Abstract: A vulcanizable rubber composition is described comprising a cross-linkable unsaturated chain polymeric base, wherein is incorporated at least one organic compound, solid at room temperature, selected from the group comprising: amorphous or semicrystalline polymers, oligomers, low-molecular weight organic substances and mixtures thereof, which compound is substantially insoluble in the polymeric base and shows a first or second order transition temperature of from 80 to 160° C. Such rubber composition allows the manufacture of treads with either a low rolling resistance at the temperature of normal use of the tire (40°-70° C.), or a high grip when the tread is subjected to thermal stresses exceeding such temperatures.

Abstract: A method for improving the archiving of a curve plotted from at least N (N≧5) measured experimental values of a dynamic parameter P of a viscoelastic material where this parameter is a function of the deformation q at a given temperature, characterized in that it comprises the following stages: a) the acquisition of N experimental measurements of the said dynamic parameter P of the said viscoelastic material where this parameter is a function of the deformation q at a predetermined temperature; b) the determination, by successive approximations, of the values P0, P1, q1, P2, q2, which, when inserted in the relation P ⁡ ( q ) = P 0 + P 1 ⁢ ⅇ

Abstract: A tire for a wheel of a vehicle comprises a toroidal carcass provided with axially opposite sidewalls and beads for anchoring the tire to a rim of the wheel, a tread band located crownwise on the carcass, comprising a surface with a plurality of hollows and grooves defining a raised tread pattern, and a belt structure interposed between the carcass and the tread band, axially extending between the sidewalls. The tread band comprises at least first and second circumferential axially-contiguous portions arranged to contact a road surface. The first portion is formed of a first composition comprising a reinforcing filler having at least 40%-by-weight carbon black and at least some white filler, the second portion is formed of a second composition comprising a reinforcing filler having at least 20%-by-weight white filler, and the first composition is different from the second composition.

Abstract: A vulcanizable rubber composition is described comprising a cross-linkable unsaturated chain polymeric base, wherein is incorporated at least one organic compound, solid at room temperature, selected from the group comprising: amorphous or semicrystalline polymers, oligomers, low-molecular weight organic substances and mixtures thereof, which compound is substantially insoluble in the polymeric base and shows a first or second order transition temperature of from 80 to 160° C. Such rubber composition allows the manufacture of treads with either a low rolling resistance at the temperature of normal use of the tire (40°-70° C.), or a high grip when the tread is subjected to thermal stresses exceeding such temperatures.

Abstract: In a process for producing a vulcanizable rubber composition containing silica and having a low content of carbon black, at least a silica-based reinforcing filler and ad least a silane-based coupling agent are added to and intimately mixed with other ingredients of the composition in subsequent steps, at a temperature of from 165.degree. and 180.degree. C. and between 110.degree. and 160.degree. C. respectively. The rubber composition so obtained has an improved silica dispersion, constant physico-mechanical characteristics and a better drawability and is particularly suitable for the manufacture of treads for tyres with low rolling resistance.

Abstract: In a process for producing a vulcanizable rubber composition containing silica and having a low content of carbon black, at least a silica-based reinforcing filler and ad least a silane-based coupling agent are added to and intimately mixed with other ingredients of the composition in subsequent steps, at a temperature of from 165.degree. and 180.degree. C. and between 1100 and 160.degree. C. respectively. The rubber composition so obtained has an improved silica dispersion, constant physico-mechanical characteristics and a better drawability and is particularly suitable for the manufacture of treads for tires with low rolling resistance.

Abstract: In a process for producing a vulcanizable rubber composition containing silica and having a low content of carbon black, at least a silica-based reinforcing filler and ad least a silane-based coupling agent are added to and intimately mixed with other ingredients of the composition in subsequent steps, at a temperature of from 165.degree. and 180.degree. C. and between 110.degree. and 160.degree. C. respectively. The rubber composition so obtained has an improved silica dispersion, constant physico-mechanical characteristics and a better drawability and is particularly suitable for the manufacture of treads for tires with low rolling resistance.

Abstract: To determine the carbon black distribution two measurements of spectral intensities of separately produced plasmas are carried out with different time delays relative to a particular laser pulse, the time delay for the second measurement for determining the spectral line intensities of a reference element carbon (I.sub.C') and at least one analysis element (I.sub.A.n') being smaller than for the first measurement; for determining the spectral line intensities of the reference element (I.sub.C) and the other analysis elements (I.sub.A.n).Evaluation of the measurements is performed by reference to calibration information based on reference measurements, which information shows the magnitude of the concentration ratio of the other analysis elements or the at least one analysis element to the reference element (c.sub.A.n /c.sub.C or c.sub.A.n /c.sub.R) as a function of the appurtenant intensity ratio values.

Abstract: To determine the carbon black distribution two measurements of spectral intensities of separately produced plasmas are carried out with different time delays relative to a particular laser pulse, the time delay for the second measurement for determining the spectral line intensities of a reference element carbon (I.sub.C,) and at least one analysis element (I.sub.A.n,) being smaller than for the first measurement; for determining the spectral line intensities of the reference element (I.sub.C) and the other analysis elements (I.sub.A.n).Evaluation of the measurements is performed by reference to calibration information based on reference measurements, which information shows the magnitude of the concentration ratio of the other analysis elements or the at least one analysis element to the reference element (c.sub.A.n /c.sub.C or c.sub.A.n /c.sub.R) as a function of the appurtenant intensity ratio values.