Multifunctional enhancement of polypropylene composite films via surface-modified palygorskite reinforcement

In this work, the effect of surface modification of palygorskite (Pal) on its dispersion and on the morphological, thermal, wettability, mechanical, optical, and gas transport properties of blown polypropylene (PP)/Pal films was investigated. PP/PPma/Pal composites containing 1 wt% modified Pal were prepared via twin-screw extrusion, followed by blown film processing. The results demonstrated that surface modification significantly improved filler dispersion within the polymer matrix, leading to a reduction of approximately 15% in crystallinity, as confirmed by SEM and XRD analyses respectively. In addition, the films exhibited enhanced thermal stability, with an increase of ∼25% in the onset degradation temperature, and improved wettability, while maintaining mechanical performance. The films showed high transparency (>91%) and reduced haze (32–37%), attributed to changes in crystallinity that increased the amorphous fraction and improved optical clarity. Notably, in contrast to the typical barrier effect reported for layered clays, the incorporation of fibrous Pal led to a substantial increase in gas permeability, with O 2 and CO 2 permeability rising by 190% and 220%, respectively. This behavior is attributed to reduced polymer chain packing and the presence of polar functional groups introduced during surface modification. These findings demonstrate a novel strategy for tuning gas transport properties in polymer films and highlight their potential for agricultural applications, particularly as greenhouse covering materials where enhanced gas exchange can promote plant growth and productivity.