On the Network Strength of Meta-Aramid Fiber Suspension and Its Relationship to Formation

Because of poor surface hydrophilicity, meta-aramid fibers readily form flocs by intertwining or interlacing, and this severely affects the uniformity of meta-aramid paper. To investigate the flocculation mechanism of meta-aramid fiber suspensions, the critical flocculant concentration, shear, and compressive network strength of meta-aramid fiber suspensions were examined. A hand sheet former was used to study the influence of the yielding properties of suspensions on the uniformity of meta-aramid paper, and the relationship between the formation index and rheological properties was determined. The results showed that the critical gel concentration ranged from 0.37 to 0.68 g/L, which was much lower than that of plant fiber suspensions. In addition, the compressive yield stress ( <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" id="M1"> <a:mi>P</a:mi> <a:mtext>y</a:mtext> </a:math> ) and shear yield stress ( <c:math xmlns:c="http://www.w3.org/1998/Math/MathML" id="M2"> <c:mi>τ</c:mi> <c:mi>y</c:mi> </c:math> ) of the meta-aramid fiber suspensions were found to increase linearly and exponentially, respectively, with an increasing concentration, and the uniformity index of the paper sheets was found to depend on a power of <e:math xmlns:e="http://www.w3.org/1998/Math/MathML" id="M3"> <e:mi>τ</e:mi> <e:mi>y</e:mi> <e:mo>⋅</e:mo> <e:mi>P</e:mi> <e:mi>y</e:mi> </e:math> . This provides an effective method for predicting paper sheet uniformity.