198
K-carrageenan as compared to ʎ-carrageenan which may be due to the presence of
additional sulphate groups in ʎ-carrageenan. The sonication breaks the Carrageenan
into its oligomers that can be applied as plant growth promoter, antiviral, antitumor,
antioxidants, anticoagulant, antithrombotic and hydrogels for burns dressings.
These functions are linked to oligomers with specific molecular weight range
(Abad 2010).
Sonication was also found to reduce the molecular weight of guar gum. The
reduction of Guar Gum (GG) molecular weight for an appropriate modulation of its
flow and gelling properties could ultimately be useful in pharmaceutical industries
for innovative drug formulations in cosmetics and food industry (Ogutu et al. 2015).
The ultrasonic degradation of CMC gum was studied under different operating
parameters such as time of irradiation, and solution concentration has been investigated. The experimental results show that the viscosity of polymer solution
decreased with an increase in the ultrasonic irradiation time. It has also been
observed that major extent of degradation takes place in the initial period of irradiation time.
Modification of Gums by Grafting
The grafting reaction usually occurs on the –OH groups of gum by a radical polymerization reaction process, in the presence of thermal initiator or redox initiators.
The radicals were generated from the decomposition of thermal initiator may strip
down the H atom of –OH groups and initiate the macromolecular chains of gums to
generate macroradicals, and these radical reactive sites may initiate the vinyl groups
of monomers to process the chain propagation. Figure 4 gives the typical grafting
mechanism of vinyl monomers onto the gum backbone. First initiators generate
radicals which strip down the hydrogen atoms of the –OH groups on gum chains to
form macro-radicals and after addition of vinyl monomers, the active radical sites
on gum chains may initiate vinyl groups of the monomers to process chain
propagation.
The graft copolymerization of gum can introduce new polymer chains and functional groups and increases the molecular weight of gums with the functional groups
forming a crosslink or cyclic structure that increases the thermal resistance of gums.
Grafting of Poly (methyl methacrylate) onto xyloglucan improved thermal stability
that was investigated by Mishra and Malhotra (2012) Gum-g-Copolymer. Samui
et al. (2007) showed improvement of degradation-resistance properties of acacia
gum by grafting ethyl methacrylate onto its molecular chains. Viscosity of grafted
gums also increases as compared to the natural ones due to the change in the molecular weight and charge and therefore can be used as thickening agents at low
concentrations.
The grafted gum polymers have strong complexing capability, and therefore
showed great prospect in the adsorption of toxic heavy metals. Guar gum grafted
P. Chatur et al.
K-carrageenan as compared to ʎ-carrageenan which may be due to the presence of
additional sulphate groups in ʎ-carrageenan. The sonication breaks the Carrageenan
into its oligomers that can be applied as plant growth promoter, antiviral, antitumor,
antioxidants, anticoagulant, antithrombotic and hydrogels for burns dressings.
These functions are linked to oligomers with specific molecular weight range
(Abad 2010).
Sonication was also found to reduce the molecular weight of guar gum. The
reduction of Guar Gum (GG) molecular weight for an appropriate modulation of its
flow and gelling properties could ultimately be useful in pharmaceutical industries
for innovative drug formulations in cosmetics and food industry (Ogutu et al. 2015).
The ultrasonic degradation of CMC gum was studied under different operating
parameters such as time of irradiation, and solution concentration has been investigated. The experimental results show that the viscosity of polymer solution
decreased with an increase in the ultrasonic irradiation time. It has also been
observed that major extent of degradation takes place in the initial period of irradiation time.
Modification of Gums by Grafting
The grafting reaction usually occurs on the –OH groups of gum by a radical polymerization reaction process, in the presence of thermal initiator or redox initiators.
The radicals were generated from the decomposition of thermal initiator may strip
down the H atom of –OH groups and initiate the macromolecular chains of gums to
generate macroradicals, and these radical reactive sites may initiate the vinyl groups
of monomers to process the chain propagation. Figure 4 gives the typical grafting
mechanism of vinyl monomers onto the gum backbone. First initiators generate
radicals which strip down the hydrogen atoms of the –OH groups on gum chains to
form macro-radicals and after addition of vinyl monomers, the active radical sites
on gum chains may initiate vinyl groups of the monomers to process chain
propagation.
The graft copolymerization of gum can introduce new polymer chains and functional groups and increases the molecular weight of gums with the functional groups
forming a crosslink or cyclic structure that increases the thermal resistance of gums.
Grafting of Poly (methyl methacrylate) onto xyloglucan improved thermal stability
that was investigated by Mishra and Malhotra (2012) Gum-g-Copolymer. Samui
et al. (2007) showed improvement of degradation-resistance properties of acacia
gum by grafting ethyl methacrylate onto its molecular chains. Viscosity of grafted
gums also increases as compared to the natural ones due to the change in the molecular weight and charge and therefore can be used as thickening agents at low
concentrations.
The grafted gum polymers have strong complexing capability, and therefore
showed great prospect in the adsorption of toxic heavy metals. Guar gum grafted
P. Chatur et al.