Xiaofang Liu,Yong Liu,Min Fan,Kunpeng Qian,Wenya Ma,Dan Li,Li Li
Starch is a natural polymer material that is widely sourced, biodegradable, and non-toxic. However, the application of starch is hindered by its hydrophilicity and lack of biological activity. In this study, ε-polylysine hydrochloride (ε-PLH) was grafted onto starch for improving antibacterial properties of starch and weakening its hydrophilicity. Subsequently, a new type of active packaging film was prepared by blending polylactic acid (PLA), polybutylene adipate terephthalate (PBAT) and grafted starch (ε-PLH-g-starch) using the melt extrusion method. ε-PLH-g-starch/PLA/PBAT film can effectively inhibit Escherichia coli and Staphylococcus aureus with inhibition rates of 48.62 ± 2.43 % and 57.31 ± 1.65 %, respectively. The addition of ε-PLH-g-starch also significantly improved the tensile strength, optical properties and barrier properties of the films. As a verification experiment, the application of ε-PLH-g-starch/PLA/PBAT film can effectively inhibit the protein hydrolysis, microbial growth and fat oxidation of beef, and extend the shelf life of beef at 4 °C from 7 to 14 days.
The lysine p-toluenesulfonic acid ionic liquid ([Lys][p-TSA]), one kinds of amino acid ionic liquids, was synthesized by one-step method, which was employed to control the interfacial structure and degradation behavior of poly(lactide)/poly(butylene adipate- co -terephthalate) (PLA/PBAT) blends. The [Lys][p-TSA] was incorporated into PLA/PBAT blends with different contents by melt blending, and the effect of [Lys][P-TSA] on the interfacial structure, thermal stability, crystallization behavior, rheological behavior and degradation behavior of PLA/PBAT blends were investigated. The SEM results demonstrate that [Lys][p-TSA] could enhance the compatibility between PLA and PBAT in the PLA/PBAT blends. Thermal gravimetric results showed that the incorporation of [Lys][p-TSA] into PLA/PBAT blends could not affect their thermal stability. Differential scanning calorimetry (DSC) measurements showed that [Lys][p-TSA] can improve the crystallinity of PLA, and the rheological behavior of the blends indicated that [Lys][p-TSA] can enhance the chain mobility of PLA and PBAT. More importantly, the degradation behavior of the blends revealed that [Lys][p-TSA] could affect the distribution of lipase in PLA/PBAT blends, so that the relative degradation rate of each component of the blends was well-controlled. As the [Lys][p-TSA] content increased, the degradation rate of the PLA/PBAT blend in phosphate buffered saline (PBS) solution, artificial seawater, porcine pancreas lipase (PPL) solution and Candida antarctica lipase B (CALB) solution was enhanced. When the contents of [Lys][p-TSA] was 4 phr in the PLA/PBAT blend, the weight loss of the blend in PPL enzyme solution reached to 31.59% after 49 days, which was 3.79 times higher than that of PLA/PBAT blend without [Lys][p-TSA]. The enzymatic degradation mechanism of the blends was studied by density functional theory (DFT) and 1 H nuclear magnetic resonance (NMR), and it was found that [Lys][p-TSA] could control the distribution of lipase in the blends, which accelerated the enzymatic degradation of the PLA/PBAT blend. This study could provide some new way on enhancing the properties of PLA/PBAT blends while reducing the harm of microplastics.
危险品化学品经营许可证（带存储）