الفهرس 
1. INTRODUCTIONOnly 14 pages are availabe for public view
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Abstract
A novel method to synthesis reactive nano-rubber
particles is described. Considered as a frontier engineering
material, reactive nano-rubber particles will find the way in
almost all applications, specifically, in toughening of rigid
structural materials (epoxy resin). The process involves two
steps: natural rubber sample (cis-1,4 polyisoprene) is
emulsified using soap-in-situ method to sub-micro (nano) size
particles, followed by a crosslinking reaction in the bulk of the
particle. Some remaining double bonds on the surface were
then used for further functionalization (epoxidation). Then,
these epoxidized nano-rubber particles have been introduced
before the curing reaction of epoxy resins which is considered
as a novel method for providing toughness with excellent
adhesion in brittle epoxies.
For the present work, natural rubber (cis-1,4-
polyisoprene) was chosen, for its elasticity, resilience, and
toughening effect for most brittle materials and has been used
to prepare the core of the desired particles. The solutionemulsification
technique was used to produce artificial latices
based on natural rubber (cis-1,4-polyisoprene). Conventional
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emulsification techniques as well as ‘miniemulsification’
methods have been investigated. In both cases, a larger volume
of polymer is reduced into tiny rubber balls in the nano scale
using an ultrasonic homogenizer.
The difference between conventional emulsification and
miniemulsification resides in stabilizing the system. For the
conventional emulsification method, an equimolar mixture of
anionic (Potassium palmitate) and nonionic (polyoxyethylene
(100) stearyl ether, Brij 700) surfactants was found to be the
optimal surfactant system. For the miniemulsification method,
a combination of Potassium palmitate as a surfactant and
hexadecane or cetyl alcohol as a costabilizer was the most
suitable system. Both conventional emulsification and
miniemulsification lead to latices with monomodal particle size
distributions and volume-average diameters ranging from 300
to 400 nm, determined with light scattering techniques.
In the second step, some remaining double bonds on the
surface were then used for further functionalization
(epoxidation). Then, these epoxidized nano-rubber particles
have been introduced before curing reaction to epoxy resins
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which is considered as a novel method for providing toughness
with excellent adhesion in brittle epoxies.
Here we show a new class of pre-formed functional
polyolefin rubber particles with well defined particle sizes;
specifically in the nano-scale which exhibits good
processibility, good chemical and physical stability, and an in
situ forming core-shell rubber particle structure with epoxy
resins.
The combination of Scanning Electron Microscope
(SEM) and Transmitting Electron Microscope (TEM) results
indicates the effectiveness of the grafting reaction and
consequently the interfacial adhesion between the dispersed
rubber particles and the continuous domain of the investigated
epoxy resins.