RHC– Total Hydrocarbon Content represents the percentage of polymer or polymers in the formulation. It is determined by subtracting the non-polymer constituents from 100%.
a white highly polymerized hydrocarbon (C5H8)n or (C10H16)n that is amorphous at ordinary temperatures and that is stereoisomeric with gutta hydrocarbon and constitutes the principal component of natural rubber : a cis form of polyisoprene.
Rubber is an example of an elastomer type polymer, where the polymer has the ability to return to its original shape after being stretched or deformed. The rubber polymer is coiled when in the resting state.
RATE OF CURE – The relative time required to reach a predetermined state of vulcanization under specified conditions.
The percentage of people in a study or treatment group who are still alive for a certain period of time after they were diagnosed with or started treatment for a disease, such as cancer.
RAW RUBBER– Natural rubber is a natural raw material that has various applications, many of them strategic.
rubber or rubber latex from a plant (especially Hevea brasiliensis) : rubber sense 2a —distinguished from synthetic rubber.
Natural rubber (Isoprene) is derived from the latex sap of the Pará rubber tree (hevea brasiliensis). Natural rubber has a high tensile strength and is resistant to fatigue from wear, such as chipping, cutting or tearing. … Natural rubber is used in gaskets, seals, shock mounts, hoses and tubing.
REBOUND TEST – The quality of rubber varies widely due to the percentage of ash content into it. To check the ash percentage, you just burn the sample in the muffle furnace and measure the left-over ash on the calibrated weight. The carbon contents will get turned into fumes and taken out.
RECLAIM – Reclaim or reclaimed rubber is any rubber recovered from vulcanized scrap rubber (as by grinding old tires and treating with alkali, oils, and plasticizers), often mixed with crude rubber for compounding. It is scrap rubber (natural or synthetic) that is prepared for reuse.
rubber recovered from vulcanized scrap rubber (as by grinding old tires and treating with alkali, oils, and plasticizers), often mixed with crude rubber for compounding, and used chiefly in mechanical rubber goods.
A process for producing reclaimed rubber has the steps of: mixing waste vulcanized rubber with unvulcanized new rubber and a devulcanizing agent; and kneading the resulting mixture in a heating atmosphere for mastication of the unvulcanized new rubber and simultaneously reclamation of the waste vulcanized rubber.
Rubber products can make your life easier. The properties of rubber make it ideal for the making of several products including rubber bands, shoes, swimming cap, wetsuits, etc. The waterproof quality of rubber makes it a popular component to manufacture a variety of products that are used in your day to day life.
RECOVERY– rubber recovered from vulcanized scrap rubber (as by grinding old tires and treating with alkali, oils, and plasticizers), often mixed with crude rubber for compounding, and used chiefly in mechanical rubber goods.
REINFORCEMENT – The term “tension stiffening” is defined as the effect of concrete acting in tension between cracks on the stress of steel reinforcement. … The most popular concept is that, by the long term loading, the tension stiffening value reduces to approximately half its initial value (ACI Committee 224R-01) [1].
to become suddenly tense, rigid, or taut, as in bracing oneself for or drawing back from shock, fear, or displeasure: He stiffened, expecting to hear the worst.
RESILIENCE– Like the unit of tensile toughness (UT), the unit of resilience can be easily calculated by using area underneath the stress–strain (σ–ε) curve, which gives resilience value, as given below: Ur = Area underneath the stress–strain (σ–ε) curve up to yield = σ × ε Ur [=] Pa × % = (N·m−2)·(unitless).
Resilience is defined as the ability of the solid material to absorb energy when it is elastically deformed. … Modulus of resilience is the area below engineering stress-strain curve up to elastic point. Modulus of toughness is the total area below engineering stress-strain curve.
RETARDER- Retarders, which are also called pre-vulcanization inhibitors (PVI), are often compounds that readily react with the accelerator (fragments) and only slowly release them. … A compound that meets both requirements is N-(cyclohexylthio) phthalimide (CTP).
REX HARDNESS– The Rex Type M durometer can be used when checking materials thinner than 1/4″ (as thin as . 050″). When testing flat specimens too thin to give accurate readings, the specimens may be stacked to provide the required thickness.
Durometer or Shore durometer is a standardized way to measure the hardness of materials like rubber (elastomers) and plastics. Durometer measurement scales range from 0 to 100 but there is no such thing as a durometer unit of measurement. Another way of saying this is that durometer is a dimensionless measurement.
ROTATIONAL MOLDING OR CASTING– The rotational molding process is quite simple: A hollow mold is filled with powdered plastic resin. The mold begins rotating bi-axially and is transferred into an oven. The mold continues to rotate as the resin melts and coats the walls of the mold. The mold is cooled until the resin hardens into the desired shape.
- Common Materials in Rotational Moulding. 1.1 Polyethylene (PE) 1.11 Linear Low density polyethylene (LLDPE) 1.12 High Density Polyethylene (HDPE) 1.13 Cross Linked Polyethylene (XLPE) …
- Other Materials in Rotational Moulding. 2.1 Polypropylene (PP) 2.2 Nylon (PA) 2.3 Polycarbonate (PC) …
- Additives.
- Contact a Moulder.
Rotational moulding machine costs are low compared to other processes and the investment required is small. There is great production flexibility with the process. There is almost no limit to the size of products and several different products can be moulded at the same time.
RUBBER–
- An elastic substance that is obtained by coagulating the milky juice of any of various tropical plants (as of the genera Hevea and Ficus), is essentially a polymer of isoprene, and is prepared as sheets and then dried. — called also caoutchouc, india rubber.
- Any of various synthetic rubberlike substances.
Natural rubber (Isoprene) is derived from the latex sap of the Pará rubber tree (hevea brasiliensis). Natural rubber has a high tensile strength and is resistant to fatigue from wear, such as chipping, cutting or tearing. … Natural rubber is used in gaskets, seals, shock mounts, hoses and tubing.
The word’s origins can be traced back to the 1600s, when the English used the term “rubber” as a reference to an object used for rubbing, or cleaning. The term found its way into the popular 16th century game of lawn bowling, which is similar to bocce ball.
RUBBER LATEX– a milky juice that is extracted from any of various plants and is the source of natural rubber.
Rubber and latex are not the same thing, but many people use the words as if they are the same. Latex is the milky white sap of rubber trees, which is found beneath the bark of a mature rubber tree. … Yes, it certainly does and we will look at the production processes of how is rubber made.
Rubber latex is a polymer, and vulcanizing solution is a proprietary mixture of sulfur and other materials.
The word “LaTeX” is an abbreviation of “Lamport’s TeX”, named after Leslie Lamport. With LaTeX Lamport added a collection of macros to the original TeX program which was made by Donald Knuth.
Rake – Carries the men into and out of the mine.
Raise – A secondary or tertiary inclined opening, vertical or near-vertical opening driven upward form a level to connect with the level above, or to explore the ground for a limited distance above one level.
Ramp – A secondary or tertiary inclined opening, driven to connect levels, usually driven in a downward direction, and used for haulage.
Ranks of coal – The classification of coal by degree of hardness, moisture and heat content. “Anthracite” is hard coal, almost pure carbon, used mainly for heating homes. “Bituminous” is soft coal. It is the most common coal found in the United States and is used to generate electricity and to make coke for the steel industry. “Subbituminous” is a coal with a heating value between bituminous and lignite. It has low fixed carbon and high percentages of volatile matter and moisture. “Lignite” is the softest coal and has the highest moisture content. It is used for generating electricity and for conversion into synthetic gas. In terms of Btu or “heating” content, anthracite has the highest value, followed by bituminous, subbituminous and lignite.
Reclamation – The restoration of land and environmental values to a surface mine site after the coal is extracted. Reclamation operations are usually underway as soon as the coal has been removed from a mine site. The process includes restoring the land to its approximate original appearance by restoring topsoil and planting native grasses and ground covers.
Recovery – The proportion or percentage of coal or ore mined from the original seam or deposit.
Red dog – A nonvolatile combustion product of the oxidation of coal or coal refuse. Most commonly applied to material resulting from in situ, uncontrolled burning of coal or coal refuse piles. It is similar to coal ash.
Regulator – Device (wall, door) used to control the volume of air in an air split.
Reserve – That portion of the identified coal resource that can be economically mined at the time of determination. The reserve is derived by applying a recovery factor to that component of the identified coal resource designated as the reserve base.
Resin bolting – A method of permanent roof support in which steel rods are grouted with resin.
Resources – Concentrations of coal in such forms that economic extraction is currently or may become feasible. Coal resources broken down by identified and undiscovered resources. Identified coal resources are classified as demonstrated and inferred. Demonstrated resources are further broken down as measured and indicated. Undiscovered resources are broken down as hypothetical and speculative.
Respirable dust – Dust particles 5 microns or less in size.
Respirable dust sample – A sample collected with an approved coal mine dust sampler unit attached to a miner, or so positioned as to measure the concentration of respirable dust to which the miner is exposed, and operated continuously over an entire work shift of such miner.
Retreat mining – A system of robbing pillars in which the robbing line, or line through the faces of the pillars being extracted, retreats from the boundary toward the shaft or mine mouth.
Return – The air or ventilation that has passed through all the working faces of a split.
Return idler – The idler or roller underneath the cover or cover plates on which the conveyor belt rides after the load which it was carrying has been dumped at the head section and starts the return trip toward the foot section.
Rib – The side of a pillar or the wall of an entry. The solid coal on the side of any underground passage. Same as rib pillar.
Rider – A thin seam of coal overlying a thicker one.
Ripper – A coal extraction machine that works by tearing the coal from the face.
Roadway – See level.
Rob – To extract pillars of coal previously left for support.
Robbed out area – Describes that part of a mine from which the pillars have been removed.
Rollerman – A workman who lubricates and maintains the rollers and pulleys over and through which haulage cables pass.
Roll – (1) A high place in the bottom or a low place in the top of a mine passage, (2) a local thickening of roof or floor strata, causing thinning of a coal seam.
Roll protection – A framework, safety canopy, or similar protection for the operator when equipment overturns.
Roof – The stratum of rock or other material above a coal seam; the overhead surface of a coal working place. Same as “back” or “top.”
Roof bolt – A long steel bolt driven into the roof of underground excavations to support the roof, preventing and limiting the extent of roof falls. The unit consists of the bolt (up to 4 feet long), steel plate, expansion shell, and pal nut. The use of roof bolts eliminates the need for timbering by fastening together, or “laminating,” several weaker layers of roof strata to build a “beam.”
Roof fall – A coal mine cave-in especially in permanent areas such as entries.
Roof jack – A screw- or pump-type hydraulic extension post made of steel and used as temporary roof support.
Roof sag – The sinking, bending, or curving of the roof, especially in the middle, from weight or pressure.
Roof stress – Unbalanced internal forces in the roof or sides, created when coal is extracted.
Roof support – Posts, jacks, roof bolts and beams used to support the rock overlying a coal seam in an underground mine. A good roof support plan is part of mine safety and coal extraction.
Roof trusses – A combination of steel rods anchored into the roof to create zones of compression and tension forces and provide better support for weak roof and roof over wide areas.
Room and Pillar – A system of mining in which the distinguishing feature is the winning of fifty percent or more coal in the first working. The coal is mined in rooms separated by narrow ribs or pillars. The coal in the pillars may be won by subsequent workings. The rooms are driven parallel with one another, and the room faces may be extended, at right angles or at an angle to the dip. This method is applicable to flat deposits, such as coal, that occur in bedded deposits.
Room and pillar mining – A method of underground mining in which approximately half of the coal is left in place to support the roof of the active mining area. Large “pillars” are left while “rooms” of coal are extracted.
Room neck – The short passage from the entry into a room.
Round – Planned pattern of drill holes fired in sequence in tunneling, shaft sinking, or stopping. First the cut holes are fired, followed by relief, lifter, and rib holes.
Royalty – The payment of a certain stipulated sum on the mineral produced.
Rubbing surface – The total area (top, bottom, and sides) of an airway.
Run-of-mine – Raw material as it exists in the mine; average grade or quality.
