Blown Bitumen

Bitumens are residues of the vacuum distillation of suitable crude oils (distillation bitumen). Residues of less suitable crudes must be partially oxidized by blowing to achieve the desired technical properties (semi-blown bitumen). Blown bitumens for special purposes can also be produced from vacuum residues. The process is executed by blowing a stream of finely distributed air through the molten bitumen (sometimes reduced in viscosity by addition of flux oil) at temperatures of 250-290 "C. 

Vaporization Start Temperature T5 % versus Mean Molecular Weight of Bitumens X Distillation Bitumens Blown Bitumens... 

See blown bitumen, blown castor oil, blown oil, and blown stand oil. 

See Blown Bitumen, Blown Castor Oil, Blown Oil, and Blown Stand Oil. ... 

Road paving. This includes bitumen, cutbacks and fluxed bitumen as well as emulsions. Each of these products is subject to very special application techniques. This list is completed by the use of poured asphalt, even though this product is better suited to smaller surfaces sidewalks, courts, etc., than to pavements. Since the middle of the 1980 s, air-blown bitumen is no longer used for road construction. 

The industrial applications, for which blown bitumen are very often used. Some of the industrial applications are given below ... 

Asphalt (qv) is prepared from petroleum and often resembles bitumen. When asphalt is produced simply by distillation of an asphaltic cmde, the product can be referred to as residual asphalt or straight-mn petroleum asphalt. If the asphalt is prepared by solvent extraction of residua or by light hydrocarbon (propane) precipitation, or if blown or otherwise treated, the term should be modified accordingly to qualify the product, eg, propane asphalt. 

In mice skin-painting studies, skin tumors were produced by steam-refined petroleum bitumens, an air-refined bitumen in toluene, two cracking residue bimmens, and a pooled mixmre of steam- and air-blown petroleum bitumens. In contrast, standard roofing petroleum asphalts produced no tumors. 

Use Solvent for nitrocellulose, cellulose ether, bitumens, metallic soaps, basic dyes, blown oils, crude rubber, many natural and synthetic resins and gums, lacquers. 

Cyclohexanone [108-94-1] (Hexanone) is insoluble in water, miscible with organic solvents. It is a high boiler with very good solvency for cellulose nitrate, cellulose ethers and esters, colophony, shellac, alkyd resins, natural and synthetic resins, chlorinated rubber, rubber, vinyl polymers and copolymers, polystyrene, ketone and ketone-formaldehyde resins, fats, oils, waxes, blown oils, and bitumen. [14.268],... 

Cyclohexyl acetate [622-45-7] is very slightly miscible with water, but completely miscible with common organic solvents. Its solvency properties are comparable to those of amyl acetate. Cyclohexyl acetate dissolves oils, fats, resins, waxes, cellulose nitrate, cellulose tripropionate and acetobutyrate, alkyd resins, unsaturated and saturated polyester resins, phenolic resins and aminoplasts, poIy(vinyI chloride), vinyl chloride copolymers, poly(vinyl acetate), poly(vinyl ethers), epoxy resins, and acrylic resins, basic dyes, blown oils, crude rubber, metallic soaps, shellac, and bitumen. 

Sample No. 9 blown propaties coiresponding to a blown bitumen 85/25... 

Samples 6, 7, 10, 11 are blown bitumens (partly oxidized) whereas the other samples represent vacuum residues (distillation bitumens). 

Data for the blown bitumens (samples 6, 7, 10 and 11) and for the low boiling samples 23-25 deviate from those of the other samples. Data for 13 samples (1-5, 8, 9,12-14,19, 20,22) show such a small scattering that statistical evaluation of the quotients... 

The relation of the residue at the inflexion point of the TGA curve, to the simulated vacuum residue (G /SVR) 100 for the group of the vacuum residues and bitumens shows widely differing values for blown (partly oxidized) products (samples 6, 7, 10, and 11). Statistical treatment (G /SVR) 100 for samples 1-13 give a mean x = 25.1 % with the very large coefficient of variation V = 20.86 % (relative). When the blown products are excluded there is a considerably smaller scattering of results ... 

The experiments were carried out on sixteen distillation bitumens of different consistency and different origin as well as on five blown bitumens [4-20]. 

Use of the same symbols in the plots shows distillation bitumens taken from the same refinery. Only the samples marked by a square symbol were taken at the same time. Each of the blown bitumens is marked with an asterisk. 

It is notable that the dispersion medium, as well as the petroleum resins of the blown bitumen are more aliphatic in character than those components of the distillation bitumens. This may be caused by the composition of the flux oils which were added. The asphaltenes of both types of bitumen display similar aromacity (Table 4-54) ... 

Table 4-54 Means x and coefficients of variation V (%) of the H C ratio of the blown bitumens...

Comparison of the means from the distillation and the blown bitumens reveals a difference between the petroleum resins of each type of petroleum, whereas the means of the bitumens and the asphaltenes are the same. 

The colloid composition of the blown bitumens shows higher asphaltene content and lower dispersion medium content than that of the distillation bitumens. 

Evaporation of the distillation bitumens and their colloidal components first starts at temperatures 200 °C (71 %) or 259 °C (75 %). Since thin-layer evaporation takes place in the thermobalance, and the evaporated parts of the sample are immediately removed by the gas flow, these temperatures are lower than the real start temperatures of an equilibrium evaporation (for example distillation according to Engler DIN 51 751 or ASTM D 285-62). The corresponding start temperatures for an equilibrium evaporation should be more than 400 °C. The evaporation start temperatures for bitumen, dispersion medium, and petroleum resins are lower in the case of blown bitumens, influenced by the flux oils which are added in order to facilitate the blowing process. Some of the index numbers of the thermogravimetry may be correlated with consistency data, and with analysis data (see chapters 4.3.2.1.1 and 4.3.2.1.2). Other values show only a small... 

The blown bitumens sometimes have two peak maxima in the DTG curve, whereas the first maximum is absent in all cases involving asphaltenes. Bitumens, dispersion medium, and petroleum resins show the first maximum in the distillation range around 300 °C. The second maximum appears in the crack (pyrolysis) range. The coefficients of variation are larger (Table 4-62) because the number of samples is small. 

The higher temperature of the peak maximum for the asphaltenes of the blown bitumen indicates that very large molecules or aggregates are formed by the condensation reaction as a consequence of the blowing process. The temperatures of the DTG peak maxima above 400 °C represent thermal cracking processes (pyrolysis). The smaU coefficients of variation of the individual colloidal components indicate that thermal cleavage of identical or similar chemical bonds has taken place. The resistance of the bitumens to pyrolysis is governed by the properties of the dispersion medium, and this is shown by the uniformity... 

The distillable portion of the samples at normal pressure, AG400, increases due to the increase of the penetration (Fig. 4-40) AG400 = f(Pen). The data of the samples from one refinery fit a straight line very well whereas the data from the other refinery form a curve passing through a minimum. The values of the blown bitumen once again form a separate group. 

The peak maximum temperatures of the DTG, representing the rate of the cracking reaction, decrease with increasing penetration (Fig. 4 1) DTG = f(Pen). These data for the samples of distillation bitumens fit a straight line fairy well but the values from the blown bitumens lie separately. The value of the distillation bitumen BIO (sample 16) lies on the line of the blown bitumens indicating that the product must be semiblown. 

The index numbers T % and T5 % of the distillation bitumen can be correlated with the softening point (Fig. 4-42 T5% = f(S.P. R B). The curves of T1 % and T5 % versus S.P. R B have very steep slopes for the distillation bitumens. The values for the blown bitumens are scattered, away from these curves. The values for the laboratory blown product (sample I) and for the bitumen BIO (sample 16) lie between the curves of the... 

The maxima of the weight loss rate also rises rapidly against the softening point DTG = f(SP R B). The values of the samples 16 and I are again situated between the distillation and the blown bitumens (Fig. 4-44). 

---