Effect of Binder

The effects of four types of binders, HTPS, HTPE, HTPA, and HTPB, on the burning rates of HMX composite propellants are shown in Fig. 7.33. The physicochemi- 

The presence of carbonaceous fragments can be attributed to the low oxygen content in the HTPB binder, 3.6%, compared to oxygen contents in the HTPS, HTPE, and HTPA binders of more than 25 %, as shown in Table 4.3. 

The combustion wave structure of RDX composite propellants is homogeneous and the temperature in the solid phase and in the gas phase increases relatively smoothly as compared with AP composite propellants. The temperature increases rapidly on and just above the burning surface (in the dark zone near the burning surface) and so the temperature gradient at the burning surface is high. The temperature in the dark zone increases slowly. However, the temperature increases rapidly once more at the luminous flame front. The combustion wave structure of RDX and HMX composite propellants composed of nitramines and hydrocarbon polymers is thus very similar to that of double-base propellants composed of nitrate esters.[1 1 

The flame stand-off distance, L4, defined in Eq. (3.70), decreases with increasing pressure, and the pressure exponent of the flame stand-off distance, d, ranges from -1.9 to -2.3 for RDX and HMX propellants. The overall order of the reaction in the dark zone is determined to be m = 2.5-2.8. This is approximately equal to the overall order of the reaction in the dark zone in the case of double-base propellants, m = 2.5, which would suggest close similarity of the reaction pathways in the dark zone for nitramine composite propellants and double-base propellants. 

However, the luminous flame front rapidly approaches the burning surface when the pressure is increased. This reaction is also caused by the reduction of NO to N2, as in the reaction process of double-base propellants. 

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FIG. 20-74 Effect of binder viscosity and liquid content on final granule porosity for the drum granulation of 15 im glass baUotini. Decreasing granule porosity corresponds to increasing extent of granule consolidation. [Iveson et al., Powder Tech., 88, 15 (1996). ] With land permission from Elsevier Science SA, Lausanne, Switzerland. 

Fig. 7 Effect of binder concentration and method of addition on granule size. (From Ref. 46.)...

When evaluating the effect of binder concentration on a number of tablet properties, surface area measurements were used to investigate the bond strength of the binder with the other particles [18]. A steady reduction in the surface area of the granules with increasing binder concentration indicated that the binder had covered or penetrated the particles, with the formation of particle-binder bonds. This was related to friability, and the increased bond strength was related to the decreased surface areas. 

Abd El-Malek, M.M., Mohsen, R.M., Ayoub, M.M.H., New approach to the effect of binder composition on antifouling efficiency using scanning electron microscopy. JOCCA 11 (1987), 337-341. 

Becker, D., Rigassi, T., and Bauer-Brandl, A., Effectiveness of binders in wet granulation A comparison using model formulations of different tabletability, Drug Dev. Ind. Pharm., 23 791-808 (1997). 

Fig. 7.17 Effect of binder on burning rate in the low-pressure region.

Fig. 7.56 Effect of binder on the burning characteristics of AP composite propellants (HTPB and HTPE).

The literature contains relatively little data on the physical properties of binder solutions and therefore conclusions must be drawn largely from qualitative observations. For example, Davies and Gloor (1972) have linked the effectiveness of binders with their adhesiveness or tackiness and have found that more viscous binder solutions increase the size of granules and reduce the bulk density. Hydroxypropylcedulose (HPG), with which atomising difficulties were encountered because of its viscosity, was responsible for the largest increase in mean particle... 

J. E. Tanner, "Effect of Binder Oxygen Content on Adiabatic Flame Temperature of Pyroteehnie Flares," RDTR No. 181, Naval Ammunition Depot, Crane, Indiana, August,... 

Figure 7.22 Effect of binder concentration on granule size in spray granulation of alumina. From J. S. Reed, Principles of Ceramics Processing, 2nd ed. Copyright 1995 by John Wiley Sons, Inc. This material is used by permission of John Wiley Sons, Inc.

Figure 16. Effect of binder type on burning rate of ammonium perchlorate propellants. Mean particle size of AP is 5fi...

Schaefer T, Worts O. Control of fluidized bed granulation IV. Effects of binder solution and atomization on granule size and size distribution. Arch Pharm Chem Sci Ed 1978 6 14-25. 

Many investigators have studied the effect of binders and their percentages on the efficiency of illuminating formulations. In general, the luminosity and luminous efficiency increase to a maximum at =4—6% of the binder and thereafter decrease. It has also been reported that binders with high oxygen content, such as unsaturated polyesters and epoxy resins, improve the efficiency... 

In order to assess the effect of binder content variation on performance, three sections with binder contents of 7.0, 7.5 and... 

Schaefer, T. and O. Worts, Control of Fluidized Bed Granulation, IV. Effects of Binder Solution and Atomization on Granule Size and Size Distribution, Arch. Pharm. Chemi. Sci., Ed. 6, 1978, pp. 14-25. 

De Longueville et al (Ref 28) also examined the interaction effects of binder content and charge diameter. The test material in each case was 72% by volume of a fixed perticle size RDX with 5 different binders. Max values of D are shown in Table 9, and D vs 1/d plots for mixts 3 and 5 of Table 9 are given in Fig 10. Note that Si content in the binder reduces D... 

Rohera BD, Zahir A. 1993. Granulation in a fluidized-bed effect of binders and their concentration on granule growth and modeling the relationship between granule size and binder concentration. Drug Dev. Ind. Pharm. 19 773-792. 

Warren JW and Price JC. 1977. Drug migration during drying of tablet granulations. II. Effect of binder solution viscosity and drying temperature. J. Pharm. Sci. 66 1409-1412. 

S. M. Iveson, J. D. Htster, B. J. Ennis, Fundamental studies of granule consolidation - part 1 Effects of binder content and binder viscosity, Powder Technol., 1996, 88,15-20. 

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