racemicradial ply tireradial polyreactionradiationradiation curableradiation inducedradiationless processradical scavengerradio frequency weldingradiochemical reactionradiofrequency plasmaradiograftingradiopacityradiotrace techniqueradiusradomeraffinateraffinate phaseraffinate strippingram extruderraman microporeraman microproberamprandomrandom accessibilityrandom copolymerrapid coolingrapid flow analyzerratere radiation coolingreactantreaction injection moldingreaction orderreactivityreactorrear spoilersrear wheel driverearrangementrecedingreceptorreciprocalreciprocal lattice pointreciprocatingreclaimed rubberrecombinationrecover abilityrecoveryrectangularrecursive solutionrecycling