Highly thermally conducting polyamide 6 (PA6) composites with high loadings of low-temperature expandable graphite (LTEG) were prepared by an in situ exfoliation melting process, and the thermal conductivity of the composites was measured by a hot-disk method. A two-point method was applied to evaluate the electrical conductivity of the composites with various graphite loadings, and the thermal percolation was observed in the vicinity of the electrical percolation threshold concentration. Dynamic rheology analysis was used to define the geometric change caused by the interconnection of the in situ exfoliated graphite flakes. X-ray diffraction measurement confirmed that the exfoliation of LTEG was crucial to the overall thermal conductivity of the composites. Dynamic mechanical analysis revealed that the incorporation of LTEG significantly improved the damping properties of PA6. Thermogravimetric analysis and differential scanning calorimetry measurements were applied to study the thermal properties of the investigated PA6/LTEG composites.
Free radical polymerization is a mature method and can be used for preparing multifunctional hydrogels by simply changing the commercial monomers, but the harsh and timeconsuming initiation conditions restrict its injectable ability, which further limits its application in the biomedical field. Though some catalysts can be used to accelerate the polymerization, their application is restrained by the biotoxicity. Hence, finding a biocompatible catalyzer for in situ free radical polymerization of hydrogels has a great prospect in biomedical application but is still challenging. In this study, we discovered that silver ions could catalyze free radical polymerization under ambient by transforming hydrone into hydroxyl radicals in the presence of ammonium persulfate, and the in situ-formed hydrogels prepared by this way showed great histocompatibility, hemocompatibility, cytocompatibility, and immunocompatibility. Benefitting from its convenience and biocompatibility, the in situ polymerization of polyacrylamide-based hydrogels for tissue adhesion, wound dressing, and conductive materials on the skin could be realized by simply blending diverse ingredients. Furthermore, this discovery may be a step toward the in situ-polymerized hydrogels for biomedical applications.
In
oil industry, wax deposition is one of the frequently encountered
problems that causes severe issues during the production, storage,
and transportation of crude oil. Recently, it is found that addition
of nanohybrids to crude oil is an effective method to solve this problem.
However, the mechanism of how nanoparticles affect the wax crystallization
and rheological behavior of crude oil has not been clearly understood.
Here we reported the influence of SiO2 nanoparticles on
crystallization and rheological behavior of model oils with and without
asphaltene and resin. It was demonstrated that the wax appearance
temperature increased upon the addition of SiO2 nanoparticles
of model oil without asphaltenes and resin, while the rheological
behavior was less affected. When in the presence of asphaltenes and
resin, the amount of wax crystals, wax appearance temperature, and
rheological parameter of model oils were found to decrease while SiO2 nanofluid was added, resulting in the improvement of flowability.
The currently used hemoperfusion adsorbents such as activated carbon and ion-exchange resin show dissatisfactory hemocompatibility, and a large dose of injected heparin leads to the increasing cost and the risk of systematic bleeding. Natural polysaccharide adsorbents commonly have good biocompatibility, but their application is restricted by the poor mechanical strength and low content of functional groups. Herein, we developed an efficient, self-anticoagulant and blood compatible hemoperfusion adsorbent by imitating the structure and functional groups of heparin. Carrageenan and poly(acrylic acid) (PAA) cross-linked networks were built up by the combination of phase inversion of carrageenan and post-cross-linking of AA, and the formed dual-network structure endowed the beads with improved mechanical properties and controlled swelling ratios. The beads exhibited low protein adsorption amounts, low hemolysis ratios, low cytotoxicity, and suppressed complement activation and contact activation levels. Especially, the activated partial thromboplastin time, prothrombin time, and thrombin time of the gel beads were prolonged over 13, 18, and 4 times than those of the control. The self-anticoagulant and biocompatible beads showed good adsorption capacities toward exogenous toxins (560.34 mg/g for heavy metal ions) and endogenous toxins (14.83 mg/g for creatinine, 228.16 mg/g for bilirubin, and 18.15 mg/g for low density lipoprotein (LDL)), thus, highlighting their potential usage for safe and efficient blood purification.
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