Multiscale Structure and Microscopic Deformation Mechanisms of Gel-Spun Ultrahigh-Molecular-Weight Polyethylene Fibers

Tensile Strength Statistics and Fracture Mechanism of Ultrahigh Molecular Weight Polyethylene Fibers: On the Weibull Distribution

To study the distribution of ultrahigh molecular weight polyethylene fiber (UHMWPE) strength, three groups of UHMWPE fibers were spun by the gel spinning method, which was undrafted raw fibers (with high strain at break) and fibers with different prespinning and postspinning draw ratios. It is found that even when the strain at break (εb) > 46%, the tensile strength of the fiber still obeys the Weibull distribution. The draw ratio has a great influence on the distribution of fiber strength, especially the draw ratios of the spinneret in the prespinning process. It may be that different drafting processes affect the fracture mechanism of the fibers. This paper analyzes and discusses that and proves it by differential scanning calorimetry and the taut tie molecules (TTMs) fractions. The parameters of the Weibull distribution suggest the quality of the fiber. The Weibull modulus is closely related to the dispersion of the fiber properties and processing parameters. The characteristic strength is similar to the test average strength, which is more suitable for the judgment of fiber reliability in actual use. At the same time, the normality of the samples was tested by Kolmogorov-Smirnov, Shapiro-Wilk, Jarque-Bera test, and quantile-quantile (Q-Q) plots, and the strength distribution was visually displayed by the bell curve. The results show that the Gaussian distribution is not so suitable to describe the strength distribution of the stretched fiber compared to the Weibull distribution.

Development of a Fibrous Adsorbent Prepared Via Green Vapor-Phase Grafting Polymerization for Uranium Extraction

Owing to many problems of the detriment by large amount of organic reagents, high cost and difficulty of industrialization, development of high-efficiency economical technologies for uranium extraction is an irresistible trend to support steady supply of nuclear energy. Herein, a novel fibrous adsorbent, named as AO-HPE fibers, was prepared by introduction of amidoxime groups using the green vapor-phase grafting polymerization (VPGP) technology of monomer acrylonitrile (AN). Gaseous AN was grafted onto the ultra high molecular weight polyethylene (UHMWPE) fibers at 80 °C in the enclosed evaporation and condensation reflux system. The innovative technology not only endowed synthetic process high monomer utilization ratio but also excellent environmental friendliness. The AO-HPE fibers exhibited an appreciable calculated maximum adsorption capacity (Q _m) of 1144.94 mg·g^-1 in uranium solution and an adsorption capacity of 14.11 mg·g^-1 in simulated seawater. Meanwhile, the higher uranium selectivity than main competing ion vanadium (adsorption mass ratio was almost 5) was achieved. The adsorption process accorded closely with chemisorption mechanism. This work provided a novel idea for the synthetic method of adsorbents for uranium extraction, and inspired the sustainable technologies for grafting polymerization of monomer AN.

Effect of Coagulation Bath Temperature on Mechanical, Morphological, and Thermal Properties of Cellulose/Antarctic Krill Protein Composite Fibers

Cellulose (C) and Antarctic krill protein (AKP) were dissolved at low temperature, and then C/AKP composite fibers were prepared by wet spinning. In this paper, the effect of coagulation bath temperature on the properties of C/AKP composite fibers were studied by FT-IR, XRD, DSC, and other tests. The results showed that, when the temperature of the coagulation bath increased from 5 to 25 °C, the intermolecular hydrogen bond content of the C/AKP composite fibers increased from 28.20% to 31.33%. When the coagulation bath temperature is 15 °C, the breaking strength of the composite fibers is 1.64cN/dtex, which is 12% higher than that of the composite fibers at room temperature. At this temperature, the crystallinity of the composite fibers is improved, the thermal stability is slightly improved, and the surface morphology is smoother. Inspiringly, when zinc sulfate is added to the coagulation bath, the formation process of the fibers is milder. Moreover, the C/AKP composite fibers have excellent antibacterial activity against Escherichia coli and Staphylococcus aureus.