RESUMO
Medical protective clothing is the first line of defense for medical staff, which makes the acquisition of protection and multiple function challenging. When it comes to contagious diseases, the physical properties of protective clothing are deemed the top priority and, subsequently, they have significant meaning for the structural design, production cost evaluation, convenient production, and innovation. In this study, nonwoven technology is employed to produce matrices in which mechanical properties are supported by Tencel fibers and recycled Kevlar fibers. Next, the electrostatic spinning is conducted to generate breathable and waterproof films. The nonwoven fabrics and membranes are combined to have diverse functions, forming lay-up compound matrices for medical protective clothing. Moreover, measurements are conducted to characterize the lay-up compound matrices in terms of the tensile strength, tearing strength, bursting strength, puncture resistance, stiffness, air-permeable property, surface resistance, comfort performance, sub-micron particulate filtration efficiency, and the penetration of synthetic blood. As for the nonwoven fabrics, the mechanical properties are significantly improved after Kevlar fibers are incorporated. The tensile strength is (62.6 ± 2.4) N along the machine direction (MD) and (50.1 ± 3.1) N along the cross machine direction (CD); the tearing strength is (29.5 ± 1.6) N along the MD and (43.0 ± 1.7) N along the CD; the bursting strength is (365.8 ± 5.0) kPa; and the puncture resistance is (22.6 ± 1.0) N. Moreover, the lay-up compound matrices exhibit a stiffness of (14.7 ± 0.2) cm along the MD and (14.6 ± 0.1) cm along the CD, a surface resistance of (2.85 × 109 ± 0.37 × 109) Ω, an air-permeable property of (45.4 ± 2.3) cm3/s/cm2, and sub-micron particulate filtration efficiency of over 98%. In the measurement for penetration of synthetic blood, the K40/PAN/TPU group prevents the synthetic blood from penetration. Hence, the incorporation of recycled Kevlar fibers and lay-up compound technique creates good physical properties, an appropriate comfort attribute, and functions, which suggests that this study provides a greater diversity and new concepts for the production of medical protective clothing.
RESUMO
This study is focused on the characterization and investigation of polyvinylidene fluoride (PVDF) nanofibers from the point of view of macro- and nanometer level. The fibers were produced using electrostatic spinning process in air. Two types of fibers were produced since the collector speed (300 rpm and 2000 rpm) differed as the only one processing parameter. Differences in fiber's properties were studied by scanning electron microscopy (SEM) with cross-sections observation utilizing focused ion beam (FIB). The phase composition was determined by Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy. The crystallinity was determined by differential scanning calorimetry (DSC), and chemical analysis of fiber's surfaces and bonding states were studied using X-ray photoelectron spectroscopy (XPS). Other methods, such as atomic force microscopy (AFM) and piezoelectric force microscopy (PFM), were employed to describe morphology and piezoelectric response of single fiber, respectively. Moreover, the wetting behavior (hydrophobicity or hydrophilicity) was also studied. It was found that collector speed significantly affects fibers alignment and wettability (directionally ordered fibers produced at 2000 rpm almost super-hydrophobic in comparison with disordered fibers spun at 300 rpm with hydrophilic behavior) as properties at macrolevel. However, it was confirmed that these differences at the macrolevel are closely connected and originate from nanolevel attributes. The study of single individual fibers revealed some protrusions on the fiber's surface, and fibers spun at 300 rpm had a core-shell design, while fibers spun at 2000 rpm were hollow.