The graft copolymers of pure granular maize starch with acrylamide, methacrylamide, acrylic acid and methacrylonitrile were synthesized using ceric ammonium nitrate as an initiator. The formation of graft copolymer was confirmed by gravimetric measurement, acid hydrolysis and IR spectroscopy. The thermal analysis of the pure granular maize starch and graft copolymers was carried out using thermogravimetric analysis (TGA), derivative thermogravimetry (DTG), differential scanning calorimetry (DSC), differential thermal analysis (DTA) and isothermal analysis. In order to determine the mechanism of decomposition of these polymers, the isothermal analysis was coupled with IR spectroscopy. The activation energies at every stage of decomposition for all the polymer samples were determined from their primary thermograms. The glass transition temperatures (Tg) for pure granular maize starch and all the graft copolymers have been reported. Except starch‐graft‐acrylic acid, all other graft copolymers showed enhanced thermal stability over pure starch. Tg of pure starch was observed as 91°C. All the graft copolymers showed lower values of Tg with a minimum of 57°C for starch‐graft‐methacrylonitrile. DTA studies indicated a delayed oxidative degradation of graft copolymers.
This paper presents a reviewal profile of water absorbing resins based on graft copolymers of acrylic acid and gelatinised starch. It first elaborates on the synthesis of these hydrogels, use of these hydrogels in a variety of commercial applications, and the role of hydrogen bonding in the water absorbing capacity of these hydrogels. It describes the exact experimental conditions for producing hydrogels based on gelatinised maize starch grafted with acrylic acid showing maximum water absorption of 260 g/g.
Die Planungs‐ und Realisierungsleistungen für die Erstellung von herausragenden Bauwerken werden in der Architektur und zunehmend konsequenterweise auch im Ingenieurbereich nach Auswertung eines Wettbewerbes vergeben. Hierfür werden neuartige Methoden benötigt, welche mithelfen, die Entwurfs‐ und Wettbewerbspraxis transparenter zu gestalten und die Prämierung jener Beiträge nachvollziehbarer zu machen, welche am ehesten den aktuellen und wenn möglich auch den zukünftigen Ansprüchen der Auftraggeber und der Gesellschaft an das Bauwerk entsprechen. Dies gilt insbesondere vor dem Hintergrund des Umdenkens in der Gesellschaft, welches verstärkt nachhaltiges Handeln fordert. Einen entsprechenden Ansatz verfolgt die Effizienzwertmethode (EWM), welche mit ihrer ganzheitlichen Betrachtung auch eine Bewertung der Nachhaltigkeit von Bauwerken ermöglicht [1]. Daneben wurde die Kritik der Bevorzugung von insgesamt mittelmäßigen Lösungen bei kritiklosem Einsatz von teilautomatisierten Bewertungsverfahren aufgenommen und ein Ausweg aus diesem Dilemma mittels Entwicklung des neuartigen Ansatzes “dynamischer Wichtungsfaktor” gefunden.
Polyurethane dispersions are gaining in importance due to their environmentally friendly coating system, versatile coating properties and ease of application. An enormous amount of research is focused on waterborne coatings such as waterborne alkyds, water-reducible alkyds, alkyd-acrylic hybrids, oil modified polyurethane dispersions and their composite latexes. This review gives a comprehensive compilation of recent studies on the synthesis and applications of waterborne coatings. The article specifically covers all of the research work carried out in the field of waterborne alkyd-acrylics, polyurethane dispersions and their hybrid latexes systematically.
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