A detailed study of the theological modelling of composite propellant slurry based on hydroxyl terminated polybutadiene (HTPB) prepolymer, Dioctyl adipate (DOA) plasticizer, toluene diisocynate curative, ammonium per chlorate (AP) oxidizer and aluminium powder as a metallic fuel is carried out and studied the effect of each of the ingredients on the composite propellant slurry (cps). The effect of temperature on viscosity of polymer and plasticizer system was studied at different temperatures, and torques (shear force). The polymer hydroxyl terminated polybutadiene (HTPB) and plasticizer (DOA) viscosity data showed temperature dependence and independent of the torque (i.e. shear force). Therefore, the viscosity data has been modelled to polynomial model of a fourth order with temperature for polymer and plasticizer.
The results showed good agreement between theory and experiment. These polynomial model results have been compared with Arrhenius model. The polynomial model showed better comparison within ± 4 % error compared to Arrhenius model with ± 4 to ± 22 % error over the temperature range of 30 - 70 °C. The viscosity of the mixture was also studied at different weight fractions of the polymer:plasticizer. The viscosity of mixture showed dependence on the weight fraction of the plasticizer and temperature.
Rheology concerns itself with the mechanism of flow and deformation of matter. Deformation is a phenomenon, which is associated with a volume element. This term was invented by Prof. Bingham of Lafayette College, Indiana. Significant advances have been made in polymer rheology, in bio-rheology and in suspension rheology. There has been a significant appreciation of the importance of rheology in the chemical processing industry like medicine, paints and printing ink technology etc. and biotechnological industries. It has also made important contributions in food technology, building and structural engineering, cosmetics, drilling operations and oil wells etc.
Table of Contents
1 INTRODUCTION
1.1 Fundamentals ofRheology
1.2 Elements ofRheology
1.3 The Flow Curve (Rheogram) and Viscosity Curves
1.4 Basics ofPropellants
1.4.1 Liquid Propellant
1.4.2 Hybrid Propellant
1.4.3 Solid Propellant
1.5 Rheology of Composite Propellant Slurry and Earlier Reviews
1.6 Scope ofthe Present Study
1.7 References
2 Materials used and Experimental Methods
2.1 Raw Materials/Chemicals
2.2 Equipment's used
2.2.1 Brookfield Viscometer
2.2.2 Rheomat RM 260 Photometer
2.3 Rheological Measurement of Polymer, Plasticizer, Curatives and their Mixtures
2.4 Rheological Measurement of Uncured Composite Propellant Slurry
2.5 Rheological Measurement ofComposite Propellant Slurry
2.6 Calculation of Percentage of Curative (TDI) required
2.7 References
3 Rheological Modelling of Polymers, Plasticizers and their Mixtures
3.1 Data Interpretation and Theoretical Modelling
3.2 Conclusions
3.3 References
4 Rheokinetic Modelling of Polymer, Plasticizer and Curative Systems
4.1 Data Analysis and Modelling
4.1.1 Temperature Modelling ofPolymer ( HTPB)
4.1.2 Temperature Modelling for Polymer (HTPB) -Curative (TDI)
4.1.3 Time Modelling ofPolymer (HTPB) -Curative (TDI) System
4.1.4 Temperature Modelling for Polymer (HTPB)-Plasticizer (DOA) - Curative(TDI) System
4.1.5 Temperature Modelling for Polymer (HTPB)-Plasticizer (DOA) - Curative(TDI) System
4.2 Conclusions
4.3 References
5 Rheological Modelling and Characterization of Uncured Composite Solid Propellant Slurry
5.1 Rheological Modelling and Characterization of Uncured Composite Solid Propellant Slurry
5.2 Data Analysis and Modelling
5.3 Conclusions
5.4 References
6 Rheological Modelling and Characterization of Cured Composite Solid Propellant Slurry
6.1 Data Analysis and Modelling
6.2 Conclusions
6.3 References
Research Objectives and Thematic Focus
The primary objective of this work is to develop a robust mathematical framework for the rheological characterization and modelling of composite solid propellant systems. The study aims to correlate material composition, temperature, and curing time with the rheological behavior of the propellant slurry to ensure optimal processing and the production of defect-free rocket motors.
- Rheological behavior of polymeric binders, plasticizers, and their mixtures.
- Rheokinetic analysis of curing reactions in propellant systems under various thermal conditions.
- Characterization of uncured composite solid propellant slurries regarding solid loading and particle size distribution.
- Mathematical modelling using polynomial and power-law approaches to predict viscosity and slurry performance.
Excerpt from the Book
Rheological Modelling and Characterization of Uncured Composite Solid Propellant Slurry
Obtaining high levels of specific impulse and density is always the ultimate goal of propellant development because these are the major factors affecting the performance of the rocket. As the solid content increases, its density increases resulting in an increase in specific impulse. Previous studies have shown that a ten percent increase in ammonium perchlorate (AP) content (from 70 % - 80 % by weight), increases the specific impulse (Isp) from 85 to 225 sec. Further increase in AP content causes Isp to reach a maximum value and beyond a particular value it shows a decreasing trend as mentioned by Cevat Eriksen et al. An increase in the Isp by increasing the solid content causes variations in the rheological properties of the propellant and difficulties in the processing and casting defect free grains. Also, increasing solid loading reduces the elongation of the cured propellant, required to take care of the strains during storage, transportation and flight environments. Therefore the solid loading should be increased to such a level that propellant still remains processable and the other properties are still satisfactory.
Uncured solid propellants generally exhibit non-Newtonian flow behaviour. This non-Newtonian behaviour of propellant is attributed to the amount of solid content in the propellant. This clearly, shows that the rheology of the propellant is important in the manufacturing process. One way to increase the solid content with a minimal change in the rheological and mechanical properties is to use the concept of packing density, the fraction of volume occupied by solid particles. Theory of particle packing is based on the selection of proper size and proportion of particulate material, so that the large voids are filled with particles of matching size and new small voids created are in turn filled with smaller particles. The packing density depends on the particle size and its distribution of the particulate material. Thus, in the studies with the concentrated suspensions, it is found that the fluidity of the suspension decreases with an increase in the packing density at specified solid content.
Summary of Chapters
1 INTRODUCTION: This chapter introduces the fundamentals of rheology and provides an overview of various propellant types, establishing the theoretical basis for subsequent research.
2 Materials used and Experimental Methods: This section details the raw materials, including polymers and curatives, and describes the specific experimental equipment and procedures used for viscosity measurement.
3 Rheological Modelling of Polymers, Plasticizers and their Mixtures: This chapter focuses on the theoretical modelling of binder components, analyzing the dependency of viscosity on temperature and composition.
4 Rheokinetic Modelling of Polymer, Plasticizer and Curative Systems: The chapter explores the kinetic aspects of curing reactions and how they influence the time-dependent viscosity behavior of the binder matrix.
5 Rheological Modelling and Characterization of Uncured Composite Solid Propellant Slurry: This chapter investigates the impact of solid loading and particle size distribution on the flow behavior of uncured propellant mixtures.
6 Rheological Modelling and Characterization of Cured Composite Solid Propellant Slurry: This concluding technical chapter analyzes the rheology of the propellant system during the transition phases and validates the developed mathematical models against experimental data.
Keywords
Rheology, Composite Solid Propellant, HTPB, Viscosity Modelling, Solid Loading, Ammonium Perchlorate, Polymeric Binder, Plasticizer, Rheokinetic, Curing Kinetics, Non-Newtonian Flow, Packing Density, Specific Impulse, Shear Stress, Mathematical Modelling
Frequently Asked Questions
What is the fundamental focus of this research?
The research focuses on the rheological modelling and characterization of composite solid propellant systems, aiming to optimize the manufacturing process for high-performance rocket motors.
Which materials are primarily studied in this work?
The study examines polymeric binders like HTPB, CTPB, and PBAN, plasticizers such as DOA and DOP, and solid additives like ammonium perchlorate (AP) and aluminum powder.
What is the primary goal of the developed models?
The models aim to accurately predict the viscosity of propellant slurries based on parameters like solid loading, temperature, and composition to minimize defects during casting.
What scientific methodology is utilized?
The work employs a combination of experimental data gathering using rotational viscometers and mathematical modelling, specifically utilizing polynomial and power-law regression analysis.
What topics are covered in the main section of the document?
The main sections cover rheological fundamentals, experimental procedures for measuring propellant viscosity, and the development of predictive models for various propellant compositions under thermal and time-dependent constraints.
How would you characterize this work based on its keywords?
The work is highly specialized in the fields of polymer science, chemical engineering, and aerospace technology, focusing on the interplay between molecular properties and macro-scale flow behavior.
Why is the "packing density" concept significant for this propellant slurry?
Packing density is crucial because it allows for the incorporation of a high volume of solid particles (oxidizers and fuels) while maintaining the slurry's fluidity, which is essential for successful casting.
How does the addition of a curative affect the propellant's rheological profile?
The curative initiates a cross-linking reaction that leads to a time-dependent increase in viscosity, which directly impacts the "pot life" of the slurry during the manufacturing process.
- Quote paper
- Dr Bapurao Bandgar (Author), 2020, Rheological characterization and modeling, Munich, GRIN Verlag, https://www.grin.com/document/512892
