Ozonized bitumen

Atmospheres polluted by oxidising agents, e.g. ozone, chlorine, peroxide, etc. whose great destructive power is in direct proportion to the temperature, are also encountered. Sulphuric acid, formed by sulphur dioxide pollution, will accelerate the breakdown of paint, particularly oil-based films. Paint media resistant both to acids, depending on concentration and temperature, and oxidation include those containing bitumen, acrylic resins, chlorinated or cyclised rubber, epoxy and polyurethane/coal tar combinations, phenolic resins and p.v.c. 

Figure 1. Surface tension of water soluble fraction of ozonized bitumen...

Table II. Analysis of Unozonized and Partly-Ozonized Bitumen...

In sampling the tube, samples were taken from four equal length sections along the tube, designated A, B, C, and D starting from the ozone inlet end. The bitumen was extracted from each of these samples... 

Table II. Surface Tensions of Ozonized and Ozonized-Sulf onated Bitumen...

The crosslinked polymers have been decrosslinked by ozone, which allowed their evaluation, especially in compositions with bitumens. The ozonized polyethylene wastes can be used in bitumens for reinforcement. In aU the examples dealt with, the study describes the analysis methods and the properties of the obtained materials and shows that ozonization constitutes an original way of treatment and utilization of plastic wastes. 

In order to understand this phenomenon and establish if a chemical reaction occurs between the ozonized PE and the bitumen, PE-bitumen coupling products were isolated. For this purpose, an ozonized bitumen/PE binder was purified by carbon tetrachloride washing in order to eliminate the bituminous fraction. The recovered polymer was crystallized in hot toluene and analyzed. The product isolated in such a manner exhibited characteristics typical for polyethylene and was studied by GPC chromatography (Table 9). 

Table 9 Molecular weight and polydispersity of the ozonized polyethylene deactivated on bitumen...

The results show that ozonization decreases the molecular weight of polyethylene molecules. The molecular mass of the ozonized product is approximately twice lower than that of initial product. Moreover, the polydispersity index rapidly increases, which indicates that chains, broken during the ozonization, have different sizes. When we examine the results obtained with the ozonized sample deactivated on bitumen, we notice that the molecular mass increases and is in the range of the standard polyethylene molecular mass. This increase can only be due to two phenomena ... 

The probability for the second hypothesis is higher because the reaction medium mainly contains bitumen and the Ro free radicals have far more chances to deactivate on bitumen. Furthermore, molecules constituting the bitumen have low molecular weight (< 1500), as verified by GPC analysis (Table 9). GPC data also indicate that the number of grafts, reacted with ozonized PE, is large because M varies from 6100 to 15800. 

Table 11 Flexural modulus of gravel bituminous mixes based on bitumen and ozonized polyethylene...

The binder adhesivity to gravel was also measured, particularly for quartzite, (the mixing with bituminous binders is difficult). Gravel-bituminous mixes with various binders were maintained at temperature 60°C in a thermostated bath and the percentage of the minerals which were not coated by bitumen quantified. The results in Table 12 show that binders containing ozonized polyethylene adhere much better than binders based on non-activated polyethylene or bitumen alone. 

Quarzite + bitumen 180/200 + ozonized PE (IF=70) Quarzite + bitumen 180/200 + recovered PE Quarzite + bitumen 180/200 + recovered ozonized PE... 

The best properties of the bitumen-decrosslinked polymer binders are obtained for wastes ozonized for 90 minutes at 47°C. In other conditions, either insufficient dissolution of the polymer in the bitumen, or too complete dissolution of the polymer, accompanied by decrease in binder performance, occurs. 

There have been numerous efforts to make use of the huge volume of 1. that result from paper pulping. Only 2% of the 1. is separated. Most of the crude material is burned in the power stations of the paper mills. ->Lignosulfonate is the only large-volume derivative of 1. All other efforts to modify Kraft 1. (ozonization, carboxylation, condensation with formaldeyde) and attempts to make cationic 1. as emulsifiers for bitumen have led to only small applications. L. has also been used for commercial production of - vanillin. 

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