Journal of Renewable Materials

The Influence of Poly(vinyl alcohol) on Oil Release Behavior of Polylactide-based Composites Filled with Linseed Cake

Olga Mysiukiewicz — 2020-05-21

In order to limit the negative impact of industry on natural environment, ecological alternatives to conventional polymers are being proposed. One of the most popular “green” polymers is polylactide, which can also be successfully applied as a matrix of composites. The application of ground linseed cake as a filler for polylactide-based composites is in line with the idea of Circular Economy, and moreover it provides a modifying effect on the polymer by increasing its crystallinity and reducing its brittleness. This effect is caused by the presence of linseed oil which can be released to the polymeric matrix in a non-controlled way. In order to control the miscibility of the oil and the polymer, we modified the filler particles with poly(vinyl alcohol) before introducing it to the polylactide. We concluded that polyvinyl(alcohol), which does not mix with oil, encapsulated the active ingredients inside the filler particles. We evaluated the mechanical properties of the composites containing 5, 10, 20 and 30 wt% of the filler in a static tensile stress and by means of dynamic mechanical thermal analysis. Crystallinity and thermal properties were tested using differential scanning calorimetry as well as thermogravimetric analysis. Horizontal burning and water absorption were also evaluated. It was found that modifying the oil-rich filler with poly(vinyl alcohol) helps to reduce its release to the matrix and thus limits the plasticizing effect of linseed cake. This result was in accordance with our hypothesis.

Physicochemical Characterization And Antimicrobial Properties Of Inulin Acetate Obtained By Microwave-Assisted Synthesis

Nadezhda Traycheva Petkova — 2020-05-21

Microwave-assisted irradiation was performed for esterification of chicory inulin with a high degree of polymerization with acetic anhydride without a solvent only with catalyst. The resulting esters were characterized by melting point, hydrophilic-lipophilic balance, thin-layer chromatography, ultraviolet spectroscopy, Fourier transform infrared spectroscopy (FTIR) and nuclear magnetic resonance (NMR) spectroscopy. Inulin acetate demonstrated a high degree of acetylation (2.5-3.0) and presented a white, water-insoluble substance with bitter taste. The FTIR and NMR spectra confirmed esterification and demonstrated the incorporation of hydrophobic residue to the water soluble inulin backbone. Swelling capacity, water holding, oil-holding capacities, the foamability, foam stability and emulsifying properties were also evaluated. Inulin acetate showed promising foam stability 52% for 60 min and formed stable emulsions at concentration 0.2 g/L with 50 and 80% oil phases. Its water holding capacity was lower than the oil holding capacity. In addition for the first time, the antimicrobial potential of inulin acetate was tested against seventeen microorganisms (Gram-positive and Gram-negative bacteria, yeasts and fungi). Inulin acetate (10 mg/ml) inhibited the growth of Bacillus cereus, Escherichia coli ATCC 8739, Salmonella abony, Candida albicans and Penicillium sp. However, inulin acetate demonstrated antimicrobial activity at concentration 1 mg/ml against Listeria monocytogenes 863, Escherichia coli 3398, Candida albicans 8673, Fusarium oxysporum and Aspergillus niger. The current study demonstrated the applications of “green” synthesized inulin acetate as a foaming agent, oil-in-water emulsion stabilizer and antimicrobial substance in pharmaceutical, agricultural and cosmetic preparations.

Composite Biomaterials Based on Poly(L-Lactic Acid) and Functionalized Cellulose Nanocrystals

Mariia Stepanova — 2020-05-21

The biocomposite films were prepared from poly(L-lactic acid) and cellulose nanocrystals. To improve interfacial compatibility of hydrophilic cellulose nanocrystals with hydrophobic matrix polymer as well as to provide the osteoconductive properties, cellulose was functionalized with poly(glutamic acid). The modified cellulose nanocrystals were better distributed and less aggregated within the matrix, which was testified by scanning electron, optical and polarized light microscopy. Biocomposites containing modified cellulose surpassed those with neat cellulose in mechanical properties, mineralization ability and biocompatibility in vivo.

Synthesis and Properties of Thermoplastic Polyisocyanurates: Polyisocyanuratoamide, Polyisocyanurato(ester-amide) and Polyisocyanurato(urea-ester)

Rui Hou — 2020-05-21

It has been proved that introducing isocyanurate into polymer chains could improve the flame retardancy of polymers. We describe in this work the synthesis and the thermal property study of three thermoplastic polyisocyanurates, which are polyisocyanuratoamide (PICA-6), polyisocyanurato(ester amide) (PICEA-6) and polyisocyanurato(urea ester) (PICUE-6). These polymers show similar and improved thermal stability and the existence of the isocyanurate rings. PICA-6 is more crystalizable than the rest two and the melting temperature is found to be around 248.4 °C but it still crystalizes slowly. For PICEA-6 and PICUE-6, only glass transition can be observed on the DSC traces. The glass transition temperature follows the order of PICA-6 > PICEA-6 > PICUE-6 (110.6, 82.8 and 52.4 °C, respectively).

Preparation and Characterization of Dicarboxyl Cellulose Nanocrystals from Agricultural Waste by Sequential Periodate-chlorite Oxidation

Xiao-Zheng Sun — 2020-05-21

Agricultural waste straw is the renewable resource with the highest annual yield in the world. In value-added applications of agricultural waste, dicarboxyl cellulose nanocrystals (DCCs) are prepared from rice, wheat, and corn straw by sequential periodate-chlorite oxidation. In this study, DCCs from rice, wheat, and corn straw were characterized by transmission electron microscopy (TEM), Fourier transform infrared spectrometer, X-ray diffractometer (XRD), and thermal gravimetric analysis (TGA). The carboxyl content of the DCCs was also investigated. XRD results show that the crystallinity index decreased after sequential periodate-chlorite oxidation; however, the cellulose I structure was maintained. TEM results show that rod-shaped DCCs with an average length and width of 287.0 nm and 9.9 nm, respectively, were successfully prepared by sequential periodate-chlorite oxidation. The carboxyl content of the DCCs was around 3.9 mmol/g, and not affected by the type of straw. Experiments to study the removal of copper ions in aqueous medium were performed with the prepared DCCs. The adsorption capacities of copper ions were 131, 162, and 144 mg/g for DCCs prepared from rice, wheat, and corn straws, respectively. The results show that DCCs prepared from rice, wheat, and corn straws by sequential periodate-chlorite oxidation have potential for the removal of copper ions from aqueous medium.

Sunflower-like SrCo2S4@f-MWCNTs hybrid wrapped by engineering N-reduced graphene oxide for high performance dye-sensitized solar cells

Guang Li — 2020-05-21

A novel sunflower-like nanocomposite of SrCo₂S₄nanoflakes and functionalized multiwall carbon nanotubes(f-MWCNTs) entanglement wrapped in nitrogen-reduced graphene oxide(N-RGO) was prepared by a cheap, simple and efficient method.The new ternary cobalt sulfide can be used as a reliable and efficient alternative to the platinum counter electrode in dye-sensitized solar cell(DSSC). The unique entanglement structure of the material exhibits higher specific surface area, better electrical conductivity and other properties. This helps to reduce the transfer resistance in the photoelectric process of the battery and improve the electrochemical activity, thus improving the photoelectric conversion efficiency of the battery.DSSC assembled from SrCo₂S₄@f-MWCNTs@N-RGO as counter electrode material shows excellent photoelectric conversion efficiency(8.06%), even surpassing than that of the DSSC based on Pt as the counter electrode(7.51%).

One-Step Synthesis of Magnetic Zeolite from Zinc Slag and Circulating Fluidized Bed Fly Ash for Degradation of Dye Wastewater

Zhi Chao Han — 2020-05-21

In this study, a magnetic Na-P zeolite was directly synthesized by use of industrial solid wastes of zinc slag (ZS) and circulating fluidized bed fly ash (CFBFA) via one-step hydrothermal method, and then was employed as a Fenton-like catalyst for degradation of direct green B dye wastewater. The XRD and VSM results indicated that the magnetic Na-P zeolite possessed finely crystal structure and superparamagnetism, and took the advantage of rapid separation and efficient recovery under the action of external magnets when it was used as a Fenton-like catalyst in a solid-liquid reaction. The effects of the solution pH, the catalyst dosage, and the H₂O₂ concentration on the degradation rate of direct green B dye wastewater were evaluated systematically. The results showed that the highest degradation of 96.3% was achieved and the magnetic Na-P zeolite showed excellent stability after four cycles.

BIO-BASED ZWITTERIONIC SURFACTANTS DERIVED FROM DIFFERENT FATTY ACIDS IN NON-EDIBLE VEGETABLE OILS AND THEIR INTERFACIAL PROPERTIES

Hong-ze Gang — 2020-05-21

Waste cooking oils and non-edible vegetable oils are abundant and renewable resources for bio-based materials and have showed great potential applications in many industries. In this study, six fatty acids commonly found in non-edible vegetable oils, including palmitic acid, stearic acid, oleic acid, linoleic acid, linolenic acid, ricinoleic acid and their mixtures, were used to produce bio-based zwitterionic surfactants through a facile and high-yield chemical modification. These surfactants demonstrated excellent surface/interfacial properties with the minimum surface tensions ranging from 28.4 mN/m to 32.8 mN/m in aqueous solutions. The interfacial tensions between crude oil and water were remarkably reduced to low values ranging from 0.0028 mN/m to 0.1983 mN/m without the aid of extra alkali, which particularly implied a great potential application in enhanced oil recovery. Meanwhile, these bio-based surfactants also showed good wetting properties and appropriate predicted biodegradability, therefore, they are alternative substitutes for traditional petroleum-based surfactants in various surfactant application fields.