•The optimum spinning parameters of carrageenan were obtained through orthogonal experiment method.•The crosslinked carrageenan fibers were prepared under the optimal conditions using a custom-made ...wet spinning device.•Structure and performance of carrageenan fibers were analyzed after processing by epoxy chloropropane.•The stability, necking phenomenon and strength property of modified fibers were studied.
Motivated by the extensive application of carrageenans, this work prepared carrageenan fibers via wet spinning. The optimum spinning parameters were explored by means of an orthogonal test. According to the results of tensile test, dope concentration, draw ratio, coagulation bath temperature, and coagulation bath concentration set to 9%, 1.2, 15°C and 5%, respectively, were the optimum spinning conditions. These parameters were then applied to fabricate fibers treated with epichlorohydrin in a stretch bath. The result of tensile testing demonstrated a positive improvement in the intensity, and SEM showed obvious necking phenomenon of the crosslinked carrageenan fibers. The structures and special groups were characterized with X-ray diffraction and FTIR, and the results indicated the regularity of the net structure and the increase in ether bond and methylene. In some, crosslinking reactions in optimum parameter conditions yield excellent fibers and thus present promising applications.
One-pot synthesis of cyclic carbonates from CO2 and epoxides over 3D monoclinic Mn–BTC.
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(CH3)2NH2M3(BTC)(HCOO)4(H2O).H2O (M–BTC, M=Mn, Ni, Co) were prepared under hydrothermal ...conditions and used as highly efficient catalysts for cycloaddition of CO2 with epichlorohydrin (ECH). The microstructure and physicochemical properties of the compounds were determined by PXRD, FT-IR, XPS, N2-adsorption, TG–DSC, NH3–TPD and CO2–TPD. 98.01% conversion of ECH and 96.05% selectivity to chloropropene carbonate was obtained over the Mn–BTC under the optimized reaction conditions (105°C, 3.0MPa, 9h, 1.5wt.% of ECH). Besides, the recyclability result exhibited the Mn–BTC compound can be utilized as least three times with a slight reduction in its catalytic ability. In addition, cycloaddition of CO2 with other epoxides and DFT calculation were also performed. The result exhibited the yield followed the order: ECH>1, 2-epoxybutane>propene oxide>Allyl glycidyl ether, which was mainly determined by the energy of reaction.
Thermoplastic elastomer (TPE) based on polypropylene (PP) and epichlorohydrin rubber (ECH) was prepared in the presence of maleic anhydride grafted polypropylene (MA-g-PP) as compatibilizer. The ...PP/ECH blends in the absence of compatibilizer showed very poor mechanical properties, especially low elongation at break values and higher tension set values. This was attributed to the poor compatibility between PP and ECH. On the other hand, in the case of compatibilized PP/ECH blends, MA-g-PP acted as a strong interfacial agent between PP and ECH phases and led to outstanding improvement in the mechanical and rheological properties. Compatibilized PP/ECH blends showed higher mixing torque values in comparison to the incompatible PP/ECH blends due to existence of better interaction between PP and ECH in the presence of MA-g-PP. Fourier transform infrared spectroscopy (FTIR) study clearly depicted the existence of strong chemical interactions between PP and ECH in the presence of MA-g-PP. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) studies suggested that the addition of MA-g-PP to PP/ECH blends increased the percentage crystallinity, which in turn enhanced the overall properties. Morphological studies clearly showed the prominent reduction in the domain size of dispersed ECH phase in the continuous PP matrix due to the incorporation of MA-g-PP as compatibilizer.
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•Thermoplastic elastomer (TPE) from polypropylene (PP)/epichlorohydrin rubber (ECH).•Maleic anhydride grafted polypropylene (MA-g-PP) as compatibilizer for PP/ECH TPE's.•MA-g-PP enhances the chemical interactions between PP and ECH.•MA-g-PP significantly reduces the domain size of the dispersed ECH rubber phase.•The overall properties of the compatibilized blends are prominently higher.
A polyamidoamine (PA) without introducing epichlorohydrin, and two epichlorohydrin-modified polyamidoamine (PAE) samples with solid contents of 12% (PAE-12) and 25% (PAE-25) were synthesized, and ...their short-term storage stabilities, evaluated at intervals of at least 3 months were assessed for chemical structure, viscosity, pH, thermal degradation behavior, crystalline degree and wet bond strength. The results showed that PA was stable during storage for 98 days, while PAE-12 had better storage stability than PAE-25. PAE was active due to complex side reactions, as the number of azetidinium groups within PAE significantly decreased resulting from the ring open reaction after storage for 42–56 days, leading to decreased crosslinking degree and thermal stability, and increased crystalline content of defatted soy flour (DSF)-PAE adhesives. Thus, the wet bond strength of the corresponding plywood decreased with the increasing storage time of PAE-12 and PAE-25, and finally decreased to 1.05 MPa and 0.66 MPa after storage for 98 days, respectively. In order to ensure the water resistance of DSF-PAE adhesives, the preferable application time at room temperature is 3 months for PAE-12 and 4 weeks for PAE-25.
Polyamidoamine epichlorohydrin (PAAE) is a permanent wet strength resin used in papermaking. When applied to paperboard, some amount of resin is retained in the sheet, and some is lost to the white ...water. The papermaker usually knows the amount of PAAE charged to the pulp but has no idea how much chemical is retained in the sheet. In addition, the influence of PAAE dosage, freeness, zeta potential, and pulp kappa number variability on PAAE retention is not well understood. Factorial design experiments using unbleached and bleached softwood (loblolly pine) kraft pulps were conducted to understand the factors that affect PAAE retention. The results revealed that PAAE retention, wet tear index, and tensile index not only depended on the PAAE charged of the pulp but also depended significantly on the pulp freeness. In lieu of freeness, zeta potential data can be used to predict PAAE retention. In addition, at similar freeness, bleached pulp has the highest retention of PAAE compared to low and high kappa unbleached kraft pulps. The results also suggest that lignin may have potential as a wet strength agent.
•A novel cationic β-cyclodextrin polymer (polyEPG-CD) was successfully synthesized.•The physicochemical properties of polyEPG-CD are dependent on the reaction parameters.•A dual cyclodextrin ...polyelectrolyte multilayer system was then realized on a non-woven PET.•A multilayer assembly up to 20 layers was obtained with a controllable weight gain.•This multilayer system shows a high density of cyclodextrin cavity.
A polyelectrolyte multilayer film (PEM) based on cationic and anionic β-cyclodextrin polyelectrolytes was coated onto a textile substrate for future drug delivery purposes. We firstly synthesized a novel cationic β-cyclodextrin polymer (polyEPG-CD) by crosslinking β-cyclodextrin (βCD) with epichlorohydrin (EP) under basic conditions, in the presence of glycidyltrimetrylammonium chloride (GTMAC) as cationizing group. The influence of preparation conditions has been investigated in order to preferably obtain a water soluble fraction whose charge density and molecular weights were optimal for the layer-by-layer (LbL) deposition process. The different cationic cyclodextrin polymers obtained were characterized by FTIR, NMR, colloidal titration, conductimetry, thermogravimetric analysis and size exclusion chromatography. Besides, the counterpart polyelectrolyte was a β-cyclodextrin polymer crosslinked with citric acid, polyCTR-CD, whose synthesis and characterization have been previously reported. Finally we realized the Layer by Layer (LbL) build-up of the PEM coating onto the textile support, using the dip coating method, by alternatively soaking it in cationic polyEPG-CD and anionic polyCTR-CD solutions. This multilayer self-assembly was monitored by SEM, gravimetry and OWLS in function of both polyelectrolytes concentrations and ratios. Solutions parameters such as pH, ionic strenght were also discussed.
► Adsorption of Cu(II) and Cd(II) ions in single and binary metal systems. ► The metal ion adsorption process is dependent on the solution pH. ► The Langmuir model provided the best fit for the ...experimental adsorption data. ► The order of the affinity of adsorbent for the metal ions was: Cu(II)≫Cd(II). ► The adsorbent could be regenerated and reused for the adsorption of metals.
In this study, chitosan (CTS) was crosslinked with both epichlorohydrin (ECH) and triphosphate (TPP), by covalent and ionic crosslinking reactions, respectively. The resulting adsorbent (CTS–ECH–TPP) was characterized by SEM, CHN, EDS, FT-IR and TGA analyses, and tested for metal adsorption. The adsorbent was used in batch experiments to evaluate the adsorption of Cu(II) and Cd(II) ions in single and binary metal solutions. In single metal solutions the maximum adsorption capacities for Cu(II) and Cd(II) ions, obtained by Langmuir model, were 130.72 and 83.75mgg−1, respectively. Adsorption isotherms for binary solutions showed that the presence of Cu(II) decreased Cd(II) adsorption due to a significant competition effect, that is, the adsorbent was selective towards Cu(II) rather than Cd(II).
Osteoarthritis (OA) is a joint pain and dysfunction syndrome resulting from severe joint degeneration. Inflammation and degeneration of the articular cartilage are two main features of OA and have ...tight interactions during OA progression. Conventional treatment with nonsteroidal anti-inflammatory drugs has been widely utilized clinically, whereas the side effects have restricted their application. Forsythoside B has been found with anti-inflammatory effects and antiapoptosis in inflammatory diseases, whereas in OA it remains poorly understood. Interleukin (IL)-1β (10 ng/mL) was taken to induce an OA cell model on HC-A chondrocytes and an OA rat model was constructed for in vivo experiments. Forsythoside B was adopted to treat HC-A chondrocytes and OA rats. As shown by the data, Forsythoside B hampered IL-1β-elicited rat chondrocyte apoptosis, oxidative stress, and facilitated proliferation. The profiles of inflammatory factors, NOD-like receptor family pyrin domain containing 3 inflammasomes, Kelch-like epichlorohydrin-associated protein-1 (Keap1), and nuclear factor-κB (NF-κB) phosphorylation were suppressed by Forsythoside B, whereas the nuclear factor E2-related factor 2 (Nrf2) and heme oxygenase-1 (HO-1) levels were promoted. Further, Forsythoside B mitigated cartilage damage and degeneration. Moreover, the oxidative stress and inflammation mediators in the cartilage tissue of OA rats were remarkably abated. Collectively, Forsythoside B hinders the NF-κB and Keap1/Nrf2/HO-1 pathways to curb IL-1β-elicited OA rat oxidative stress and inflammation both in vivo and ex vivo, ameliorating OA development. All over, this study provides an underlying strategy for treating OA, which might help the clinical treatment of OA patients.
The presence of pollutants in the water bodies deteriorate the water quality and make it unfit for use. From an environmental perspective, it is essential to develop new technologies for the ...wastewater treatment and recycling of dye contaminated water. The surface modified chitin and chitosan biopolymeric composites based adsorbents, have an important role in the toxic organic dyes from removal wastewater. The surface modification of biopolymers with various organics and inorganics produces more active sites at the surface of the adsorbent, which enhances dye and adsorbent interaction more reliable. Herein, the work brought in the thought of the application of various chitin and chitosan composites in wastewater remediation and suggested the versatility in composites for the development of rapid, selective and effective removal processes for the detoxification of a variety of organic dyes. It further emphasizes the existing obstruction and impending prediction for the deprivation of dyes via adsorption techniques.
•Water pollution leads to water scarcity, which requires remediation.•Dyes cause water toxicity and adversely affect living organisms.•Adsorption is the one of the most appropriate method for dye removal.•Surface modified chitin and chitosan are used as effective dye adsorbents.•Dye sorption mostly follows pseudo-second-order kinetics and Freundlich isotherm.
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•Key amino acid residues located at halide ion channels of HheCPS were modified.•The kinetic parameters of HheCPS were regulated.•Optically pure (S)-ECH was biosynthesized for the ...first time by HheCPS mutants.
Asymmetric synthesis of chiral epichlorohydrin (ECH) from 1,3-dichloro-2-propanol (1,3-DCP) using halohydrin dehalogenases (HHDHs) is of great value due to the 100% theoretical yield and high enantioselectivity. The vital problem in the asymmetric synthesis is to prepare optically pure ECH. In this study, key amino acid residues located at halide ion channels of HheC (P175S/W249P) (HheCPS) were modified to regulate the kinetic parameters. HheCPS I81W, F86N and V94R were constructed with the corresponding halide ion channels destroyed. The catalytically efficiencies (kcat/Km) of the three mutants exhibited 0.38-, 0.23- and 0.23-fold decrease toward (S)-ECH and the reverse reaction was significantly inhibited. As the results, (S)-ECH was synthesized with >99% enantiomeric excess (e.e.) and 63.42%, 67.08% and 57.01% yields, respectively, under 20 mM 1,3-DCP as substrate. To our knowledge, this is the first investigation of the molecule kinetic modification of HHDHs and also the first report for the biosynthesis of optically pure (S)-ECH from 1,3-DCP using HHDHs.
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