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Intelligent pH-indicator films based on soy protein isolate (SPI) were prepared using pH-sensitive dyes (bromothymol blue and methyl red). The addition of mixed indicators imparts pH-indicator films with an appreciable microstructure, acceptable water resistance, and favorable optical properties. The incorporation of the mixed indicators did not lead to significant improvement in the mechanical properties of films due to weak ionic cross-linking by hydrogen bonding between the SPI macromolecules and low-molecularweight indicators. Fourier-transform infrared spectroscopy indicated hydrogen bond-mediated intermolecular interactions, and scanning electron microscopy showed that BB/MR were well dispersed in the SPI film. The indicator addition hindered the sorption and passage of water molecules. The water vapor permeability, moisture sorption, moisture content, and total soluble matter were 4.32 to 6.12 ×10 -12 g⋅cm/cm 2 ⋅s⋅Pa, 36.70% to 73.33%, 25.28% to 44.11%, and 8.21% to 25.56%, respectively. Also, the addition of indicators reduced UV light transmittance with minimal effect on the transparency of the film. The presence of indicators enhanced the pH sensitivity, seen as a visible color reaction at different pHs (total color difference, ΔE > 5). When the pH-indicator film containing 8 ml/100 ml final film emulsions was used to monitor the fresh-cut apple freshness, a green color for fresh status was observed, which turned blue after 60 h. Collectively, our findings suggested that indicator-containing SPI films have the potential for monitoring the freshness of fruits.Practical Application: pH-indicator films can help consumers to identify the freshness of packaged food by a change in the color of the packaging material, which is easily visible to the unaided eye without the need for opening the packaging. This protects consumers' interests.

In this study, four typical biocomposites from lignin blended with poly-3-hydroxybutyrate-3-hydroxyhexanoate (PHBH) using inorganic nanoparticles (INPs) (SiO 2 , MMT, CaCO 3 , and BN) as fillers were evaluated, which enhanced the thermal, mechanical, and barrier properties of composites. The results revealed that the selection of suitable INPs doped into the lignin/PHBH (L/P) composites was an important approach to achieve available function. MMT/L/P nanocomposites were significantly higher than those of untreated L/P composites in thermal stability (T max exceed 10%) and barrier properties (water vapor and oxygen resistance increased by 48% and 46%), and BN particles increased the initial thermal decomposition temperature by 8%. The elongation at break of CaCO 3 /L/P and BN/L/P composites were increased by 344% and 319%, while SiO 2 /L/P composites had the best tensile strength (18.8 MPa).Besides, the INPs/L/P nanocomposites in this paper exhibited excellent ultraviolet (UV) resistance and might become potential anti-UV packaging materials for grease foods.

A nanocomposite of poly(3-hydroxybutyrate-co-3-hydroxyhexanoate) (PHBH)/ montmorillonite (MMT) modified with silane coupling agent 3-aminopropyltriethoxysilane (KH550) (PHBH/MMT/KH550) was prepared by solution casting method. The effects of KH550 content on properties of nanocomposites were comparatively investigated. According to the Fourier transform infrared spectra, the new chemical bonding between the PHBH and the MMT was formed by adding KH550. The crystallinity, thermal properties, mechanical properties, and barrier properties of the nanocomposites were improved because of the good dispersion of MMT. Compared with pure PHBH, a 220.05%, 158.25%, and 58.91% improvement in young's modulus, tensile strength, and elongation at break was obtained. The water vapor transmission coefficient was decreased by 113.30%. Moreover, it was notable that the nanocomposite possessed the optimal mechanical properties when the KH550 content was 5 wt%.The obtained results revealed that the nanocomposite will expand the practical application of PHBH base plastics as a substitute of traditional petrochemical materials.

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A series of silica surface-capped with hexamethyldisilazane (denoted as H-SiO2) were prepared by liquid-phase in-situ surface-modification method. The as-obtained H-SiO2 was incorporated into acrylic amino (AA) baking paint to obtain AA/H-SiO2 composite extinction paints and/or coatings. N2 adsorption–desorption tests were conducted to determine the specific surface area as well as pore size and pore volume of H-SiO2. Moreover, the effects of H-SiO2 matting agents on the physical properties of AA paint as well as the gloss and transmittance of AA-based composite extinction coatings were investigated. Results show that H-SiO2 matting agents possess a large specific surface area and pore volume than previously reported silica obtained by liquid-phase method. Besides, they have better dispersibility in AA baking paint than the unmodified silica. Particularly, H-SiO2 with a silica particle size of 6.7[Formula: see text][Formula: see text]m and the dosage of 4% (mass fraction) provides an extinction rate of 95.2% and a transmittance of 79.3% for the AA-based composite extinction coating, showing advantages over OK520, a conventional silica matting agent. Along with the increase in the silica particle size, H-SiO2 matting agents cause a certain degree of increase in the viscosity of AA paint as well as a noticeable decrease in the gloss of the AA-based composite extinction coating, but they have insignificant effects on the hardness and adhesion to substrate of the AA-based composite coatings. This means that H-SiO2 matting agents could be well applicable to preparing low-viscosity and low-gloss AA-based matte coatings.

Commonly used crosslinker agents often have a low crosslinking efficiency with guar gum, the major component of fracturing fluid for crude oil recovery, and it often required a high loading of guar gum for achieving desired recovery from low‐permeability reservoir. Nevertheless, a high‐loading of guar gum might result in excessive residue and reduce the conductivity of the reservoir. Therefore, boric acid, a commonly used crosslinking agent, was introduced onto the surface of pentaerythritol to afford a composite crosslinking agent denoted as PB. The as‐prepared PB crosslinker was characterized by Fourier‐transform infrared spectrometry. The guar gum fracturing gel crosslinked with the PB had fantastic viscoelasticity and thermal stability and could reduce the guar gum loading by 16.7%, with boric acid as a control. Besides, the gel‐broken liquid had good compatibility with the simulated water and caused reduced damage to rock core, showing potential for hydraulic fracturing of low‐permeability reservoirs. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2020, 137, 48528.