Environmentally-Friendly Acrylates-Based Polymer Latices - Advanced Materials for Agriculture, Food and Environmental Safety - page 150

poly(n-alkyl (meth) acrylate)s. Increasing the bulkiness of the alkyl group
also restricts the motion of backbone polymer chain, and hence the Tg
within a series of isomers increases. h e Tg of polymer is important for
attainment of properties required for specii c applications. Control of
the Tg is achieved through copolymerization of various combinations of
monomers. h e selection of monomer is based on the lowest cost com-
mensurate with achieving the properties for end-use applications.
J.K. Fink [11] gave an overview of acrylic and methacrylic ester poly-
mers. A large variety of monomers is known and discussed because of the
possibility of esterifying the acrylic acid and methacrylic acid with vari-
ous alcohols. Acrylic resins are appreciated for their exceptional clarity,
self-extinguishing, transparency, and superior design adaptability. Special
formulations are also described in detail.
Poly(methyl methacrylate) (PMMA) is type of thermoplastic used
throughout the world in applications such as transparent all-weather
sheets, electrical insulation, bathroom units, automotive parts, sur-
face coating and ion exchange resins, etc. Hamielec et al. [12] studied
the free radical polymerization of MMA initiated by an ultraviolet (UV)
light. h ey found that the termination rate constant decreases at high
conversions.
Wunderlich [13] investigated polymerization of butyl acrylate in ben-
zene and butyl propionate at 30, 50, and 70

C as a function of the con-
centration of initiator and monomer. h e rate of polymerization and the
molecular weight distribution of the formed polymers were measured at
conversions less than 3%. h e results deviate from the ideal kinetic model
of radical polymerization. h e reaction rate constants were obtained based
on the conversion and molecular weight data.
Scott and Senogles [14] investigated the polymerization kinetics of
n-lauryl acrylate (LA) in ethyl acetate and n-heptane at 40

°

C. h ey found
that primary radical terminations were unlikely to play any signii cant role
at higher monomer concentration, and autoacceleration ef ects do not
occur during the high conversion polymerization of LA.
h e homopolymers of sot monomers like alkyl acrylates, having 4-17
carbon atoms in the alkyl group, such as 2-ethylhexyl acrylate (2-EHA),
BA and EA have Tg below 0

°

C. h ese monomers possess inherent tacki-
ness and lack of sui cient cohesive strength. Since homopolymers are
produced from a single monomeric species, the properties of such latexes
are predetermined, and cannot be modii ed without the incorporation of
additional chemical components. For this reason, most commercial emul-
sions are comprised of a comonomer system (i.e., a combination of dif er-
ent monomers) rather than a single monomer. h e properties (e.g., glass

°