various trials are designed and carried out. Part of the trials is the testing and comparison of different textiles (e.g., glass woven fabrics and aramid woven fabrics) under different conditions (e.g., different ratios of MBPs and flame retardants). The finished textiles are then analysed and validated regarding their flammability and the amount of adhered flame retardants.