Method for measuring yield value of solid propellant slurry

Abstract

The invention relates to a method for measuring the yield value of solid propellant slurry, which comprises the following steps of: measuring by using a stress control or strain control type rotational rheometer, and measuring by using a parallel plate test system, a steady-state or transient shear rate change mode and a test mode of changing from a high shear rate to a low shear rate; data obtained through measurement are made into a shear rate-stress or viscosity-stress double-logarithmic curve, the shear rate-stress double-logarithmic curve is an incremental curve, the viscosity-stress double-logarithmic curve is a decline curve, first-order derivatives of the shear rate-stress or viscosity-stress double-logarithmic curve are solved, and a second-order derivative of the shear rate-stress or viscosity-stress double-logarithmic curve is obtained; the stress value corresponding to the maximum absolute value of the first derivative value is the yield value of the sample. According to the parallel plate testing system of the rotational rheometer, the diameter and the gap of the parallel plate are small, the required sample amount is small, high-viscosity samples are easy to fill, and yield value measurement from low-viscosity samples to high-viscosity samples can be realized. The method has the advantages of being easy to implement, high in accuracy and high in universality.

Description

Technical Field

[0001] This invention belongs to the field of polymer material analysis and characterization, and specifically relates to a method for determining the yield value of solid propellant slurry. Background Technology

[0002] Solid propellants primarily consist of a liquid binder system as the matrix, with a large amount of solid filler, including oxidizers, explosives, and reducing agents. The solid filler content can reach 70%–90%, and most are non-Newtonian fluids with yield stress. Yield value is an important parameter for evaluating the leveling performance of propellant slurries. Currently, yield value is mostly measured using a viscometer rotary drum testing system. However, this method requires a large sample volume, making it difficult to measure for samples with high solid content or high viscosity, such as slurries that have undergone a certain degree of curing. Summary of the Invention

[0003] The purpose of this invention is to provide a method for determining the yield value of solid propellant slurry, applicable to both low-viscosity and high-viscosity solid propellant slurries, which can provide technical support for the study of solid propellant process performance.

[0004] The technical solution adopted in this invention is as follows: a method for determining the yield value of solid propellant slurry, which is performed by a stress-controlled or strain-controlled rotational rheometer, using a parallel plate test system, steady-state or transient shear rate change mode, and a test mode from high shear rate to low shear rate change.

[0005] Plot the measured data as a double logarithmic curve of shear rate versus stress or viscosity versus stress. The double logarithmic curve of shear rate versus stress is an increasing curve, while the double logarithmic curve of viscosity versus stress is a decreasing curve. Calculate the first derivative of the double logarithmic curve of shear rate versus stress or viscosity versus stress. The stress value corresponding to the point where the absolute value of the first derivative is the maximum is the yield value of the sample.

[0006] The diameter of the parallel plates in the parallel plate testing system is between 20 and 60 mm, and the test gap is between 0.5 and 2.5 mm.

[0007] The steady-state or transient shear rate change mode is either a steady-state shear rate scan or a transient shear rate ramp test mode.

[0008] The high shear rate is 1~10 s. -1 The low shear rate is 0 s. -1 .

[0009] The advantages of this invention compared to the prior art are as follows:

[0010] This invention utilizes a parallel plate testing system within a rotational rheometer. The parallel plates have small diameters and small gaps, requiring a small sample volume and facilitating the loading of high-viscosity samples. This system enables measurements from low to high viscosity samples. The invention gradually changes the shear rate from a relatively high shear rate to 0 s⁻¹, calculating the first derivative of the shear rate-stress or viscosity-stress double logarithmic curve. The stress value corresponding to the point where the absolute value of the first derivative is maximum is the yield value of the sample. Measurements are performed using shear rate scanning or shear rate ramp testing modes, which are easy to implement, highly accurate, and universally applicable in the field of polymer composite slurries.

[0011] This invention is simple and easy to implement, requires a small sample volume, and can accurately measure the yield value of both low-viscosity and high-solids-content slurries. It overcomes the problem that the rotary drum test system cannot measure the yield value of high-solids-content slurries, and the measured yield value is not affected by the shear rate, making the method highly universal. Attached Figure Description

[0012] Figure 1 The graphs shown are the viscosity-stress, shear rate-stress double logarithmic curves and viscosity-stress first derivative curves of the GAP propellant slurry in Example 1 of this invention.

[0013] Figure 2 The graphs shown are of the viscosity-stress, shear rate-stress double logarithmic curves and the shear rate-stress first derivative curve of the GAP propellant slurry in Example 1 of the present invention.

[0014] Figure 3 The figures show the viscosity-stress and shear rate-stress double logarithmic curves of four different NEPE propellant slurries in Example 2 of this invention.

[0015] Figure 4 The graphs show the viscosity-stress and first derivative curves of four different NEPE propellant slurries in Example 2 of this invention.

[0016] Figure 5 The graph shows the double logarithmic curves of shear rate-stress and their first derivative curves for four different NEPE propellant slurries in Example 2 of this invention.

[0017] Figure 6 The graphs show the viscosity-stress, shear rate-stress double logarithmic curves and the viscosity-stress first derivative curve of the ADN gel propellant slurry in Example 3 of the present invention.

[0018] Figure 7 The graphs shown are of the viscosity-stress, shear rate-stress double logarithmic curves and the shear rate-stress first derivative curve of the ADN gel propellant slurry in Example 3 of the present invention. Detailed Implementation

[0019] The present invention will now be described in further detail with reference to specific embodiments and accompanying drawings. Obviously, the described embodiments are merely some, not all, of the embodiments of the present invention. The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the present invention or its application or use. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0020] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0021] Unless otherwise specified, the test methods or experimental methods described in the following examples are conventional methods; unless otherwise specified, the reagents and materials are obtained from conventional commercial sources or prepared by conventional methods.

[0022] Example 1

[0023] Yield stress tests were performed on GAP propellant slurry with a solid content of 72% using a rotational rheometer. The viscosity at 50 °C was 2109.7 Pa·s. Test parameters were: parallel plate diameter 25 mm, test gap 2.0 mm, steady-state shear rate scanning mode, and shear rate range 10–0 s⁻¹. -1 The test curves are shown in the attached figure. Figure 1 , 2 As shown.

[0024] According to the appendix Figure 1 Or attached Figure 2 The yield value of the GAP propellant slurry was 16.44 Pa, obtained from the stress corresponding to the maximum absolute value in the first derivative curve.

[0025] Example 2

[0026] Yield stress tests were performed on four batches of NEPE propellant slurry with a solid content of 75%, named NEPE-1 to NEPE-4, using a rotational rheometer. The test parameters were: parallel plate diameter 25 mm, test gap 2.0 mm, steady-state shear rate scanning mode, and shear rate range of 10–0 s⁻¹. -1 The test curves are shown in the attached figure. Figure 3 , 4 As shown in Figure 5.

[0027] From the appendix Figure 4 Or attached Figure 5 The stress corresponding to the maximum absolute value in the first derivative curve is read from the yield values ​​of different NEPE propellant slurries, as shown in Table 1.

[0028] Table 1. Viscosity and Yield Value of 4 Batches of NEPE Propellant Slurry

[0029]

[0030] Example 3

[0031] Yield stress tests were performed on ADN gel propellant slurry with a solid content of 60% using a rotational rheometer. The viscosity at 25°C was 16.2 Pa·s. Test parameters were: parallel plate diameter 25 mm, test gap 1.0 mm, steady-state shear rate scanning mode, and shear rate range of 5–0 s⁻¹. -1 The test curves are shown in the attached figure. Figure 6 , 7 As shown.

[0032] According to the appendix Figure 6 , 7 The yield value of the GAP propellant slurry was 27.96 Pa, obtained from the stress corresponding to the maximum absolute value in the first derivative curve.

[0033] The contents not described in detail in this specification are common knowledge to those skilled in the art.

[0034] The above description is only the best specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the protection scope of the present invention.

Claims

1. A method for determining the yield value of solid propellant slurry, characterized in that: Measurements were performed using a stress-controlled or strain-controlled rotational rheometer, employing a parallel plate testing system, and measuring steady-state or transient shear rate change modes, as well as test modes ranging from high to low shear rates. Plot the measured data as a double logarithmic curve of shear rate versus stress or viscosity versus stress. The double logarithmic curve of shear rate versus stress is an increasing curve, while the double logarithmic curve of viscosity versus stress is a decreasing curve. Calculate the first derivative of the double logarithmic curve of shear rate versus stress or viscosity versus stress. The stress value corresponding to the point where the absolute value of the first derivative is the maximum is the yield value of the sample.

2. The method for determining the yield value of solid propellant slurry according to claim 1, characterized in that: The diameter of the parallel plates in the parallel plate testing system is 20–60 mm, and the test gap is 0.5–2.5 mm.

3. The method for determining the yield value of solid propellant slurry according to claim 1, characterized in that: The steady-state or transient shear rate change mode is either a steady-state shear rate scan or a transient shear rate ramp test mode.

4. The method for determining the yield value of solid propellant slurry according to claim 1, characterized in that: The high shear rate is 1~10 s. -1 The low shear rate is 0 s. -1 .

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