The outbreak of COVID-19 provided a warning sign for
society worldwide:
that is, we urgently need to explore effective strategies for combating
unpredictable viral pandemics. Protective textiles such as surgery
masks have played an important role in the mitigation of the COVID-19
pandemic, while revealing serious challenges in terms of supply, cross-infection
risk, and environmental pollution. In this context, textiles with
an antivirus functionality have attracted increasing attention, and
many innovative proposals with exciting commercial possibilities have
been reported over the past three years. In this review, we illustrate
the progress of textile filtration for pandemics and summarize the
recent development of antiviral textiles for personal protective purposes
by cataloging them into three classes: metal-based, carbon-based,
and polymer-based materials. We focused on the preparation routes
of emerging antiviral textiles, providing a forward-looking perspective
on their opportunities and challenges, to evaluate their efficacy,
scale up their manufacturing processes, and expand their high-volume
applications. Based on this review, we conclude that ideal antiviral
textiles are characterized by a high filtration efficiency, reliable
antiviral effect, long storage life, and recyclability. The expected
manufacturing processes should be economically feasible, scalable,
and quickly responsive.
The dynamic covalent chain polyester oligomer PCG5 is prepared and applied to epoxy thermoset. Preliminary tests including pattern stamping, healing, shape memory, indentation, and adhesion test of the cured epoxy resin show that PCG5 can accelerate deformation, crack-healing, and transesterification rates at high temperatures. The transesterification rate and activation energy are quantitatively determined by a newly developed TGA method in the authors' group. This method is used to further realize a virtual acceleration mechanism of PCG5 in the transesterification reaction with cured epoxy resins, pointing out that the increase in cross-link density and ester concentration improves the mobility of structure units and collision of ester groups. Moreover, introduction of PCG5 doesn't sacrifice glass transition temperatures (T g ) of the cured epoxy resin and strengthens the fiber composites. An 85% recovery in storage modulus and an 88% recovery in tensile strength are achieved after 10 000 cycle's fatigue tests.
Herein, the successful design of a highly bio‐based family of unsaturated polyester resins (UPRs) is presented, comprising of an isosorbide (ISO) incorporated unsaturated polyester prepolymer (UP) and a reactive diluent of 4‐vinylguaiacol acetyl ester (ACVG). A series of UPs are prepared by copolymerizing ISO with other green monomers, i.e., itaconic acid, ethylene glycol and oxalic acid, in a variation of ISO fraction. The UP/ACVG mixtures exhibit very low viscosity ranging from 2.8 to 3.7 Pa s. After curing at 135 °C to form a network, the resulting thermosets exhibit remarkable improvements in terms of glass transition (Tg, about 131 °C), storage modulus (2564–3342 MPa), and tensile strength (around 76.6 MPa), which are significantly better than the UP thermosets reported in previous works, The incorporation of ISO units into the UPs reveals a favorable effect on thermal stability of the thermosets as well. The best Td5% is measured to be 320.4 °C, and the volatile molecular information collected using a TGA‐GC/MS set suggests that the decomposition mechanism of the cross‐linked resins becomes heat‐resistant due to the ISO incorporation. Moreover, after being reinforced by cotton fabrics, an outstanding compatibility between the ISO containing UPRs and cotton fibers is found to be suitable for composite fabrication.
Experimental study on the flexural property of self-compacting recycled concrete (SCRC) beams with discontinuous graded recycled coarse aggregate is carried out with different replacement ratio of recycled aggregate and concrete grade. The similarities and differences on the failure modes between 4 SCRC beams and 2 normal beams were discussed. According to various replacement ratio of recycled aggregate and concrete grade,the influence on the carrying
capacity,cracking ability,etc. of SCRC beams with discontinuous graded recycled coarse aggregate was also analysed.
The results show that the failure modes, cracks of pure bend of SCRC beams and normal ones are similar. The vertical
crack width of SCRC beams are bigger than the normal beams. There are small cracks in the shear bending section. The
ultimate strength decrease slightly and the calculation formulas of current design standard can be used of flexural members which are made of SCRC.
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