Water absorption kinetics of palygorskite nanoclay/polypropylene composite foams

• Published in: Polymer bulletin (Berlin, Germany) Vol. 81; no. 5; pp. 4149 - 4174
• Main Authors: Perez-Matu, R. R., Avilés, F., Gonzalez-Chi, P. I.
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer Berlin Heidelberg 01.04.2024; Springer Nature B.V
• Subjects: Cellular structure; Characterization and Evaluation of Materials; Chemistry; Chemistry and Materials Science; Clay; Complex Fluids and Microfluidics; Dispersion; Electron microscopy; Extrusion dies; High density polyethylenes; Kinetics; Mechanical properties; Microscopy; Molecular weight; Morphology; Nanocomposites; Optical microscopy; Organic Chemistry; Original Paper; Physical Chemistry; Plastic foam; Polymer Sciences; Polymers; Polypropylene; Porous materials; Soft and Granular Matter; Surface chemistry; Twin screw extruders; Water absorption; Mexico; Water absorption; Kinetics; Polypropylene foams; Palygorskite; Modular extrusion
• ISSN: 0170-0839; 1436-2449
• DOI: 10.1007/s00289-023-04822-5

The present work studies the water absorption kinetics of polypropylene foams modified with palygorskite nanoclay. The polypropylene/palygorskite composites were prepared with a modular twin-screw extruder and then foamed in a conical twin-screw extruder. The mechanisms of water absorption kinetics of the polypropylene/palygorskite foams were analyzed using a multi-stage model to understand the influence of the clay concentration, nanoclay dispersion and foam cell morphology on the water absorption behaviour of the foams. The solid nanocomposites were characterized by transmission electron microscopy to measure the clay dispersion in the matrix. The nano-reinforced foams were characterized by optical microscopy to measure the cell size and by scanning electron microscopy to measure the size of the foam micropores. Water absorption, foam density and cell morphology were also measured. The nanoclay modifies the foam cellular structure, generating non-homogeneous and non-uniform open cells; these cells encompass micropores which facilitate water diffusion consequently the water absorption properties of the foams are modified. The different screw configurations used during the extrusion process of the composites yield polypropylene foams with different clay dispersion and consequently different foam cellular structure.