Enhanced antifungal properties of poly(butylene succinate) film with lignin nanoparticles and trans-cinnamaldehyde for mango packaging.

Sustainable poly(butylene succinate) (PBS) films incorporating lignin nanoparticles (LN) and trans-cinnamaldehyde (CN) have been developed to preserve mango freshness and provide food safety. PBS/LN, PBS/CN, and PBS/LN/CN composite films were produced by blown film melt extrusion. This study investigated the effect of CN-LN on the CN remaining content, thermal, mechanical, and barrier properties, diffusion coefficient, and antifungal activity of PBS films both in vitro and in vivo. Results showed that LN in the PBS/LN/CN composite film contained more CN than in the PBS/CN film. The compatibility of CN-LN with PBS produced homogeneous surfaces with enhanced barrier properties. PBS/LN/CN composite films demonstrated superior antifungal efficacy, inhibiting the growth of Colletotrichum gloeosporioides and preserving mango quality during storage. Results suggested that incorporating LN into PBS composite films prolonged the sustained release of antifungal agents, thereby inhibiting microbial growth and extending the shelf life of mangoes. Development of PBS/LN/CN composite films is a beneficial step toward reducing food waste and enhancing food safety.

Enhancing Gas Transmission Rate of PBS/PBAT Composite Films: A Study on Microperforated Film Solutions for Mango Storage.

This study focused on improving the mechanical properties of the poly(butylene succinate) (PBS) film by incorporation of poly(butyrate adipate terephthalate) (PBAT). At 20 wt % PBAT, elongation in the transverse direction improved by 373% while maintaining high tensile strength (27 MPa) and Young's modulus (262 MPa). The PBS80/PBAT20 composite film exhibited optimized mechanical properties. The absorbance coefficient of microperforated film at 980/cm for the 80PBS/20PBAT mix, corresponding to the 10.2 µm CO2 laser wavelength, was 65/cm, indicating high film capability to absorb energy from the CO2 laser. The introduction of microholes enhanced the gas permeability of the PBS/PBAT film. As fluences increased from 187 to 370 J/cm2, there was a notable increase in microhole area in 80PBS/20PBAT film from 19,375 to 46,421 µm2. Concurrently, the gas transmission rate for a singular hole increased from 45 to 210 cm3/d for the oxygen transmission rate (OTR) and from 115 to 220 cm3/d for the CO2 transmission rate (CO2TR). For mango packed in microperforated 80PBS/20PBAT films, the O2 levels inside the package gradually dropped and remained at 14.2% in PBS80/PBAT20-MP1 (OTR ∼ 68,900 cm3/m2·d) and 16.7% in PBS80/PBAT20-MP2 (OTR ∼ 131,900 cm3/m2·d), while CO2 content increased to 6% for PBS80/PBAT20-MP1 and 4% for PBS80/PBAT20-MP2 throughout 33 days. On day 2 of storage in the nonperforated package, O2 content dropped to 2% while CO2 content rose to 22%. Mango packed in the 80PBS/20PBAT film package exhibited an unsatisfactory freshness quality due to the detection of a fermentative odor on day 5 of the storage period. Total soluble solids, color, and weight loss of mango remained stable during storage in all microperforated films. Results demonstrated that the mango shelf life was significantly extended by 35 days using 80PBS/20PBAT-MP1. Laser perforation offered a practical method for improving gas transmission rates (OTR and CO2TR) of 80PBS/20PBAT film for mango packaging.

Microfabrication of Thermoplastic Polypropylene Surface Structures via Thermal Imprinting for Controlling the Adhesion of Easy Peel Package.

Micropatterns were fabricated on polypropylene (PP) surfaces using the hot embossing technique with various temperatures ranging from 160 to 175 °C and applying force conditions from 100 to 300 N. To evaluate the replication quality, an effective filling ratio of 1 indicates that the volume of the formed pattern is similar to the mold cavity volume. From the results, the filling ratio increased with increasing the embossing temperature. For instance, under a constant force of 100 N, the filling ratio of polypropylene (PP) with small square arrays (pattern SS) increased from 0.08 to 0.41 when the embossing temperature was raised from 160 to 175 °C, respectively. With the increase of applied force, the filling ratio also increased. At an imprinting temperature of 175 °C and an applied force of 300 N, the highest effective filling ratio that was achieved was approximately 0.99. Furthermore, the effect of PP with different melt flow indexes (MFIs) on the filling ratio was investigated. For food packaging applications, a micropatterned PP sheet was heat-sealed with a biaxially oriented polypropylene (BOPP) film. The micropatterned PP sheet demonstrated easy-opening properties by varying sealing contact areas and micropattern geometries between the sheet and the BOPP film. All micropatterned PP sheets with an MFI of 25 g/10 min exhibited an easy peel property with adhesive failure characteristics at a heat-sealing temperature of 150 °C and a dwell time of 3 s. There was no residue on the PP substrate surface. The overall findings are beneficial in understanding the hot embossing technology for fabricating micropatterns on polymer surfaces, and it can be applied in an easy peel property for packaging applications.

Lignin Nanoparticles for Enhancing Physicochemical and Antimicrobial Properties of Polybutylene Succinate/Thymol Composite Film for Active Packaging.

The natural abundance, polymer stability, biodegradability, and natural antimicrobial properties of lignin open a wide range of potential applications aiming for sustainability. In this work, the effects of 1% (w/w) softwood kraft lignin nanoparticles (SLNPs) on the physicochemical properties of polybutylene succinate (PBS) composite films were investigated. Incorporation of SLNPs into neat PBS enhanced Td from 354.1 °C to 364.7 °C, determined through TGA, whereas Tg increased from -39.1 °C to -35.7 °C while no significant change was observed in Tm and crystallinity, analyzed through DSC. The tensile strength of neat PBS increased, to 35.6 MPa, when SLNPs were added to it. Oxygen and water vapor permeabilities of PBS with SLNPs decreased equating to enhanced barrier properties. The good interactions among SLNPs, thymol, and PBS matrix, and the high homogeneity of the resultant PBS composite films, were determined through FTIR and FE-SEM analyses. This work revealed that, among the PBS composite films tested, PBS + 1% SLNPs + 10% thymol showed the strongest microbial growth inhibition against Colletotrichum gloeosporioides and Lasiodiplodia theobromae, both in vitro, through a diffusion method assay, and in actual testing on active packaging of mango fruit (cultivar "Nam Dok Mai Si Thong"). SLNPs could be an attractive replacement for synthetic substances for enhancing polymer properties without compromising the biodegradability of the resultant material, and for providing antimicrobial functions for active packaging applications.

Physicochemical properties of lignin nanoparticles from softwood and their potential application in sustainable pre-harvest bagging as transparent UV-shielding films.

Technical lignin can be mainly obtained as a waste by-product from pulp industry, and it exhibits unique properties including ultraviolet adsorption, biodegradable, antibacterial, and antioxidant which can be utilized for bioplastic applications. However, common limitations of technical lignin for plastic applications are compatibility mainly due to poor interfacial adhesion, relatively large particle size and impurity. In this study lignin nanoparticles from softwood (S-LNPs) were successfully produced through a continuous-green-scalable antisolvent precipitation and the suitability of S-LNPs for fabrication of bio-composite polybutylene succinate (PBS) films using conventional blown film extrusion was examined. The attained S-LNPs showed lower ash content, higher phenolic content and higher lignin content compared to pristine softwood kraft lignin (S-lignin). Rheological property including shear viscosity and melt-flow index was determined. The obtained PBS/S-LNP composite films showed improved tensile modulus, higher water vapor transmission rate and excellent UV-shielding ability compared to neat PBS and PBS/S-lignin films. Accelerated weathering testing was conducted to replicate outdoor conditions. Degradation indices including carbonyl, vinyl and hydroxyl of the weathered PBS/lignin composites were evaluated for photo-oxidative stability. The S-LNPs as multifunctional bio-additives in biodegradable composite film exhibited superior performances of transparency, UV-absorption and stiffness with high photo-oxidative stability suitable for outdoor applications.