To extract polylactic acid (PLA) from a blend with epoxidised natural rubber (ENR), a solvent extraction technique based on the difference in solubility of the two polymers can be employed. PLA is a polar polymer that dissolves readily in solvents like chloroform, dichloromethane (DCM), tetrahydrofuran (THF), or dioxane, whereas ENR, being more non-polar, is insoluble or much less soluble in these solvents. The extraction process begins by finely shredding or cutting the PLA/ENR blend to increase its surface area. The shredded material is then immersed in a suitable solvent such as chloroform or DCM and stirred at room temperature or slightly elevated temperatures (around 30–40°C) for 1 to 2 hours. During this time, PLA dissolves into the solvent, while ENR remains undissolved.

After sufficient mixing, the mixture is filtered using filter paper or a Buchner funnel to separate the solid ENR residue from the PLA-containing solution. The filtrate, which contains dissolved PLA, is then subjected to solvent evaporation using a rotary evaporator. This step allows the recovery of PLA as a solid film or residue. To enhance the purity of the recovered PLA, an additional washing step with cold methanol may be performed, followed by vacuum drying at 40–50°C until a constant weight is obtained. This method selectively isolates PLA from the blend, preserving its structure and enabling further characterization if needed. Techniques such as FTIR, NMR, DSC, TGA, or GPC can be employed post-extraction to confirm the identity and integrity of the recovered PLA.

To separate PLA from a mixture of ENR/PLA and ascertain if ring-opening or grafting has occurred, you may dissolve PLA using solvents like dichloromethane (DCM) or chloroform, but they do not dissolve ENR and grafted PLA-g-ENR to any great extent. Chop the mixture into very small pieces and stir it in DCM or chloroform at room temperature for 12–24 hours, and filter the suspension to separate the solid residue (ENR + PLA-g-ENR) and the dissolved free PLA. The filtrate is precipitated in methanol to remove PLA for characterization. The solid residue can be analyzed by FTIR or NMR to identify grafting by the detection of ester or hydroxyl peaks, and thermal analysis (DSC/TGA) or GPC could provide further evidence of structural change to indicate successful ring-opening or grafting.