This research focused on composite solid propellant that was made from solid and liquid materials become a slurry. Homogeneity of the propellant slurry is important to investigate because it can affect specification and performance of the propellant. This research objective was to study effect of mixing time to homogeneity of propellant slurry that was processed by horizontal sigma blade mixer. Density data were used to assess the homogeneity and stated as degree of homogeneity. The result showed that the mixing time affect the density values and it was obtained the most homogeneous slurry was at total mixing time 135 minutes.
Pengembangan pengetahuan terhadap sifat rheologikal isian cair dari propelan berguna untuk mendapatkan sifat slurry yang optimum. Pengembangan ini dapat dimulai dari campuran HTPB-DOA sehingga penelitian ini bertujuan untuk mengetahui pengaruh DOA terhadap sifat rheologikal HTPB-DOA yang meliputi sifat alir terhadap shear rate, viskositas dan viskositas saat zero shear rate. Dalam metodenya, DOA divariasi 0, 5, 10, 15 dan 20% dan dicampur dengan HTPB. Sifat rheologikal dipahami dengan mengukur viskositasnya pada kecepatan putar 0,5; 1; 1,5; 2; 2,5; 3; 4 dengan spindel tipe 2 dari viskometer Brookfield dan menganalisa grafik shear stress vs shear rate serta viskositas vs shear rate. Berdasarkan analisa tersebut, diketahui bahwa campuran HTPB-DOA bersifat shear thickening. Semakin banyak DOA yang ditambahkan, semakin rendah viskositas campuran, semakin rendah nilai viskositas pada zero shear rate dan semakin kuat sifat shear thickening dari campuran.
In developing flow behavior of plasticized prepolymer as liquid content of composite solid propellant, zero shear viscosity (ZSV) is a critical parameter that Goh-Wan equation is developed to model it recently [1]. Thus, this work aims to analyze the compatibility of the Goh-Wan equation toward the liquid content of propellant, characterize it, and determine the limit. In this work, a varied flow behavior index was obtained by using Hydroxy terminated polybutadiene (HTPB) and HTPB-DOA (Dioctyl adipate) system with the variable of its concentration, pre-heating, and pre-stirring methods as samples. Viscosity was measured at 2, 3, 4, and 5 rpm by using the disc spindle of Brookfield viscometer. For the minimum shear-rate investigation, as a limit of compatibility, other three sets of shear rates are applied, which are 0.6 – 5 rpm, 1 – 5 rpm, and 1,5 – 5 rpm. By functioning Goh-Wan equation (model 1) and Power-Law (model 2), a model was categorized as compatible if yields lower value of ZSV than the first experimental measured viscosity (η1st). Characterization was determined by a graph of plotting percentage difference of ZSV obtained from models 1 and 2 towards the index of flow behavior. The 3% of the difference between ZSV obtained from model 1 and η1st was set to be a minimum value for a set of applied shear-rate to be acceptable. It is reported that the Goh-Wan model is compatible with the liquid content of propellant and characterized by a perfect linear correlation. It is also found that a minimum applied shear rate of 1.5 rpm is acceptable for model compatibility.
HTPB is the ultimate component of matrix builder for high-filled composite materials. Flow behavior of HTPB in low shear is crucial in casting the composite. Considering the characteristics of hydrocarbon, this work aims to investigate the effect of microstructure composition of HTPB on its flow behavior. In this work, HTPB with different composition of 1,4-cis, 1,2-vinyl and 1,4-trans microstructures were used. Fourier-Transform Infra-Red spectroscopy (FT-IR) was used to determine the composition. It was calculated as a ratio of peak area of 710, 910 and 970 cm-1 for 1,4-cis, 1,2-vinyl, 1,4-trans isomers respectively. Viscosity was measured using a rotational viscometer at various low shear rates. It is found that HTPB with high 1,2-vinyl/1,4-trans isomers shows shear thickening behaviour, distinguished significantly from Newtonian flow of the others. It is suggested that mechanism of shear thickening involves a certain configuration of 1,2-vinyl and 1,4-trans isomers that builds different degrees of flow resistance from one to other shear layers. The configuration and flow resistance changes among layers as shear increases.
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