La pyrolyse de poly(adipate de butylène-1,4)

1977 ◽  
Vol 55 (14) ◽  
pp. 2732-2740 ◽  
Author(s):  
François Messier ◽  
Don C. DeJongh
Keyword(s):  
Adipic Acid ◽  
Atmospheric Pressure ◽  
Quartz Tube ◽  
Heated Zone ◽  
Volatile Products

Poly(1,4-butylene adipate) (1) was pyrolyzed in a porcelain boat placed in a quartz tube heated by a furnace. Volatile products were carried out of the heated zone into traps by a flow of nitrogen. Polyester 1 was pyrolyzed both near the entrance and near the exit of the heated zone, at 500 and 700 °C with and without a vacuum. Adipic acid (2), cyclopentanone (4), and a mixture of mono (5) and diesters (6) of the monomer, dimer, and trimer, were isolated as products of the pyrolyses.The pyrolyses of 1 at 500 °C near the exit of the heated zone at atmospheric pressure gave 14% of 2, 10% of 4, 40% of 5, and 18% of 6; 5 consisted of 26% monoester of monomer and 74% monoester of dimer, whereas 6 consisted of 63% diester of monomer and 37% diester of dimer. At 700 °C, 0.2–0.3 Torr, with 1 near the entrance of the heated zone, the yield of 2 was higher (∼35%), and trimers were found in the monoesters 5 and diesters 6, along with dimers and monomers.

scholarly journals University of Kiel Radiocarbon Measurements II

Radiocarbon ◽  
1967 ◽  
Vol 9 ◽  
pp. 257-260
Author(s):  
H. Willkomm ◽  
H. Erlenkeuser
Keyword(s):  
Proportional Counter ◽  
Atmospheric Pressure ◽  
Statistical Error ◽  
Quartz Tube ◽  
Sensitive Volume ◽  
Concrete Wall ◽  
Lead Shield ◽  
Double Ring

Most of the measurements reported here have been obtained with the 4.5-L CO2 counter previously described (Kiel I; Erlenkeuser, 1965). A few samples have been dated with a 3-L proportional counter. The copper counter is surrounded by 28 GM counters in the form of a double ring. The total assembly is shielded by 10 cm of old lead. Neither an inner lead shield between counter and anticoincidence ring nor screening of sensitive volume by a quartz tube-as in the 4.5-L counter-has been used. Background of the small counter is 17.20 cpm or The 0.95 x NBS value is 9.5 cpm at 400 torr. Within statistical error background does not depend on atmospheric pressure. The 3-L counter is placed under a concrete wall, 2.5 m in length and 9.4 m in height.

Chemical Reactions of Rubber

1943 ◽  
Vol 16 (1) ◽  
pp. 111-123
Author(s):  
R. L. Sibley
Keyword(s):  
Molecular Weight ◽  
Atmospheric Pressure ◽  
Rapid Heating ◽  
Slow Heating ◽  
Gutta Percha ◽  
Volatile Products ◽  
Almost All ◽  
Isomeric Product ◽  
Derivatives Of ◽  
Complete Investigation

Abstract Most of the literature descriptive of the various known derivatives of rubber is found published as patents rather than as technical papers, thus indicating the commercial possibilities that may be expected from these developments. Fisher, Schidrowitz and, more recently, Jones have summarized and discussed the chemistry of rubber and its commercial derivatives. The decomposition of rubber by heat has been studied by several investigators. Williams showed that isoprene is one of the main products formed by the destructive distillation of either caoutchouc or gutta percha. Later investigators have shown that slow heating in vacuo at 300° C converts somewhat more than one-half of rubber hydrocarbon into a solid, thermoplastic, isomeric product, which has a high molecular weight and less unsaturation than that of the original hydrocarbon. Rapid heating, especially in vacuo, converts almost all the rubber into volatile products. The most complete investigation of the products obtained by the heat decomposition of rubber apparently was carried out by Midgley and Henne. These investigators destructively distilled 200 pounds of pale crepe rubber in 16-pound batches by raising the temperature as rapidly as possible to 700° C at atmospheric pressure in an iron kettle. The condensate was fractionally distilled, and cuts were made every degree between 50 to 176° C. Each cut was then separately examined. Twenty-three different hydrocarbons were identified in the distillate.

Durable-Press Cotton by Wet Fixation

1969 ◽  
Vol 39 (6) ◽  
pp. 512-520 ◽  
Author(s):  
R. L. Colbran ◽  
C. C. Maitland ◽  
W. J. Roff
Keyword(s):  
Atmospheric Pressure ◽  
Abrasion Resistance ◽  
Zinc Nitrate ◽  
Full Width ◽  
Durable Press ◽  
Volatile Products ◽  
Nitrate System

The development of both continuous and batch steaming techniques suitable for the wet fixation of full-width cloth is described. When resin-impregnated cloth in open width is passed through steam at atmospheric pressure, steaming times of 15 sec to 2 min lead to a good fabric performance; further prolongation of steaming results in lower recoveries but greater strength and abrasion resistance. When fabric is held in steam in rolled-up form, so that the escape of volatile products from the cloth during steaming is minimized, good wrinkle recovery is obtained even after 60-min steaming. Other aspects of the process, such as the variation of impregnation conditions, the effect of partial drying immediately after impregnation, and the conditions of the final dry cure are also discussed. For comparable wrinkle recoveries and smoothness ratings, wet fixation gives fabrics with better strength and abrasion resistance than conventional pad-dry-press-cure with a DHDMEU-zinc nitrate system, the same amount of polyethylene lubricant being applied in both types of treatment.

Thermal Degradation of Unvulcanized and Vulcanized Rubber in a Vacuum

1957 ◽  
Vol 30 (1) ◽  
pp. 93-111 ◽  
Author(s):  
Sidney Straus ◽  
S. L. Madorsky
Keyword(s):  
Thermal Degradation ◽  
Natural Rubber ◽  
Atmospheric Pressure ◽  
Average Molecular Weight ◽  
Degradation Process ◽  
Extensive Study ◽  
Vulcanized Rubber ◽  
Volatile Products ◽  
History Of ◽  
Cis And Trans

Abstract The history of distillation of rubber under various conditions of temperature, pressure, and atmosphere goes back more than a century. As far back as 1860, Williams distilled rubber in an iron retort at relatively low temperatures and obtained some 5 per cent of crude isoprene. In 1922, Staudinger and Fritschi distilled rubber at 275° to 320° C at 0.1- to 0.3-mm. pressure and obtained 3.1 per cent of isoprene. In 1926 Staudinger and Geiger distilled rubber below 300° C at ordinary pressure in an atmosphere of carbon dioxide and obtained 4.3 per cent of crude isoprene. Distillation of rubber at higher temperatures and under atmospheric pressure yielded as much as 58 per cent of isoprene. In addition to isoprene, dipentene and higher terpene compounds were also identified in the distillation products of natural rubber. More recently, distillations of pure synthetic polyisoprene (a mixture of cis- and trans-polyisoprene), purified natural rubber (cis-polyisoprene), and purified gutta hydrocarbon (trans-polyisoprene) were carried out by the present authors in a vacuum under conditions of molecular distillation. The volatile products were fractionated and analyzed both qualitatively and quantitatively, using the mass spectrometer for the lighter fractions. The volatiles consisted of about 3 to 4 per cent of isoprene and 13 to 20 per cent of dipentene, the rest being large terpene fragments of average molecular weight of about 600. The present paper describes an investigation of the effects of various additions to natural rubber, with or without subsequent vulcanization, on the degradation process during pyrolysis in a vacuum, with the view that such a study might throw some light on the structure of vulcanized rubber. In addition to pyrolysis, a study was also made with unvulcanized and vulcanized rubber of the rates and activation energies of thermal degradation in a vacuum, using techniques and apparatus that were previously developed by the authors in connection with an extensive study of thermal degradation of a number of polymers.

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