Helium plasma treatment voltage effect on adhesion of ramie fibers to polybutylene succinate

• Ramie fabrics were plasma treated with ethanol pretreatment to enhance mechanical properties.
• Surface roughness and water contact angle increased after plasma treatment.
• Plasma treatment voltage significantly affected treatment effect.
• Treated fibers had up to 45% improved adhesion to PBS resin.

Plasma modification effect on fiber surfaces is closely related to the plasma treatment voltage. In this study, ramie fibers with ethanol pretreatment were treated by helium plasma under four different applied voltages of 1.5, 3, 6, and 9 kV, respectively, to study the influence of plasma voltage on treatment effect. Scanning electron microscopy (SEM) showed rougher fiber surfaces with increasing plasma voltage. Dynamic contact angle analysis and X-ray photoelectron spectroscopy revealed that the fiber surface wettability decreased and more CC bonds were incorporated to ramie fiber surface by plasma treatment when the voltage was above 3 kV. Microbond pullout test showed that interfacial adhesion between ramie and polybutylene succinate for 1.5, 3, 6, and 9 kV group increased by 9.6, 29.6, 45.5, and 19.4%, respectively. Single fiber tensile strength test confirmed no significant strength loss for all groups after the plasma treatments. This study showed that proper selection of treatment voltage was critical for optimal improvement of bonding between cellulose fiber and thermoplastic resin using ethanol pretreatment followed by plasma treatment.