Reactive compatibilization of biodegradable poly(lactic acid)/poly(ε‐caprolactone) blends with reactive processing agents

Abstract

Poly(lactic acid) (PLA) blended with poly(e-caprolactone) (PCL) was prepared with various reactive processing agents. Four isocyanates-lysine triisocyanate (LTI); lysine diisocyanate (LDI); 1,3,5-tris(6-isocyanatohexyl)-1,3,5-triazinane-2,4,6-trione (Duranate TPA-100); 1,3,5-tris(6-isocyanatohexyl)biuret (Duranate 24A-100)and an industrial epoxide-trimethylolpropane triglycidyl ether (Epiclon 725)-were used as reactive processing agents. PLA/PCL blended in the presence of LTI had the highest torque in a mixer test. The test specimens were prepared by injection molding. The mechanical properties, thermal properties, molecular weight, melt viscosity, phase behavior, and morphology were investigated using tensile strength, impact strength, differential scanning calorimetry, melt mass-flow rate measurements, capillary rheometery, gel permeation chromatography, laser scanning confocal microscopy (LSCM), and visco-elasticity atomic force microscopy (VE-AFM). The impact strength increased considerably at 20 wt% PCL. The nominal tensile strain of PLA/PCL blended with LTI increased by 270%. The MFR values of PLA/PCL blends decreased with increasing LTI. Similar results were observed for shear viscosity. LSCM measurements showed that the diameters of PCL were dispersed about 0.4 lm in the presence of LTI. VE-AFM showed that spherical particles with diameters of 50 nm were PCL-rich domain. These results indicate that isocyanate groups of LTI react with both terminal hydroxyl or carboxyl groups of polymers, and the compatibility of PLA/PCL blends improves with LTI by reactive processing.

Reactive extrusion of bio-based polymer blends and composites – Current trends and future developments

“…Harada et al [89] Similar observations were described by Takayama and coworkers [90,91], which proved that addition of LTI decrease the immiscibility between PLA and PCL. This consequently resulted in an enhanced toughness of the PLA/PCL blends.…”

Effect of Ethyl Ester L-Lysine Triisocyanate addition to produce reactive PLA/PCL bio-polyester blends for biomedical applications

“…All of these studies demonstrate how, even at low amounts of LTI, the toughness of the blends, can be sensibly increased [4,[9][10]. They have used different LTI amounts, generally 0,15-0,3-0,5 phr, but also higher amounts, such as 1 phr, and 2 phr, which, to our knowledge, is the maximum amount of this reactive agent used till now.…”

Employing a novel bioelastomer to toughen polylactide

“…The most practical and economic used methods for toughening PLA is to adopt flexible polymers or elastomers. Poly (ε-caprolactone) (PCL) was the earliest polymer used for toughening PLA [15][16][17][18][19][20][21]. Since PCL and PLA are not compatible, compatibilizers such as PLLA-PCL-PLLA triblock copolymer have been developed [18]; it produced an improvement in notched Charpy impact strength from 1.1 to 3.7 kJ/m 2 at 30 wt% PCL.…”

“…Since PCL and PLA are not compatible, compatibilizers such as PLLA-PCL-PLLA triblock copolymer have been developed [18]; it produced an improvement in notched Charpy impact strength from 1.1 to 3.7 kJ/m 2 at 30 wt% PCL. Compatible PLA/PCL blends were prepared through reactive processing induced by catalysts [19] or crosslinkers [20,21]. Jiang et al [22] improved Izod impact strength by 170 % via mixing PLA with 20 wt% poly (butylene adipate-co-terephthalate) (PBAT).…”