Mayans can use it to make shoes.
Although the Central American natives did not vulcanize formally as the modern people did, they could still use organic substances to achieve similar functions, such as mixing unprocessed emulsions with sap of different varieties of trees or juice of some rattan plants. Some indigenous people in Brazil use waterproof cloth.
There was a rumor that Portuguese people brought these clothes back to their motherland, frightened their fellow villagers, and were accused of witchcraft and tried. After it was introduced into Britain, people found that this material can effectively erase the traces left by pencils. So today's English rubber is also used to describe erasers. Interestingly, today's Americans are used to calling it eraser, but rubber is used to describe condoms. The natural origin of trefoil supply. More commercial. When it is damaged, it will secrete a lot of emulsion rich sap. In addition, fig trees and some Euphorbiaceae plants can also be supplied.
In Germany, the supply was cut off during World War II, and it was tested to obtain it from these plants, but later it was changed to manual production. At first, the trees were good at growing in South America, but now there are many trees planted in Southeast Asia through artificial transplantation.
In fact, Asia has become an important place of origin. It is made of inulin and can be cut quickly. Although more than half of the other materials are artificial at present, nature is still very important in some fields, such as automobile and military industries.
Electric butterfly valve: a butterfly valve made of the compressibility of air in a closed container. The working principle is to fill the closed pressure cylinder with inert gas or oil gas mixture, so that the pressure in the chamber is several times or dozens of times higher than the atmospheric pressure. The movement of the piston rod is realized by using the pressure difference generated by the cross-sectional area of the piston rod being less than the cross-sectional area of the piston. Today, Dongfeng's editor focuses on the impact of vibration frequency on Shanghai electric butterfly valve, which is very important because if we reduce the vibration frequency of our electric butterfly valve, we can get a better valve function both in the use of electric butterfly valve and in the installation of electric butterfly valve, The details are as follows:
General electric butterfly valves can bear axial and radial loads at the same time, and can also transmit torque. By adjusting the internal pressure, electric butterfly valves can obtain different bearing capacities, so they can meet the needs of multiple loads: electric butterfly valves are light in weight, long in service life, and have good high-frequency vibration isolation and sound insulation performance. The electric butterfly valve requires small installation space and is easy to replace.