Optically Active Polyurethane/Silica Aerogel Coated Cotton Fabrics for Thermal Protection

Application of SiO2 aerogel in thermal protective clothing has been limited due to its brittle nature, ordinary mechanical properties, and poor film forming performance. This work is aimed to develop thermal protective cotton fabrics by coating blended OPU/SiO2 aerogel with enhanced mechanical properties and thermal protection performance. The OPU/SiO2 aerogel composites with different ratio were applied onto cotton fabrics by knife-coating. The morphology, chemical component, crystalline structure, thermal stability and compression strength were characterized by scanning electron microscopy (SEM), Fourier transfer Infrared spectroscopy (FTIR), X-ray diffraction (XRD), thermogravimetric analysis (TG) and compression test, respectively. Besides, the warmth retention performance and heat protection performance together with air and moisture permeability of the coated fabrics were studied. The results showed that OPU/SiO2 aerogel were successfully coated onto cotton fabrics with enhanced mechanical properties and thermal stability together with better film forming capacity. The heat transfer coefficient of the coated cotton fabrics was distinctly dropped due to the synergistic effect of OPU and SiO2 aerogel, which resulted in higher warmth retention. The OPU/SiO2 aerogel coated fabrics exhibited obvious heat insulation performance with its surface temperate almost 4°C than the uncoated fabrics. This work demonstrates a new strategy of fabricating stronger thermal insulating textiles using OPU/SiO2 aerogel composites.

Effect of Keratin Extracted from Chicken Feather Filled Electrospun Polyacrylonitrile Nanocomposite Membrane

Chicken feathers are known for its unique properties such as low density, warmth retention, and distinct morphological structure [1]. Despite these unique properties, chicken feathers are considered a waste byproduct of the poultry industry [2]. To utilize feather waste, it was used as an additive to reinforce Polyacrylonitrile (PAN) polymer in the form of Keratin Extract. The highlight of the study is to prepare and characterize PAN with chicken feather keratin as additive by electrospinning. Keratin was extracted under reduction method with the use of sodium sulphide and solubilized with NaOH [3]. The presence of Keratin was confirmed with Fourier Transform Infrared Microscopy (FTIR) and Ultraviolet–visible Spectroscopy (UV-Vis).PAN nanofibers with different keratin loadings were formed by electrospinning process and Dimethylformamide (DMF) as solvent. The electrospun nanocomposite membranes were analyzed using Scanning Electron Microscopy (SEM), FTIR, contact angle goniometer, and Ion-Adsorption test. Addition of keratin into the polymer solution, decreased the average fiber diameter from 91nm (Pure Keratin), 84nm (PAN/1%Keratin), 71nm (PAN/3%Keratin) to aggregates (PAN/5%Keratin). Also, the change in morphology affected the polymer’s hydrophilicity. As the percentage loading of keratin increases, the average contact angle decreases. The average contact angle of Pure Pan, 1%, 3%, and 5% keratin decreased from 28.21°, 18.85°, 16,76° to 15.34°. The effect of the fiber on conductivity was also tested with a salt bath method. 3M of NaCl solution presented a conductivity of 93.0 mS. Upon the addition of Pure PAN in saltwater Solution, the conductivity had decreased to 60.0mS which indicated that some ions from the NaCl had adhered to the membrane. Upon the addition of Keratin nanofibers, it can be observed that the conductivity increases to 61.0 mS, 96.8 mS. and 100.1 mS as the percentage of keratin loading increases.

Ultrafine and High-Strength Silk Fibers Secreted by Bimolter Silkworms

Ultrafine fibers are widely employed because of their lightness, softness, and warmth retention. Although silkworm silk is one of the most applied natural silks, it is coarse and difficult to transform into ultrafine fibers. Thus, to obtain ultrafine high-performance silk fibers, we employed anti-juvenile hormones in this study to induce bimolter silkworms. We found that the bimolter cocoons were composed of densely packed thin fibers and small apertures, wherein the silk diameter was 54.9% less than that of trimolter silk. Further analysis revealed that the bimolter silk was cleaner and lighter than the control silk. In addition, it was stronger (739 MPa versus 497 MPa) and more stiffness (i.e., a higher Young’s modulus) than the trimolter silk. FTIR and X-ray diffraction results revealed that the excellent mechanical properties of bimolter silk can be attributed to the higher β-sheet content and crystallinity. Chitin staining of the anterior silk gland suggested that the lumen is narrower in bimolters, which may lead to the formation of greater numbers of β-sheet structures in the silk. Therefore, this study reveals the relationship between the structures and mechanical properties of bimolter silk and provides a valuable reference for producing high-strength and ultrafine silk fibers.