A cationic metal−organic framework (MOF) ZJU-48 with one-dimensional pores of about 9.1 × 9.1 Å 2 has been prepared from zinc ions, adenine, and carboxyl ligands. ZJU-48 displays excellent water stability for about one week, exhibiting its potential application for adsorption and separation of dyes. Cationic and anionic dyes with similar sizes are adopted to study the adsorbing and separating properties of ZJU-48. Cationic dyes are adsorbed better than anionic dyes because of the negatively charged zeta potential of the material surface, implying its selective adsorption to cationic dyes, and it is charge-based adsorption. Meanwhile, the adsorption ability of the MOF to cationic dyes with different sizes is also investigated. We find that the adsorbed amount decreases with increase in the size of organics ,indicating that it is sizebased adsorption. Furthermore, the cationic dye methylene blue (MB) is employed and focused on for its suitable charge and fitting size to evaluate the maximum adsorption capacity and desorption progress of ZJU-48. The results show that the maximum loaded amount of MOF toward MB reaches 582.44 mg/g, and about 90% of loaded dyes can be released from frameworks in N,N-dimethylformamide with NaCl over 6 h, exhibiting satisfactory adsorptive property and possibility as a reusable adsorbent.
The rGO/PP composites with high dielectric constant and low dielectric loss at a low filler content were prepared via constructing a segregated graphene network by encapsulating of GO on PP latex particles and the in situ reduction in GO.
A green and facile strategy is represented to obtain edge-oxidized graphene by exploiting sulfate radicals generated from Na2S2O8 with Fe2+ activation.
In order to obtain higher thermoelectric and mechanical properties in nonpolar thermoplastic vulcanizates (TPVs), the butyl rubber/polypropylene (TPVs)/hydroxylated graphene (HGE) composites with nanosheet network were prepared through masterbatch technique and based on thermodynamic calculations, using polypropylene-graft-maleic anhydride (PP-MA) as a compatibilizer. The Fourier transform infrared (FTIR) and Raman spectra revealed the introduced maleic anhydride group on PP-MA can form strong interfacial interaction with hydroxyl-containing functional groups on HGE. Morphology study indicated the rubber particles in the composites occupied the most volume of the PP phase, as expected to hinder the aggregation of HGE and form the effective nanosheet network. The nanosheet network can be combined with the butyl rubber (IIR) cross-linked particles during the dynamic vulcanization process to improve the interface bonding between PP and IIR, thus increasing the tensile strength of TPVs. The prepared TPVs/HGE composites have significantly improved in mechanical properties, thermal properties and dielectric properties, which provides a guarantee for their potential application as multifunctional TPVs polymers.
In order to obtain higher thermoelectric and mechanical properties in non-polar thermoplastic vulcanizates (TPVs), the Butyl rubber/Polypropylene (TPVs)/hydroxylated graphene (HGE) composites with nanosheet network were prepared through masterbatch technique and based on thermodynamic calculations, using polypropylene-graft-maleic anhydride (PP-MA) as a compatibilizer. The FTIR and Raman spectra revealed the introduced maleic anhydride group on PP-MA can form strong interfacial interaction with hydroxyl-containing functional groups on HGE. Morphology study indicated the rubber particles in the composites occupied the most volume of the PP phase, as expected to hinder the aggregation of HGE and form the effective nanosheet network. The nanosheet network can be combined with the IIR cross-linked particles during the dynamic vulcanization process to improve the interface bonding between PP and IIR, thus increasing the tensile strength of TPVs. When the content of HGE reached the percolation threshold (2 wt.%), the nanosheet network of HGE was formed, and the AC conductivity, dielectric permittivity and thermal conductivity increased sharply. The prepared TPVs/HGE nanocomposites have significantly improved in mechanical properties, thermal properties and dielectric properties, which provides a guarantee for their potential application as multifunctional TPVs polymers.
Hydrogenated natural rubber (HNR) was prepared by diimide reduction of natural rubber (NR) latex and characterized by FT‐IR, 1H NMR and TG‐DTG. The thermal degradation kinetic models of HNR were studied under a nitrogen atmosphere by TG‐DTG. Achar and Coats–Redfern methods were used to study the non‐isothermal kinetics models change during the thermal degradation process of NR after hydrogenation. The results indicated that HNR with 34.69% and 63.74% hydrogenation degree were prepared. A one‐stage pyrolysis pathway could be observed from all the TGA curves which were shifted to higher degradation temperatures with the rise of saturation degree. The similar activation energies obtained by both Coats–Redfern and Achar methods confirmed that the kinetics calculation was accurate. The results showed the best‐fit models of the samples with the highest regression coefficient values (R2 > 0.90) were chemical reaction models. The reaction order was three (N3) in NR case and the corresponding mechanism functions were g(α) = [(1‐α)−2–1]/2, f(α) = (1‐α)3. The reaction order was two (N2) when it came to HNR with hydrogenation degree of 34.69%. The most probable mechanism functions were g(α) = (1‐α)−1–1, f(α) = (1‐α)2. As the degree of hydrogenation increased to 63.74%, the reaction order best‐fit changed to one (N1) which was proved to be the same as the ethylene‐propylene diene rubber samples. And the mechanism functions were g(α) = −ln(1‐α), f(α) = 1‐α. The thermal degradation models of polymers was closely related to the structure. And the structure effects affected the degradation behavior as well as the thermal properties of polymers.
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