Plastics' Aim- New Uses in Rockets
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ΡΡςΡΔΡΓΜ Moly "ideal 77 for Liquid State Studies 1 3 6 ACS NATIONAL MEETING Colloid Chemistry Molybdenum disulfide, used as a dry lubricant where graphite won't work, gives an "ideal surface for studying fundamentals of the liquid state," says General Electrie's Dr. Peter Cannon. MoS.j, says Dr. Gannon (shown check- ing a ga\ imetric adsorption system used in his experiments), has a lamellar struc- ture which allows detailed study of interactions of relatively small numbers of gaseous atoms or molecules. These studies lead -to an atomic theory of the liquid state, Dr. Cannon feels. One finding so far: The melting point of MoS.j is at least 2375 C, not 11S5~ C, as puhlished in the literature. however, sugar ferments so fast that the oxidation of lactic acid, the product of fermentation, does not keep pace with its formation. Result: Lactic . jid builds up in the tumor, then spills over into the blood stream. Dr. Racker, R. YVu, and J. B. Alpers used a system- atic analysis of the enzymes, cofactors, and regulatory mechanisms that take part in sugar metabolism to find the reason for the rapid production of lactic acid in tumors. Oxidation of food takes place in spe- cific intracellular structures called mito- chondria. Glycolysis ( fermentation of sugar) is catalyzed outside the mito- chondria by soluble glycolytic enzymes. Oxidation as well as glycolysis needs certain cofactors such as nucleotide adenosine diphosphate and inorganic phosphate for proper function. Dr. Racker and bis coworkers find that mitochondria and glycolytic enzymes compete for these cofactors. In normal cells, the oxidation process prevails; the glycolytic process is inhibited. In cancer cells, the enzyme which utilizes inorganic phosphate and the two en- zymes which utilize^ adenosine diphos- phate are present in such excess that they permit fermentât ion to proceed too rapidly. Plastics 7 Aim- New Uses in Rockets Aerojet studies plastic noz- zles; ARC works on new plastic heat insulators 1 3 8 ACS NATIONAL MEETING Paint, Plastics, and Printing Ink Chemistry Rocket engineers are taking an extra hard look at plastics these days. At- lantic Research Corp., for example, sees plastics, combined with ceramic or refractory materials, as promising heat insulators in rocket motors. And Aerojet-General Corp. has high hopes for plastic rocket motor nozzles. ARC is out to find a better insulat- ing flame shield than the carbon char formed by pyrolysis bf plastics. Car- bon char formed by current plastic in- sulators in rocket motors does much to prevent the insulation from eroding from the motor wall. But it can't hold up under the extended burning times and ultrahigh temperatures reached by the newer rocket motors, ARC's Dr. Walter C. Hourt told the Division of Paint, Plastics, and Printing Ink Chem- istry. The firm is now studying combina- tions of high and low char-forming plas- tics with ceramics and refractories such as metal oxides, nitrides, carbides, zir- conates, and titanates. Two ap- proaches have been tried: using ce- ramic or refractory as the continuous phase, and adding them as a discontin- uous phase in a continuous plastic matrix. Each combination, says Dr. Hourt, has giver, an insulation superior in one or more properties to current rocket motor insulations. For example, eval- uation of such composites in an oxy- aeetylene flame shows them to have much better erosion and thermal re- sistance than carbon char, he claims. Aerojet is working hard on a plastic rocket motor nozzle which will weigh less than current models and still be dimensionally stable under the neces- sary service conditions. Heat-resistant phenolic and phenolic-silicone resins currently appear to be* most suited to such nozzles, Aerojet's George Epstein says. For reinforcement, glass fabric made of Refrasii (96 to 9 9 % SiO._.) fiber gives the best performance, he believes. Other conclusions readied by Aero- jet: Fibrous fillers art 1 better than non- fibrous fillers; for a given nozzle ma- terial and design, ablation rate de- pends on time, gas pressure, and stag- nation temperature; and reinforcements oriented to provide an edge-grain ef- fect (fibers lie perpendicular to gas flow) are desirable. SEPT. 2 8, 1959 C&EN 47
Transcript of Plastics' Aim- New Uses in Rockets
Ρ Ρ ς Ρ Δ Ρ Γ Μ
Moly "ideal77 for Liquid State Studies
1 3 6 ACS NATIONAL MEETING
Colloid Chemistry
Molybdenum disulfide, used as a dry lubricant where graphi te won't work, gives an "ideal surface for studying fundamentals of the liquid s tate ," says General Electrie's Dr. Peter Cannon. MoS.j, says Dr. Gannon (shown check
ing a ga\ imetric adsorption system used in his exper iments) , has a lamellar structure which allows detailed study of interactions of relatively small numbers of gaseous atoms or molecules. These studies lead -to an atomic theory of the liquid state, Dr. Cannon feels. One finding so far: The melting point of MoS.j is at least 2375 C , not 11S5~ C , as puhlished in the literature.
however, sugar ferments so fast that the oxidation of lactic acid, the product of fermentation, does not keep pace with its formation. Result: Lactic . j id builds up in the tumor, then spills over into the blood stream. Dr. Racker, R. YVu, and J. B. Alpers used a systematic analysis of the enzymes, cofactors, and regulatory mechanisms that take part in sugar metabolism to find the reason for the rapid production of lactic acid in tumors.
Oxidation of food takes place in specific intracellular structures called mitochondria. Glycolysis ( fermentation of sugar) is catalyzed outside the mitochondria by soluble glycolytic enzymes. Oxidation as well as glycolysis needs certain cofactors such as nucleotide adenosine diphosphate and inorganic phosphate for proper function. Dr. Racker and bis coworkers find that mitochondria and glycolytic enzymes compete for these cofactors. In normal cells, the oxidation process prevails; the glycolytic process is inhibited. In cancer cells, the enzyme which utilizes inorganic phosphate and the two enzymes which utilize^ adenosine diphosphate a re present in such excess that they permit fermentât ion to proceed too rapidly.
Plastics7 Aim-New Uses in Rockets
Aero je t studies plastic nozzles; ARC works on new plastic heat insulators
1 3 8 ACS NATIONAL MEETING
Paint, Plastics, and Printing Ink Chemistry
Rocket engineers are taking an extra hard look at plastics these days. Atlantic Research Corp. , for example, sees plastics, combined with ceramic or refractory materials, as promising heat insulators in rocket motors. And Aerojet-General Corp. has high hopes for plastic rocket motor nozzles.
ARC is out to find a bet ter insulating flame shield than the carbon char formed by pyrolysis bf plastics. Carbon char formed by current plastic insulators in rocket motors does much to prevent the insulation from eroding from the motor wall. But it can't hold up unde r the extended burning times
and ultrahigh temperatures reached by the newer rocket motors, ARC's Dr. Walter C. Hourt told the Division of Paint, Plastics, and Printing Ink Chemistry.
The firm is now studying combinations of high and low char-forming plastics with ceramics and refractories such as metal oxides, nitrides, carbides, zir-conates, and titanates. Two approaches have been tried: using ceramic or refractory as the continuous phase, and adding them as a discontinuous phase in a continuous plastic matrix.
Each combination, says Dr. Hourt , has giver, an insulation superior in one or more properties to current rocket motor insulations. For example, evaluation of such composites in an oxy-aeetylene flame shows them to have much better erosion and thermal re
sistance than carbon char, he claims. Aerojet is working hard on a plastic
rocket motor nozzle which will weigh less than current models and still be dimensionally stable under the necessary service conditions. Heat-resistant phenolic and phenolic-silicone resins currently appear to be* most suited to such nozzles, Aerojet's George Epstein says. For reinforcement, glass fabric made of Refrasii (96 to 9 9 % SiO._.) fiber gives the best performance, he believes.
Other conclusions read ied by Aerojet: Fibrous fillers art1 better than non-fibrous fillers; for a given nozzle material and design, ablation rate depends on time, gas pressure, and stagnation temperature; and reinforcements oriented to provide an edge-grain effect (fibers lie perpendicular to gas flow) are desirable.
SEPT. 2 8, 1 9 5 9 C & E N 4 7
