Study On The Properties Of The Warp-Knitted Bi-Axial Flexible Composites

As a newly arisen material, flexible composites have been used widely in many fields. In the present market, the reinforced part of the flexible composites are mostly woven fabric and warp-knitted bi-axial fabric. In contrast to the woven fabric, warp-knitted possess better tensile strength , elastic modulus ,tearing resistance and lower cost. Therefore the using percentage of warp-knitted fabric have been raised as the reinforcement part of the composites.Composites will inevitably suffer various outside power such as tensile, tear, shear effect once being used. Accordingly the mechanical behaviors are to be considered in emphasis during the process of designing the composites. At present there are mainly two methods to product flexible composites: coating and heat-melt laminating. We adopt the latter one in this paper and study the tearing property and interfacial adhesion property. Moreover we try to use the plasma effect on the fabric to improve the interfacial adhesion effect.We choose the warp-knitted bi-axial fabric made fromhigh-strength PET as the reinforcement, utilizing heat-melt laminating to make the fabric and PVC film become composites. With reference to relevant documents we know that the relationship between technical parameters of laminating and mechanical properties. In this paper we get the same conclusion that the temperature and time have more effect on the tearing and the interfacial adhesion properties, while the pressure are scarce.We found that the reason lies in the decrease of the degree of the yarn-concentration, which the tear resistance of the composites are lower than the basement fabric. Meanwhile, the diameter and the number of inserted yarn are the main factor of the tear resistance of the fabric. Moreover the way of inserting the yarn have impact on it too. We introduce the yarn strength utilizing ratio to analyze the difference because of the density and warp/weft direction.We make the first research on the composites we produced according to the present interfacial adhesion theory. From the view of fabric (changing fabric density and structure) we get the relevant conclusions. Apart from this, the results shows that the tear resistance are in reverse proportion to the interfacial adhesion property. Therefore we should consider this point when designing the product.In the paper we use the plasma to improve the interfacialadhesion. With the increase of the coarse degree on the fabric surface, the mechanical bonding ability increase . At the same time the active or group stimulated by the plasma effect improve the attraction and proliferation ability between the two surfaces. It is the two points mentioned above that make the interfacial adhesion of the composites better through plasma. The advantage lies in that we can assure the mechanical property. The main factors include handling time, voltage, strength and the kind of the plasma air.The conclusion we have got and the work we have done in the paper will do a great help to understand the properties of the bi-axial warp-knitted flexible composites. For the practical production they also possess a certain reference value.