Improvement of wetting properties of expanded perlite particles
Expanded perlite particles were surface functionalised using poly(hydroxyethyl methacrylate) (PHEMA) thin film under radio frequency (RF) plasma conditions in a rotating-bed plasma enhanced chemical vapor deposition (PECVD) system.
Using a rotating-bed system allowed effective agitation and mixing of the particles during depositions, which ensure uniform surface coating of highly porous and particulate materials.The effects of plasma power and plasma operation mode, namely pulsed and continuous modes on the deposition rates, structure, wettability and water holding capacities of expanded perlite particles were investigated. Chemical and morphological properties of uncoated and coated expanded perlites were determined by SEM, FTIR, contact angle, and BET analyses. Observed deposition rates changed between 10 and 35 nm/min., which were dependent on the deposition conditions.
Increasing the water holding capacity
It was found that pulsing the discharge helped to minimise undesirable monomer fragmentation while providing better film structure. The most hydrophilic PHEMA thin films were fabricated at 50 W plasma power and under pulsed-plasma mode. When the expanded perlite was modified with PHEMA under suitable experimental conditions, the water holding capacity of untreated particles is increased by more than twenty percent.
The study is published in: Progress in Organic Coatings Volume 120, July 2018, Pages 190-197.
Image Source: Pixabay
