Thermal degradation behaviour of nanoamphiphilic chitosan dispersed poly (lactic acid) bionanocomposite films

Prodigiosin-Loaded Poly(lactic acid) to Combat the Biofilm-Associated Infections

Poly(lactic acid) (PLA) is an emerging biobased implant material. Despite its biocompatibility and the aseptic procedures followed during orthopedic surgery, bacterial infection remains an obstacle to implementing PLA-based implants. To tackle this issue, prodigiosin-incorporated PLA has been developed, which possesses improved hydrophobicity with a contact angle of 111 ± 1.5°. The degradation temperature of the prodigiosin is 215 °C, which is more than the melting temperature of PLA, which supports the processability and sterilization of the PLA-based implants without any toxic gases. Further, prodigiosin improves the transparency of PLA and acts as a nucleation site. The spherulite density increases three times compared to that of neat PLA. The inherent methoxy group of prodigiosin is an active site responsible for the inhibition of bacterial attack and biofilm formation. The in vitro study on biofilm formation shows excellent inhibition activity against implant-associated pathogens such as Klebsiella aerogenes and Staphylococcus aureus.

Bio-based active food packaging materials: Sustainable alternative to conventional petrochemical-based packaging materials

In food industry, a growing concern is the use of suitable packaging material (i.e., biodegradable coatings and films) with enhanced thermal, mechanical and barrier characteristics to prevent from contamination and loss of foodstuff. Biobased polymer resources can be used for the development of biodegradable bioplastics. To achieve this goal, biopolymers should be economic, renewable and abundantly available. Bioplastic packaging materials based on renewable biomass could be used as sustainable alternative to petrochemically-originated plastic materials. This review summarizes the recent advancements in biopolymer-based coatings and films for active food packaging applications. Microbial polymers (PHA and PLA), wood-based polymers (cellulose, hemicellulose, starch & lignin), and protein-based polymers (gelatin, keratin, wheat gluten, soy protein and whey protein isolates) were among the materials most widely exploited for the development of smart packaging films. These biopolymers are able to synthesize coatings and films with good barrier properties against food borne pathogens and the transport of gases. Biobased reinforcements e.g., plant essential oils and natural additives to bioplastic films improve oxygen barrier, antibacterial and antifungal properties. To induce the desired functionality the simultaneous utilization of different synthetic and biobased polymers in the form of composites/blends is also an emerging area of research. Nanoscale reinforcements into bioplastic packaging have also been reported to improve packaging characteristics ultimately increasing food shelf life. The development of bioplastic/biocomposite and nanobiocomposites exhibits high potential to replace nonbiodegradable materials with characteristics comparable to fossil-based plastics, additionally, giving biodegradable and compostable characteristics. The idea of utilization of renewable biomass and the implications of biotechnology can firstly reduce the burden from fossil-resources, while secondly promoting biobased economy.

Study on Thermal Behavior of Some Biocompatible and Biodegradable Materials Based on Plasticized PLA, Chitosan, and Rosemary Ethanolic Extract

Thermal characterization of some multifunctional environmentally friendly materials based on plasticized poly (lactic acid) (PLA)/chitosan (CS) and rosemary extract (R) previously obtained is presented. Differential scanning calorimetry (DSC) associated with other complex investigations such as chemiluminescence and coupled thermogravimetry (TG)/Fourier-transform infrared spectroscopy (FT-IR)/mass spectroscopy (MS) was performed in order to test both the thermal behavior and the biocomposition–property relationship. It was established that the rosemary ethanolic extract offers an efficient protection against thermoxidative degradation to the new developed plasticized PLA-based biocomposites which show good thermal properties, being suitable for both medical and food packaging applications.

Obtaining and Characterization of the PLA/Chitosan Foams with Antimicrobial Properties Achieved by the Emulsification Combined with the Dissolution of Chitosan by CO2 Saturation

A new method of obtaining functional foam material has been proposed. The materials were created by mixing the poly lactic acid (PLA) solution in chloroform, chitosan (CS) dissolved in water saturated with CO₂ and polyethylene glycol (PEG), and freeze-dried for removal of the solvents. The composite foams were characterized for their structural (SEM, FT-IR, density, porosity), thermal (DSC), functional (hardness, elasticity, swelling capacity, solubility), and biological (antimicrobial and cytotoxic) properties. Chitosan in the composites was a component for obtaining their foamed form with 7.4 to 22.7 times lower density compared to the neat PLA and high porosity also confirmed by the SEM. The foams had a hardness in the range of 70-440 kPa. The FT-IR analysis confirmed no new chemical bonds between the sponge ingredients. Other results showed low sorption capacity (2.5-7.2 g/g) and solubility of materials (less than 0.2%). The obtained foams had the lower T_g value and improved ability of crystallization compared to neat PLA. The addition of chitosan provides the bacteriostatic and bactericidal properties against Escherichia coli and Staphylococcus aureus. Biocompatibility studies have shown that the materials obtained are not cytotoxic to the L929 cell line.

Thermal and thermo-oxidative degradation kinetics and characteristics of poly (lactic acid) and its composites

Thermal degradation behavior and kinetics of starch/PLA composites in an inert and oxygen atmosphere were investigated by TG and TG-FTIR techniques. It is shown that the thermal degradation process can be divided into three stages, and a significant difference between thermal and thermo-oxidative degradation is the third stage in which the residual chars are further cracked for the thermo-oxidative degradation. The activation energy was calculated using the iso-conversional Flynn-Wall-Ozawa (FWO) method. The lower activation energy for thermo-oxidative degradation indicated that oxygen had an accelerated effect on thermal degradation. The variation of activation energy indicated that the decomposition of all the samples was a complex process that included at least two different mechanisms. Evolution of the evolved gaseous products with temperature was studied to understand the thermal and thermo-oxidative decomposition comprehensively. According to the TG-FTIR analysis, the gaseous products mainly contained lactide, cyclic oligomers, aldehydes, CO₂, CO, and H₂O.

Theoretical and analyzed data related to thermal degradation kinetics of poly (L-lactic acid)/chitosan-grafted-oligo L-lactic acid (PLA/CH-g-OLLA) bionanocomposite films

The theoretical and analyzed data incorporated in this article are related to the recently published research article entitled “Thermal degradation behaviour of nanoamphiphilic chitosan dispersed poly (lactic acid) bionanocomposite films” (http://dx.doi.org/10.1016/j.ijbiomac.2016.11.024) (A.K. Pal, V. Katiyar, 2016) [1]. Supplementary information and data (both raw and analyzed) are related to thermal degradation kinetics and explains various model fitting and is conversional methods, which are used in this research work to enhance the knowledge about degradation behaviour of PLA/CH-g-OLLA bionanocomposite system. Non-isothermal degradation kinetics of such polymeric system was proposed using Kissinger, Kissinger–Akahira–Sunose, Flynn–Wall–Ozawa and Augis and Bennett models to estimate the activation energies (E_a) and R² values.