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Cesium tungsten bronze (CsxWO3)-doped PEG/sweet potato form-stable composites are fabricated through a facile two-step method of lyophilization and vacuum impregnation. Abundant starch microsphere enhances the PEG loading capacity above 72 % and also supplies capillary force as well as hydrogen bonding to improve the form-stability of the composites. Here, the latent heat, relative crystallinity (Xc), and light-thermal conversion efficiency of the system with 0.99 wt% CsxWO3 reach to 137.7 J/g, 97.7 %, and 83.5 %, respectively. The light-thermal conversion efficiency increases from 64.3 % to 91.1 % with 2.00 wt% CsxWO3. Besides, the composites exhibit improved thermal stability and excellent thermal reliability. The prepared bio-based composites with low-cost have broad application prospects in the field of energy storage. [ABSTRACT FROM AUTHOR]

The morphology and helium-barrier properties of thermoplastic polyurethane (TPU)/ethylene-vinyl alcohol (EVOH) blends with and without dicumyl peroxide (DCP) were investigated by melting blending. A lamellar dispersion of EVOH with good helium-barrier properties was observed in the TPU matrix with DCP. The evolution of the morphology of the blends is mainly related to the variation of the viscosity ratio between the dispersed phase and the matrix phase. Compared with pure TPU, lamellar morphology increased the helium-barrier properties of the TPU/EVOH (60/40) blend by as much as 10-fold. We also explored the effects of composition, DCP content, and blending sequence on the morphology and helium-barrier properties of the TPU/EVOH blends. The morphology of the blends ranged from a droplet-matrix to a lamellar structure. We determined the optimum amount of DCP to improve the helium barrier of the blends. The helium-barrier properties of the blends prepared by direct blending were superior to those of the blends prepared by two-segment blending, and the blends prepared by direct blending exhibited a well-developed lamellar morphology. We compared the permeability of the samples with the theoretical results to explain the relationship between morphology and helium-barrier properties., INTRODUCTION Thermoplastic polyurethane (TPU) exhibits numerous excellent properties as a polymer material, including good low-temperature flexibility and excellent resistance to abrasion, damping, chemical solvents, and impact. TPU is therefore used [...]

A series of linear polyurethane (PU) elastomers containing various amounts (ca. 2-10 wt%) of a diolfunctionalized polyhedral oligomeric silsesquioxane (diolPOSS) were synthesized from organic solvent dispersions. Fourier transform infrared spectroscopy was used to characterize the chemical structure of the diolPOSS-reinforced PU. Transmission electron microscopy (TEM) indicated that the diolPOSS aggregation was formed in the polymer matrix at the scale of 20-50 nm. The introduction of diolPOSS into such system led to high glass transition temperature, enhanced storage modulus, and improved stability compared with the pristine PU according to the differential scanning calorimetry, dynamic mechanical analysis, and thermal gravimetric analysis, respectively. Moreover, contact angle measurements indicated a significant enhancement in surface hydrophobicity as well as a reduction in surface free energy after introducing diolPOSS into the synthesized PU. The improvement of surface properties could be ascribed to the enrichment of the diolPOSS moiety on the surface of the hybrids. POLYM. ENG. SCI., 51:795-803, 2011. [C] 2011 Society of Plastics Engineers, INTRODUCTION In recent years, organic-inorganic hybrid composites have undergone a significant evolution because of the outstanding properties of these materials compared with pristine polymers [1]. Polyhedral oligomeric silsesquioxane (POSS)-based polymers [...]

We developed a polyurethane material has an excellent self-healing ability as well as mechanical strength. This system was achieved based on dual-crosslinked Diels-Alder (DA) covalent bonding reaction. The first cross-linking point is realized by the DA bonding of polyurethane chain. Because of grafted maleimide group, the maleimide functionalized GO (mGO) sheets can be regarded as analogous cross-linker and provide the second cross-linking point in the system. We investigated and compared the effects of as-produced GO and mGO loading and maleimide functionalization on the mechanical properties and healing efficiency of composites. As a result, compared with those of the pure polyurethane and composites filled with the GO, such maleimide functionalization is found to effectively improve the compatibility between mGO and polymer matrix, increasing mechanical properties and healing efficiency of polyurethane composites. The mechanical properties and healing efficiency of polyurethane can be tuned readily by varying mGO concentration. The healing efficiencies were up to 99% for the nanocomposite containing mGO. These results confirm maleimide functionalization improved dispersion and interfacial interaction between the fillers and the polyurethane matrix. [ABSTRACT FROM AUTHOR]

There is a contradiction in making completely opaque and white plastic film with a required high TiO2 filling fraction, which resulted in inefficient pigment utilization and high cost. Two methods were used here to overcome the contradiction. Firstly, TiO2 was grafted with poly(methyl methacrylate) (PMMA) by atom transfer radical polymerization to improve the pigment dispersion in poly(vinylidene) fluoride (PVDF). Secondly, minute amounts of carbon black (CB) were added into the PMMA-g-TiO2/PVDF system to enhance opacity and decrease TiO2 fraction. The structure, morphology, and properties of PMMA-g-TiO2 hybrid particles and composite films were investigated by FTIR, TEM, TGA, SEM, DMA, covering power meter, and UV/VIS spectrophotometer, etc. It was observed that PMMA-g-TiO2 was dispersed uniformly as individual particles in PVDF due to the good compatibility between PMMA and PVDF. Therefore, the opacity of PMMA-g-TiO2/PVDF films was markedly higher than unmodified-TiO2/PVDF ones. Adding minute amounts of CB can significantly increase the opacity of the thin film due to its absorption effect on decreasing light transmittance. The contrast ratio (CR) of the PMMA-g-TiO2/PVDF film with 20 lm thickness and 25 vol % TiO2 was 97.67%, lower than the critical CR 98% for a complete opacity, however, the CR of sample with 10 vol % TiO2 was 98.1% as the CB concentration was 2 3 10-4 g/cm³, saved more than 15% TiO2. We proposed that a critical thickness d0 existed for the CB/PMMA-g-TiO2/PVDF composite films, under which the light reflectance increased as a function of thickness, otherwise, the reflectance kept constant. Besides, d0 could be decreased by increasing CB concentration. [ABSTRACT FROM AUTHOR]

Polyurethane elastomers (PUEs) based on 4,4′-diphenylmethane diisocyanate (MDI), 1,4-butanediol (BDO) and two kinds of aliphatic polycaprolactone (PCL) diols with molecular weight of 1000 Da and 2000 Da have been synthesized and melt-blended with polycarbonate (PC). The compatibility of PC and PUEs was investigated by differential scanning calorimetry (DSC), dynamic mechanical analysis (DMA) and scanning electron microscopy (SEM). The results indicated that the glass transition temperature ( T g) of PC decreased by 0-40°C when 0-10 wt % of PUEs incorporated into the PC matrix. Phase separation in the blends was not detected by means of DSC characterization, but measurements of DMA and SEM indicated that phase separation existed in the blends of PC and PUEs synthesized with 1000 Da PCL-diol. As for PUEs/PC blend in which 2000 Da PCL-diol as PUEs' soft segments, it turned from completely compatible to partially when the NCO/OH ratio for the PUEs prepolymer was increased from 2 : 1 to 4 : 1. The compatibilities of PC and PUEs were greatly influenced by the molecular weight of polyols and the ratio of NCO/OH in the PUE prepolymer, higher molecular weight of polyols and lower NCO/OH ratio resulted in better compatibility. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012 [ABSTRACT FROM AUTHOR]

The paper presents a simple and effective approach to fabricating a poly(vinylidene fluoride) (PVDF) film with excellent ultraviolet (UV) shielding performance. Carbon quantum dots (CQDs) with a highly UV absorbing property were made via a hydrothermal reaction and were then added to a poly(vinyl alcohol) (PVA) solution. The PVDF membrane pretreated with an alkaline solution was immersed in the prepared CQD/PVA solution to coat a UV‐shielding layer on the film surface. Fourier transform infrared spectroscopy, X‐ray photoelectron spectrometry, X‐ray diffraction, transmission electron microscopy, and UV–visible spectrophotometry were applied to study the structure, morphology, and optical performance of the CQD particles. The stability and UV‐shielding performance of the obtained PVDF‐OH@CQDs/PVA composite film were further investigated. The results showed that the CQD particles with diameter of 18 nm could be well dispersed in solution. Additionally, the CQDs had fairly high UV absorbance, and the PVDF‐OH@CQDs/PVA composite film could shield the UV light completely. The method described in this paper is a promising one for fabricating UV‐shielding composite films. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019, 136, 47555. [ABSTRACT FROM AUTHOR]

Thermosetting polymers, such as epoxy resins, have found widespread applications because of their excellent thermomechanical and solvent resistance properties. However, the recycling of thermosets remains a challenge, due to the irreversible covalent crosslinking bonds in the network. The exchangeable covalent bonds in vitrimers open opportunities in the way that materials can be dynamically repaired. However, in the case of polyolefins, the strategy of exchangeable vitrimers is still underexplored. Herein, a simple way is reported to prepare a high‐density polyethylene (HDPE) vitrimer with a triple shape memory effect, where exchangeable esters are introduced into the network of covalently crosslinked HDPE. With the incorporation of polyethers or polyesters into the crosslinked network, the two obtained vitrimers show outstanding recyclability and a good triple shape memory effect. This new strategy of preparing an HDPE vitrimer might allow the high‐value utilization of crosslinked polyolefins. A simple way is reported to prepare a high‐density polyethylene (HDPE) vitrimer with triple shape memory effect, where exchangeable esters are introduced into the network of covalently crosslinked HDPE. With the incorporation of polyethers and polyesters into the crosslinked network, both the obtained vitrimers show outstanding recyclability and a good triple shape memory effect. [ABSTRACT FROM AUTHOR]