Invention of biobased polymer alloys and their application in plastic automobile parts

• Published in: Polymer journal Vol. 55; no. 7; pp. 753 - 760
• Main Authors: Kawada, Jumpei, Kitou, Masayuki, Mouri, Makoto, Ario, Toshiyuki, Kato, Keisuke
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.07.2023; Nature Publishing Group
• Subjects: 639/301; 639/925; Automotive parts; Biomaterials; Bioorganic Chemistry; Bioplastics; Chemistry; Chemistry and Materials Science; Chemistry/Food Science; Compatibility; Compatibilizers; Emission analysis; Impact strength; Impact tests; Injection molding; Mechanical properties; Modulus of rupture in bending; Morphology; Plastic foam; Polyamide resins; Polymer Sciences; Polypropylene; Scanning electron microscopy; Surfaces and Interfaces; Technical Review; Thin Films; Transmission electron microscopy; Twin screw extruders; Weight reduction
• ISSN: 0032-3896; 1349-0540
• DOI: 10.1038/s41428-023-00760-1

Polyamide 11 (PA11), a 100% biobased plastic derived from inedible plants, and polypropylene (PP) were mixed with a reactive compatibilizer using a twin-screw extruder. The mechanical properties and morphology of the resulting injection-molded PP/PA11 bioalloys were investigated by flexural tests, Charpy notched impact tests, field-emission scanning electron microscopy (FE-SEM), and transmission electron microscopy (TEM), among other tests. We found that it was possible to control the morphology of the bioalloy and that it had a wide range of mechanical properties depending on the morphology. When the morphology of the bioalloy was a “ nanosalami” structure, as revealed by FE-SEM, the material had a Charpy notched impact strength of 70–85 kJ/m 2 , which is superior to that of polycarbonates, without a large reduction in the flexural modulus. TEM observations showed that the reactive compatibilizers were located in the interphase between the matrix and dispersed phase. The compatibilizers played a key role in improving impact strength. The bioalloy could be used for foam injection molding; therefore, it was able to be applied as a foamed door trim, resulting in an approximately 30% weight reduction for the plastic part. Sustainable and 100% biobased plastics, polyamide 11 (PA11), derived from nonedible plants are mixed with polypropylene (PP) and a reactive compatibilizer in a twin-screw extruder. It is found that PP/PA11 bioalloys exhibited surprisingly good impact strength without losing flexural modulus only when the morphology of the PP/PA11 bioalloys was well controlled at nano-meter level, such as “nano-salami” structure. This leads to overcome a past and traditional issues in biobased plastics, resulting in applying for automobile plastic parts. This technology would contribute to realizing “carbon neutrality”.