Meaning
Polybutylene adipate terephthalate is a biodegradable aliphatic aromatic copolyester used in flexible packaging and agricultural mulch films. Thermoplastic polyester manufacturers synthesise the material through the polycondensation of 1,4-butanediol, adipic acid, and dimethyl terephthalate or terephthalic acid. Industrial processors rely on PBAT for extrusion blown film lines and injection moulding compounds requiring controlled soil degradation.
Thermal Window
Melt processing temperatures require strict thermal control to prevent polymer chain scission and associated molecular weight drop. Barrel zone set points usually range from one hundred fifty degrees Celsius at the feed throat up to one hundred ninety degrees Celsius at the die adapter. Exceeding these thermal ceilings reduces melt strength, leading to bubble instability on blown film towers and inconsistent wall thickness across moulded parts.
Rheological Profile
Shear sensitivity during extrusion dictates screw design and residence time parameters. The resin exhibits high melt elasticity compared to low density polyethylene, requiring modified die gap clearances to prevent melt fracture during high output extrusion runs. Moulders transition between virgin resin and post-industrial regrind by adjusting back pressure and screw recovery speeds to compensate for intrinsic viscosity loss caused by repeated thermal exposure.
Deformation Resistance
Tensile elongation at break exceeds five hundred percent, providing the puncture resistance necessary for high speed automated packaging machinery. Crystallization kinetics remain slow during cooling stages, causing prolonged post-moulding dimensional drift before final part stabilization occurs. Environmental stress cracking resistance depends on proper molecular weight distribution maintained during compounding rather than subsequent additive modification.
