Simultaneously reinforce and toughen polypropylene by in‐situ introducing polylactic acid microfibrils

Abstract

A petroleum-based polymer, isotactic polypropylene (iPP), and a biodegradable polymer, poly(lactic acid) (PLA), were compounded and molded into parts through the micro-injection technique. A systematic structural investigation indicated that the microfibrillation of PLA minor phase depended on the operation parameter of inter-mixer, ie, rotor speed. The higher rotor speed, the lower viscosity ratio of the PLA/iPP pair was favorable for microfibrillation occurred during micro-injection process. The PLA microfibrils with high aspect ratio was successfully introduced into iPP matrix, and the tensile strength and strain at break of iPP/PLA blends were simultaneously improved. This study suggests a promising method for designing special microfibrillar morphology in polymer blend by using conventional melt processing techniques.

Toughening modification of PLLA with PCL in the presence of PCL‐b‐PLLA diblock copolymers as compatibilizer

“…PLLA exhibited a number of interesting properties, including excellent biodegradability and biocompatibility, easy processability, and good mechanical strength . Until now, PLLA had enjoyed great success in replacing conventional petroleum‐based plastics in commercial applications, even in biomedical applications . However, the commercially available PLLA had small elongation at break and had poor toughness; the inherent brittleness limited PLLA widespread application in package bags, medical devices, automotive parts, etc …”

In Situ Microfibril Structure in Incompatible Isotactic Polypropylene/Polylactic Acid Blends Controlled By Viscosity Ratio

“…As we have systematically studied the influence of component ratio on the phase morphology of iPP/PLA blends in our previous work . It is the finest component ratio of 60/40 (iPP/PLA) that can promote the formation of in situ microfibril structure and then the excellent mechanical properties can be obtained.…”

“…Therefore, it will be significant to explore a more easily implemented process, such as injection molding process, to directly obtain MFC with well‐orientated fibrils. In our previous works , the well‐oriented polylactic acid (PLA) fibrils, taken the isotactic polypropylene (iPP)/PLA blends as subject, had been generated during microinjection molding process. At this point, the identical T m of iPP and PLA makes the MFC cannot be realized by extrusion‐stretching method .…”

“…In our previous works , composition ratio as an important factor on the influence of microfibril structure and mechanical properties of iPP/PLA blends has been systematically studied. However, the critical factors, such as processing parameter, viscosity ratio, and interfacial tension, have not been carefully analyzed on the influence of phase morphology.…”

In‐situ generation of biodegradable poly(lactic acid)/poly(butylene succinate) nanofibrillar composites via a facile and cost‐effective strategy of pressure‐induced flow processing

“…Currently, it has been reached a consensus that the formation of unique microfibril or nanofibrill structures using processing flow fields is one of the effective and eco-friendly methods to achieve expected macro-performance. 7 Several new-type polymer processing techniques, including slit die extrusion-hot stretching-quenching (SDEHSQ), [8][9][10][11] oscillation shear injection molding (OSIM), [12][13][14] multistage stretching extrusion (MSE), [15][16][17][18][19] and loop oscillating push-pull molding (LOPPM), [20][21][22][23] have successfully produced in-situ fibrillation reinforced composites. The reported literature showed that the existence of a fibrillated phase in in-situ composites not only endows higher specific interfacial area but also plays a heterogeneous nucleation effect to induce the formation of hybrid shish-kebab superstructure.…”