Energy storage enabled by cross-linked multilayer films using block copolymer-modified nanocapsules and chitosan biopolymers

During storage, food undergoes transformations, often producing volatile nitrogen compounds known as total volatile basic nitrogen (TVB‐N), which serves as an indicator of food freshness. In this study, chitosan (CTS) was blended with polyvinyl alcohol (PVA) and incorporated with anthocyanins (ACNs) to monitor the quality changes in fish fillets over different time intervals. The results demonstrated that the presence of PVA in the CTS membrane enhanced light transmittance and reduced water absorption due to the reinforcement of the membrane structure through chemical interactions. In the freshness monitoring experiments, the CTS/PVA membranes exhibited an improved value of total color difference (ΔE), facilitating better detection of pH changes of the surrounding environment. Moreover, the ΔE value of the CTS/PVA film was observed to be quite similar to the value at pH 9 after 24 h and at pH 11 after 36 h when the fish fillet was stored at 25°C. In contrast, the ΔE value of the CTS/PVA film closely matched the value at pH 11 after 96 h of storage at 4°C. Additionally, the correlation between the generated TVB‐N and the ΔE values indicated a higher correlation coefficient (R2) for the composite membranes compared to the pristine CTS or PVA membranes.

Colorimetric chitosan/polyvinyl alcohol composite membrane incorporated with anthocyanins as pH indicator for monitoring fish freshness

Nguyen,

Phung,

Nguyen

et al. 2024

Synthesis and thermal behavior of acrylonitrile/guanidine crotonate copolymer for carbon fiber precursor

Wang,

Malik,

et al. 2024

The thermal oxidation stabilization of polyacrylonitrile (PAN) copolymer is a highly exothermic process. It significantly impacts the quality of the finished PAN‐based carbon fiber, which is often addressed by adding appropriate comonomers. This paper synthesized guanidine crotonate (GCA) as a comonomer and copolymerized with acrylonitrile (AN) to prepare P(AN‐GCA). DSC analysis revealed that when compared to PAN and P(AN‐CA) copolymers, the initial exothermic temperature, maximum exothermic heat flux, and heat flux of P(AN‐GCA) copolymer were greatly reduced. FT‐IR spectroscopy showed that the degree of pre‐oxidation increased with the increasing comonomer GCA content, indicating that the addition of comonomer GCA could promote PAN pre‐oxidation cyclization and improve the copolymer's degree of pre‐oxidation. The activation energies of PAN and P(AN‐GCA) were 160 and 126 KJ/mol, respectively. It was shown that the addition of GCA could effectively reduce the activation energy of the cyclization reaction of the polymer while simultaneously promoting it. TGA analysis shows that the introduction of GCA improves the copolymer's thermal stability, and the yield at 800°C is more than 54%, which is at least 19% higher than PAN homopolymer. P(AN‐GCA) has the potential to be carbon fiber precursor.

Synthesis and Properties of High Melt Strength Poly(Butylene Succinate)

Jia,

Liu,

Han

et al. 2024

Due to the good combined properties, poly(butylene succinate) (PBS) is a biodegradable polymer material with good application potential. Nevertheless, it has the drawback of low melt strength arising from its inherent linear macromolecular structure, which greatly restricts its processing, such as blowing. Multifunctional branching agents can be applied to boost polyester melt strength and improve blowing processability. In this work, the branched PBS was synthesized by introducing various branched agents, such as tartaric acid (TA), citric acid (CA), and pentaerythritol (PER), and their effect on the characteristics was systematically analyzed. Due to the incorporation of branched chains and micro‐crosslinking structures, mechanical characteristics and melt strength of polymers have been improved effectively. PBS‐PER0.1% exhibited tensile strength and elongation at break as high as 50.71 MPa and 347.92%, respectively. Additionally, crystallinity increases with the increase of PER content, which is opposite to the crystallinity of polymer synthesized from other branching agents. Thus, mechanical properties and rheological properties of PBS can be facilely controlled by regulating the chemical structure and content of branching agent.