Meaning
A random copolymer consisting of butylene adipate and butylene terephthalate units functions as a fully biodegradable aliphatic-aromatic thermoplastic polyester. Manufacturers produce polybutylene adipate terephthalate through the polycondensation of adipic acid, terephthalic acid, and 1,4-butanediol to balance mechanical strength with enzymatic breakdown capacity. This chemical architecture allows the material to mimic the physical performance of conventional low-density polyethylene while remaining susceptible to microbial degradation in industrial composting environments.
Processing Variables
The melt flow index of polybutylene adipate terephthalate determines its suitability for film blowing or extrusion coating operations. Temperature stability during the conversion process prevents chain scission, which manifests as reduced tensile strength and brittleness in the finished polymer film. Moulders hold the barrel temperature slightly below the degradation threshold to maintain molecular weight distribution across high-volume production cycles.
Resin Economics
Virgin grades command a premium price due to the synthesis costs associated with bio-based monomers and the proprietary catalyst systems required for consistent polymerization. Reprocessed or regrind material exhibits lower elasticity and accelerated thermal oxidation because the repeated heat history shortens polymer chain lengths during initial melt cycles. Procurement teams manage these costs by optimizing the percentage of regrind allowed in film formulations before the degradation of structural properties exceeds the threshold required for commercial packaging performance.
Material Specification
Datasheet values for this resin include tensile strength at break and elongation percentage measured under standardized laboratory conditions. Such values provide a baseline for material selection, yet they do not guarantee the performance of a moulded component in end-use applications where environmental stress and load rates vary. Actual component density and surface hardness result from specific cooling rates and shear forces applied during the conversion phase rather than from the raw resin characteristics alone.
