The paper continues the research into the wet mesh breaking strengths of commercial fishing nets exposed to freezing and thawing. In the first paper, it was discovered that the strengths generally increase during exposure. However, in this paper the strengths of polyamide multifilament nettings were found to decrease, when tensile measurements were conducted in a frozen state in an environmental chamber. The changes in the netting yarns caused by freeze-thaw cycling were analysed by using mechanical and thermoanalytical methods (DSC and DMTA) and wide angle X-ray diffraction scans, (WAXS). DMTA revealed changes in transition temperatures typical of the early stages of degradation. More detailed interpretation of the analyses was not possible due to a lack of information concerning the production and thermomechanical background of the yarns. WAXS patterns of polyamide monofilament nets were resolved by a curve fitting method to distinguish between the crystalline and amorphous phase. Changes in crystallinity did not alone explain the changes in the wet mesh breaking strengths although they may have contributed to them. In polyethylene nettings, the increase of the wet mesh breaking strengths can also be explained as a result of crosslinking reactions at the early phase of degradation. In both polyamide and polyethylene nets, the rising of wet mesh breaking strengths was probably partly due to settling and tightening of knots caused by relaxation and creep. Differences in the heat setting processes of the yarns and nets provide a possible explanation for the different dispositions to degradation. Low service temperatures, in general, are favourable to fishing gear because the strengths of the yarns were higher in a frozen state than at room temperature.
The effect of cold winter conditions on fishing gear materials. Part II: Strength examination of freeze-thawed polyamide and polyethylene multifilament nettings
Einfluß winterlicher Bedingungen auf Material für Fischereigeschirr. Teil 2: Prüfung des Frost-Tau-Verhaltens von Polyamid- und Polyethylenmultifilamentnetzen
Journal of the Textile Institute ; 87 , 3 Part 1 ; 572-585
1996
14 Seiten, 9 Bilder, 2 Tabellen, 15 Quellen
Article (Journal)
English
Investigation of the effects of cold winter conditions on fishing gear materials
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