Melt blending is considered a significant method to develop antibacterial textile materials. However, it is still challenging to the homogeneous dispersion and efficient antibacterial activity of ...inorganic nanoparticles in polymer fibers. In this work, ZnO/Ag@SiO2 inorganic nanohybrid antibacterial agents were prepared by the direct precipitation method. The prepared antibacterial material had efficient antibacterial and thermal stability properties. Specifically, the decomposition temperature of the ZnO/Ag@SiO2 was higher than 400°C, which was appropriate for melting polymers at high temperatures. Here, polyethylene terephthalate (PET) was used as a fiber matrix, and PET/ZnO/Ag@SiO2 fibers were prepared by melt spinning technology. The results showed that the antibacterial material was well dispersed in the PET matrix, and the crystallization was promoted during the cooling process. The modified PET fibers presented better antibacterial properties against Escherichia coli (E. coli) and Staphylococcus aureus (S. aureus), with a maximum antibacterial rate of 99.9%. Additionally, the modified PET fibers provide superior laundering durability, with an antibacterial rate of 95.7% for S. aureus and 94.8% for E. coli after 50 washes. This work offers a novel approach to preparing thermotolerant and efficient antibacterial agents and antibacterial‐modified PET fibers.
Highlights
ZnO/Ag@SiO2 nanohybrid antibacterial agents were prepared.
High temperature resistant and highly antibacterial material.
The particles dispersed uniformly in PET matrix.
Excellent antibacterial and laundering properties of the fiber
Preparation and characterization of antibacterial PET/ZnO/Ag@SiO2 fibers.
•Design of experiments is a robust tool to model fiber spinning.•Screw velocity has more impact on fiber diameter than spool speed and temperature.•Thick fibers have cracked skin-core structure after ...stabilization and carbonization.•Petroleum pitch as a possible substitute for coal tar pitch in carbon fiber production.
The structure of a mesophase pitch carbon fiber evolves in spinning and is perfected through stabilization and carbonization. Thus, it is crucial to control extrusion variables to form standard carbon fibers. Design of experiments was employed in melt spinning to investigate the influence of three process variables on the diameter of petroleum-derived pitch filaments. Optimized conditions were validated in an experiment that produced filaments with average diameter of 14 μm. Pitch filaments with different thickness were thermally treated to verify structure discrepancies and quantify the relation between mechanical properties and fiber’s diameters. Diameters smaller than 45 μm could be stabilized in air. Thinner fibers reached average strength of 1.4 GPa and 150 GPa modulus, thicker fibers only supported 120 MPa with 65 GPa modulus.
Different softwood lignin O‐acyl derivatives, i.e., methacrylated, hexanoylated, benzoylated, methoxybenzoylated, and cinnamoylated lignin are synthesized and subjected to melt spinning. In the ...presence of spinning aids such as vanillin and ethylene glycol dimethacrylate, multifilament melt spinning is accomplished with spinning speeds up to 500 m min−1, which allowed for realizing uniform precursor fibers 17 μm in diameter. Out of all acyl‐derivatives of softwood lignin investigated, cinnamoylated softwood lignin (CL) turned out to be superior in terms of processability. CL‐derived precursor fibers are oxidatively thermostabilized and then carbonized applying carbonization temperatures up to 2200 °C. Carbon fiber structure formation is followed in detail by wide‐angle X‐ray scattering and Raman spectroscopy. An orientation ≤53% and a d
002 spacing of 0.353 nm is achieved. According to small angle X‐ray scattering, carbon fibers have a porosity of ≈38%. CL‐derived carbon fibers are also characterized in terms of mechanical properties. Tensile strengths up to 0.93 GPa (average 0.75 GPa) are obtained and follow Weibull statistics. Elastic moduli are ≤66.5 GPa (average 41.1 GPa).
Different softwood lignin O‐acyl derivatives are subjected to multifilament melt spinning with spinning speeds up to 500 m min–1. Cinnamoylated softwood lignin‐(CL) derived precursor fibers are oxidatively thermostabilized and carbonized. An orientation ≤53% and a d002 spacing of 0.353 nm is achieved. Tensile strengths up to 0.93 GPa are obtained and followed Weibull statistics. Elastic moduli are ≤66.5 GPa.
•In-plane uniaxial anisotropy induced by stress annealing.•Anisotropy probed by broadband ferromagnetic resonance.•Permeability determination from ferromagnetic resonance is non destructive.
We ...report on the broadband characterization of Co74.6Fe2.7Mn2.7Nb4Si2B14 (at%) melt-spun, soft magnetic alloy ribbons after various secondary processing treatments. Ribbons were investigated in the as-cast (melt-spun) condition, after annealing under stress at 50–200 MPa, and after transverse magnetic field (TMF) annealing. The magnetization dynamics of these materials have been studied from 10 to 60 GHz using ferromagnetic resonance (FMR). The in-plane uniaxial anisotropy was determined from the FMR data and permeability extracted for each condition. The permeability determined from broadband FMR was in good agreement with independently determined values using vibrating sample magnetometry and impedance spectrometry of toroidal cores. The effective damping parameter (αeff) of all the samples was close to 0.015 except for the TMF sample, which showed higher damping, possibly due to two magnon scattering.
A Cu–Ni-based alloy with a high power factor is a commercially utilized metallic thermocouple material. However, the high thermal conductivity has been a major limitation to achieving thermoelectric ...performance in semiconductor materials. Herein, this work presents a 76.1% reduced thermal conductivity (∼7.7 W m–1 K–1) in Cu70Ni30, which is one of the lowest reported values in the literature. Such suppression of thermal conductivity can be attributed to the varied frequency phonon scattering by the interfacial potential barrier, built from micron-scale defects formed via sintering melt-spun ribbons. However, the defects simultaneously reduce the charge carrier concentration, mobility, and thus the electrical conductivity. The lowest thermal conductivity leads to the highest zT and ZT avg in the sample sintered at 673 K under 15 MPa. The values are 0.24 (@573 K) and 0.15 (323–573 K), respectively, which are 130.3 and 140.0% higher than the values of the pristine counterpart. Our work demonstrates that improved thermoelectric performance in Cu–Ni-based alloys can be obtained by creating various interfacial defects even at micron scales, which paves the way to suppress thermal conductivity largely in metallic thermoelectric materials via melt-spinning (MS) and spark plasma sintering (SPS) synthesis.
A strategy of similar elements synergistic substitution was implemented to enhance the amorphous forming ability (AFA), thermal stability, and soft magnetic properties of Fe-Nb-B nanocrystalline ...alloys. Substitution of B by 2–6 at.% P in a Fe84Nb7B9 alloy increases the AFA and transforms the partially crystallized melt-spun ribbon into a fully amorphous structure. 2–4 at.% P lowers the grain size and enhances the size uniformity and volume fraction of the α-Fe phase in the annealed alloys, thus decreasing coercivity (Hc) from 20.0 to 12.8 A/m and increasing saturation magnetic flux density (Bs) from 1.50 to 1.57 T, whereas 6 at.% P coarsens the α-Fe grains and reduced the magnetic softness. Subsequent replacement of Nb by 2–3.5 at.% Hf increases the thermal stability of a Fe84Nb7B5P4 amorphous alloy, and further refines the α-Fe grains and improves the structural uniformity of the nanocrystalline alloys, thereby enhancing the soft magnetic properties and enlarging optimum annealing temperature window (ΔToa). The Fe84Nb3.5Hf3.5B5P4 nanocrystalline alloy with an average grain size of 9 nm exhibits a low Hc of 11.2 A/m, high Bs of 1.55 T, and wide ΔToa of 90 K. The mechanism of P and Hf substitutions affecting the structure and magnetic properties of the Fe84(Nb, Hf)7(B, P)9 nanocrystalline alloys was discussed in terms of primary crystallization behavior regulation.
•Adding P increases AFA of a Fe84Nb7B9 alloy and further adding Hf enhances thermal stability.•B/P and Nb/Hf synergistic substitution refines the nanostructure of the annealed alloy.•The synergistic substitution improves soft magnetic properties of the nanocrystalline alloys.•A Fe84Nb3.5Hf3.5B5P4 nanocrystalline alloy exhibits a Hc of 11.2 A/m, Bs of 1.55 T, and ΔToa of 90 K.
Up-Scaling of Melt-Spun LDH/HDPE Nanocomposites Kutlu, Burak; Meinl, Juliane; Leuteritz, Andreas ...
Macromolecular materials and engineering,
July 2014, Letnik:
299, Številka:
7
Journal Article
Recenzirano
Layered double hydroxide (LDH) was melt‐mixed with high‐density polyethylene (HDPE) using a co‐rotating twin screw microcompounder with a volume of 15 ml (small‐scale) and using a co‐rotating twin ...screw extruder with a production rate of 10 kg h−1 (large‐scale). The nanocomposites were further melt‐spun with a piston‐type spinning device and a universal laboratory high‐speed spinning device with respect to the scale of the nanocomposite preparation. The spinnability and mechanical properties of the nanocomposites were found to be comparable with the neat polyethylene. Bicomponent fiber preparation was also carried out, in which neat polyethylene was set as core and the nanocomposite as sheath.
Layered double hydroxide (LDH) can be incorporated into melt‐spun polyethylene fibers if it is initially organomodified and well dispersed in the matrix. LDH/polyethylene nanocomposites show high melt‐spinnability, which can serve large‐scale fiber production purposes. Moreover, preparation of bicomponent fibers, where the sheath is the composite and the core is the polyethylene, is also possible.
•The amorphousized Cu18Al25RE57 (RE = Ho and Tm) ribbons were fabricated.•Magnetic properties and MCE in Cu18Al25RE57 amorphous ribbon were studied.•Large values of −ΔSMmax, RC and RCP were observed ...at low temperatures.•Cu18Al25RE57 ribbons are competitive for cryogenic magnetic cooling.
The rapidly solidified Cu18Al25Ho57 and Cu18Al25Tm57 melt-spun ribbons have been successfully synthesized. Both ribbons show complete amorphous characteristics based on the analysis of the X-ray diffraction (XRD) and differential scanning calorimeter (DSC). Magnetic measurements illustrate that a paramagnetic to ferromagnetic type transition takes place at Curie temperatures TC of 22.2 and 4.9 K for Cu18Al25Ho57 and Cu18Al25Tm57, respectively, which are companied with a considerable magnetocaloric effect (MCE). For a magnetic field change (ΔH) of 0–7 T, Cu18Al25Ho57 and Cu18Al25Tm57 ribbons display the maximum magnetic entropy (ΔSMmax) of 24.8 and 20.9 J kg−1 K−1, the refrigerant capacity (RC) determined from the area below a full-width at half-maximum (δTFWHM) forΔS(T)curve of 582.9 and 385 J kg−1, respectively. The large MCEs at low temperatures demonstrate that Cu18Al25RE57 (RE = Ho and Tm) are competitive candidates among the MCE materials working at liquid hydrogen and liquid helium temperature zones.
•Ce addition suppresses the phase decomposition of 2:14:1 main phase due to La doping.•La substitution make grain refining of NdFeB based alloys.•Magnetic properties of La-Ce co-doped alloys are ...superior to single-doped alloys.•The (BH)max of Nd0.5(La0.6Ce0.4)0.52Fe14B reaches 12.4MGOe.•La-Ce co-doped NdFeB alloys can be applied due to its ideal magnetic performance.
Investigation of the phase structure of Nd1−x(LayCe1−y)x2Fe14B (x = 0–0.7, y = 0, 0.2, 0.4, 0.5, 0.6, 0.8, 1.0) melt spun ribbons and their magnetic properties is presented. The La-Ce co-doped Nd-Fe-B alloys are compared with the La doping and Ce doping respectively by controlling the doping ratio of La/Ce. It can be found that the Nd-Fe-B alloys remain single 2:14:1 phase with Ce doping. In contrast, the 2:14:1 phase begins to decompose when the doping content of La reaches 30at.%. The 2:14:1 phase decomposes seriously with the La doping content over 50at.%, accompanied by the rising of secondary phases. The magnetic properties of Nd-Fe-B alloy decrease with the increasing of La, Ce doping content. The performance of La-doped Nd-Fe-B is superior to that of Ce-doped when the addition of La is less than 50at.%. However, severe phase decomposition of 2:14:1 phase with x more than 0.5 leads to the sharp decline of magnetic properties of La-doped Nd-Fe-B. In general, the magnetic properties, especially for the Br and (BH)max of La-Ce co-doped Nd-Fe-B are better than single-doped cases. And the co-doped Nd-Fe-B alloys show greater enhancement of (BH)max with the increasing amount of total doping content. For example, when the total doping concentration reaches 50at.%, the (BH)max of Nd0.5(La0.6Ce0.4)0.52Fe14B still reaches 12.4MGOe, which is much higher than (Nd0.5Ce0.5)2Fe14B ((BH)max = 8.2MGOe).
