Chemical and Functional Properties of Food Saccharides

© 2004 by CRC Press LLC
19.3.8 AMINOSTARCHES AND CARBAMATES
Amino ethers (either free or preferably cationized) have a broad range of current
and potential applications in paper manufacturing as coatings and sizes that improve
paper strength, in retention of pigments and dyes, production of conductive coatings,
textile finishes, and other uses. In the textile industry, cationic starches have been
used as fiber sizes. Use of cationic starches in the processing of poly(vinyl alcohol)
is also reported. Cationic starches are used as components of various latexes, as
additives that decrease fluid loss (filtration rate) during aqueous drilling of soils,
and as coatings for glass fibers.
Starch anthranilates have been proposed as optical brighteners. They improve
the retention of inorganic fillers and fiber fines in paper processing.
Soluble carbamates have been considered for applications such as adhesives,
pigmented coatings, paper coatings, and surfactants. Starch carbamates having double
bonds in side chains are UV-curable and have been reported as coatings.
Starch carbamate block copolymers are biodegradable. During production, the
reaction mixture can be supplemented with vegetable derivatives, molasses, polysaccharide
agricultural waste, and vegetable oil fractions. Biodegradability of such
materials reaches 6.7% during 12 weeks of exposure to soil. In the late 1950s, starch
was used as filler for polyurethane polymers in order to reduce the cost of final
products. Polyesters that were modified by reacting with diisocyanates were also
molded with starch. Starch carbamate was also used for blending aminoplast or
phenolic resins in order to obtain wood adhesives.
Starch polyurethane foams can be converted into sorbents for water when
starch–acrylonitrile or starch–methacrylonitrile graft copolymers are cross-linked
with diisocyanates. Such polyurethanes have been proposed as occlusive wound
dressings and as sizes for cotton yarns. Reinforced paper starch polyurethanes are
produced in a reaction of N-chlorocarbamoylethyl starch with cresol or thiolignin.
Addition of mineral salts to polyurethanes prepared from starch and urea improve
their performance as adhesives.
Starch and urea are prepared under pressure in order to produce an adhesive for
corrugated paperboard and a thickener for frozen food. Carbamoylated starch can
also be further reacted with formaldehyde and amines or with acrylamide and
accompanying dimethylaminomethylation, giving flocculants for sewage disposal
applications. Reactions of starch urethanes with alkylene oxides and aldehydes are
used to produce hardenable compounds in waterproof films, coatings, and adhesives.
Thiosemicarbazones of starch dialdehyde and thiosemicarbazones and condensation
products of starch dialdehyde with isoniazid were evaluated for their antituberculostatic
activity and showed positive effects with the mice that were intravenously
infected with Mycobacterium tuberculosis.
19.3.9 COPOLYMERS
After more than a decade of intensive studies on graft copolymerization of vinyl
monomers onto starch, the first applications for these materials appeared. Applications
include coatings; reinforcing materials for tires, rubbers, and plastics; anticor-