Mechanical propellant

In a reaction vessel equipped with mechanic propeller stirrer, argon inlet, and reflux condenser an emulsion is prepared of distilled water (300 g), methyl methacrylate (MMA 9.5 g),allyl methacrylate (ALMA 0.5 g) and sodium dodecyl sulfate (5D5 ... 

TTHE PLANKTON OF THE SEAS AND OCEANS adjacent to the British Isles have been studied for over 50 years with the continuous plankton recorder (CPR) (i). Continuous plankton recorders are towed at a fixed depth of 10 m at monthly intervals by ships-of-opportunity (merchant ships and weather ships) on standard routes. They retain the plankton on a mechanically propelled, continuously advancing band of silk for subsequent laboratory analysis (2). A few CPRs have carried temperature recorders and sensors for other environmental parameters (3, 4). 

Samples from these films were again placed between Teflon-coated aluminum foil and were suspended in a forced convection oven at 170°C for 30 min. The molten polymer was then mechanically propelled into a bath of isopentane slurry at — 160°C as described previously (53). The isopentane was cooled with an outer jacket of liquid nitrogen. The quenched sample was removed from the isopentane and was allowed to anneal at room temperature for 20 hr prior to examination by IR spectroscopy at 78-290 K. 

The jetting mechanism propels small dots at rates up to 200 Hz in four software-controlled modes distance based, time based, fixed number of dots per line, and continuous line with breaks, enabling the construction of many different sizes and shapes of dots and lines. Because the momentum of the fluid comes from the jetting action, proximity to the substrate (dispense gap) is much less critical than it is in needle dispensing. 

In a reaction vessel equipped with mechanic propeller stirrer, argon inlet, and reflux condenser an emulsion is prepared of distilled water (300 ml), methyl methacrylate (MMA 9.5 g), allyl methacrylate (ALMA 0.5 g) and sodium dodecyl sulfate (SDS 50 mg). The emulsion is heated (75°C), and ammonium peroxodisulfate (APS 0.6 g) dissolved in water (5 ml) is added. After 50 min a mixture of MMA (28.5 g) and ALMA (1.5 g) is added dropwise (within 1 h). Subsequently, a monomer emulsion formed by water (250 ml), SDS (1.1 g), MMA (252 g), ALMA (8 g), and APS (0.5 g) is added ccaitinuously (within 225 min) to the reaction mixture. After complete addition, stirring is continued for further 1 h at 75°C and for further 2 h at 85°C. Finally, the emulsion is allowed to cool down to room temperature. 

For any machine or plant to be used efficiently, the operators must be trained and, in the case of cranes, capstans, winches, woodworking machines and mechanically propelled vehicles, there is a legal obligation for them to be so. Operators of these machines should be over 18 years old unless being trained and under the direct supervision of a competent person. 

There are also mechanical techniques for introducing DNA containing specific genes into plant cells. One of them concerns the use of DNA bullets whereby metal particles (tungsten or gold) combined with DNAfragments are mechanically propelled into host cells where the donor DNA combines with that of the host plant. 

Do all mechanically propelled site plant carry suitable extinguishers ... 

Compressed gas systems were originally developed simply to provide a means of expelling a product from its container when the valve was depressed. SemisoHd products such as a cream, ointment, or caulking compound are dispensed as such. A Hquid concentrate and a compressed gas propellant (Fig. 3) produce a spray when a mechanical breakup actuator is used. Nitrogen, insoluble in most materials, is generally used as the propellant. 

Trimethylolethane trinitrate (metriol trinitrate) is not satisfactory as a plasticizer for nitrocellulose, and must be used with other plasticizers such as metriol triacetate. Mixtures with nitroglycerin tend to improve the mechanical properties of double-base cast propellants at high and low temperatures. Metriol trinitrate has also been used in combination with triethylene glycol dinitrate as a plasticizer for nitrocellulose. Its physical properties are Hsted in Table 7 (118-122). 

Rocket Propellants. SoHd rocket propellants are mostly based on chemically cross-linked polymeric elastomers to provide the mechanical properties required in launchings and the environmental conditions experienced in storage, shipment, and handling (see Elastomers, synthetic). Double-and triple-based nitrocellulose propellants are also employed as rocket propellants. 

Polymer-based rocket propellants are generally referred to as composite propellants, and often identified by the elastomer used, eg, urethane propellants or carboxy- (CTPB) or hydroxy- (HTPB) terrninated polybutadiene propellants. The cross-linked polymers act as a viscoelastic matrix to provide mechanical strength, and as a fuel to react with the oxidizers present. Ammonium perchlorate and ammonium nitrate are the most common oxidizers used nitramines such as HMX or RDX may be added to react with the fuels and increase the impulse produced. Many other substances may be added including metallic fuels, plasticizers, stabilizers, catalysts, ballistic modifiers, and bonding agents. Typical components are Hsted in Table 1. 

Gun Propellents. Although the stresses on individual gun propellant grains are less severe because of the small size, these propellants must withstand much higher weapon pressures and accelerations. Formulation options are usually more limited for gun propellants than for rocket propellants because the products of combustion must not foul or corrode a gun, should have a low flame temperature, and should exhibit minimum flash and smoke characteristics. Gun propellants are examined microscopically for porosity, are tested for mechanical characteristics, and fired in closed bombs to determine the burning characteristics. 

Oxidizers. The characteristics of the oxidizer affect the baUistic and mechanical properties of a composite propellant as well as the processibihty. Oxidizers are selected to provide the best combination of available oxygen, high density, low heat of formation, and maximum gas volume in reaction with binders. Increases in oxidizer content increase the density, the adiabatic flame temperature, and the specific impulse of a propellant up to a maximum. The most commonly used inorganic oxidizer in both composite and nitroceUulose-based rocket propellant is ammonium perchlorate. The primary combustion products of an ammonium perchlorate propellant and a polymeric binder containing C, H, and O are CO2, H2, O2, and HCl. Ammonium nitrate has been used in slow burning propellants, and where a smokeless exhaust is requited. Nitramines such as RDX and HMX have also been used where maximum energy is essential. 

Gun Propellents. Low sensitivity gun propeUants, often referred to as LOVA (low vulnerabUity ammunition), use RDX or HMX as the principal energy components, and desensitizing binders such as ceUulose acetate butyrate or thermoplastic elastomers (TPE) including poly acetal—polyurethane block copolymers, polystyrene—polyacrjiate copolymers, and glycidyl azide polymers (GAP) to provide the required mechanical... 

All five processes requite plasticization of the nitrocellulose to eliminate its fibrous stmcture and cause it to bum predictably in parallel layers. Mechanical working of the ingredients contributes to plasticization and uniformity of composition. The compositions of representative nitroceUulose-based gun propellants are shown in Table 7. 

S olid Propellant Mging, Mechanical Pehavior and Grain Structural Integrity, CPIA Pubhcation LS 77-27, CPIA, Johns Hopkins University, Laurel, Md., 1977. 

G. K. Adams, in Proceedings of the Fourth Symposium of Naval Structural Mechanics Mechanics and Chemisty of Solid Propellants, Pergamon Press, Inc., New York, 1967, p. 117. 

J. A. Stein, P. L. Stang, and M. Summerfield, The Burning Mechanism ofMmmonium Perchlorate-Based Composite Propellants, Aerospace and Mechanical Sciences Report 830, Princeton University, N.J., 1969. 

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