Classification of acid catalysts

There are four main types of catalysts: dinonylnaphthalene disulfonic acid, dinonylnaphthalene sulfonic acid, dodecylbenzene sulfonic acid, and p-toluenesulfonic acid.

Static and dynamic friction
Will drop because the dynamic friction force fk is overcome at this time, fk <fs, as long as the force F exceeds fk, the object will keep moving.

When moving an object, the whole process of friction change. The non-linear state of fk is caused by the unevenness of local attachment and unattachment between the molecules on the surface of the moving object teflon powder price and the molecules on the surface of the substrate (placement plane) in contact with it.

Friction f
We call the ratio of the horizontal force F required by the object to slide on the surface to the weight P of the object as the friction coefficient time/s
The change of friction when moving the object p, namely p knot. Since the force required to start sliding is greater than the force required to keep sliding, the static friction coefficient ps is always greater than the dynamic friction coefficient pk. Table 13-2 lists the typical friction coefficient values ​​of various contact surfaces.

Increase the coefficient of friction
During normal walking, when people encounter ground slip or water on the ground, the sole of the foot suddenly slips. At this time, the static friction coefficient ps between the sole and the ground has been overcome, so that the friction is reduced, and the dynamic at this moment The friction coefficient pk is smaller or much less than ps, that is, slipping will be unavoidable.

From the value of s and pk depends on the nature of the contact surface (chemical and physical structure, mechanical shape and surface energy, etc.) and their cleanliness and the temperature and humidity of the environment. Especially the mechanical shape of the contact surface plays an important role in the value of Js and k.