Biodegradable polymeric materials include plastics that can be degraded or degraded by chemical, biological or physical influences by bacteria, fungi, algae and other natural microorganisms or animal and plant enzymes. The previous article gave you a detailed introduction to microbial synthetic PLA biodegradable polymer, and today I will introduce you to chemically synthesized PBAT biodegradable polymer.
1. What is PBAT material
Among microbial synthetic biodegradable polymers, polylactic acid (PLA) is most widely used microbial synthetic biodegradable polymer on market; Among chemically synthesized biodegradable polymers, polyadipic acid/terephthalic acid Butylene formate (PBAT) is most widely used. mainly consists of PTA (or DMT), AA and BDO as raw materials. It is produced directly by esterification and polycondensation under catalyst conditions. The structure is shown in Figure 1-1. The mechanical properties and processing properties of PBAT are similar to those of LDPE, and it has good thermal stability. It can be processed through extrusion molding, blow molding, injection molding and other processing methods. At present, company with a large scale production of PBAT in the world is carried out by BASF in Germany. .
Figure 1-1 Chemical structure of PBAT
Unlike completely biodegradable PLA plastic, PBAT is a material with good toughness and high elongation but low strength. The Tg of PBAT is -30°C, crystallization temperature is 110°C, melting point is is 375°C ℃. The aliphatic soft segment of PBAT has good decomposition performance and can be decomposed into CO2 and H2O by microorganisms in soil, while hard segment gives it excellent physical properties, heat resistance and impact resistance.
2. PBAT modification
2.1 Modification of mixture of PBAT and degradable polymer
Table 2-1 Modification of mixture of PBAT and degradable polymer
2.2 PBAT/CaCO3 mixture
Sustainable materials can be obtained by mixing biodegradable PBAT and CaCO3 materials. During mixing process, addition of a small amount of compatibilizer and coupling agent can significantly improve mechanical properties of mixture. Powder. The addition can not only reduce cost of enterprise, but also accelerate overall degradation of system. It can be applied to field of film, lunch box, etc., and has good practical value.
2.3 PBAT/starch blend
Mixing PBAT with starch can greatly improve physical and mechanical properties of material, improve flowability during processing, provide good water resistance and reduce decomposition time of system.
2.4 Mixed modification of PBAT and PC
PBAT has both flexibility of long methylene chains and impact resistance of aromatic rings, PC has good transparency, excellent thermal stability, and good compatibility between PBAT and PC, which can be used to improve friability of PBAT. high crystallinity.
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