1. 330 440 650 680 720 525-600 442-30 1 13 20 33
2. 66 20-66 20-66 Thermocouple Optical pyrometry IR pyrometry IRpyrometry IR pyrometry Phasetransition Reanalysis ofRef.46 65 66 53 53 53 46 67 thattheliquidlayerformed duringcombustionisfrothy asaresultoftheformation of the gaseous products. The degree of exothermicity is not sufficient to sustain the burning of AP below about 15-atm pressure. Heat feedback from the flame zoneisneeded, and anestimateof the amount of heatreleased atthe surface is as highas 70% (Ref. 57).The thicknessoftheliquidlayer decreaseswithincreasing pressure, andthelayer appears goneby about 60 atm(Refs. 3, 29, and 30).
3. The surface temperature ofburningAPhasbeen estimatedby severalmethods and a fewof the values are given in Table 1(Refs. 46, 53, and 65-67). As is the casewithmanyotherenergeticmaterials,theagreementamongthesedataispoor, which reflects the difficulty of making an accurate measurement on a transient, multiphase,reaction surface.
4. Although radicals such as OH, CIO, and NH are detected after laser pyrolysis,10'13mostoftheproductsdetectedbyothermethodsarestablemolecules with mostly even, but some odd, electronCOunts2'9'20'55'59'73'74: N2O, NO, NO2, NOC1,HNO3, HC1O4, HC1, C1O2,NH3,H2O,C12, O2,N2, H2, andhydrated HC1 and HC1O4. For example, the IR spectrum over AP flash heated at 800°C s"1to 500°Cunder 4atmofArisshowninFig.2andrevealssomeoftheseproducts.The speciesjustlistedarelater-stageproductsfrom thenumerouselementaryreactions between N, H, O, and Cl. Many of these products, along with some of the more reactive radicals, escape the surface and initiate the AP flame. Discussion of the flame structure is not the subject of thispaper,but closure of this sectionis aided by summarizing the flame zone chemistry modeling efforts. Kishore6reviewed some ofthemodels devisedbefore 1976.
5. The use of HTPB as a binder in solid rocket propellants appears to date from about 1962inworkbytheAerojet Corporation.42Many structuresofHTPBexist, andthemostcommonlyusedtype (R45M,whose structurewasshownin Sec.II) canbe thought of asaterpolymer ofcis-trans- andvinyl-linkedbutadieneunits. Inaddition,theterminalgroups,thatare -OHinR45Mareanadditionalvariable. Also,CO2H hasbeenused as aterminal group (called CTPB), butis nolonger used as a propellant binder in the United States. The copolymer of polybutadiene and acrylic acid (PBAA) and terpolymer of polybutadiene, acrylic acid, and acrylonitrile (PBAN) alsohaveapplicationaspropellantbinders.Severaldetailed reviews27'82andmore specialized summaries3'6'24'83ofpolybutadienes,including their useinrocketpropellant formulations, are available.