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The effects of substituting the B cation in A3BO7 ceramics on their thermal physical properties were investigated by applying a large mass difference. Y3(Nb1‐xTax)O7 (x = 0, 0.1, 0.2, 0.3, 0.4, and 0.5) ceramics were synthesized, and their structural characteristics were determined. All the fabricated Y3(Nb1‐xTax)O7 ceramics showed defective fluorite structures and glass‐like low thermal conductivity (1.18−2.04 W/m∙K at 25°C) because of the highly distorted crystal structure and significant mass difference. Substitution with Ta5+ enhanced the sintering resistance, leading to superior thermal‐insulating performance via grain boundary scattering. Furthermore, the ceramics exhibited excellent coefficients of thermal expansion, implying the promising applicability of Y3(Nb1‐xTax)O7 as new thermal barrier materials. The effect of mass difference on the thermomechanical properties of the ceramics was examined, suggesting a simple strategy for engineering the chemical composition of new thermal barrier materials. [ABSTRACT FROM AUTHOR]

A new type of poly(ether‐amide) thermoplastic elastomer (TPAE) was synthesized using poly(decamethylene terephthalamide (10T)/decamethylene isophthalamide) as hard segment and poly(ethylene glycol) as soft segment via an efficient, accessible and low‐pollution melt polymerization method. Thermoplastic elastomer was synthesized based on semi‐aromatic polyamide for the first time. The effects of various compositions of hard segments on the thermal and mechanical properties were investigated. The results show that TPAE synthesized from semi‐aromatic polyamide has excellent thermal stability, the initial decomposition temperature of all samples being between 370 and 378 °C. With an increase of 10T content, crystallization ability of the hard segment increased. As 10T content increased, TPAE changed from amorphous to crystalline, and the melting temperature ranged from 175 to 236 °C. Tensile testing revealed that TPAE had excellent and adjustable mechanical properties, and that tensile strength, elongation at break and elasticity modulus were in the ranges 7–40 MPa, 468–835% and 0.036–1.80 MPa. Furthermore, high‐temperature tensile test results showed that TPAE‐4 still maintained considerable mechanical properties, and had better mechanical properties compared with Pebax® 5533. In particular, TPAE‐4 had higher performance decay point for which elasticity modulus and stress at ε = 500% decreased rapidly when the temperature was higher than 80 °C, this point for Pebax® 5533 appearing at 50 °C. Such outstanding performance indicated that this new class of elastomer has the potential to be used in high‐temperature conditions. © 2020 Society of Industrial Chemistry [ABSTRACT FROM AUTHOR]

The last decade has witnessed multiple thermally responsive materials emerge as a significant class of stimuli‐responsive materials. These materials are elaborately designed and exert interesting properties. Herein, an overview of thermally responsive materials with respect to design strategies, fabrication procedures, and their applications is presented. Recently reported thermally responsive materials are highlighted. Then, applications of thermally responsive materials in bioimaging are summarized. Hot response: Recently reported thermally responsive materials are highlighted and the applications of thermally responsive materials in bioimaging are summarized. [ABSTRACT FROM AUTHOR]

ABSTRACT: Two novel fluorene functionalized polyacetylenes with different conjugation bridge architectures (stilbene and azobenzene), poly[2‐[4‐vinyl‐4′‐(N‐methyl, N‐ethyl‐yl propargyloxy) phenyl azo]‐9,9‐dioctylfluorene] (PC1), poly[2‐[4‐vinyl‐4′‐(N‐methyl, N‐ethyl‐yl propargyl group) stilbene ethenyl]‐9,9‐dioctylfluorene] (PC2), were designed and prepared through using [Rh(nbd)Cl]2‐Et3N as the catalysts, respectively. These polymers are soluble in common organic solvents, such as toluene, chloroform, 1,2‐dichloromethane, and tetrahydrofuran, which their structures and properties were systematically characterized by means of Fourier transform infrared spectroscopy, nuclear magnetic resonance, elemental analyses, UV–vis, photoluminescence, thermogravimetric analysis, gel permeation chromatography, and Z‐scan technique. The optical limiting properties were investigated at 780 nm with 450 fs laser pulses. Remarkably, it is expected that, by incorporation of fluorene into functional polyacetylene has endowed the resultant polymers with well optical limiting properties and thermal stability. Additionally, the nonlinear optical properties of functionalized polyacetylenes were significantly affected by different molecular structure of conjugated bridge of substituted group. The polyacetylenes with azobenzene (PC2) conjugated bridge displaying well two‐photon absorption cross‐sections of 3950 cm/GM (2010 cm/GM for PC1 containing stilbene), owning to stronger π‐conjugated chromophores of objective polymer and intramolecular charge transfer effect. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46100. [ABSTRACT FROM AUTHOR]

ABSTRACT One of disadvantages of polymer composites is poor electrical and thermal conductivity. As a first step in this direction, graphene-modified polypropylene polymer is being developed to improve its electrical and thermal conductivity. Two techniques were investigated: surface coating and extrusion. In the case of coating technique, the percolation threshold was found to be 0.5 wt % of graphene and electrical conductivity of polypropylene increased around 13 log cycles. Coating technique breaks the agglomerations due to magnetic stirring followed by sonication and gives homogeneous graphene-coated polypropylene pellets. When polymer melts under compression molding, the graphene platelets network formed on the surface of polypropylene pellets as well as through-the-thickness of the molded disk, which provide continuous network of graphene. However, in extrusion technique, graphene segregated and did not disperse properly in polypropylene. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 45833. [ABSTRACT FROM AUTHOR]

Biodegradable polymer blends prepared by blending poly(3-hydroxybutyrate) (PHB) and corn starch do not form intact films due to their incompatibility and brittle behavior. For improving their compatibility and flexibility, poly(vinyl acetate) (PVAc) was grafted from the corn starch to prepare the PVAc-modified corn starch (CSV). The resulting CSV consisted of 47.2 wt% starch- g-PVAc copolymer and 52.8 wt% PVAc homopolymer and its structure was verified by FT-IR analysis. In comparison with 35°C of the neat PVAc, the glass transition temperature ( Tg) of the grafted PVAc chains on starch- g-PVAc was higher at 44°C because of the hindered molecular mobility imposed from starch on the grafted PVAc. After blending PHB with the CSV, structure and thermal properties of the blends were investigated. Only a single Tg was found for all the PHB/CSV blends and increased with increasing the CSV content. The Tg-composition dependence of the PHB/CSV blends was well-fitted with the Gordon-Taylor equation, indicating that the CSV was compatible with the PHB. In addition, the presence of the CSV could raise the thermal stability of the PHB component. It was also found that the presence of the PHB and PVAc components would not hinder the enzymatic degradation of the corn starch by α-amylase. POLYM. ENG. SCI., 55:1321-1329, 2015. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]

New oleogel formulations based on high-oleic sunflower oil (HOSO) and ethylene vinyl acetate copolymer (EVA)/polypropylene (PP) blends were prepared using the mixing rheometry technique and further characterized. The effects of PP tacticity and EVA vinyl acetate (VAc) content on the rheological, morphological, and thermal behavior of derived oleogels were investigated. Differential scanning calorimetry (DSC) and polarized-light optical microscopy (PLOM) observations indicated that VAc segments markedly influence the crystalline structure of polymeric fractions and phase morphology of oleogels. The normalized crystallinity of isotactic polypropylene (iPP) phase increased linearly with its concentration whereas syndiotactic polypropylene (sPP) content does not exert a significant influence. PLOM observations showed that VAc content plays an important role in the phase morphology of PP frictions (size and shape of crystals). The viscoelastic response of oleogels depended on PP tacticity and VAc content, which may be explained attending to the different microstructures attained. POLYM. ENG. SCI., 55:1429-1440, 2015. © 2015 Society of Plastics Engineers [ABSTRACT FROM AUTHOR]