Dynamic mechanical analysis, electrical properties and water sorption behaviour, of phenol formaldehyde nanocomposite reinforced with multiwalled carbon nanotubes

Electrically conductive bioplastics based on chitosan, polyvinyl alcohol, polyvinyl pyrrolidone, and plant extract nanoparticles for detecting Rhizopus stolonifer on tomato fruit

“…10,29 Similarly, Cheng et al 30 reported that the TS of hordein/chitosan films significantly increased, reaching values of 23 MPa with the chitosan polymer and 30-35 MPa with the combination of hordein/chitosan from 0:1 to 1:5 ratio. Additionally, the TS of our bioplastics was similar to that of the synthetic polymers such as polystyrene (35)(36)(37)(38)(39)(40)(41)(42)(43)(44)(45)(46)(47)(48)(49)(50)(51), poly(vinyl chloride) (40-52 MPa), and phenol-formaldehyde (34.5-62.1 MPa), which, according to Kaplan, 31 could be used in the manufacture of a sensor.…”

“…[40][41][42][43] On the other hand, the lack of total phenols in the NPs of roselle calyces compared to its extract should be attributed to the compound degradation that occurs during the NPs preparation process (e.g., by compound oxidation) or to the strong interactions between phenols and chitosan, thus reducing the number of compounds available which can be effectively released into the solvent during the extraction process, as was reported by Andrade et al 44 during the incorporation of cinnamic and ferulic acids on films of poly (vinyl alcohol). Additionally, it has been reported that phenolic compounds modify the electrical conductivity of nanomaterials, as stated by Ravindran et al 45 They found that phenol formaldehyde nanocomposite reinforced with multiwalled carbon nanotubes (MWCNT) increased its electrical conductivity from 0.04 to 2.4 S m À1 by increasing the phenol-formaldehyde from 0.05% to 0.08% and had a low resistance (1.7-0.02 Ω); however, above 0.12% of phenol formaldehyde the conductivity decreased to 0.01 S m À1 , and the resistance increased to 3.9 Ω, concluding that the agglomeration of MWCNT due to the van der Waals force adversely affects conductivity. In this sense, an increase in nanocomposites of phenolic compounds does not guarantee an increase in the conductivity of a material since phenols could favor interactions that lead to agglomeration.…”