Abstract In this work, starch obtained from mango kernel seeds was applied in the preparation of films in combination with its hydrophobic derivatives. Chemical modification of starch was carried out at two different concentrations of vinyl laurate, in dimethyl sulfoxide, under basic catalysis. The degrees of substitution of the starch laurates were 2.4 and 0.3, respectively. None of the products formed films when dispersed in water. However, blends of starch/starch laurate (degree of substitution = 0.3) formed films after microfluidization of their aqueous suspensions. The blends with up to 15% wt of starch laurate (degree of substitution = 0.3) resulted in films of higher elongation at break, higher opacity and lower tensile strength and elastic modulus. The microfluidization of biopolymer suspensions was crucial to obtain films with lower water vapor permeability. X-ray diffraction results corroborated to the mechanical properties of the films, showing that the incorporation of starch laurate reduced the starch films crystallinity.

Abstract Drilling fluids are multicomponent systems used to aid the removal of cuttings from a borehole, and subject to a number of requirements to ensure a safe drilling operation. One of the most important is to form a low permeability cake on the walls of the hole penetrated by the bit, to avoid excessive filtrate loss. To that end, carboxymethylcellulose (CMC) associated with calcite (CaCO3) can be used. In this paper, the effect of carboxymethylcellulose on the colloidal properties of calcite suspensions in brine was systematically evaluated by rheological properties, filtrate volume and zeta potential. Higher viscosity fluids, lower filtrate loss and less negative zeta potential were obtained using small calcite particles with wide size distribution and CMC with high average molecular weight (Mw) and low average degree of substitution (DS), highlighting the importance of effective interactions between CMC and calcite to improve drilling fluid properties.

<title>Abstract</title><p>A great deal of research on polymers over the past two decades has been focused on the development of stimuli-responsive polymers to obtain materials able to respond to specific surroundings. In this paper, an overview is presented of the concepts, behavior and applicability of these “smart polymers”. Polymers that are temperature- or pH-sensitive are discussed in detail, including the response mechanisms and types of macromolecules, because they are easy to handle and have a wide range of applications. Finally, the combination of pH and temperature responsive properties by means of graft copolymerization of chitosan with poly (<italic>N</italic>-isopropylacrylamide) (PNIPAM) was chosen to represent some synthetic routes and properties of dual-sensitive polymeric systems developed currently.</p>

O óleo de mamona é um óleo vegetal que permite várias reações em seus grupos funcionais hidroxila. O ácido ricinoleico (ácido 12-hidroxioleico) compõe cerca de 90% dos ácidos graxos presentes, enquanto os outros 10% são não hidroxilados. Este trabalho teve como objetivo obter polióis a partir de misturas do óleo de mamona tipo I (OM) com dietanolamina (DEA), visando elevar o grau de reticulação dos produtos finais, para uso em circuitos eletroeletrônicos. A intenção de se introduzir a dietanolamina nas formulações de resina de poliuretana advém das dificuldades apresentadas por empresas do ramo na aquisição da trietanolamina, que atualmente se encontra sob controle de órgãos federais. Análises químicas e espectroscópicas evidenciaram a obtenção de polióis com índice de hidroxila entre 230 e 280 mgKOH/g. A cinética da reação de poliadição entre os polióis resultantes e o isocianato de isoforona (IPDI) foi acompanhada pelas mudanças nas propriedades reológicas do meio, a 60 ºC. As poliuretanas apresentaram propriedades compatíveis com as dos produtos atualmente disponíveis no mercado, obtidos com trietanolamina (TEA).

Castor oil (CO) is a vegetable oil that allows for multiple reactions in their hydroxyl functional groups. Ricinoleic acid (12-hidroxioleic acid) comprises about 90% of the fatty acids present while the remaining 10% are not hydroxylated. The aim of the present work was to obtain polyols from castor oil (CO) and diethanolamine (DEA), to improve the crosslinking degree of final products to be used in electronic circuits. The use of diethanolamine instead of triethanolamine in the polyurethane resin formulation is of special interest of companies, due to the difficulties in acquiring triethanolamine, which is controlled by the Brazilian Army. Chemical and NMR characterization showed that the polyol obtained had a hydroxyl number between 230 and 280 mgKOH/g. The kinetics of the polyaddition reaction from polyols and isophoronediisocyanate (IPDI) was evaluated employing rheological assays at 60 ºC. The polyurethane based on DEA had compatible properties with the commercial products obtained from triethanolamine (TEA).