Grafting of Poly(Methacrylic Acid) on Starch and Poly(Vinyl Alcohol)

Abstract

Grafting of methacrylic acid (MAA) on starch, poly(vinyl alcohol) (PVA), and a mixture of starch and PVA, using a potassium persulfate/ sodium thiosulfate redox initiation system was carried out. Polymerization was studied with respect to graft yield, homopolymer formation and total conversion. These polymerization criteria were found to depend largely on the concentration of both MAA and initiators, duration and method of polymerization.The results reveal a number of interesting points which reflect the impact of the condition of the treatment. The main product of the polymerization reaction [poly(MAA)starch/PVA graft copolymer] was formed and precipitated during polymerization and can be easily separated by filtration as pure product.Application of these copolymers to cotton fabric was also carried out to evaluate the suitability of such modified products as sizing agents.

Influence of Acacia catechu Extracts and Urea and Gamma Irradiation on the Mechanical Properties of Starch/PVA-Based Material

“…Figure 5 represents the water absorption of St/PVA, St/PVA/Ac, and St/PVA/Ac/urea and irradiated St/PVA/Ac/Urea film. Water uptake was measured by soaking the films in static glass beakers contained deionized water at room temperature (25 • C) for different time series (1,3,5,10,20,40, and 60 minutes).…”

“…Other effective means commonly used to modify the PVA/starch composites in order to improve their mechanical and water resistance properties include (1) chemically modifying PVA or starch [1], for example, esterification, oxidation, etherification, crosslinking, and methylation [2][3][4][5][6][7][8], (2) physically modifying the SP (starch/PVA) composites, for example, by adding corn fibers to the blends [9], or (3) chemically modifying the SP composites during or after the blending process, for example, cross-linking reactions, grafting [10,11]. Examples of crosslinking reagents include glutaraldehyde [12], boric acid [13], and epichlorohydrin [14], and those of methods include radiation [15] and photo-cross-linking [16].…”

Copolumers obtained by grafting of vinyl monomers on starch - influence of amines on synthesis and degradation processes in environment

“…Maksimalna adsorpcija tripsina na ove kopolimere ostvarena je na pH = 7, a ravnoteţno vreme, nakon kojeg se adsorpcija dalje ne čega je dodata odreĎena količina redoks inicijatora [242]. [244]. MKK se moţe lako kalemiti na skrob korišćenjem Ce 4+ inicijatora (CAN) u vodenoj sredini [245].…”

“…Maksimalne G vrednosti u literaturi su se kretale oko 30 %, što je znatno vise nego u disertaciji, a razlog verovatno leţi u korišćenju amina kao aktivatora polimerizacije [242]. Athawale i Rathi su pratili uticaj temperature u intervalu od 30 do 50 0 C na G vrednosti, pri čemu su najveće G vrednosti od oko 15 % postignute na 50 0 C. Kada je u pitanju uticaj koncentracije MKK na G, literaturni podaci potpuno odgovaraju zavisnosti pronaĎenoj u doktorskoj tezi, gde je sa povećanjem koncentracije MKK, rastao i G [242,243,244,245,246]. Najveća G vrednost u literaturi iznosila je oko 33 % [246], što je skoro dvostruko više od 17,63 % prikazanih u Tabeli 3.8., pri čemu je vrednost iz literature dobijena na mnogo niţoj temperaturi (37 0 C) i uz korišćenje drugog inicijatora (CAN).…”

“…Optimalna reakciona vremena koja se sreću u literaturi pri sintezi PMKK-g-SK kopolimera su različita i kretala su se od 40 do 180 min, a za sva ova istraţivanja vaţi da G vrednosti u početku sa produţenjem reakcionog vremena rastu da bi se nakon nekog vremena dostigao plato, pri čemu se G vrednost ne menja [242][243][244][245], što je u potpunoj saglasnosti sa rezultatima našeg istraţivanja koje je prikazano u Tabeli 3.9. i na Slici 3.16..…”