Bio-plastics such as polylactic acid (PLA) have been investigated as a sustainable alternative to petroleum-based plastics. In this study, the carbon footprint of packaging films made from LDPE, PLA, and PLA/PBAT blends was measured with three different waste scenarios based on the database of South Korea using life cycle assessment (LCA). The LCA followed ISO standards, and was a cradle-to-grave analysis. The functional unit was defined as 400,000 pieces of a film of 300 × 250 mm with thickness of 0.06 mm for packaging bag manufacturing. The waste treatments considered were incineration, landfill, and recycling applied with the present conditions of South Korea. Under the present analysis conditions, the PLA film with landfill was the most effective for reducing carbon emission. The PLA/PBAT with incineration was the worst case among the packaging films tested. Incineration was the worst choice of waste treatment in terms of carbon dioxide emissions. Generally, landfill may not be the best option in terms of sustainability but landfill was a better option for waste treatment than incineration. In addition, before bio-plastics are blended with other material, the blending material should first be evaluated for its environmental impact. The blended bio-plastics with PLA, such as PLA/PBAT, can be more inimical to the environment in terms of carbon dioxide emissions than existing materials, such as LDPE.

Poly(butylene sebacate-co-terephthalate) (PBSeT) is a biodegradable flexible polymer suitable for melt blending with other biodegradable polymers. Melt blending with a compatibilizer is a common strategy for increasing miscibility between polymers. In this study, PBSeT polyester was synthesized, and poly(lactic acid) (PLA) was blended with 25 wt% PBSeT by melt processing with 3–6 phr PLA-grafted maleic anhydride (PLA-g-MAH) compatibilizers. PLA-g-MAH enhanced the interfacial adhesion of the PLA/PBSeT blend, and their mechanical and morphological properties confirmed that the miscibility also increased. Adding more than 6 phr of PLA-g-MAH significantly improved the mechanical properties and accelerated the cold crystallization of the PLA/PBSeT blends. Furthermore, the thermal stabilities of the blends with PLA-g-MAH were slightly enhanced. PLA/PBSeT blends with and without PLA-g-MAH were not significantly different after 120 h, whereas all blends showed a more facilitated hydrolytic degradation rate than neat PLA. These findings indicate that PLA-g-MAH effectively improves PLA/PBSeT compatibility and can be applied in the packaging industry.

In this study, poly(butylene sebacate-co-terephthalate) (PBSeT) was successfully synthesized using various ratios of sebacic acid (Se) and dimethyl terephthalate (DMT). The synthesized PBSeT showed a high molecular weight (M_w, 88,700–154,900 g/mol) and good elastomeric properties. In particular, the PBSeT64 (6:4 sebacic acid/dimethyl terephthalate mole ratio) sample showed an elongation at break value of over 1600%. However, further increasing the DMT content decreased the elongation properties but increased the tensile strength due to the inherent strength of the aromatic unit. The melting point and crystallization temperature were difficult to observe in PBSeT64, indicating that an amorphous copolyester was formed at this mole ratio. Interestingly, wide angle X-ray diffraction (WAXD) curves was shown in the cases of PBSeT46 and PBSeT64, neither the crystal peaks of PBSe nor those of poly(butylene terephthalate) (PBT) are observed, that is, PBSeT64 showed an amorphous form with low crystallinity. The Fourier-transform infrared (FT-IR) spectrum showed C–H peaks at around 2900 cm⁻¹ that reduced as the DMT ratio was increased. Nuclear magnetic resonance (NMR) showed well-resolved peaks split by coupling with the sebacate and DMT moieties. These results highlight that elastomeric PBSeT with high molecular weight could be synthesized by applying DMT monomer and showed promising mechanical properties.

Poly (lactic acid) (PLA) is the most widely available commercial bioplastic that is used in various medical and packaging applications and three-dimensional filaments. However, because neat PLA is brittle, it conventionally has been blended with ductile polymers and plasticizers. In this study, PLA was blended with the high-ductility biopolymer poly (butylene-sebacate–co–terephthalate) (PBSeT), and hexamethylene diisocyanate (HDI) was applied as a crosslinking compatibilizer to increase the miscibility between the two polymers. PLA (80%) and PBSeT (20%) were combined with various HDI contents in the range 0.1–1.0 parts-per-hundred rubber (phr) to prepare blends, and the resulting physical, thermal, and hydrolysis properties were analyzed. Fourier-transform infrared analysis confirmed that –NH–C=OO⁻ bonds had formed between the HDI and the other polymers and that the chemical bonding had influenced the thermal behavior. All the HDI-treated specimens showed tensile strengths and elongations higher than those of the control. In particular, the 0.3-phr-HDI specimen showed the highest elongation (exceeding 150%) and tensile strength. In addition, all the specimens were hydrolyzed under alkaline conditions, and all the HDI-treated specimens degraded faster than the neat PLA one.