Plastic Compunding
- 2. DefinitionDefinition The Process by which ingredients are intimately mixed together into as nearly a homogeneous mass is known as compounding.
- 3. CRITERIA FOR COMPOUNDINGCRITERIA FOR COMPOUNDING • Selection of polymer.Selection of polymer. • Selection of compounding ingredients.Selection of compounding ingredients.
- 4. SELECTION OF POLYMERSELECTION OF POLYMER The performance requirement of the intendedThe performance requirement of the intended end use.end use. The economic factors.The economic factors. The availability of suitable and processingThe availability of suitable and processing equipment.equipment.
- 5. Selection of compounding ingredientsSelection of compounding ingredients REQUIREMENT:-REQUIREMENT:- •Their degree of effectiveness.Their degree of effectiveness. •The efficiency of processing ingredients.The efficiency of processing ingredients. •The condition of processingThe condition of processing •The requirement of the end useThe requirement of the end use •The environmental exposure to which theThe environmental exposure to which the product will be subjected.product will be subjected.
- 6. FACTORS THAT INFLUENCEFACTORS THAT INFLUENCE COMPOUNDINGCOMPOUNDING • Physical form & melting characteristics of thePhysical form & melting characteristics of the polymer considered .polymer considered . •Degree of dispersion or solubilisation of theDegree of dispersion or solubilisation of the additive in the final mixture.additive in the final mixture. •Physical form of the plastics raw material orPhysical form of the plastics raw material or compound to be produced.compound to be produced.
- 7. METHODS OF INCOPORATINGMETHODS OF INCOPORATING ADDITIVESADDITIVES • Added to the monomer is before or during theAdded to the monomer is before or during the production of the polymer.production of the polymer. •Added during the working up of the polymer.Added during the working up of the polymer. •Added in a separate manufacturing step.Added in a separate manufacturing step. •Incorporated directly before or during moldingIncorporated directly before or during molding of a plastic to a semi-finished product orof a plastic to a semi-finished product or finished article.finished article.
- 8. Addition of additives before or duringAddition of additives before or during a polymerisation processa polymerisation process •Additives should be inert.Additives should be inert. •Used by the producer of the base resins.Used by the producer of the base resins. Examples-Examples- Stabilization of impact resistant PS and preStabilization of impact resistant PS and pre stabilasation of PVC produced by suspentionstabilasation of PVC produced by suspention polymerisation.(in both cases antioxidants arepolymerisation.(in both cases antioxidants are added to the monomers)added to the monomers)
- 9. Addition of additives during theAddition of additives during the working up of the polymerworking up of the polymer •Used by polymer manufacturer.Used by polymer manufacturer. •Additives used must satisfy specificAdditives used must satisfy specific requirements determined by the process such asrequirements determined by the process such as emulsifiability , solubility in certain solvents ,emulsifiability , solubility in certain solvents , low volatility or stability to hydrolysis.low volatility or stability to hydrolysis. •Polymer must be in dispersed form.Polymer must be in dispersed form. Example- In modification of styrene polymer,Example- In modification of styrene polymer, such as ABS.such as ABS.
- 10. Methods of CompoundingMethods of Compounding There are four basic methodsThere are four basic methods – Dry mixing,Dry mixing, – Batch mixing,Batch mixing, – Continuous mixing,Continuous mixing, – Compounding by Screw extruder.Compounding by Screw extruder. The selection of the method determined byThe selection of the method determined by –Condition of the material,Condition of the material, –The volume of end product required,The volume of end product required, –The sensitivity of the material to breakdownThe sensitivity of the material to breakdown
- 11. Dry MixingDry Mixing Dry mixing the plastic with its additives in aDry mixing the plastic with its additives in a 500 pound capacity paddle mixer.500 pound capacity paddle mixer. The paddles are turned at 30 to 90 seconds orThe paddles are turned at 30 to 90 seconds or until the mix is homogeneous.until the mix is homogeneous. If the mix is too long, it will develop lumps ofIf the mix is too long, it will develop lumps of glass, while too short a mix will produce anglass, while too short a mix will produce an unequal dispersion of glass fibres.unequal dispersion of glass fibres. Dry mixer are preferred for powders, plasticDry mixer are preferred for powders, plastic pellets with fibers and also for mixingpellets with fibers and also for mixing plasticizers with PVC.plasticizers with PVC.
- 12. Types of Dry mixersTypes of Dry mixers There are four types of dry mixers:There are four types of dry mixers: – High speed impellers,High speed impellers, – Ribbon mixers,Ribbon mixers, – Paddle mixers andPaddle mixers and – Drum tumblersDrum tumblers..
- 13. Dry mixerDry mixer The mixer consists of an enclosed container withThe mixer consists of an enclosed container with a higher speed impeller mounted at the bottom.a higher speed impeller mounted at the bottom. An impeller is similar to the rotating blades of aAn impeller is similar to the rotating blades of a helicopter.helicopter. The impeller is capable of 80 to 3600 revolutionsThe impeller is capable of 80 to 3600 revolutions per minute (RPM). Mixing is fast with materialsper minute (RPM). Mixing is fast with materials blended within 2-4 minute cycles.blended within 2-4 minute cycles. Heat generated during the mixing process mustHeat generated during the mixing process must be drawn off through a cooling jacket to retardbe drawn off through a cooling jacket to retard decomposition of the material and to block thedecomposition of the material and to block the development of lumps.development of lumps.
- 14. Drum TumblerDrum Tumbler Drum tumblers are popular with moldingDrum tumblers are popular with molding operation for the dispersion of powderedoperation for the dispersion of powdered colorants with the plastic pellets.colorants with the plastic pellets. In a drum tumbler, plastic pellets (withIn a drum tumbler, plastic pellets (with approximately 1 to 2% colorant) areapproximately 1 to 2% colorant) are placed in a 250 gallon drum and tumbledplaced in a 250 gallon drum and tumbled dry for approximately 30 minutes.dry for approximately 30 minutes. Drum tumblers are used when the additivesDrum tumblers are used when the additives disperse easily throughout the mixturedisperse easily throughout the mixture without tending to lump or cluster together.without tending to lump or cluster together.
- 15. High Speed MixtureHigh Speed Mixture
- 16. Continue……Continue…… High speed mixture is widely used for PVC dryHigh speed mixture is widely used for PVC dry blending and for the dispersion of colorants,blending and for the dispersion of colorants, pigments etc….pigments etc…. And also it is using for mixing polymer powderAnd also it is using for mixing polymer powder with pellets.with pellets. HSM is made of impellers mounted in theHSM is made of impellers mounted in the bottom of stationary vessel.bottom of stationary vessel. Rotational speed of impellers is upto-1000rpm.Rotational speed of impellers is upto-1000rpm. The motors are using for rotating impellers.The motors are using for rotating impellers.
- 17. Two Roll MillTwo Roll Mill
- 18. Continue……Continue…… Two roll mills are used mostly for mixingTwo roll mills are used mostly for mixing materials with coarse particles.materials with coarse particles. In roll mills, the size reduction takes placeIn roll mills, the size reduction takes place between two rolls can have either a smooth or abetween two rolls can have either a smooth or a profiled surface.profiled surface. It is reducing the particles size from 1mm to˃ ˃It is reducing the particles size from 1mm to˃ ˃ 0.010mm.0.010mm. Rolls are rotating as counter-rotating only.Rolls are rotating as counter-rotating only. Toll roll mill are mainly using in calenderingToll roll mill are mainly using in calendering
- 19. Banbury mixers :
- 20. The Banbury mixer is a brand of internal batch mixer, named for inventor Fernley H. Banbury. Banbury batch mixer consists of cylindrical chamber or shell with in which materials to be mixed are deformed by rotating blades or rotors. The blade motion causes the mixture to be shear between blade and tip and shell and creating shuffling of material Cycle time 2-4 min Size 50-75 kg Producing large shapeless lumps. Banbury mixers
- 21. Cont…… Internal batch mixers such as the Banbury mixer are used for mixing or compounding rubber and plastics. Its invention resulted in major labor and capital savings in the tire industry. It is also used for reinforcing fillers in a resin system.
- 23. Continue……Continue…… Ribbon Blender is useful for convectiveRibbon Blender is useful for convective mixing.mixing. In most of convective mixers, a mixing rotorIn most of convective mixers, a mixing rotor within a static housing, moving groups ofwithin a static housing, moving groups of particles from one region to another.particles from one region to another. Ribbon mixtures are available both as batchRibbon mixtures are available both as batch mixture as well as continuous mixture.mixture as well as continuous mixture. The rotational speed in ribbon blender isThe rotational speed in ribbon blender is typically in the range of 10 to 60 rpm.typically in the range of 10 to 60 rpm.
- 25. Planetary MixturePlanetary Mixture The mixing blade is set off center and is carriedThe mixing blade is set off center and is carried on a rotating arm. It therefore travels round theon a rotating arm. It therefore travels round the circumference of the mixing bowl whilecircumference of the mixing bowl while simultaneously rotating around its own axis.simultaneously rotating around its own axis. This is therefore a double rotation similar toThis is therefore a double rotation similar to that of a spinning planet rotating around thethat of a spinning planet rotating around the sun, hence the name.sun, hence the name.
- 26. Conti……….. Planetary Mixers are used for dry mixing and dough mixing. The homogenous mixing if various lngredients of different densities in different proportions for solid/solid, liquid/solid, and liquld/Iiquid is achieved effectively by the use of Planetary Mixer.
- 27. Continue…Continue… Planetary Mixers for the preparation ofPlanetary Mixers for the preparation of ointment, toothpaste, creams.ointment, toothpaste, creams. The blades each rotate on their own axes, andThe blades each rotate on their own axes, and at the same time on a common axis, therebyat the same time on a common axis, thereby providing complete mixing in a very shortproviding complete mixing in a very short timeframe.timeframe.
- 28. ExtrudersExtruders Screw extruders are the process tool used inScrew extruders are the process tool used in compounding, injection molding, injectioncompounding, injection molding, injection blow molding, extrusion, and extrusion blowblow molding, extrusion, and extrusion blow molding.molding. Screw extrusion technology is used as theScrew extrusion technology is used as the plastic mixing and melting device.plastic mixing and melting device. GF are efficiently compounded with plasticGF are efficiently compounded with plastic using screw extruders.using screw extruders. Two TypesTwo Types – Single Screw ExtruderSingle Screw Extruder – Twin Screw ExtruderTwin Screw Extruder
- 29. A single screw extrudersA single screw extruders It classified by the ratio of the length of theIt classified by the ratio of the length of the screw to the inside diameter of the screw.screw to the inside diameter of the screw. Standard extruders have 30 to 1 ratios.Standard extruders have 30 to 1 ratios. The size of extruders range from smallThe size of extruders range from small laboratory models with 1/2 inch diameters tolaboratory models with 1/2 inch diameters to large production extruders with 8" diameterlarge production extruders with 8" diameter barrels.barrels. Consist of long steel screw which rotates steelConsist of long steel screw which rotates steel tube called barreltube called barrel Extruder outputs range from a few pounds anExtruder outputs range from a few pounds an hour up to 1,000 pounds per hour.
- 30. Continue…Continue… Barrel, is wrapped with heating elements toBarrel, is wrapped with heating elements to maintain the barrel at the melt temperature ofmaintain the barrel at the melt temperature of the plasticthe plastic.. The plastic is pumped from one end of theThe plastic is pumped from one end of the screw to the other by rotating the screw.screw to the other by rotating the screw. The rate at which the plastic moves from oneThe rate at which the plastic moves from one end of the extruder to the other is controlled byend of the extruder to the other is controlled by the speed of the screw.the speed of the screw.
- 31. Feed Zone: Transport the material from hopper to compression zone. Compression Zone: Compacts, eliminates air gap -Transport the material from compression to metering zone. - Softens the material Metering zone: Melts, Mixes, the material pressurizes and pumps the melt. Zones of Extruder & its Functions
- 33. Twin Screw ExtruderTwin Screw Extruder The efficiency of the mixing action of theThe efficiency of the mixing action of the single screw extruder compounder depends onsingle screw extruder compounder depends on maintaining higher friction between the wall ofmaintaining higher friction between the wall of the barrel and the material than between thethe barrel and the material than between the materials and the screw surface.materials and the screw surface. If the friction is higher on the screw surface,If the friction is higher on the screw surface, plastic will stick to the screw surface,plastic will stick to the screw surface, decompose and clog the mixing process.decompose and clog the mixing process.
- 34. Conti…….. In a single screw, extruder's plastic pastes, flakes. Sometimes low bulk density materials tend to stick to the screw surface. To overcome these restrictions, the twin screw extruder was developed. The twin screw extruder has two screws that are arranged side by side and intermesh. The intermeshing action of the two screws constantly self-wipes the screw flights.
- 35. ContinueContinue It is impossible for plastics to stick to the screwIt is impossible for plastics to stick to the screw surface. The positive pumping action of thesurface. The positive pumping action of the intermeshing screws allows for theintermeshing screws allows for the compounding of all forms of plastic materialscompounding of all forms of plastic materials not possible with a single two stage extruder.not possible with a single two stage extruder.
- 36. Continue…Continue… There are two type of rotatingThere are two type of rotating 1.1. Co-rotating.Co-rotating. 2.2. Counter –rotating.Counter –rotating. Co-rotating:Co-rotating: When two screws rotates along same side in a barrel then the phenomena is called co-rotating
- 37. Continue…Continue… Counter-Rotating:Counter-Rotating: When the two screws rotates the different side in a barrel, then the phenomena is called counter-rotating.