Amber extract as a bio-additive to poly(lactic acid) films: Multimethod analysis of crystallinity and stability

Poly(lactic acid) (PLA) films with 1 wt% of amber extract (AbE) as a bio-additive were obtained through solvent mixing using 1,4-dioxane, which was later evaporated. The extract, derived from the residual amber generated during jewelry manufacturing in the Gdansk region (Poland), was evaluated for its morphology and thermal response. The resulting films were transparent, and the addition of AbE imparted a yellow hue. The crystallinity characteristics of the PLA/AbE films were analyzed through FTIR, DSC, POM, and XRD results. The cold crystallization ability of PLA in the presence of AbE was assessed by comparing the films with their annealed counterparts. The annealed films demonstrated a slight increase in the crystalline phase without any change in transparency. The presence of amber extract particles impeded the formation of stable polymorph crystals within the PLA structure, leading to an expanded size distribution of spherulites and a reduced crystallization rate. Furthermore, the addition of AbE showed promise in enhancing the UV–vis blocking of PLA, as AbE particles decreased the transmission rate across the entire UV–vis spectrum.

Highlights

• PLA thin films with 1% AbE were produced by the casting method.
• Amber extract from isopropanol fraction has a porous structure.
• PLA and amber extract exhibit homogeneous mixing in 1,4-dioxane solution.
• The AbE particles improved the UV–vis blocking of PLA.