Effects of lysine triisocyanate on the mode I fracture behavior of polymer blend of poly (l-lactic acid) and poly (butylene succinate-co-l-lactate)

Excerpt

Poly(l-lactic acid) (PLLA), a typical biodegradable polymer made from bioresources, has extensively been used in many industrial fields such as automotive, electrical, and medical industries. Fracture properties of PLLA are generally better than those of brittle polymers such as PMMA and polystyrene, however, much lower than engineering polymers with high toughness. For example, the mode I energy release rate of PLLA was reported to be about 4 kJ/m² [1], that is, actually much lower than typical engineering polymers such as polyethylene (20 kJ/m²) and HIPS (16 kJ/m²) [2]. Different types of PLLA-based polymer blends have been developed to overcome such low fracture property, and their physical and chemical properties have been tried to be characterized [3‐13]. These polymer blends are fabricated by blending PLLA with ductile biodegradable polymers such as poly(ε-caprolactone) (PCL), poly(butylene succinate) (PBS), and poly(butylene succinate-co-l-lactate) (PBSL) in order to keep its biodegradability. Although the fracture property of PLLA is effectively improved by such polymer blending, in general, phase separation caused by the immiscibility between PLLA and the blending partner tends to prevent further improvement of the fracture property [1]. Just recently, it was found that addition of lysine triisocyanate (LTI) can dramatically improve the immiscibility in PLLA/PCL and PLLA/PBS blend systems and as a result, their mechanical properties are effectively improved [13‐16]. However, the effect of LTI on PLLA/PBSL has not been clarified yet. …