PBAT is a thermoplastic biodegradable plastic, which is a copolymer of butanediol adipate and butanediol terephthalate. It has both PBA and PBT characteristics, and has good ductility and elongation at break, as well as good heat resistance and impact properties. In addition, it also has excellent biodegradability and is one of the most active biodegradable materials in the research of biodegradable plastics and best applied in the market.
Among the biodegradable polymers synthesized by microorganisms, polylactic acid (PLA) is the most widely used biodegradable polymer in the market at present. Among biodegradable polymers in chemical synthesis, polyadipic acid/butylene terephthalate (PBAT) is the most widely used. PBAT is mainly prepared by direct esterification and polycondensation reaction with PTA (or DMT), AA and BDO as raw materials under the condition of catalyst. The structure is shown in Figure 1-1. The mechanical properties and processing properties of PBAT are similar to LDPE, with good thermal stability, and can be processed by extrusion, blow molding, injection molding and other processing methods.
Different from PLA, a fully biodegradable plastic bag material, PBAT is a material with good toughness, high elongation but low strength. The Tg of PBAT is -30℃, crystallization temperature 110℃, melting temperature 130℃, and decomposition temperature 375℃. The soft aliphatic segment of PBAT has good degradation performance and can be decomposed into CO2 and H2O by microorganisms in soil. The hard segment makes it have excellent physical properties, heat resistance and impact resistance.
According to the results of biodegradation experiment, PBAT can be completely degraded under 5 months of soil burial under normal climate conditions.
If PBAT is in seawater and there are microorganisms adapted to high salt environment in seawater, it can be completely degraded in about 30-60 days at the temperature of 25℃±3℃. However, regardless of the kind of biodegradable plastic, its degradation needs certain environmental conditions, if there is no degradation conditions in the environment, especially under the living conditions of microorganisms, its degradation will be slow. PBAT biodegradable plastics can be biodegradable under composting conditions, but also in other conditions such as anaerobic digestion device biodegradation, but also in natural environment such as soil, sea water and other conditions biodegradation. However, the specific degradation situation and degradation time of PBAT are related to its specific chemical structure, product formulation and degradation environmental conditions. Therefore, the degradation time of PBAT biodegradable garbage bags should be combined with the actual situation.