Surface chain cleavage behavior of PBIA fiber induced by direct fluorination

Direct Fluorination as Method of Improvement of Operational Properties of Polymeric Materials

“…Mild fluorination of hydrophilic polymers with a mixture containing an inert gas (He or N 2 ) gives rise to the cleavage of hydrogen bonds in the surface layers, the transition of the terminal polar groups (-OH, C=O, -COOH, -NH 2 ) to the surface and its subsequent hydrophilization (Figure 2) [71,84]. This technique is used to improve the adhesion of hydrophilic components of composite materials at the prepreg stage in order to improve mechanical properties (see Section 3).…”

“…As a rule, the advancing contact angles are measured: i.e., the contact angles of test liquid drops on the surface investigated (Figure 1a); the angle is determined either goniometrically using a horizontal microscope, or using an approximate solution of the Laplace equation [68], which describes the shape of a drop in a gravitational field; the latter method is the basis of modern devices for determining the contact angle. The Laplace equation can also be used if the polymer object is a fiber in contact with the test liquid, as it was done before in the work of Cheng et al [71]. Determination of the edge angle through capillary rise [72] and the Wilhelmy plate [36] methods are used in single studies of changes in the surface properties of polymers as a result of fluorination.…”

Toward high-performance poly(para-phenylene terephthalamide) (PPTA)-based composite paper via hot-pressing: the key role of partial fibrillation and surface activation

“…[24][25][26] Since the chopped ber surface is smooth and has less chemical reactive groups, changing the inert surface and improving surface activity of the aramid chopped ber is of great importance. 8,[27][28][29] Previous reports have made great efforts including chemical etching by mixed acids, 30 ionization, surface irradiation by plasma, [31][32][33][34] ultrasonic treatment, chemical graing methods, [35][36][37] and uorinated modication of the molecular chains 38 and other approaches. 35,[39][40][41] For instance, phosphoric acid treatment on PPTA showed increasing content of surface functional groups but resulted in a declined mechanical property of PPTA bers.…”

Surface modification of an aramid fiber via grafting epichlorohydrin assisted by supercritical CO2

“…The peaks at the binding energies of 285, 400 and 532 eV, corresponding to carbon, nitrogen and oxygen, represent the main elemental composition of the untreated AF surface. 35 There were no signicant changes in the chemical composition of the ber surface when the bers were treated with pure ScCO 2 , as summarized in Table 1, indicating that pure ScCO 2 had no obvious modication effects on the ber surface. Aer treatment with ECH in ScCO 2 , a new binding energy peak appeared at 201 eV, corresponding to chlorine.…”