Design, Characterization, and Evaluation of Textile Systems and Coatings for Sports Use: Applications in the Design of High-Thermal Comfort Wearables

Abstract

Exposure to high temperatures during indoor and outdoor activities increases the risk of heat-related illness such as cramps, rashes, and heatstroke (HS). Fatal cases of HS are ten times more common than serious cardiac episodes in sporting scenarios, with untreated cases leading to mortality rates as high as 80%. Enhancing thermal comfort can be achieved through heat loss in enclosed spaces and the human body, utilizing heat transfer mechanisms such as radiation, conduction, convection, and evaporation, which do not require initial energy input. Among these, two primary mechanisms are commonly employed in the textile industry to enhance passive cooling: radiation and conduction. The radiation approach encompasses two aspects: (1) reflecting solar spectrum (SS) wavelengths and (2) transmitting and emitting in the atmospheric window (AW). Conduction involves dissipating heat through materials with a high thermal conductivity. Our study focuses on the combined effect of these radiative and conductive approaches to increase thermal energy loss, an area that has not been extensively studied to date. Therefore, the main objective of this project is to develop, characterize, and evaluate a nanocomposite polymeric textile system using electrospinning, incorporating graphene oxide (GO) nanosheets and titanium dioxide nanoparticles (TiO₂ NPs) within a recycled polyethylene terephthalate (r-PET) matrix to improve thermal comfort through the dissipation of thermal energy by radiation and conduction. The textile system with a 5:1 molar ratio between TiO₂ NPs and GO demonstrates 89.26% reflectance in the SS and 98.40% transmittance/emittance in the AW, correlating to superior cooling performance, with temperatures 20.06 and 1.27 °C lower than skin temperatures outdoors and indoors, respectively. Additionally, the textile exhibits a high thermal conductivity index of 0.66 W/m K, contact angles greater than 120°, and cell viability exceeding 80%. These findings highlight the potential of the engineered textiles in developing high-performance sports cooling fabrics, providing significant advancements in thermal comfort and safety for athletes.

Figure 1

Workflow of elaboration, characterization, and evaluation of r-PET textile systems with GO nanoconjugates and titanium dioxide nanoparticles for thermal comfort by heat dissipation through conduction and radiation.

Figure 2

Mesh configuration and boundary conditions of microheater. Red is the ground, blue is the electric potential, yellow is the FR4 substrate, orange is the copper piste, a is the distance between piste, and b is the thickness of the copper piste. Scale bar: 1 cm.

Figure 3

(A) FTIR spectra of TiO₂, TiO₂-APTES, GO, GO-PEG, TiO₂-GO 1:1, TiO₂-GO 5:1, and TiO₂-GO 10:1. (B) TGA thermograms of TiO₂, TiO₂-APTES, GO, TiO₂-GO 1:1, TiO₂-GO 5:1, and TiO₂-GO 10:1. (C) DLS histogram for the size intensity distribution of TiO₂-GO conjugate timeline.

Figure 4

SEM images of GO (A,B) and TiO₂ (C,D) NPs at high (100 k×) and low magnification (30 k×) using an accelerating voltage of 10 kV. Red arrows in (B,D) indicate tightly stacked GO nanosheets and spherical aggregates of TiO₂ NPs, respectively.

Figure 5

SEM images of TiO₂-GO 1:1 (A,B), TiO₂-GO 5:1(C,D), and TiO₂-GO 10:1 (E,F) nanoconjugates at high (100 k×) and low magnification (30 k×) utilizing an accelerating voltage of 10 kV. The red arrows in (B) indicate nonuniformly dispersed TiO₂ NPs on the GO nanolayer, while those in (D) show a better distribution of TiO₂ NPs on the surface of the nanolayer. The red arrow in (F) highlights a large cluster of TiO₂ NPs, which obscure the GO structure.

Figure 6

FTIR spectra of electrospun r-PET, r-PET/GO, r-PET/TiO₂, r-PET/TiO₂-GO 1:1, r-PET/TiO₂-GO 5:1, and r-PET/TiO₂-GO 10:1 textiles.

Figure 7

SEM images of r-PET nanofibers electrospun from a solution of (A) 10, (B) 15, and (C) 20% (w/v) concentration at 30 k× magnification and 6 kV accelerating voltage. The red arrow in (A) indicates agglomerates of the polymer within the nanofiber structure, while the red arrow in (C) highlights the breakage of the r-PET fibers due to the insufficient formation of the polymer chain network.

Figure 8

SEM images of r-PET nanofibers filled with (A) 1.5, and (B) 3 wt % TiO₂-GO concentration at 30 k× magnification and 6 kV accelerating voltage. The red arrow in (B) indicates a node-like lump and irregular morphology in the r-PET fiber resulting from the use of a high concentration of the TiO₂ NPs with GO nanoconjugate.

Figure 9

SEM images of (A) rPET, (B) rPET/GO, (C) rPET/TiO₂-GO 1:1, (D) rPET/TiO₂-GO 5:1, and (E) rPET/TiO₂-GO 10:1 at 30 k× magnification and 6 kV accelerating voltage and (F) diameter distribution of textile fibers. The red arrows indicate defect-free fibers in the developed formulations, attributed to optimal electrospinning parameters.

Figure 10

Reflectivity (A) spectrum and (B) values of r-PET, r-PET/GO, r-PET/TiO₂, r-PET/TiO₂-GO 1:1, r-PET/TiO₂-GO 5:1, and r-PET/TiO₂-GO 10:1 textiles in the 0.4–2.5 μm wavelength range.

Figure 11

(A) Surface temperature (including corresponding infrared and digital images of samples for comparison) and (B) transmissivity/emissivity values of r-PET, r-PET/GO, r-PET/TiO₂, r-PET/TiO₂-GO 1:1, r-PET/TiO₂-GO 5:1, and r-PET/TiO₂-GO 10:1 textiles.

Figure 12

Thermal conductivity (A) schematic of the setup, (B) picture of the homemade assembly, and (C) coefficients of r-PET, r-PET/GO, r-PET/TiO₂, r-PET/TiO₂-GO 1:1, r-PET/TiO₂-GO 5:1, and r-PET/TiO₂-GO 10:1 textiles.

Figure 13

Electro–thermo–mechanical simulation results for microheaters with varying loop configurations, alongside the experimental temperature map. (A–D) Simulated thermal maps for microheaters with 2, 3, 4, and 5 loops, respectively. (E) Experimental heat map of the manufactured microheater with 5 loops. (F) Measurement distance of the temperature profile evaluated in panel (G). (G) Line graph of temperature variation as a function of distance across the microheater. Scale bar: 2 cm.

Figure 14

Measuring the thermal cooling performance of textiles outdoors. (A) Schematic of the setup used to measure the temperature of the simulated skin covered with the fabrics. (B) Photograph of the experimental setup under direct solar irradiance. The setup features a microheater designed to replicate the thermal properties of human skin. The microheater is connected to a power source to maintain a stable temperature of 35 °C using a current of 1.65 A, ensuring consistent conditions throughout the experiment. A 0.2 mm diameter T-type thermocouple is attached directly to the microheater to record real-time temperature data. The device is enclosed with walls and a floor made of expanded polystyrene insulation boards supported by four wooden pedestals at the bottom to reduce thermal conduction, all covered in aluminum foil to reflect sunlight. A transparent polymer cover reduces convective heat loss. (C) Temperature data of the microheaters with the textiles on their surface under sunlight for 70 min in Bogota.

Figure 15

(A) Schematic of the indoor measuring device. (B) Temperature of the external surface of the textiles on the simulated skin.

Figure 16

Mechanical properties of r-PET, r-PET/GO, r-PET/TiO₂, r-PET/TiO₂-GO 1:1, r-PET/TiO₂-GO 5:1, and r-PET/TiO₂-GO 10:1 textiles.

Figure 17

Cell viability of r-PET, r-PET/GO, r-PET/TiO₂, r-PET/TiO₂-GO 1:1, r-PET/TiO₂-GO 5:1, and r-PET/TiO₂-GO 10:1 textiles at 24 and 72 h.

Figure 18

Water contact angles of r-PET, r-PET/GO, r-PET/TiO₂, r-PET/TiO₂-GO 1:1, r-PET/TiO₂-GO 5:1, and r-PET/TiO₂-GO 10:1 textiles.