Attached
A method for the preparation of granular rubber using a styrene/acrylic co-polymer as
the encapsulating agent is described. Two types of lattices, a 1:1 blend of compounded
latex & tow ammonia TMTD/ZnO stabilised centrifuged latex and low ammonia
TMTD/ZnO stabilised centrifuged latex, were used. The method consists of
encapsulating the lattices with styrene/acrylic co-polymer by varying the percentages
(i.e. 10%,30% and 50%), followed by coagulation with alum. The reagglomeration of
rubber particles was prevented by adding a partitioning agent. The resulting granules
were vacuum pumped and air dried. Based on the percentage of polyisoprene content
granular rubber with polyisoprene content of over 50% were selected for further study.
The two types of granular rubber samples were formulated to the ACS-l formula, and
their rheological and technological properties were evaluated. Also the two virgin
granular rubber samples were blended with different proportions of RSS-SLR 20 and
formulated to ACS-l and rheological and technological properties were determined.
Analysis of rheological behaviour of the vulcanizates with LATZ and compounded latex
have shown that as the percentage of granular rubber of the blends increases the rate of
vulcanization increases. The results show that physical properties such as tensile
strength, tear strength and abrasion volume, improve by the incorporation granular rubber
from LATZ and compounded latex and with a blend of above granular rubber with
RSS-SLR 20. This suggests that the presence of compounded latex in the medium
improves the reinforcing effect introduced by the acrylic polymer when incorporated into
the elastomer.
It could therefore be suggested that when compounded latex is present in latex medium,
the encapsulation process is taking place with already partially crosslinked or chemical
incorporated rubber particles. Once the encapsulation process takes place it could be
difficult the chemical ingredients to react with the rubber particles forming strong
crosslinks. Hence the physical properties of the systems with the compounded latex tend
to show improved properties.
