PurposeThe present work aims to prepare biocomposites blend based on linear low density polyethylene/ starch without using harmful chemicals to improve the adhesion between two phases. Also, the efficiency of essential oils as green plasticizers and natural antimicrobial agents were evaluated.Design/methodology/approachBarrier properties and biodegradation behavior of linear low density polyethylene/starch (LLDPE/starch) blends plasticized with different essential oils including moringa oleifera and castor oils wereassessed as a comparison with traditional plasticizer such as glycerol. Biodegradation behavior forLLDPE/starch blends was monitored by soil burial test. The composted samples were recovered then washed followed by drying, and weighting samples after 30, 60, and 90 days to assess the change in weight loss. Also, mechanical properties including retention values of tensile strength and elongation at break were measured before and after composting. Furthermore, scanning electron microscope (SEM) was used to evaluate the change in the morphology of the polymeric blends. In addition to, the antimicrobial activity of plasticized LLDPE/starch blends films was evaluated using a standard plate counting technique.FindingsThe results illustrate that the water vapor transition rate increases from 2.5 g m-2 24 h-1 for LLDPE/5starch to 4.21 g m-2 24 h-1 and 4.43 g m-2 24 h-1 for castor and moringa oleifera respectively. Also, the retained tensile strength values of all blends decrease gradually with increasing composting period. Unplasticized LLDPE/5starch showed highest tensile strength retention of 91.6% compared to the other blends that were 89.61, 88.49 and 86.91 for the plasticized LLDPE/5starch with glycerol, castor and M. oleifera oils respectively. As well as, the presence of essential oils in LLDPE/ starch blends increase the inhibition growth of escherichia coli, candida albicans and staphylococcus aureus.Originality/valueThe objective of this work is to develop cost-effective and environmentally-friendly methods for preparing biodegradable polymers suitable for packaging applications.

A novel thermoset biopolymer was developed from citric acid and glycerol (referred to as Polyglycerol citrate (PGC)) through polycondensation. PGC is a completely biodegradable and water-soluble polymer, but it has poor thermal stability, fire retardant and mechanical properties. To enhance the usability of this material in food packaging, insulations, and other domestic products, its strength was enhanced by reinforcement through jute fiber (JF) which is also biodegradable and environmentally friendly. The thermal stability and fire-retardant properties of the jute/PGC composite were improved by incorporating aluminum trihydride (ATH) particles in it. The concentration of ATH was varied between 0% and 12% to evaluate the optimum composition for improved thermal, mechanical and flammability properties. The strength and modulus of the material were evaluated using a tensile test while the fire retardant and thermal properties were determined using burning tests, cone calorimetry and thermogravimetric analysis. The surface morphology was studied through a scanning electron microscope. The maximum tensile strength was obtained by incorporating 9% ATH in the jute/PGC composite, which is 236% higher than the strength of neat PGC resin. Similarly, the heat release rate of jute/PGC composite was reduced by 17% with the incorporation of ATH particles. Also, the burning rate of jute/PGC was reduced by 72%. Thermal stability was also observed to improve. Possible chemical interaction between the constituents of the composite was confirmed through Fourier transform infrared spectroscopy (FTIR). The biodegradation of the composite specimens was validated through a soil burial test.

Effect of cement, Ground Granulated Blast Furnace Slag (GGBS), GGBS:magnesia (MgO) and GGBS:MgO:cement were studied as agents on stabilisation of a clay soil contaminated with glycerol solution. The contaminated soil was mixed with 5, 10 and 15% of the above agents. Atterberg limits and compaction tests were conducted on these mixtures. Additionally, strength and durability tests were performed on prepared samples at different curing times. The strength of soil contaminated with 4, 8, and 12% glycerol was reduced by 23.5, 30.1, and 36.5%, respectively, compared to the natural soil. By adding 5% cement to the soil contaminated with 4% glycerol, its strength after 7, 14, and 28 days of curing time was increased to 1581, 1984.5, and 2343.4 kPa, respectively. All the selected agents increased the strength of the contaminated soil and its increase was dependent on the percentage of the agent and curing time. It was revealed that GGBS:MgO:cement was more effective in increasing the strength than the other used agents. Durability tests also showed that the weight loss of the samples at different conditions was less than 10%. SEM results showed that the increase in strength of the soil results from the interaction between soil and agent.

This study used rice straw-based and palm fiber-based degradable plastics with glycerol and sorbitol. AThe strength of rice straw cellulose-based degradable plastics using 20% glycerol ranged from 2 to 5.75 MPa. Similarly, the strength of palm fiber cellulose-based degradable plastics using 40% sorbitol ranged from 5 to 11.13 MPa. In a chemical analysis, the peaks between 3444.87 cm-1 and 3651.25 cm-1 represented the O-H stretching of the alcohol group. This is shown by the C-O-H hydroxyl group at the wave numbers of 1627.92, 1724.36, and 1745.58 cm-1. Moreover, these groups are hydrophilic, binding water, so they can be degraded by microbial activity in the soil. In the thermal analysis, degradable plastics from rice straw lost a lot of weight between 431.53 and 520.79 degrees C. Plastics derived from palm fibers as green products also showed extreme weight loss between 334.28 and 482.20 degrees C. Most of the material was decomposed at 600 degrees C. Both types of samples lost a lot of hydrogen groups and started to decompose and depolymerize. Rice straw plastic absorbed 10.73%-20.23% of water, while palm fiber plastic absorbed 15.34%-85.01%. The lowest water absorption rates were observed in rice straw and palm fiber degradable plastics. Rice straw and palm fiber cellulose plastics broke down in 45-48 days, in line with the American Standard Testing and Materials (ASTM) D-20.96 standard, which says that degradable plastic should take no more than 180 days to break down.

Petroleum-based polymers pose significant environmental challenges; this prompts researchers to seek alternatives for the same. The foremost solution to replace petroleum-based packaging lies in bio-based polymers that can degrade with water, soil, and the environment. The most common and economical bio-based polymer today is polyvinyl alcohol (PVA), however, it has certain limitations such as brittleness, hydrophilic nature, etc. The primary objective of this study is to enhance the flexibility, transparency, barrier properties, and thermal stability of PVA by incorporating glycerol as a plasticizer. In this regard, thin films were prepared by utilizing a solution-casting technique (blade coating) upon the addition of numerous concentrations of glycerol ranging from 1 to 5 wt%. Here two sets of thin films were prepared i.e., with glycerol (modified) and without glycerol (pure PVA). Results suggest exceptional mechanical flexibility and enhanced optical properties in terms of improved transmittance (>90%) upon incorporation of glycerol into PVA. The modified films also demonstrated a significant increase in their water barrier capabilities in comparison to pure PVA films. When the concentration of glycerol reached to 5 wt%, a substantial increase in biodegradability and flexibility was witnessed resulting in reduced brittleness. Thus, the mechanical properties of the modified thin films exceeded that of pure PVA counterparts. The prepared thin films unveil exciting possibilities to be used in diverse applications; such as food packaging, membranes, biodegradable materials, etc,. The extensive discussion is presented in the light of observed results.