Most users generally believe that the elongation at break of skeleton material is bigger, then the conveyor belt more prone to "run length". This is a very typical misunderstanding, the habits and cotton fiber canvas, we emphasize a bit, for the EP canvas, we need to know the existing canvas cotton Lun aside, we believe that "the main reason for the long run" is not the nominal strength elongation and 10% skeleton material at elongation, "run length" only with the type of skeleton material related, namely and the skeleton of creep on. Here, we talk about the creep and relaxation properties of material, this point in the discussion of skeleton material properties in the future is very useful:

Fiber creep

Fiber and yarn in the constant tensile force effect, its deformation and tensile force some proportion. But in fact, the constant tensile force effect, deformation is not a constant, but rather a continuous changes over time, it will always continue to increase. In a in a tensile force effect, time-dependent deflection phenomenon, called "creep". This is the so-called conveyor belt "run length" the fundamental reason, in theory, and the elongation at break is almost independent of.

Fiber relaxation

In the constant tensile deformation, the internal fiber or yarn stress (tension) over time will continue to decline, this phenomenon is called "relaxation".

The basic reason of creep and relaxation of the fiber in the fiber structure. In the constant tension, high molecular fibre wrinkles extension Song state, especially the increasing chain length and the bond angle of Zhang He, only need to extreme can be completed on time, this is the instantaneous elastic deformation. As time went on, the macromolecular backbone local rotation, make the big molecule extension, position adjusting microfibril room, especially the large molecules are pulling sliding in the non crystalline region (visco elastic deformation or creep) so that the elongation length fiber, presents the creep phenomenon, gradually make Zhang Lijiang low.

Canvas creep and relaxation in addition to the fiber factors, for short fiber canvas, sliding correlation between it and the yarn fibre.

The effect of fiber creep and relaxation causes

The main reasons of fiber creep and relaxation is the slip between the molecules, so the impact force between the molecules (such as temperature, humidity) will influence the creep and relaxation.

Many fibers easily creep and relaxation in high temperature and high humidity environment, so it is commonly used in high temperature and high humidity eliminate stress. Especially the cotton fibers. The moisture absorption rate of male was 4.5%, the moisture will cause the diameter, the length of variable length, while water is similar to a plasticizer, the fiber is more susceptible to creep, and polyester public moisture absorption rate was 0.3%, and therefore will not have the similar phenomenon. Polyester stretch deformation relaxation rarely, so the springback and wrinkle resistance polyester good, this one from the polyester fabric and other fabric materials compared to analysis. So the transportation skeleton material should first choose polyester.

When the elongation rate, tensile time are also different, the slow elastic deformation is also different, tensile curve will be different, so in the skeleton material tests, must be the same tensile rate.

The above theoretical analysis, the cotton fiber is prone to creep, cotton canvas due to the slip between fibers, also can appear permanent variable length, so the conveyor belt of the so-called "run length" phenomenon is NN canvas and cotton canvas "patent". We don't have to worry about EP canvas conveyor belt will have "run length".