Anti-PVA polyclonal antibody

Composites based on aramid fibres are widely used to protect people and vehicles from high-velocity impact threats. Currently, quite a lot of attention is paid to methods for increasing the efficiency of such structures without a significant increase in areal density. The article demonstrates the results of experimental and computational studies of two types of multilayer fabric systems based on Twaron (R) 709. The first system consisted of dry fabric layers, and the second one was based on the fabric layers with polyvinyl acetate (PVA) surface coating. Experimental studies included quasi-static yarn pull-out tests, high-velocity impact tests of specimens without backing support, and tests on a plasticine block to assess the back face bulging. The results of the experiments showed that thin coatings of PVA contributed to a significant pull-out force increase due to polymer connections between the yarns. This effect led to the fact that specimens based on coated fabrics had a ballistic limit twice as much and showed a three-fold decrease in the depth of the dent on plasticine in comparison with dry fabrics. The total increase in surface density did not exceed 6% while maintaining high flexibility of the package. Also, numerical simulations were used to confirm the results of experiments. It was shown that mesoscale yarn-level models allow to predict plasticine indentation depths of the dry and coated multilayer fabric targets.

Nanomaterials are regularly added to crosslinkable polymers to enhance mechanical properties; however, important effects related to gelation behavior and crosslinking kinetics are often overlooked. In this study, we combine cellulose nanocrystals (CNCs) with a photoactive poly(vinyl alcohol) derivative, PVA-SbQ, to form photocrosslinked nanocomposite hydrogels. We investigate the rheology of PVA-SbQ with and without CNCs to decipher the role of each component in final property development and identify a critical CNC concentration (1.5 wt%) above which several changes in rheological behavior are observed. Neat PVA-SbQ solutions exhibit Newtonian flow behavior across all concentrations, while CNC dispersions are shear-thinning <6 wt% and gel at high concentrations. Combining semi-dilute entangled PVA-SbQ (6 wt%) with >1.5 wt% CNCs forms a percolated microstructure.In situphotocrosslinking experiments reveal how CNCs affect both the gelation kinetics and storage modulus (G ') of the resulting hydrogels. The modulus crossover time increases after addition of up to 1.5 wt% CNCs, while no modulus crossover is observed >1.5 wt% CNCs. A sharp increase inG ' is observed >1.5 wt% CNCs for fully-crosslinked networks due to favorable PVA-SbQ/CNC interactions. A percolation model is fitted to theG ' data to confirm that mechanical percolation is maintained after photocrosslinking. A similar to 120% increase inG ' for 2.5 wt% CNCs (relative to neat PVA-SbQ) confirms that CNCs provide a reinforcing effect through the percolated microstructure formed from PVA-SbQ/CNC interactions. The results are testament to the ability of CNCs to significantly alter the storage moduli of crosslinked polymer gels at low loading fractions through percolation-induced reinforcement.