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Studies on the High Performance Characteristics of an Aluminized Ammonium Perchlorate Composite Solid Propellant Based on Nitrile Butadiene Rubber

Sudhir Singh, Sidharth Raveendran, Dhirendra Kshirsagar R., Gupta Manoj, Chetan Bhongale

Central European Journal of Energetic Materials

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2021

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Vol. 18, no. 4

492--511

EN

n the present study, a high performance composite solid propellant formulation was prepared based on nitrile butadiene rubber (NBR) and dibutyl phthalate (DBP) plasticizer, which has a longer pot life and high density specific impulse. The developed cost effective novel binder system was prepared with readily available raw materials (NBR and DBP). The formulation of the composition was performed by varying the content of the NBR/DBP binder in the range of 14-20%. The rocket performance characteristics were determined theoretically using PROPEP and compared with those of an HTPB based propellant. The rheological, mechanical, physical, ballistic and thermal properties of the NBR/DBP propellant were studied and compared with literature data for similar compositions based on an HTPB/dioctyl adipate (DOA) binder. The yield stress was determined by spreadibilty measurements, and indicated the superiority of this binder based propellant over existing composite propellants. It was concluded that following decreasing the content of the NBR/DBP binder in the propellant from 20 to 14%: in the range 58.83-78.45 bar (5.883-7.845 MPa), the pressure index increased from 0.159 to 0.371, – at 68.64 bar (6.864 MPa), the burning rate increased from 4.10 to 6.54 mm/s, but the theoretical specific impulse value did not change significantly (258.0259.8 s), – the tensile strength and E-modulus increased from 6.03 to 9.88 (0.591-0.969) to and from 18.00 to 75.00 kgf/cm2 (1.765 to 7.355 MPa), respectively. Moreover, a DSC and TGA study indicated a lower decomposition temperature for the NBR/DBP propellant compared to the HTPB propellant. The NBR/DBP propellant exhibited a pot life more than double that of a conventional HTPB/ DOA based propellant.

2

Rheological investigations in coating formulation

Kostinsyn A., Kulikova O., Indeikin E.

Farby i Lakiery

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2014

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nr 6

12--15

EN

State-of-the-art rheometry enables the formulator to measure product viscosities in a wide range of shear conditions, from the state of rest to exposure to high shear rates. Various shear forces acting at different stages of coating production and application change its flow behavior. In the present study the main rheological measurements taken during coating formulation are considered, i.e. flow behavior vs. shear rate, a three-interval thixotropy test, etc. Small-amplitude oscillatory shear (SAOS) provides a way of extending the use of rheometry in coating formulation. We considered a method of studying the influence of different types and amounts of surfactants on the rheological behavior of the system that could allow us to choose specifically the most suitable type and amount of surfactant. We also present the results of our study assessing the structure formation in the polyester melamine oven-cured coatings that enables the formulator to choose the suitable catalyst type.

3

Epoxy adhesive formulations using latent imidazole metal cation complexes

Pilawka R., Maka H.

Polish Journal of Chemical Technology

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2011

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Vol. 13, nr 1

63-66

EN

Complexes of 2-methylimidazole with cations from several metal sulfates were prepared and investigated as curing agents for epoxy resins. The reactivity of one-part formulations of these complexes with a bisphenol A type epoxy resin was determined by the differential scanning calorimetry and the pot life observed by viscosity measurements. Tensile lap shear tests at room temperature and at 120°C were used to evaluate the adhesive strength of the formulations directly after preparation as well as after one and three months of storage at room temperature. The DSC measurements showed much lower reactivity (7 - 32%) and higher reaction temperatures of the complex formulations in comparison to the mixtures with pure 2-methylimidazole. The viscosity of most formulations remained almost unchanged over the observed period of three months. The adhesive strength of the freshly prepared complex formulations is comparable to a formulation with pure 2-methylimidazole and decreases over time, depending on the type of metal cation and the cation-to-imidazole molar ratio. The obtained results indicate that complexes of 2-methylimidazole with cations are suitable as latent curing agents for epoxy resins.