Sulfonated poly(arylene ether nitrile)-based composite membranes enhanced with Ca2+ bridged carbon nanotube-graphene oxide networks

As the core component of proton exchange membrane fuel cell, proton exchange membranes (PEM) have attracted much attention of researchers. To trade-off the proton conduction, dimensional stability and anti-oxidation ability, graphene oxide (GO) and acidized multi-walled carbon nanotubes (MWCNT) using calcium ion as coordination bridge (GO-Ca2+-MWCNT) was synthesized, and then incorporating into sulfonated poly(arylene ether nitrile) (SPEN) to fabricate SPEN/GO-Ca2+-MWCNT organic-inorganic composite membranes by solution-casting method and explore the influence of varying loading on performances as PEM. It was found that the proton conductivity of the composite membranes was higher than that of SPEN, while maintaining better dimensional stability, excellent anti-oxidation ability and good mechanical properties. All of these were attributed to the formation of three-dimensional structure between GO and MWCNT bridged by Ca2+. Particularly, the SPEN/GO-Ca2+-MWCNT-1 composite membrane exhibited excellent tensile strength of 71.45 MPa, better thermal stability as well as high proton conductivity (0.054 S/cm at 30 ℃, and 0.193 S/cm at 90 ℃), above 10-2 S/cm, satisfying the requirement of fuel cells. All in all, the results indicate that the filler with three-dimensional network structure can effectively improve the performances of SPEN, and the prepared composite membranes show potential applications in many fields.

Bioepoxy based hybrid composites from nano-fillers of chicken feather and lignocellulose Ceiba Pentandra

In this work, fillers of waste chicken feather and abundantly available lignocellulose Ceiba Pentandra bark fibers were used as reinforcement with Biopoxy matrix to produce the sustainable composites. The aim of this work was to evaluate the mechanical, thermal, dimensional stability, and morphological performance of waste chicken feather fiber/Ceiba Pentandra bark fiber filler as potential reinforcement in carbon fabric-layered bioepoxy hybrid composites intended for engineering applications. These composites were prepared by a simple, low cost and user-friendly fabrication methods. The mechanical (tensile, flexural, impact, hardness), dimensional stability, thermal stability, and morphological properties of composites were characterized. The Ceiba Pentandra bark fiber filler-reinforced carbon fabric-layered bioepoxy hybrid composites display better mechanical performance compared to chicken feather fiber/Ceiba Pentandra bark fiber reinforced carbon fabrics layered bioepoxy hybrid composites. The Scanning electron micrographs indicated that the composites exhibited good adhesion at the interface of the reinforcement material and matrix system. The thermogravimetric studies revealed that the composites possess multiple degradation steps, however, they are stable up to 300 °C. The thermos-mechanical studies showed good dimensional stability of the composites. Both studied composites display better thermal and mechanical performance compared to neat bioepoxy or non-bioepoxy thermosets and are suitable for semi-structural applications.

A Promising Potential of Brown Algae Sargassum polycystum as Irreversible Hydrocolloid Impression Material

This study aimed to investigate the potential use of brown algae Sargassum polycystum as irreversible hydrocolloid (alginate) impression material. Potassium alginate extracted from Sargassum polycystum was prepared in three different compositions (14%, 15%, and 16%) and mixed with other standard components to form an alginate impression material. Prior to that, the purity of potassium alginate was quantified with Fourier Transform Infrared Spectroscopy (FTIR) analysis. As a control material, the alginate impression material from a commercially available product was used. All alginate impression materials were then applied to a die stone model. Dimensional accuracy was measured by calculating the mesiodistal width of incisors in the generated dental cast using a digital caliper 0.01 accuracy (five replications). In addition, to evaluate the dimensional stability, the impression results were poured at four different periods (immediately, 5 min, 10 min, and 15 min). An independent t-test was performed to compare the measurement results with p < 0.05 considered significant. Analytical results confirm that the impression material containing 15% potassium alginate gives the best dimensional accuracy similar to control (p > 0.05). Meanwhile, the optimal dimensional stability was produced in the impression material containing 16% potassium alginate. Our study suggested that brown algae Sargassum polycystum has a promising potential to be used as an alginate impression material in clinical application.

Low density rigid polyurethane foam incorporated with renewable polyol as sustainable thermal insulation material

Palm olein-based polyol (PP) was used as a partial replacement for commercial sucrose/glycerine initiated polyether polyol (GP) for the production of low density rigid polyurethane foams (RPUFs). The hydroxyl value (OHV) of the GP was 380 mg KOH/g, whereas the OHV for PP was 360 mg KOH/g. The RPUFs were prepared by replacing the GP with PP up to 50 parts per hundred parts of polyols (pph). Characterisation of the RPUFs, including density, compressive strength and strain, cell morphology and thermal conductivity ( k-value), were conducted. The dimensional stability of the foams was also evaluated. The study showed improvement in the compressive strength and strain for palm-based RPUFs with the incorporation of up to 30 pph PP as compared to GP foams. The lowest k-value (0.0232 W/m.K) of RPUF with density below 30 kg/m3 was obtained with the incorporation of 10 pph PP. This was due to the smallest and uniform pore size distribution observed using SEM images. The dimensional stability of the RPUF prepared from PP was within the acceptable range. Thus, the RPUFs made from PP are potential candidates to be used as insulation for refrigerators, freezers and piping.

Bamboo as future bio-industrial material: Physical behaviour and bending strength of Malaysia’s Beting bamboo (Gigantochloa levis)

In this paper, bending strength and physical properties (specific gravity, dimensional stability and equilibrium moisture content) of a Malaysian bamboo locally known as Beting bamboo (Gigantochloa levis) are addressed. Characterizations of physical and bending strength of G. levis in terms of the variability of location along culm height (top, middle, bottom), culm section (nodes and internodes), fiber orientation (longitudinal, tangential and radial) and culm layer (outer and inner) were conducted. Comparison of these properties is also made to some bamboo and commercial timber species. It was found that G. levis has favorable physical and mechanical properties although the specific gravity of G. levis has tendency to be on the higher side. The characteristics studied were found to have some variability at different locations, sections, and directions. There was variability in terms of bending strength along with the culm height of bamboo. It is indicated from this study that the bending strength and physical properties of G. levis were found to be satisfactory.

Improving the stability of beech wood with polyester treatment based on malic acid

The improvement of durability and dimensional stability of wood properties via modification of the microstructure and wood–water interaction has been widely utilised. This study investigated polyester treatments, a possible alternative, using environmentally friendly chemicals such as malic acid to improve the beech wood (Fagus sylvatica) properties. The modified properties have been studied with four treatments using malic acid, glycerol, butanediol and succinic anhydride, mixing polycarboxylic acids and polyols. Results showed that the anti-swelling-efficiency (ASE) improved up to 70%, and the bulking coefficient improved around 23%, exhibiting an efficient penetration within the cell walls. The leaching rates (LR) of treatments and the extractables remained low, between 0.05 and 2.4%. The equilibrium moisture content (EMC) decreased by 50% for the four treatments, compared to untreated beech wood.

Study of form-stable features of transforming parts of youth kit

The article examines the quality indicators of adhesive materials that form the dimensional stability of the transformed parts, and substantiates the processing methods. As a result, the order of gluing the parts and the order of gluing the adhesive materials used in the manufacture of transformable sets were determined.