Bitumen-modified rubbers

Uses Bitumen modifier hot-melt pressure-sensitive adhesives roller coverings rubber shoe soling compds. sealants food-contact and medical applies. 

Bitumen modifiers can be synthetic polymers, natural rubber (latex) and some chemical additives such as sulfur and certain organo-metallic compounds. Fibres and fillers (inorganic powders) are not considered to be bitumen modifiers. Table 3.16 gives some typical bitumen modifiers, as well as significant improvements to asphalts. Polymers are the most common type of bitumen modifiers, with thermoplastic elastomers being the most popular polymer. 

Ke)rwords amorphous polypropylene (aPP), atactic polypropylene (aPP), additives, hot-melt adhesive, rubber extender, bitumen modifier, metallocene synthesis, molecular weight, properties of aPP, applications of aPP, thermoplastic dynamic vulcanizate (TDV). 

Piazza S., Arcozzi A., and Verga G., Modified bitumen containing thermoplastic polymers. Rubber... 

The solvency of cycloaliphatic hydrocarbons is between that of aliphatic and aromatic hydrocarbons. They have a high solvency for fats, oils, oil-modified alkyd resins, styrene-modified oils and alkyd resins, bitumen, rubber, and other polymers. Polar resins (e.g., urea-, melamine-, and phenol-formaldehyde resins), as well as alcohol-soluble synthetic resins and cellulose esters are, however, insoluble. 

The use of blending GRT with asphalt has been in existence for quite some time. Depending on the type of tire, the composition of GRT may include different rubbers. These crosslinked rubbers are mostly immiscible in bitumen. The blends show an improvement in basic asphalt properties as well as rubberlike characteristics. The blend is thought of as a dispersion of undissolved swollen rubber particles acting as an elastic aggregate within asphalt, modified by the portion of the rubber particles that have dissolved. 

The penetration grade, softening point, and ductility of the GRT-modified bitumens were studied as a function of rubber selection, temperature, rotational speed, shearing time, order of rubber, and oil addition (Li et al 2009). It was established that a shearing time of 40 min, a temperature of 180" C, a rotational speed of7000 rpm, and a rubber concentration below 25 wt.% with oil content below 4 wt.% were optimal for carrying out the technological process for preparation the GRT-modified asphalts. 

The crumb rubber is either blended with the bitumen or added to the aggregates in the asphalt plant mixer before the bitumen is charged to the mixer. The first process is known as the wet process and effectively modifies the bitumen. The second process is known as the dry process and effectively modifies the properties of the asphalt. Better results are expected when the wet process is employed. 

With respect to crumb rubber modification, a recent study has shown that crumb rubber (size 0/0.8 mm and quantity 5%, 10% and 15% by mass of bitumen), when blended to 70/100 and 50/70 graded bitumens, results in improved penetration, softening point, flexural creep stiffness and shear modulus G. The quantity of the crumb rubber and the provenance of the bitumen directly influence the above properties of the modified bitumen (Neutag and Beckedahl 2011). 

In another study using crumb rubber (size 0/0.7 mm and quantity 15% and 18%), it was also found that the characteristic and rheological properties of the bitumen improved. However, the storage stability requirement of the rubberised modified bitumen (RmB) was not satisfied. When wet and dry processes were compared on extracted RmB from an asphalt concrete mixture (AC 8 mm), it was found that the effect of crumb rubber was more profound when the wet process was used (Lukac and Valant 2011). 

RuBind is added directly to the pug mill or dryer drum, replacing part of the bitumen. Extensive research and development during 2011 and 2012 showed that mixtures produced with RuBind outperform conventional hot mix asphalts and even common modified and asphalt rubber mixes (RuBind 2013). 

According to ASTM D 6932 (2008), the binder content of an OGFC mixture typically ranges from 5% to 7% when paving grade bitumen is used, from 6% to 8% when modified bitumen is used or from 8% to 10.5% when bitumen-rubber is used. 

According to AC 150/5370-10F, Item P-402 (FAA 2011b), the binder should be viscosity-graded bitumen (asphalt cement) with a synthetic rubber (polymer) added at a percentage of not less than 2%, by mass of bitumen. The properties of the modified bitumen should comply with the requirements of Table 5.21. 

It is noted that the durabihty of asphalt concrete pavements is determined by the time of the trunk cracks formation in the poljmier-containing composites in the modified by elastomers (e.g., by rubber) bitumenous binder of asphalt. Developed by the authors [ 1 ] previously the theory of the cracks propagation in heterosystems has allowed to investigate the problem of the cracks propagation in the rubber-bitumen composite. This investigations show that most effectively to prevent the trunk cracks formation in asphalt concrete can ultrafine mbber particles (150-750 run) in a bitumenous binder of asphalt. 

Rubber modifier is characterized by a slow rate of fatigue growth under external cyclic loads as well as high energy of new surface significantly exceeding (by tens or hundreds times) of bitumen surface energy y. ... 

The insulation system for pitched roofs usually provides the advantage of a continuous, homogeneous insulating layer with an economy in construction. Bitumen (asphalt) as well as its different versions modified with various polymers and a number of different roofing membranes, i.e., preformed or liquid applied sheets of PVC, terpolymer of ethylene-propylene-diene monomer (EPDM), chlorosulfonated polyethylene (Hypalon), PU, butyl rubber, polychloroprene (Neoprene) [36], all have been used as insulating layers. 

PVC and PE have played a major role in the shift of early roof waterproofing technology and materials. After the introduction of elastomeric and other thermoplastic materials, flexible membranes of polychloroprene (Neoprene) rubber, butyl rubber and Hypalon were used. Later on, liquid PU, solvent-based liquid acrylate and liquid EPDM systems, in addition to new materials like SBS modified bitumens, were also used in the management of roofing. All fall into the single-ply family of roofing, which offers a much cleaner, safer, energy-efficient and cost-effective alternative to built-up roofs. 

Polymer-modified bituminous membranes were developed in Europe in the mid- 1960s and have been in use in North America since 1975. The polymeric systems have varied from natural rubber to more complex synthetic systems sueh as block copolymers and polymer blends. Most common polymers used as modifiers are polyisobutylenes, polybutadienes, polyisopienes, styrene-butiene-monomer, styrene-butadiene-rubber, butyl rubber, ethylene-vinylaeetate (EVA), atactic polypropylene (APP) as well as natural rubber. Polymers, such as atactic polypropylene or styrene-butadiene-styiene (SBS), impart flexibility and elasticity, improve cohesive strength, resist flow at high temperatures, and toughness.1 1 They are the most widely used modifiers of bitumen-based roofing materials. 

Thanks to all these properties, the dolocarbonate seems promising for different applications, first of all for all the applications of traditional low density mineral fillers. This material could for instance be used as a component in thermal insulating materials like panels or foams, as a filler in mortars or plasters or concretes to decrease their thermal conductivity, as a filler in polymer or rubber compositions to improve their fire and/or mechanical properties, as a filler in paints, papers, cosmetic compositions, as a rheology modifier (viscosifying agent) in mineral slurries, glues, bitumen or asphalts, polymer compositions, as an ad- or absorbant in different applications such as water or flue gas treatment or even in the field of catalysis, as e.g. a catalyst support, or as a carrier for perfumes, aromas, active substances, medicines... 

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