Jinchao Zhao

Fabrication of interpenetrating polymer network chitosan/gelatin porous materials and study on dye adsorption properties

One kind of adsorbent based on chitosan and gelatin with interpenetrating polymer networks (IPN) and porous dual structures was prepared using genipin as the cross-linker. These dual structures were demonstrated by means of Fourier transform infrared spectroscopy (FT-IR), thermogravimetric analysis (TGA) and scanning electron microscopy (SEM). Adsorptions of acid orange II dye from aqueous solution were carried out at different genipin contents, adsorption times and pH values. The results showed that this material was put up the largest adsorption capacity when the genipin content is 0.25 mmol/L, meanwhile, the lower the solution pH value the greater the adsorption capacity. The chitosan/gelatin interpenetrating polymer networks porous material displayed pH-sensitive and rapidly response in adsorption and desorption to pH altered. It is indicated that the cross-linked chitosan/gelatin interpenetrating polymer networks porous material could be used as a recyclable adsorbent in removal or separation of anionic dyes as environmental pH condition changed.

The Flame Retardancy, Thermal Properties, and Degradation Mechanism of Zinc Alginate Films

The coordination structure, flame retardancy, thermal stabilities, and degradation mechanism of zinc alginate films were studied by Fourier transform infrared spectroscopy (FTIR), limiting oxygen index (LOI), vertical burning (UL-94), and thermogravimetric analysis (TGA) tests. The FTIR results showed that the structure of zinc alginate was correlated to its bidentate bridging coordination. The LOI (49.3) and UL-94 (V-0 rating) results indicated that zinc alginate was an inherent flame retardant material. The TG results showed that zinc alginate had better thermal stabilities than sodium alginate in the lower temperature zones; however, the thermal stabilities of zinc alginate were worse than those of sodium alginate at higher temperatures because of the decomposition of zinc oxalate formed in the degradation process of zinc alginate. Based on the TG results and FTIR of the residues at different temperatures, the effect of zinc ions on the degradation process of alginate was different from that of sodium ions. The zinc ions can catalyze alginate to form the residues and increase the amount of the residues, finally forming zinc oxide. Further, it could decrease the release of flammable gases and increase the flame retardancy of alginate.

Bio-based nickel alginate and copper alginate films with excellent flame retardancy: preparation, flammability and thermal degradation behavior

A bio-based nickel alginate film and copper alginate film were prepared via a facile ion exchange and casting approach. Their flame retardancy, thermal degradation and pyrolysis behavior, and thermal degradation mechanism were investigated systematically by the limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA), thermogravimetric analyzer coupled with Fourier transform infrared analysis (TG-FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). It was shown that the nickel alginate film had a much higher LOI value (50.0%) than those of the sodium alginate film (24.5%) and copper alginate film (23.0%). Moreover, the nickel alginate film passed the UL-94 V-0 rating, while the sodium alginate film and copper alginate film showed no classification. Importantly, the peak of heat release rate (PHRR) of the nickel alginate film in the MCC test was much lower than those of the copper alginate film and sodium alginate film. This indicated that the introduction of nickel ions decreased the release of combustible gases. TGA results showed that the addition of copper ions and nickel ions accelerated the thermal degradation of alginates and changed the thermal degradation mechanism of the alginates. TG-FTIR and Py-GC-MS results indicated that the pyrolysis of copper alginate and nickel alginate produced much less flammable products than that of sodium alginate in the whole thermal degradation process. Finally, a possible degradation mechanism for copper alginate and nickel alginate was proposed. The results of our study provide useful information for understanding the flame retardancy mechanism of alginate as well as for designing bio-based materials with excellent fire retardancy.

Bio-based barium alginate film: Preparation, flame retardancy and thermal degradation behavior.

A bio-based barium alginate film was prepared via a facile ionic exchange and casting approach. Its flammability, thermal degradation and pyrolysis behaviors, thermal degradation mechanism were studied systemically by limiting oxygen index (LOI), vertical burning (UL-94), microscale combustion calorimetry (MCC), thermogravimetric analysis (TGA) coupled with Fourier transform infrared analysis (FTIR) and pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS). It showed that barium alginate film had much higher LOI value (52.0%) than that of sodium alginate film (24.5%). Moreover, barium alginate film passed the UL-94 V-0 rating, while the sodium alginate film showed no classification. Importantly, peak of heat release rate (PHRR) of barium alginate film in MCC test was much lower than that of sodium alginate film, suggested that introduction of barium ion into alginate film significantly decreased release of combustible gases. TG-FTIR and Py-GC-MS results indicated that barium alginate produced much less flammable products than that of sodium alginate in whole thermal degradation procedure. Finally, a possible degradation mechanism of barium alginate had been proposed.

Flame retardancy and thermal degradation properties of cotton/alginate fabric

Alginate fiber, a kind of bio-based fiber, is a type of inherently flame retardant material. Can the addition of alginate fiber to cotton fiber improve flame retardancy of prepared cotton/alginate fabric? To solve this question, in the present work, flammability and thermal degradation properties of the cotton and cotton/alginate fabrics were studied by thermogravimetric analysis (TG), microscale combustion calorimetry (MCC), cone calorimeter (cone) and thermogravimetric analysis coupled with Fourier transform infrared analysis. Compared to cotton fabric, TG results showed that the addition of alginate fiber decreased initial degradation temperature (Tinitial) and maximum-rate degradation temperatures (Tmax) of cotton/alginate fabric; however, the addition of alginate fiber improved the char residual amount at higher temperature. MCC and cone results indicated that the addition of alginate fiber reduced the peak heat release rate value and total heat release, showing improvement on flame retardant properties of cotton/alginate fabric. The release amounts of inflammable gases, such as H2O, for cotton/alginate fabric, were almost the same as cotton fabric in the thermal degradation process; however, compared to cotton fabric, the release amounts of flammable gases, such as compounds containing –C–H groups, alcohol, compounds containing carbonyl groups and ethers, were reduced. On the basis of the results mentioned above, the flame retardant properties of cotton/alginate fabric were enhanced. The results obtained in the present study can supply a flame retardant method by the addition of inherently bio-based flame retardant alginate fiber to flame-retard cotton fabric and enlarge the applied fields of alginate fiber.

Neutralisation and compatibilisation effects on novel water-swellable rubber composites

A novel water-swellable rubber (WSR) composite, modified by a compatibiliser, was prepared by blending poly(dimethylsiloxane) rubber (PDMS) as a matrix and poly(acrylic acid) (PAA) partially neutralised by sodium hydroxide (NaOH) as a superabsorbent polymer. The addition of hydrophilic PAA into hydrophobic PDMS improved water swelling ability but without good durability, mainly due to the poor interfaces between PAA and PDMS. Meanwhile, the tensile properties of the WSR before and after swelling decreased dramatically. With NaOH added as the neutraliser for PAA or with aminopropyltriethoxysilane added as the compatibiliser for PDMS and PAA, water swelling ability and/or durability increased. However, when the compatibiliser and the neutraliser were added together, the water swelling ability and durability of the WSR composites further increased by virtue of the synergistic effects due to the increased interfacial cohesion between the PDMS and PAA.