The Brazilian male beauty market occupies the second place in world consumption of cosmetics. Among the numerous products consumed by such audience is the capillary fixation mask, which is mainly composed by fixatives. These additives act on stabilizing the cosmetic emulsion, protecting the hair against moisture and also increasing the intensity of hair fixation. In this work, three formulations for modelling creams were prepared by different concentrations of the fixatives StylezeTM W20 and PVP K90 and their properties characterized by physicochemical, rheological and sensory analysis. The capillary masks produced were stable oil-in-water (O/W) emulsions with uniform droplets of 2.05-2.82 μm sizes and pseudoplastic thixotropic behavior (0.19 < n < 0.26). It was possible to correlate the increased concentration of PVP K90 to a greater thixotropy and an improved yarn fixation, despite the worsening in the spreadability of the formulations. These results suggest properly conducted rheological measurements can contribute to the prediction of the emulsion’s sensory properties, which can save time and funds on the development of new cosmetics.

Resumo Polímeros termoplásticos podem ser utilizados como veículo orgânico (VO) em processos de conformação de peças cerâmicas por extrusão. Neste contexto, termoplásticos à base de amido surgem como uma alternativa sustentável ao emprego das poliolefinas convencionalmente utilizadas na formulação de pastas cerâmicas. O passo inicial para o desenvolvimento de um feedstock (carga extrudável) é a seleção adequada do sistema polimérico ligante, o qual é responsável por conferir propriedades reológicas adequadas durante o processamento. O presente trabalho se propôs a caracterizar termoplásticos a base de amido obtidos na presença de ácido cítrico e avaliar o potencial de utilização destes materiais na extrusão de pós cerâmicos. A processabilidade das pré-misturas de amido foi avaliada em extrusora dupla-rosca e em reômetro de torque. A variação dos teores de água e glicerol na composição das pré-misturas de amido influenciou significativamente as interações entre as cadeias poliméricas, promovendo alterações nos valores de densidade e de viscosidade para a maior parte das amostras analisadas. O amido foi parcialmente esterificado como efeito da ação do ácido cítrico no sistema. Dentre as formulações investigadas, a amostra hidratada e processada com 34% p/p de glicerol (H-34) foi a que apresentou as melhores propriedades de pasta, podendo ser futuramente empregada em processos de conformação de pós cerâmicos.

Abstract Thermoplastic polymers can be used as organic vehicle (OV) in ceramic parts forming by extrusion. In this context, starch-based thermoplastics arise as a sustainable alternative to polyolefins conventionally used in ceramic slurry formulation. The initial step for the development of a feedstock (extrudable load) is the selection of the polymeric binder system, which is responsible for providing appropriate rheological properties during processing. Accordingly, in this work thermoplastic starches obtained in the presence of citric acid are characterized and evaluated as for the potential use in the extrusion of ceramic powders. The processability of the premixed starches was investigated in a twin-screw extruder and in a mixer torque rheometer. The variation of water and glycerol contents in the composition of the premixed starches significantly influenced the interactions between polymer chains, promoting changes in density and viscosity for most analysed samples. The thermoplastic starches were partly esterified as an effect of the citric acid presence in the system. Among all formulations investigated, the H-34 sample (hydrated and processed with 34% w/w of glycerol content) showed the best paste properties and can be further employed in ceramic powder forming processes.