Polymers explained from SKMClasses Bangalore
Gutta-percha latex is biologically inert, resilient, and is a good electrical insulator with a high dielectric strength. The wood of many species is also valuable.
Western inventors discovered the properties of gutta-percha latex in 1842, although the local population in its Malayan habitat had used it for a variety of applications for centuries. Allowing this fluid to evaporate and coagulate in the sun produced a latex which could be made flexible again with hot water, but which did not become brittle, unlike rubber prior to the discovery of vulcanization.
By 1845, telegraph wires insulated with gutta-percha were being manufactured in the United Kingdom. It served as the insulating material for some of the earliest undersea telegraph cables, including the first transatlantic telegraph cable. Gutta-percha was particularly suitable for this purpose, as it was not attacked by marine plants or animals, a problem which had disabled previous undersea cables. The material was a major constituent of Chatterton's compound used as an insulating sealant for telegraph and other electrical cables. Polyethylene's superior insulation property has displaced it.
Western inventors discovered the properties of gutta-percha latex in 1842, although the local population in its Malayan habitat had used it for a variety of applications for centuries. Allowing this fluid to evaporate and coagulate in the sun produced a latex which could be made flexible again with hot water, but which did not become brittle, unlike rubber prior to the discovery of vulcanization.
By 1845, telegraph wires insulated with gutta-percha were being manufactured in the United Kingdom. It served as the insulating material for some of the earliest undersea telegraph cables, including the first transatlantic telegraph cable. Gutta-percha was particularly suitable for this purpose, as it was not attacked by marine plants or animals, a problem which had disabled previous undersea cables. The material was a major constituent of Chatterton's compound used as an insulating sealant for telegraph and other electrical cables. Polyethylene's superior insulation property has displaced it.
Thixotropy is a time-dependent shear thinning property. Certain gels or fluids that are thick, or viscous, under static conditions will flow (become thin, less viscous) over time when shaken, agitated, sheared or otherwise stressed (time dependent viscosity).
It is an isothermal slow recovery when the stress is removed. Increase in rate of shear is due to decrease in viscosity.As stress is applied the final saturation state is Sol state. Gum solutions are Thixotrophic.
They then take a fixed time to return to a more viscous state. In other words: some non-Newtonian pseudoplastic fluids show a time-dependent change in viscosity; the longer the fluid undergoes shear stress, the lower its viscosity. A thixotropic fluid is a fluid which takes a finite time to attain equilibrium viscosity when introduced to a steep change in shear rate. Some thixotropic fluids return to a gel state almost instantly, such as ketchup, and are called pseudoplastic fluids. Others such as yogurt take much longer and can become nearly solid. Many gels and colloids are thixotropic materials, exhibiting a stable form at rest but becoming fluid when agitated.
Some fluids are anti-thixotropic: constant shear stress for a time causes an increase in viscosity or even solidification. Constant shear stress can be applied by shaking or mixing. Fluids which exhibit this property are usually called rheopectic. They are much less common.
Milk of Magnesia is Antithixotrophic.
Negative thixotropy, also called antithixotropy, is the effect of a flow-induced increase in viscosity that has been observed for many polymer solutions.
Rheopexy
A solid with Rheopexy properties becomes Gel at the saturation. A property of certain materials in which an increased rate of shear favors an increase in viscosity.
[rheo- + G. pēxis, fixation]
Rheopecty or rheopexy is the rare property of some non-Newtonian fluids to show a time-dependent increase in viscosity (time-dependent viscosity); the longer the fluid undergoes shearing force, the higher its viscosity.
Rheopectic fluids, such as some lubricants, thicken or solidify when shaken. The opposite and much more common type of behaviour, in which fluids become less viscous the longer they undergo shear, is called thixotropy.
Examples of rheopectic fluids include gypsum pastes and printer inks. In the body synovial fluid exhibits the extraordinary property of inverse thixotropy or rheopexy.
https://www.youtube.com/watch?v=Ol6bBB3zuGc
A solid with Rheopexy properties becomes Gel at the saturation. A property of certain materials in which an increased rate of shear favors an increase in viscosity.
[rheo- + G. pēxis, fixation]
Rheopecty or rheopexy is the rare property of some non-Newtonian fluids to show a time-dependent increase in viscosity (time-dependent viscosity); the longer the fluid undergoes shearing force, the higher its viscosity.
Rheopectic fluids, such as some lubricants, thicken or solidify when shaken. The opposite and much more common type of behaviour, in which fluids become less viscous the longer they undergo shear, is called thixotropy.
Examples of rheopectic fluids include gypsum pastes and printer inks. In the body synovial fluid exhibits the extraordinary property of inverse thixotropy or rheopexy.
https://www.youtube.com/watch?v=Ol6bBB3zuGc