A Comparative Study on the Felting Propensity of Animal Fibers
The felting propensity of different animal fibers, particularly alpaca and wool, has been examined. The Aachen felting test method was employed. 1 g of each type of fiber was soaked in 50 ml of wetting solution and agitated in a dyeing machine to make felt balls. The diameter of each ball was measured in nine directions and the ball density was calculated in g/cm3; the higher the density value of the ball, the higher the feltability of the fibers. The effects of fiber diameter and fiber length on the felting propensity of these fibers were investigated. The results show that the alpaca fibers felt to a higher degree than wool fibers, and short and fine cashmere fibers have lower felting propensity than wool fibers at a similar diameter range. There is a higher tendency of felting for bleached and dyed alpaca fibers than for untreated fibers. Fiber length has a remarkable influence on the propensity of fiber felting. Cotton and nylon fibers were also tested for felting propensity to verify the mechanism responsible for the different fiber felting behavior.
Structure and mechanics of aegagropilae fiber network
Significance Aegagropilae are centimeter-sized, nearly spherical fiber aggregate found on Mediterranean beaches. They result from aggregation and compaction of the remains of the seagrass Posidonia oceanica. We find that they possess remarkable mechanical properties, which are unexpected for a structure formed by random agitation caused by sea motion and held together solely by friction between the fibers. The study of such material offers perspectives for complex materials, such as felts and insulation materials. Fiber networks encompass a wide range of natural and manmade materials. The threads or filaments from which they are formed span a wide range of length scales: from nanometers, as in biological tissues and bundles of carbon nanotubes, to millimeters, as in paper and insulation materials. The mechanical and thermal behavior of these complex structures depends on both the individual response of the constituent fibers and the density and degree of entanglement of the network. A question of paramount importance is how to control the formation of a given fiber network to optimize a desired function. The study of fiber clustering of natural flocs could be useful for improving fabrication processes, such as in the paper and textile industries. Here, we use the example of aegagropilae that are the remains of a seagrass (Posidonia oceanica) found on Mediterranean beaches. First, we characterize different aspects of their structure and mechanical response, and second, we draw conclusions on their formation process. We show that these natural aggregates are formed in open sea by random aggregation and compaction of fibers held together by friction forces. Although formed in a natural environment, thus under relatively unconstrained conditions, the geometrical and mechanical properties of the resulting fiber aggregates are quite robust. This study opens perspectives for manufacturing complex fiber network materials.
11—THE NUMERICAL DISTRIBUTION OF FIBRES IN PILLS
A wearing action on a fabric first produces a fuzz of fibres, which then tangle together to form pills. In this paper, a theory is developed in which, by assuming the probability that a fibre becomes part of a pill to be constant, it is shown that the distribution of the number of fibres in pills is the sum of binomial distributions. Experimental data are shown to be consistent with theoretical predictions. In one sample, it was found that the pills developed in three phases, with a decreasing number of fibres entering the pills, whereas in another sample the pills developed in a single stage.