Intrinsically flame-retardant calcium alginate fibre was prepared by wet spinning and its pyrolysis products and thermal degradation mechanism studied. Combustion behaviour and flammability were assessed using the limiting oxygen index (LOI) and cone calorimetry. LOI results showed that calcium alginate fibre was intrinsically flame retardant with LOI value of 48.0, as compared to about 20.0 for viscose fibre. Cone calorimetry indicated that heat release rate and total heat release values of intrinsically flame-retardant fibre were significantly less than those of viscose fibre. It also shown that intrinsically flame-retardant fibre combustion produced greater quantities of residues than did viscose fibre combustion. Combustion residues were examined using scanning electron microscopy, indicating that calcium alginate fibre produced consistent, thick residue crusts. Pyrolysis was investigated using pyrolysis-gas chromatography-mass spectrometry (Py-GC-MS) which showed that cracking products produced from calcium alginate fibres combustion were less than those in viscose fibre combustion, and pyrolysis of the intrinsically flame-retardant fibre was incomplete. Thermogravimetric analysis (TG) indicated that calcium alginate fibre generated more residues containing carbonaceous char and calcium carbonate, as compared with viscose fibre. We propose a condensed phase mechanism for the calcium alginate fibre flame-retardancy effect. 相似文献
Microgels with alginate (Alg) gel cores and shells of SiO2 nanoparticles (so-called colloidosomes) were prepared by self-assembly of SiO2 nanoparticles at ALG aqueous solution–hexane interfaces and subsequent in situ gelation caused by Ca2+ ions that were released from calcium-ethylenediamine tetraacetic acid chelate by decreasing the pH value through the slow hydrolysis of D-Gluconic-δ-lactone. The packing density of SiO2 nanoparticles in the shell was about 0.906, indicating that the SiO2 nanoparticles were present monolayer on the surfaces of the colloidosomes. The half release times of insulin microcrystals were 4 h for Alg gel microspheres and 10 h for Alg/SiO2 colloidosomes at pH 7.4, compared to 1.5 h for bare insulin. The half release times of insulin microcrystals were 12 min for Alg gel microspheres and 30 min for Alg/SiO2 colloidosomes at pH 1.2, compared to 30 s for bare insulin. The release rates of insulin from the colloidosomes with core–shell structure were slower than that from bare insulin crystals due to the dual barriers of the hydrogel cores and the close-packed inorganic shells. The release curves were nicely fitted by the Weibull equation and the release followed Fickian diffusion. 相似文献
Sodium alginate (SA), acting as a trypsin inhibitor by means of electrostatic interaction, is studied. The half‐maximal inhibitory concentration (IC50 = 0.05 μg mL−1) of this natural anionic polymer is about 400 times lower than that of commercial soybean trypsin inhibitor (STI). Unlike the Ca2+‐deprivation mechanisms, its inhibition may be attributed to preventing the trypsin active site (TAS) from accessing the macromolecular substrates instead of denaturing it. SA is an efficient, innocuous, and cost‐effective inhibitory excipient that can be conveniently used in many peptide and protein dosage formulations.
The influence of polyglycerol polyricinoleate (PGPR) and biopolymers (gelatin and sodium alginate) on the stabilization of water-in-oil (W/O) emulsions was investigated to improve the encapsulation efficiency (EE) of water-in-oil-in-water (W/O/W) emulsions containing mango seed kernel extract (MSKE). The physical properties and EE of the emulsions were found to depend more strongly on PGPR than on biopolymers. High EE values of MSKE were obtained when W/O emulsions stabilized by 4–8 wt% PGPR were incorporated with 1–5 wt% gelatin, or by 6–8 wt% PGPR incorporated with 0.5–1.5 wt% sodium alginate in the inner aqueous phase. 相似文献
Graft copolymerization reaction among sodium alginate (NaAlg), sodium acrylate (NaA), and nanoscale attapulgite (APT) was performed to fabricate a novel pH-sensitive NaAlg-g-PNaA/APT superabsorbent nanocomposite. FTIR spectra proved NaA monomers were grafted onto NaAlg backbone and APT participated in polymerization. FESEM, TEM, and TGA analyses revealed the better dispersion of APT fibrils in the matrix and the improved thermal stability. The swelling capacity and rate of the superabsorbent was clearly enhanced after introducing APT. The external salts and surfactants showed greater influence on the swelling behaviors. The nanocomposite exhibited reversible On-Off pH-sensitivity between pHs 2.0 and 7.4, and the intriguing pH-triggered deswelling behavior in various polyvinylperrodone (PVP) solutions was observed. 相似文献
Complex coacervation of gelatin A and sodium alginate was carried out to obtain the maximum coacervate yield. Turbidity and coacervate yield (%) measurements were carried out to support the ratio of the two polymers and pH that produced maximum coacervation. The optimum ratio between gelatin A-sodium alginate and pH to form the maximum coacervate complex was found to be 3.5:1 and 3.5–3.8, respectively. Olive oil microencapsulation was carried out at the optimized ratio and pH. Microcapsules were crosslinked by using glutaraldehyde. Scanning electron microscopy studies confirmed the formation of free flowing spherical microcapsules of different sizes. The size of microcapsules increased with the increase in the concentration of the polymer. The encapsulation efficiency and the release rates of olive oil were dependent on the amount of crosslinker, oil loading and polymer concentration. Thermogravimetric study revealed improvement of thermal stability with crosslinking. Fourier Transform Infrared Spectroscopy study showed that there was no significant interaction between olive oil and gelatin-alginate complex. 相似文献