Study On The Tearing Strength Of PU Coated Fabrics

In this paper, the mechanical model expressing trapezoid tearing strength of coated fabric was proposed, and the factors influencing Single-rip tear strength of coated fabrics were studied. At the same time, the measuring methods of tearing strength and the influence of coating processing parameters on tearing strength were also studied.Tearing strength of the twelve kinds of coated fabrics with different specifications were measured by using four different tearing methods, the results show that double-rip tearing strength and trapezoid tearing strength are bigger, while single-rip tearing strength and falling-pendulum tearing strength are smaller. The correlative coefficient of single-rip tearing strength double-rip tearing strength and falling -pendulum tearing strength is 0.76 -0.98, however the correlative coefficient of trapezoid tearing strength and other methods tearingstrength is very small. And the tensile properties of coated fabric and uncoated fabric were tested, after coating, tensile strength of fabric is raised, but breakingelongation and trapezoid tearing strength are reduced. Moreover, the influences of coating processing on tearing strength were studied, as curing temperature and coating thickness increase, the tearing strength of coated fabric decreases. While baking tune has no significant impact on tearing strength of coated fabric. In the trapezoid tearing method, stress concentration will be occurred near the cut because cut was made in the samples, the stress concentration weaken coefficient of coated fabric was smaller than that of uncoated fabric.Based on previous experiment and analysis, tearing failure mechanism were obtained, coating agent enters interspaces of yarns, friction and concretion of yarns were enhanced, thus slippage of yarns are reduced. Coating film didn't contribute to tearing strength of fabric, while it lowered tearing strength because PU entered the fabric, therefore the number of yarns in tearing triangle decreases, and there is severely stress concentration. A mechanical model expressing trapezoid tearing strength of coated fabric is proposed; the experimental results showed that the mechanical model could be used to predict trapezoid tearingstrength of coated fabric with certain precision.The relationship between the warp single-rip tearing strength and the yarn tensile properties as well as fabric structure is studied by multi-element linear regression for the eighteen kinds of coated fabrics with different specifications. The analysis shows that the main factor influencing the warp single-rip tearing strength of coated fabrics is warp strength followed by pull-out force, weft density and warp density while the influence of warp breaking elongation and other factors is very small.