Characterization and Evaluation of The Mechanical Properties of Blended of Yarns Based on Alpaca and Milk Protein Fibers

Purpose: The purpose of this study was to characterize and evaluate the mechanical strength of individual yarns as a blend of alpaca fiber and milk protein fiber. In addition, to obtain a product with a comfort factor suitable for textile applications.   Method: Different alpaca fiber diameters were used, such as alpaca huarizo fiber (AHF), alpaca superfine fiber (ASF) and alpaca baby fiber (ABF), and then mixed with milk protein fiber (MPF) to perform tests and methods, including the optical fiber diameter analyzer 4000 (OFDA 4000), tensile strength testing, scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX) and Fourier transform infrared spectroscopy (FTIR).   Results and Discussion: In SEM observation, MPF showed a smooth morphology with areas of irregular grooves and protrusions, while AHF, ASF and ABF fibers showed a smooth surface with thin flakes. EDAX analysis revealed a chemical composition of C, N, O, Na and Si for MPF, while AHF, ASF and ABF presented C, N, O and S. By FTIR, specific chemical groups were identified. MPF showed amide I groups at 1647 cm-1 and amide II group at 1540 cm-1, confirming the presence of protein. AHF, ASF and ABF fibers presented at 1624 cm-1 the amide I band due to contributions from the C=O stretching vibration of the peptide skeleton, and at 1514 cm-1 the amide II group, arising from N-H bending and C-N stretching vibrations. The results of the comfort factor (CF) of AHF is significantly lower than that of MPF. Specifically, the CF of AHF was 38.15%, while that of MPF reached 99.69%. This indicates that, in terms of comfort, AHF does not equal MPF. Furthermore, when combining these fibers, the addition of MPF increases the CF, while reducing the diameter and the variability of the coefficient of variation (CV). Finally, in single yarn tensile strength tests, AHF demonstrated higher tensile strength, with a value of 63.3±4.9 MPa and a % strain of 6.98±1%, compared to ASF and ABF. However, MPF exhibited a maximum tensile stress of 67.2±4.9 MPa and a % strain of 11.71±1.3%, far exceeding AHF. In mixtures, the MPF-50%_AHF-50% combination showed a maximum tensile stress of 64.9±4.8 MPa, but with a low % strain, compared to the MPF-70%_AHF-30% mixture, which had a % strain of 10.39±1%.   Research Implications: The synergy between both fibers (alpaca yarns, blended with other natural fibres) not only seeks to improve the tactile experience of the garment, but also to contribute to the manufacture of more sustainable and environmentally friendly garments.    Originality/Value: This study contributes to the field of the textile industry by providing an alternative to the processing of textile fibers from the mixture of milk protein fibers and alpaca fibers. offering important knowledge for industry and academia.