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A food model was formulated in this work by blending cassava starch with small amounts of protein (6%), corn oil (4.5%) and sugar (6%). The calorimetric and mechanical properties of this realistic food model were studied as a function of moisture content. An anti-plasticization behavior of the food model at moisture contents lower than 9% was detected by increases in the glass transition temperature (Tg) values. Higher moisture contents induced a strong reduction in Tg values. The presence of hydrophilic groups was responsible for both behaviors. Tensile tests revealed that the glassy food model was brittle, while neat glassy starch was ductile under similar moisture contents. This was probably due to the presence of protein aggregation during thermomoulding, as previously reported in starchy cereal materials. The composition of the food model can be tailored to control water sorption, thermal transitions, and mechanical properties of the food system considered here.

Poly(ε-caprolactone-ran-ε-caprolactam)random copolymers, P(CLo-ran-CLa), were studied ina wide composition range (0 ≤ PCLo ≤ 55 wt %) and inthe wet and dry states. Both crystalline and amorphous phases of thepoly(ester amide)s were characterized, the first by wide-angle X-rayscattering and the latter by the thermally stimulated depolarizationcurrent technique. Only PCLa presented 3D order, i.e., γ* andα structures, in addition to increasing lamellar thicknessesas PCLo amount rises. The amorphous phase of wet PCLa shows additionallyto moisture plasticization a loss of rigidity due to the presenceof PCLo units, which affects both segmental and local mobilities.Two cooperative modes are caused by the intercalated water with twodifferent bounds (loosely, tightly), and their behavior during thedrying process is the result of two competing effects, i.e., the lossof moisture and the coexistence of the PCLo segments. In the dry statethe miscible amorphous phase presents a single drastic composition-dependentsegmental mobility. [ABSTRACT FROM AUTHOR]

Dc and ac conductivities in a broad angular frequency, 2π × 10−3s−1< ω < 2π × 107s−1, and temperature range, 133 K < T< 323 K, were measured in poly(ε-caprolactone)/multiwalled carbon nanotube nanocomposites as a function of weight concentration (0 wt % ≤ p≤ 3 wt %) . The universal dynamic response was observed at low pvalues, and the parameters were adjusted by working in several domains. Scaling laws predicted by the variation of dc conductivity as a function of por characteristic frequency in percolation theory were followed and showed the formation of a 3D percolative cluster at concentration values as low as 0.3 wt %. The existence of tunneling conduction was proved, and its independence on temperature indicates that we are in the presence of a conventional tunnel effect among nanoparticles not yet in physical contact, through energy barriers made by the polymer chains. All these combined facts allowed construction of a master curve evidencing the time−temperature−composition superposition existing in the poly(ε-caprolactone)/multiwalled carbon nanotube nanocomposites studied here. [ABSTRACT FROM AUTHOR]

Abstract  A series of comb like poly(p-n-alkylstyrene)s with linear alkyl groups, containing even numbers of carbon atoms from 12 up to 22 were synthesized by radical polymerization and characterized by FTIR, 1H NMR, TGA, TVA DSC, and WAXS. All polymers were obtained in good yields and were soluble in organic solvents as chloroform, dichloromethane or tetrahydrofuran and insoluble in methanol; they are stable up to temperatures near 300 °C. On the other hand, the alkylic side chains of all series are able to crystallize in a paraffinic phase in which the melting temperature and enthalpy increase with the methylene number of the n-alkyl chain. [ABSTRACT FROM AUTHOR]

A series of complexes from poly(itaconic acid) and poly(mono methyl itaconate) and bromide surfactants with linear alkyl groups, containing even number of carbon atoms from 12 up to 22 were synthesized. The complexes were obtained in good yields and were soluble in organic solvents and stable up to temperatures near 150°C. On the other hand, the paraffinic side chains are able to crystallize depending on the methylene number of the surfactantn-alkyl chain. [ABSTRACT FROM AUTHOR]