Cause of wear-resistance enhancement of a polyurethane film composite by plasma-functionalized carbon nanotubes

Abstract

Our previous investigation demonstrated that the wear-resistance of polyurethane (PU) film was enhanced by making the film composite utilize carbon nanotubes (CNTs). The use of plasma-treated CNTs further provides enhancement; this led to the hypothesis that the improvement could be more effective by applying isocyanate groups modified on CNTs treated with plasma. This was determined as the plasma contained nitrogen and oxygen species and because a material with isocyanate groups can function as a hardener of polyurethane. This article documents findings ensuant to our previous publication. Here, we present our investigation of the microscopic morphology of the PU film (physical aspect) and identified the chemical bonds (chemical aspect) in order to present the theorem of the enhancement. Observation of the morphology showed no specialty on the PU films with plasma-treated CNTs. On the other hand, an observation with an organic fluorescence, acridine yellow, showed evidence of the chemical aspect used to enhance the film composite with CNTs. Therefore, we concluded that the most effective method was to use isocyanate groups attached through plasma treatment, in order to improve PU wear-resistance.

Quantitative effect of plasma‐processed multi‐walled carbon nanotubes for mechanical property of in situ polymerized polyurethane composite

“…The possible reason is that the plasma treatment gives surface modification of the CNTs improving the interfacial interactions between CNTs and PU film. As reported previously, 19–21 the plasma treatment functionalized NCO groups on the CNT surface, and the CNTs also can react with polyols during the in situ polymerization as other isocyanates do. This chemical reaction should give good interfacial interaction (bonding) between the filler and polymer so that the mechanical property of the composite film is improved due to the mechanical excellency CNTs have.…”

“…Interestingly, the pCNT has a different decreasing trend from the dispersion of nCNT, which shows pCNT is more dispersive in the solvent where both HDI and toluene coexist. In our previous report, we detected isocyanate groups (NCO) on the pCNTs with a fluorescent measurement, 19–21 so this dispersion difference could be due to NCO groups on the CNT surface. The molecular structure of HDI has NCO‐modified groups so the modified group could assist pCNT‐dispersion in the solvent.…”

“…The functionalized CNTs improved the material properties of polymers when the CNTs were utilized as a composite filler 3,4,31 . Our previous works show the improvement of wear resistance of PU due to the plasma functionalized CNTs 19,32 . Then, our most recent work showed the effectiveness of the in situ polymerization for PU synthesis with plasma‐treated CNTs 33 .…”

“…3,4,31 Our previous works show the improvement of wear resistance of PU due to the plasma functionalized CNTs. 19,32 Then, our most recent work showed the effectiveness of the in situ polymerization for PU synthesis with plasma-treated CNTs. 33 In situ polymerization is a technique in which the plasma-treated CNTs are included in a solvent during the synthesis, but which allows us to include the CNTs in PU composite before the urethane reaction occurs.…”

“…We have researched the CNTs exposed to low-temperature plasma, and realized plasma functionalization with amino groups (ÀNH 2 ) 18 and isocyanate groups (ÀNCO) [19][20][21] on the CNT surface. Also, we investigated the effect of plasma-treated CNTs as a composite filler on polymers, mainly focusing on polyurethane (PU).…”