Impregnation Yield Research Articles

Flax mucilage and barley beta-glucan aerogels obtained using supercritical carbon dioxide: Application as flax lignan carriers

Flax lignan, secoisolariciresinol diglucoside (SDG), has been implicated in the prevention of hormonally related cancers and other diseases. Polysaccharide aerogels, dried using supercritical carbon dioxide (SCCO 2 ), have low densities and high porosities, making them ideal as bioactive carriers. Barley β-glucan (5%) and flax mucilage (10%) hydrogels were first converted to alcogels and then dried using SCCO 2 , and their characteristics were analyzed. SDG concentrate was incorporated into the gels prior to drying using several approaches. Both aerogels had low densities; however, surface area and % of hydrogel volume of mucilage (201 m 2 /g and 57%) were higher compared to those of β-glucan aerogel (166 m 2 /g and 38%). When SDG concentrate was added to the hydrated polysaccharide mixtures, regardless of the technique used, SDG contents were similar; however, the impregnation yield was less than 50%. SCCO 2 -dried polysaccharide aerogels show promise for use as a delivery vehicle for nutraceuticals, including flax SDG. The functional food and nutraceutical industry is looking for ways to enhance the delivery and efficacy of various bioactive ingredients. One approach is to use aerogels as a delivery system. Use of SCCO 2 for the preparation of aerogels offers the advantage of eliminating the use of organic solvents and being able to operate at relatively low temperatures to minimize the degradation of bioactives. This study demonstrates one potential application where polysaccharide aerogels are impregnated with flax lignans with the anticipation to increase bioavailability, which requires further testing. • Barley β-glucan and flax mucilage aerogels prepared using supercritical CO 2 drying • Flax mucilage aerogels had higher surface area and maintained higher % hydrogel volume. • Flax lignans were impregnated onto polysaccharide aerogels. • Polysaccharide gels dried using SCCO 2 show potential for bioactive delivery.

Effect of Concentration and Time Factors on Carbon Nanofiber Supported Iron Catalyst Preparation by Incipient Wetness

This paper discusses the influence of residence time and iron concentration factors on the impregnation yield for preparation of the carbon nanofiber supported iron material by incipient wetness impregnation. The samples were characterized by nitrogen physisorption, thermogravimetric analysis and electron spectroscopy techniques. The technique of effective impregnation was studied by atomic adsorption spectrophotometry. The results show that the morphology of the iron was distributed and well supported and the size of iron was in a wide range of 1μm to less than 2nm. The impregnation yield has been achieved 78% for 3 hours of residence time of 3%wt Fe/CNF sample with surface area of 102.292 m2/g.

Supercritical impregnation of cellulose acetate with thymol

Present work was aimed to investigate supercritical solvent impregnation of thymol into cellulose acetate in order to explore the possibility of developing a new functionalized solvent-free material with antimicrobial properties. Impregnation experiments were carried out with supercritical carbon dioxide at 10, 15 and 20MPa, and at 35 and 50°C. The time of impregnation was varied from 2 to 44h. Samples of impregnated cellulose acetate were tested against selected microorganisms. Thymol release kinetic studies were performed and obtained results were correlated.The impregnation yield varied from 4.51% to 72.26% depending on the operating conditions and impregnation time. Morphology of the samples changed significantly with the high impregnation yields, implying the impact of thymol on the cellulose acetate. The rate of impregnation was dependent on the impregnation conditions. Strong antimicrobial effect of impregnated samples against Escherichia coli, Staphylococcus aureus and Candida albicans strains with microbial reduction up to 99.9% was observed. Depending on the impregnation yield, samples of impregnated cellulose acetate have continuously released thymol in period from 2 to 21 days.

Isosorbide-based microcapsules for cosmeto-textiles

New microcapsules based on renewable materials and containing perfume were designed for cosmeto-textile application. Such microcapsules contained the neroline fragrance as core material and a bio-based polyurethane as wall material. The polymer wall was synthesized by interfacial polycondensation of isosorbide and methylene bis(phenyl isocyanate). The chemical structure of the microcapsules was confirmed by IR and 1H NMR spectroscopies. The encapsulation efficiency of perfume was determined using 1H NMR analysis technique accounts for 30%. Microcapsules of spherical shape and 27μm diameter consisted of a liquid core and a polymer wall, as revealed by means of small-angle light scattering measurements and scanning electron microscopy (SEM) observations. Neroline-loaded microcapsules were impregnated on polyamide textile substrate. The impregnation yield was about 80%. The presence of microencapsulated perfume and the durability of the impregnation effect were tested by SEM, UV–visible spectroscopy and gas chromatography. The polyamide knitting finished with microcapsules slowly released its microcapsule content and the neroline remained until twentieth washing cycles.

Physico-chemical characterization of Tunisian plant fibers and its utilization as reinforcement for plaster based composites

Alfa leaves, rush stems, palm leaflets and date palm wood are important renewable raw materials available in Tunisia where they are commonly used in handcrafts (like basketwork and carpets for example). To add value to these plants by using them as a potential reinforcement in so called natural fiber composites a better understanding of their physico-chemical properties is needed. As an application, we have studied the possibility of using alfa leaves, rush stems, palm leaflets as reinforcement in building materials trying to replace commercial fibers. Thus, the effect of hygroscopic parameters were studied and showed different behaviors depending on the raw material origin and morphology. Palm tree stipe is more sensitive than other fibers concerning the impregnation yield and saturation degree. The chemical composition was established. The contents of holocellulose and lignin were comparable to those found with fibers and wood (softwood and hardwood). Extractives in different solvents and ash contents are relatively high. Extractives from fibers are similar in their values and correspond also to those of palm tree stipe, but they are higher than those of hardwood. About ash contents, the same observation was found.Flexural strength of Tunisian fiber-plaster based composites show a maximum of resistance between 4.8 and 5.6MPa with a strengthening rate of 5% in comparison with commercial plant fiber that presents a bending strength of 4.8MPa for also a strengthening rate of 5%.

Determination of phenomena involved in impregnation of softwood chips. Part 2: Alkali uptake, alkali consumption and impregnation yield

Determination of phenomena involved in impregnation of softwood chips. Part 2: Alkali uptake, alkali consumption and impregnation yield

Supercritical CO 2 impregnation of lactulose on chitosan: A comparison between scaffolds and microspheres form

Nowadays, the application of green chemistry principles in the production of new polymeric materials is receiving an increasing attention. In the present work, we have investigated the impregnation of chitosan with lactulose using supercritical fluids under various operating conditions, in order to improve the solubility of this natural polymer at neutral or basic pH. A comparison between chitosan scaffolds and microspheres is also presented; both chitosans were characterized using scanning electron microscopy (SEM), mercury intrusion porosimetry (MIP) and Fourier transform infrared spectroscopy (FTIR). The degree of impregnation was evaluated by quantitative gas chromatography (GC-FID) analysis and interactions chitosan–lactulose by ninhydrin method. The supercritical carbon dioxide impregnation proved to be feasible for both chitosan forms. The highest impregnation yield (8.6%) was obtained for chitosan scaffolds using the following impregnation parameters: continuous process, 60 min contact time, 14% (v/v) of co-solvent ethanol:water (95:5), depressurization rate equal to 3.3 bar/min, 100 bar of pressure and 100 °C. Under these conditions, Maillard reaction also occurred.

Preparation of chitosan scaffolds loaded with dexamethasone for tissue engineering applications using supercritical fluid technology

Supercritical fluid impregnation was tested to prepare a new scaffold loaded with a bioactive compound. Dexamethasone is used in osteogenic media to direct the differentiation of stem cells towards the osteogenic lineage. Dexamethasone was impregnated in chitosan scaffolds at different operating conditions, in order to optimize the impregnation process. Pressure and temperature affect the carbon dioxide density and influence the swelling of the polymer and the drug solubility in the fluid phase, therefore these are two important parameters that were studied in this work. Chitosan sponges prepared by freeze drying were impregnated with the active compound at pressures from 8.0 up to 14.0 MPa and temperatures from 35 up to 55 °C. The effect of the impregnation contact time (3 h and 6 h) was also evaluated. From the experiments performed we can conclude that the yield of impregnation is lower when increasing pressure and temperature. The contact time will mainly influence the amount of drug impregnated in the scaffold and for higher contact times the impregnation yield is also higher. Scanning electron microscopy shows particles of dexamethasone in the bulk of the scaffold, which confirms the feasibility of the supercritical fluid impregnation technology for the preparation of delivery devices. The loading capacity of the scaffolds was determined by spectroscopic analysis and the highest loading was achieved for the experiments performed at 8.0 MPa and 35 °C. Furthermore, in vitro drug release studies were carried out and the results show that dexamethasone was sustainably released. Supercritical fluid impregnation proved to be feasible for the preparation of a drug delivery system for bone tissue engineering purposes.

Improvement of wood properties by impregnation with multifunctional monomers

AbstractSouthern pine samples with different dimensions and bulk densities were impregnated with the multifunctional monomer ethyl α‐hydroxymethylacrylate (EHMA) and 5 mol % of fluorinated or nonfluorinated crosslinking agent. The maximum impregnation yield (105% by weight) was achieved under vacuum with good improvement of water repellency.Impregnation with EHMA plus another multifunctional monomer 2‐vinyl‐4,4‐dimethyl‐2‐oxazolin‐5‐one (vinyl azlactone) was carried out to improve the mechanical properties of wood samples. Water repellency was also improved depending on the amount of vinyl azlactone in the monomer solution. A maximum of 41% antiswell efficiency (ASE) was obtained by impregnation with a 9 : 1 w/w mixture of EHMA and vinyl azlactone. Improvements of 38–54% in impact strength and 27–44% in compression modulus were achieved depending on the relative amount of vinyl azlactone incorporated. FT‐IR and solution or solid‐state NMR spectroscopy were used for chemical characterization of the polymers themselves and the wood‐polymer composites.