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Acetylene coating on cornstarch plastics produced by cold plasma technology

Bastos, Daniele Cruz, dos Santos, Anastácia Evangelina Fonseca, Simao, Renata Antoun
Die Stärke = 2014 v.66 no.3-4 pp. 267-273
Raman spectroscopy, acetylene, coatings, cold, contact angle, corn starch, gases, plastics, polymerization, starch, sulfur hexafluoride
This study tested the effectiveness of sulfur hexafluoride (SF₆) plasma treatment and acetylene (C₂H₂) plasma polymerization for turning thermoplastic starch (TPS) hydrophobic. A surface modification method was employed using different precursor gases, SF₆ and C₂H₂, and a combined treatment using SF₆ followed by C₂H₂ (SF₆/C₂H₂) and then the reverse, using C₂H₂ first followed by SF₆ (C₂H₂/SF₆). The same self‐bias voltage and treatment time was used for each gas across all treatments: −100 V and 480 s for SF₆, −200 V and 2400 s for C₂H₂. The best results were obtained from a C₂H₂‐coated surface, treated with SF₆ (C₂H₂/SF₆). This process increased the contact angle to >128°. When treated in the opposite order (SF₆/C₂H₂), the contact angle decreased to 90° and a homogeneous, smoother coating was produced. Raman spectroscopy confirmed the presence of D and G bands in plasma‐treated films. Under these treatments, all surfaces presented a contact angle higher than 75°.