What to do with old over-matured latex compounds?

Manufacturer: Would you please suggest some inputs on how to utilize old compounded latex collected from the dipping tank ?

During plant shutdown, compounded latex from the dipping tank is collected and stored but later becomes over-matured.When resuming dipping operations, some quantities of over-matured latex are mixed with fresh compound but the defect rate increases. Can you please suggest some ideas based on your experience in this regard?

What are the properties to be tested for the over-matured latex before using? Is it possible to use the over-matured latex for some other purpose?

John Woon (Senior Latex Consultant): The use of old and over matured compounded latex for dipping is not recommended because it tends to give cracking during the dipping process due to weak gel strength and the final products will also exhibit poor tensile properties with low tensile strength and elongation at break. This is due to the poor rubber particle-to-particle integration during drying.

You can mix a low percentage of the over-cured latex with fresh latex compounds, treating it as a filler.

The quality of the over-cured latex could be accessed by determining the physical properties of the cast films. These include tensile strength, modulus, elongation at break and tear strength. Based on these results, you could then decide on the ratio of the blend to be used.

Needless to say, the film properties of the blend must also be tested to ensure that the final products are still acceptable as per your own quality assurance requirement.

Perhaps you could look into using the over-matured latex compounds for other applications such as carpet backings and impregnation of textile such as non-woven fabrics. However, some lab works should be carried out to access the suitability of this approach.