(A) Concentration The concentration of the latex is expressed as the total solid content and the dry gel content. The dry content refers to the content of dry rubber in the latex. The total solid content refers to the content of all solid matter in the latex after removal of water and volatile components, expressed as a percentage. Total solid content and dry rubber content generally have a difference, this value is called the total dry poor, used to explain latex non-volatile non-rubber content. These indicators have important significance for guiding production and product quality.
Fresh latex concentration with age, season, tapping system, there are differences, generally only 20% -40% of the total solid content.
(B) the relative density
The relative density of the fresh latex is between 0.96 and 0.98, which is determined by the relative density of the whey (1.02) and the relative density of the rubber hydrocarbon (0.9064), which can be approximated by the relative density. The higher the rubber hydrocarbon content, the smaller the relative density of the latex, as shown in the table.
(C) viscosity
The fresh latex having a total solids content of about 35% has a viscosity of about 12 to 15 mPa · s, which varies considerably with the acquisition period and other factors. Generally the higher the total solids content of the viscosity, but the same total solid content of latex, due to preservation methods, storage time, the size of the different particles, the viscosity will be different.
(D) surface tension
The size of the surface tension indicates that the latex is evenly distributed over the solid surface - the so-called wetting performance. Rubber is insoluble in water, but latex contains a large number of surface tension substances can reduce the water surface activity, such as proteins, fatty acids, etc., they can reduce the surface tension of latex. Such as the total solids content of 38% to 40% of the latex, the surface tension of about 38 ~ 40mN / m, far lower than the water (72Mn / m), and thus hydrophilic surface such as cloth, leather and other wetting and penetration Can often often with the reduction of its surface tension increases, the production of latex still can not meet the technical requirements, the need to add some surfactants, in order to further improve the surface properties and increase wetting.
(E) PH value
The pH of the latex has a great influence on its stability. Fresh latex was neutral, slightly weak alkaline tendency, PH value of 7 to 7.2. After several hours to more than 10 hours, due to the impact of bacteria and enzymes in latex, PH value will be reduced and become acidic, resulting in coagulation. To this end, often add ammonia or other alkali, so that PH value increased to 10 ~ 10.5, in order to be able to save a longer time.