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In recent years, elastomeric rubber-plastic blends have become technologically
interesting for use as thermoplastic elastomers (TPE). They can have many of the
propertiesof rubbers, but they can be processable as thermoplastics.
This project looked into the processmg conditions and upscalling of recycled
rubber/plastic blends. Recycled elastomers were obtained from commercial sources,
and included a mixture of styrene-butadiene rubber (SBR), and natural rubber (NR),
with two different mesh sizes. A blend of recycled Linear Low Density Polyethylene
(LLDPE) and Low Density Polyethylene (LDPE) was used as the thermoplastic
polymermatrix.
In this study, the crumb rubber and polyethylene has been characterised. Then having
noted some of their properties, rubber/plastic blends were prepared by melt mixing, in
a HaakeBatch mixer varying test temperature and residence time.
Fourdifferent compatibilization techniques were used to improve the compatibility at
the interface between the rubber particles and polyethylene, these were: 1) Titanate
CouplingAgent, 2) Silane, 3) IBE (ethylene-co-glycidyl methacrylate) 4) Delinker.
Attempts were also made to assess the extent to which the devu1canization system
scissionsthe crosslinks in the rubber vulcanizate by means of an experimental grade
delinker.
Results indicate that the best method of processing was melt blending in a Haake
batch mixer compared to a twin screw extruder. A 32% improvement was found for
the control blend when blended in the Haake mixer compared with the twin-screw
extruder. IBE compatibilized blends and delinked rubber/plastic blends gave better
tensile properties when compared with silane and titanate coupling agents
compatibilized blends. Delinked, rubberlNR compounds also had superior
elongational capability. Recycled elastomers with smaller particle size were observed
to improve mechanical properties of resultant blends.
