The influence of the structural parameters of polycarboxylate superplasticizer on the dispersion and adsorption

Polycarboxylate superplasticizers with different structural parameters were synthesized by isobutylene polyoxyethylene ether, acrylic acid and ammonium persulfate as raw materials from the perspective of molecular design. The influence of polycarboxylate superplasticizer on cement adsorption was characterized by cement adsorption capacity test and fluidity test, etc. At the same time, the adsorption change of polycarboxylate superplasticizer on the surface of cement particles was also revealed. It was found that the best adsorption and dispersion properties on cement paste were obtained under the heating synthesis process when the structure of the water reducing agent was designed to have a weight average molecular weight of 55128, a macromonomer conversion rate of 84.61%, and a side chain density of 0.1725. For the normal temperature process, when the weight average molecular weight was 103920, the macromonomer conversion rate 92.03%, and the side chain density 0.3115, the best effects in cement can be achieved.

Study on Spectro-Electrochemical Behaviour of Thin-Layer Polymer of 3-(9H-Carbazol-9-yl)propanenitrile

A film of electrically active poly(3-(9H-carbazol-9-yl)propanenitrile) was prepared on platinum (Pt) electrode surface by oxidative electro-polymerization of 3-(9H-carbazol-9-yl)propanenitrile monomer. The polymerization reaction was performed in a reaction medium containing monomer, and 0.1 M tetrabutylammonium tetrafluoroborate (TBABF4 ) mixture in acetonitrile (ACN) using repeated cycling at a scanning rate of 250 mV. Electrochemical polymerization of carbazole (Cz) and 3-(9H-carbazol-9-yl)propanenitrile (25 mM) were studied with cyclic voltammetry on both Pt and ITO electrodes. The structure of the poly(3-(9H-carbazol-9-yl)propanenitrile) was elucidated by nuclear magnetic resonance (1H and 13C NMR) and Fourier transform infrared (FTIR) spectroscopy. The weight average molecular weight (Mw) of the electrochemically synthesized poly(3-(9H-carbazol-9-yl)propanenitrile) was determined using gel permeation chromatography (GPC), where it was found that the Mw of the polymer is equal to 37900 g/mol. The polymer was characterized using dry conductivity measurement, scanning electron microscopy (SEM) and UV-Vis spectroscopy, while the spectro-electrochemical studies indicated that poly(3-(9H-carbazol-9-yl)propanenitrile) films revealed a green color in the oxidized state and a high transmittance in the neutral state. Moreover the poly(3-(9H-carbazol-9-yl)propanenitrile) film is soluble in common organic solvents, like DMSO, THF, NMP and DMAC. The conductivity of poly(3-(9H-carbazol-9-yl)propanenitrile) was found to be 1.62x10-4 S/cm.

In Vitro Starch Digestibility, Rheological, and Physicochemical Properties of Water Caltrop Starch Modified with Cycled Heat-Moisture Treatment

This study focused on the effect of cycled heat-moisture treatment (cHMT) on the in vitro digestibility, rheological, and physicochemical properties of water caltrop starch. The amylose content increased significantly by cHMT, whereas damaged starch content decreased only in the groups with more than two cycles applications. cHMT generally increased the weight-average molecular weight, except for single cycle treatment which showed the reverse result. In thermal properties, the onset temperature (T0), peak temperature (Tp), and conclusion temperature (Tc) increased, while the enthalpy needed to complete the gelatinization was lowered by cHMT. Water caltrop starch paste showed less shear-thinning behavior with cHMT. Meanwhile, the viscosity and tendency to form strong gel were enfeebled with modification. cHMT significantly changed predicted glycemic index (pGI) value, especially in samples that underwent the most cycles of treatment, which showed the lowest pGI compared to native and other treatment. These results suggested that cHMT water caltrop starch was effectively modified and showed diversified properties.

Understanding thermal and rheological behaviors of bimodal polymethyl methacrylate (BPMMA) fabricated via solution blending

In this work, a series of bimodal polymethyl methacrylate (BPMMA) was fabricated via solution-blending two neat PMMA resins. Rheology, DMTA, thermal infrared imager measurements were used in an attempt to probe the internal structure of the as-prepared BPMMA. It was demonstrated that the thermorheological behavior of the BPMMA was heavily dependent on shear rate, temperature as well as blending ratio. In addition, a typical “V-shaped” response, namely, a dip in storage modulus (G′) followed by an upturn in the plot of G′ versus measuring temperature for D4 (with lower weight-average molecular weight) was observed, characteristic of occurrence of thermorheological complexity. Our experimental results of physical–mechanical testings suggested that the BPMMA had better comprehensive properties than those of their neat PMMA counterparts.

A Preliminary Study on the Synthesis of poly(vinylbenzyl chloride) with Different Solvents

Polyvinyl benzyl chloride (PVBC) was synthesized by free radical polymerization of 4-vinylbenzyl chloride using benzoyl peroxide initiator at 60 °C. PVBC was synthesised in different solvents such as toluene, xylene, 1,4-dioxane, and tetrahydrofuran. The polymers were structurally characterized by 1H NMR and FTIR spectroscopic techniques. The thermal property of the polymer was investigated by thermogravimetric analysis (TGA) and differential thermogravimetric analysis (DTA).The number average molecular weight, weight average molecular weight and polydispersity index of PVBC synthesised in different solvents were determined and compared by gel permeation chromatography technique.

Biosynthesized Poly(3-Hydroxybutyrate) on Coated Pineapple Leaf Fiber Papers for Biodegradable Packaging Application

This paper is aimed at investigating the usage of biosynthesized poly(3-hydroxybutyrate) (P(3-HB)) for a coating on pineapple leaf fiber paper (PLFP). For this purpose, (P(3-HB)) was produced by Rhodococcus pyridinivorans BSRT1-1, a highly potential P(3-HB) producing bacterium, with a weight-average molecular weight (Mw) of 6.07 × 10 −5 g/mol. This biosynthesized P(3-HB) at 7.5% (w/v) was then coated on PLFP through the dip-coating technique with chloroform used as a solvent. The respective coated PLFP showed that P(3-HB) could be well coated all over on the PLFP surface as confirmed by scanning electron microscopy (SEM) and Fourier transform infrared (FTIR) spectroscopy. The brightness and mechanical properties of PLFP could be improved by coating with biosynthesized P(3-HB) in comparison to commercially available P(3-HB) and non-coated PLFP. Furthermore, coating of P(3-HB) significantly increased the water drop penetration time on the surface of PLFP and was similar to that of the commercial P(3-HB) with the same content. The results showed that all the coated PLPF samples can be degraded under the soil burial test conditions. We have demonstrated that the P(3-HB) coated PLFP paper has the ability to prevent water drop penetration and could undergo biodegradation. Taken together, the P(3-HB) coated PLFP can be applied as a promising biodegradable paper packaging.

Fabrication of Magnetic Catalyst Fe3O4-SiO2-V3 and Its Application on Lignin Extraction from Corncob in Deep Eutectic Solvent

Fe3O4-SiO2-V3 was prepared by deposited H6PMo9V3O40 on Fe3O4-SiO2 and employed as a catalyst to extract lignin from corncob in deep eutectic solvent (choline chloride/lactic acid = 1/10). Batch experiments were conducted in an autoclave under the conditions of 500 kPa, 90–130 °C and 15 h, while the dosage of the catalyst was set as a variable. Results indicated that the catalyst could effectively improve the qualities of the lignin, while the characteristics of the lignin showed prominent changes with the participation of the catalyst: the extraction rate increased from 71.65% to 98.13%, the purity was improved from 85.62% to 97.09%, and both the number average molecular weight and the weight average molecular weight also decreased significantly. Besides, the molecular distribution of the lignin achieved from the CC-LA-Fe-Si-V3 reaction system was found to be more highly concentrated (Polydispersity index = 1.746). Results from 2D NMR HSQC analysis indicated that lignin fractions achieved from the CC-LA-Fe-Si-V3 system showed distinct destruction involving C2-H2 in guaiacyl units (G), C5-H5 in guaiacyl units (G), and the Cγ-Hγ in γ-hydroxylated β-O-4′ substructures, but little changes in the Cγ-Hγ in phenylcoumaran substructures.

A novel dextrin produced by the enzymatic reaction of 6-α-glucosyltransferase I: The effect of non-reducing ends of glucose with by α-1,6 bonds on the retrogradation inhibition of high molecular weight dextrin

We prepared a high-molecular-weight modified dextrin (MWS-1000) from a partial hydrolysate of waxy corn starch with a weight average molecular weight of 1 × 106 (WS-1000) using Paenibacillus alginolyticus PP710 α-glucosyltransferase. The gel permeation chromatography showed that the weight average molecular weight of MWS-1000 was almost the same as that of WS-1000. The side chain length of WS-1000 and MWS-1000 after isomaltodextranase digestion were also shown to be similar to each other by high performance anion exchange chromatography with pulsed amperometric detection. Since MWS-1000 confirmed the presence of α-1,6 bonds by enzyme digestibility, methylation, and 1H-NMR analyses, it was presumed that the structure of MWS-1000 was based on the introduction of α-1,6 glucosyl residues at the non-reducing ends of the partial hydrolysate of waxy corn starch. Furthermore, the MWS-1000 solution was not retrograded even during refrigerated storage or after repeated freeze-thaw cycles.

Structure, mechanical properties and degradation behavior of electrospun PEEU fiber meshes and films

The capability of a degradable implant to provide mechanical support depends on its degradation behavior. Hydrolytic degradation was studied for a polyesteretherurethane (PEEU70), which consists of poly(p-dioxanone) (PPDO) and poly(ε-caprolactone) (PCL) segments with a weight ratio of 70:30 linked by diurethane junction units. PEEU70 samples prepared in the form of meshes with average fiber diameters of 1.5 µm (mesh1.5) and 1.2 µm (mesh1.2), and films were sterilized and incubated in PBS at 37 °C with 5 vol% CO2 supply for 1 to 6 weeks. Degradation features, such as cracks or wrinkles, became apparent from week 4 for all samples. Mass loss was found to be 11 wt%, 6 wt%, and 4 wt% for mesh1.2, mesh1.5, and films at week 6. The elongation at break decreased to under 20% in two weeks for mesh1.2. In case of the other two samples, this level of degradation was achieved after 4 weeks. The weight average molecular weight of both PEEU70 mesh and film samples decreased to below 30 kg/mol when elongation at break dropped below 20%. The time period of sustained mechanical stability of PEEU70-based meshes depends on the fiber diameter and molecular weight. Graphic abstract

Differences between two sodium hyaluronate-based submucosal injection materials currently used in Japan based on viscosity analysis

In Japan, two 0.4% sodium hyaluronate (HA)-based submucosal injection materials (SIMs) are currently used in endoscopic submucosal dissection (ESD): MucoUp (HA-Mc) and Ksmart (HA-Ks). HA-Mc and HA-Ks have the same concentration and are, thus, construed by most endoscopists to have no difference. Nevertheless, visual observation conveys the impression that HA-Ks have a higher viscosity than HA-Mc, suggesting that HA-Ks performs better than HA-Mc. This study aimed to examine the differences between HA-Mc and HA-Ks. HA-Ks exhibited higher viscosity due to greater weight-average molecular weight compared with HA-Mc. HA-Ks had significantly greater submucosal elevation height (SEH) than HA-Mc; the SEH of HA-Ks-80% (80% dilution of HA-Ks) was the same as that of HA-Mc. The ESD procedure time was significantly shorter with HA-Ks than with HA-Mc (15.2 ± 4.1 vs. 19.5 ± 5.9; P = 0.049). The total injection volume for HA-Ks was significantly lower than that for HA-Mc (10.8 ± 3.6 vs. 14.4 ± 4.6; P = 0.045). However, no significant difference in these items was observed between HA-Mc and HA-Ks-80%. HA-Mc and HA-Ks were considered to be almost the same. Nonetheless, HA-Ks exhibited higher viscosity and SIM performance than HA-Mc. HA-Ks-80% had almost the same performance as HA-Mc. Thus, understanding SIM performance and characteristics requires a focus on the viscosity of SIMs.