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Open AccessArticle

Hydrophobicity Tuning by the Fast Evolution of Mold Temperature during Injection Molding

1
Department of Industrial Engineering, University of Salerno, via G. Paolo II 132, 84084 Fisciano (SA), Italy
2
Institute for Polymers, Composites and Biomaterials (IPCB-CNR), via Previati n. 1/E, 23900 Lecco, Italy
*
Author to whom correspondence should be addressed.
Polymers 2018, 10(3), 322; https://doi.org/10.3390/polym10030322
Received: 2 February 2018 / Revised: 26 February 2018 / Accepted: 9 March 2018 / Published: 15 March 2018
(This article belongs to the Special Issue Processing-Structure-Properties Relationships in Polymers)
The surface topography of a molded part strongly affects its functional properties, such as hydrophobicity, cleaning capabilities, adhesion, biological defense and frictional resistance. In this paper, the possibility to tune and increase the hydrophobicity of a molded polymeric part was explored. An isotactic polypropylene was injection molded with fast cavity surface temperature evolutions, obtained adopting a specifically designed heating system layered below the cavity surface. The surface topology was characterized by atomic force microscopy (AFM) and, concerning of hydrophobicity, by measuring the water static contact angle. Results show that the hydrophobicity increases with both the temperature level and the time the cavity surface temperature was kept high. In particular, the contact angle of the molded sample was found to increase from 90°, with conventional molding conditions, up to 113° with 160 °C of cavity surface temperature kept for 18 s. This increase was found to be due to the presence of sub-micro and nano-structures characterized by high values of spatial frequencies which could be more accurately replicated by adopting high heating temperatures and times. The surface topography and the hydrophobicity resulted therefore tunable by selecting appropriate injection molding conditions. View Full-Text
Keywords: hydrophobicity; contact angle; polypropylene; atomic force microscopy; injection molding; mold temperature evolution hydrophobicity; contact angle; polypropylene; atomic force microscopy; injection molding; mold temperature evolution
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MDPI and ACS Style

Liparoti, S.; Pantani, R.; Sorrentino, A.; Speranza, V.; Titomanlio, G. Hydrophobicity Tuning by the Fast Evolution of Mold Temperature during Injection Molding. Polymers 2018, 10, 322.

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