A power transmission belt is at least partially formed of a rubber composition. The rubber composition contains a rubber component, cellulose nanofibers, and carbon black. The amount of the cellulose nanofibers to be added is from 0.1 parts by mass to 20 parts by mass, relative to 100 parts by mass of the rubber component. The amount of the carbon black to be added is from 5 parts by mass to 80 parts by mass, relative to 100 parts by mass of the rubber component. The sum of the amount of the carbon black to be added and three times the amount of the cellulose nanofibers to be added is from 15 to 90.

A fabric substrate is prepared from woven coated yarns. Each coated yarn has a yarn core and a coating disposed coaxially on the yarn core. This coating contains: (i) porous particles in an amount of 4-20 weight %, each porous particle comprising a continuous polymeric phase and discrete pores dispersed within the continuous polymeric phase, a mode particle size of 2-50 m; (ii) a film-forming binder material having a T.sub.g of less than or equal to 25 C., in an amount of 40-90 weight %; and (iii) an inorganic filler material having a value of less than 5 on the MOHS scale of mineral hardness, which inorganic filler material is present in an amount of 4-30 weight %.

A fabric substrate is prepared from woven coated yarns. Each coated yarn has a yarn core and a coating disposed coaxially on the yarn core. This coating contains: (i) porous particles in an amount of 4-20 weight %, each porous particle comprising a continuous polymeric phase and discrete pores dispersed within the continuous polymeric phase, a mode particle size of 2-50 m; (ii) a film-forming binder material having a T.sub.g of less than or equal to 25 C., in an amount of 40-90 weight %; and (iii) an inorganic filler material having a value of less than 5 on the MOHS scale of mineral hardness, which inorganic filler material is present in an amount of 4-30 weight %.

An aqueous composition is used to clad yarn cores to provide unique coated yarns. This aqueous composition contains: (i) porous particles present in an amount of at least 2 weight % and up to and including 10 weight %, each porous particle comprising a continuous polymeric phase and discrete pores dispersed within the continuous polymeric phase, the porous particles having a mode particle size of 2-50 m; (ii) a film-forming binder material having a T.sub.g of less than or equal to 25 C., that is present in an amount of 25-60 weight %; (iii) an inorganic filler material having a value of less than 5 on the MOHS scale of mineral hardness, in an amount of at least 2-15 weight %; and (iv) an aqueous medium in an amount of at least 35 weight % in which the film-forming binder material is soluble or dispersible.

A coated yarn has a yarn core and a coating disposed coaxially on the yarn core. This coating contains: (i) porous particles present in an amount of at least 4 weight % and up to and including 20 weight %, each porous particle comprising a continuous polymeric phase and discrete pores dispersed within the continuous polymeric phase, having a mode particle size of 2-50 m and up to and including 50 m; (ii) a film-forming binder material having a T.sub.g of less than or equal to 25 C., which is present in an amount of 40-90 weight %; and (iii) an inorganic filler material having a value of less than 5 on the MOHS scale of mineral hardness, which inorganic filler material is present in an amount of 4 weight % and up to and including 30 weight %.

A coated yarn has a yarn core and a coating disposed coaxially on the yarn core. This coating contains: (i) porous particles present in an amount of at least 4 weight % and up to and including 20 weight %, each porous particle comprising a continuous polymeric phase and discrete pores dispersed within the continuous polymeric phase, having a mode particle size of 2-50 m and up to and including 50 m; (ii) a film-forming binder material having a T.sub.g of less than or equal to 25 C., which is present in an amount of 40-90 weight %; and (iii) an inorganic filler material having a value of less than 5 on the MOHS scale of mineral hardness, which inorganic filler material is present in an amount of 4 weight % and up to and including 30 weight %.

A process for the manufacturing of self-lubricating elements such as bearings, plates, bushings and the like with composites obtained by impregnating special synthetic fabrics with thermosetting resins, catalyst and nano graphite and/or molybdenum disulfide nano and/or nano PTFE and/or nanoboron nitride, each of these, or other nanometric lubricants, added according to the tribological applications and requirements of the product.

A process for the manufacturing of self-lubricating elements such as bearings, plates, bushings and the like with composites obtained by impregnating special synthetic fabrics with thermosetting resins, catalyst and nano graphite and/or molybdenum disulfide nano and/or nano PTFE and/or nanoboron nitride, each of these, or other nanometric lubricants, added according to the tribological applications and requirements of the product.

A power transmission belt is at least partially formed of a rubber composition. The rubber composition contains a rubber component, cellulose nanofibers, and carbon black. The amount of the cellulose nanofibers to be added is from 0.1 parts by mass to 20 parts by mass, relative to 100 parts by mass of the rubber component. The amount of the carbon black to be added is from 5 parts by mass to 80 parts by mass, relative to 100 parts by mass of the rubber component. The sum of the amount of the carbon black to be added and three times the amount of the cellulose nanofibers to be added is from 15 to 90.

A power transmission belt is at least partially formed of a rubber composition. The rubber composition contains a rubber component, cellulose nanofibers, and carbon black. The amount of the cellulose nanofibers to be added is from 0.1 parts by mass to 20 parts by mass, relative to 100 parts by mass of the rubber component. The amount of the carbon black to be added is from 5 parts by mass to 80 parts by mass, relative to 100 parts by mass of the rubber component. The sum of the amount of the carbon black to be added and three times the amount of the cellulose nanofibers to be added is from 15 to 90.