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Basic Resins Used for Plastic Injection Molding
Posted: 12/14/2015 03:43:56  Hits: 133
Basic resins used for plastic injection molding are classified into commodity resin and engineering resin.

Commodity resin is a kind of inexpensive resins which are easy to be processed. Commodity resin has been widely applied, including toys, packaging and consumer products.

Compared with commodity resin, engineering resin has better mechanical and thermal properties. With high strength, engineering resin has excellent high temperature resistance, abrasion resistance and corrosion resistance. Engineering resin is often used to take place of wood or metal in order to reduce cost or weight while maintaining strength and performance. 

Commodity resins

ACRYLONITRILE BUTADIENE STYRENE (ABS) 
Strength: Low – Med
Strength at Elevated Temp: Low
Resistance to Impact: High
Material Flow: Fair – Good
Resistance to Shrinkage/Warpage: Fair – Good
Resistance to Flash: Good
Cost of Resin: Low – Med
Impact on Mold (wear): Low Impact
Advantages: Chemical resistant, easily processed, good surface finish, RoHS Compliant, flame retardant
Disadvantages: Limited weathering resistance
Common Uses: Consumer Goods, auto interiors, toys
Brand Examples: Cycolac, Lustran, Trilac

ACRYLIC (PMMA) 
Strength: Med
Strength at Elevated Temp: Low
Resistance to Impact: Low
Material Flow: Good
Resistance to Shrinkage/Warpage: Good
Resistance to Flash: Good
Cost of Resin: Med
Impact on Mold (wear): Low Impact
Advantages: Good weatherability, insulation, clear/colorable
Disadvantages:  
Common Uses: Glass replacement, lenses, casings, aquariums
Brand Examples: Acrylite, Kydex, Plexiglass

HIGH DENSITY POLYETHYLENE (HDPE) 
Strength: Low
Strength at Elevated Temp: Low
Resistance to Impact: High
Material Flow: Excellent
Resistance to Shrinkage/Warpage: Fair
Resistance to Flash: Poor
Cost of Resin: Low
Impact on Mold (wear): Low
Advantages: Food contact acceptable, easily processed
Disadvantages: High thermal expansion, poor weather resistance
Common Uses: Toys, Buckets
Brand Examples: Chevron, Dow, Relene

POLYPROPYLENE (PP)  
Strength: Low
Strength at Elevated Temp: Low
Resistance to Impact: High
Material Flow: Excellent
Resistance to Shrinkage/Warpage: Fair
Resistance to Flash: Poor
Cost of Resin: Low
Impact on Mold (wear): Low
Advantages: Food contact acceptable, easily processed
Disadvantages: Degraded by UV
Common Uses: Consumer Goods / Living Hinge Applications
Brand Examples: Hival, Lupol, ProFax


POLYETHYLENE (PE) 
Strength: Low
Strength at Elevated Temp: Low
Resistance to Impact: High
Material Flow: Good
Resistance to Shrinkage/Warpage: Excellent
Resistance to Flash: Poor
Cost of Resin: Low
Impact on Mold (wear): Low
Advantages: Corrosion resistant, low weight, high flexibility, food contact acceptable, easily processed
Disadvantages: Poor weatherability, high thermal expansion
Common Uses: Toys, Bearings, Buckets
Brand Examples: Bapolene

POLYSTYRENE (PS) 
Strength: Low – Med
Strength at Elevated Temp: Low
Resistance to Impact: Low – Med
Material Flow: Good
Resistance to Shrinkage/Warpage: Fair – Good
Resistance to Flash: Fair
Cost of Resin: Low
Impact on Mold (wear): Low
Advantages: Food contact acceptable, flame retardant, fast cycle time, expandable
Disadvantages: Poor solvent and chemical resistance
Common Uses: Toys, packaging, product casings (Crystal PS for clear cases, cups)
Brand Examples: Starex, Styron

POLYVINYL CHLORIDE (PVC) 
Strength: Low – Med
Strength at Elevated Temp: Low – Med
Resistance to Impact: Med
Material Flow: Med
Resistance to Shrinkage/Warpage: Med
Resistance to Flash: Med
Cost of Resin: Low
Impact on Mold (wear): Med – High
Advantages: Flame retardant, high Gloss, UV resistant
Disadvantages: High density, UV sensitive
Common Uses: Soft, flexible parts; fencing; containers, can also be rigid to add strength
Brand Examples: Mixvil, Vital-line

STYRENE ACRYLONITRILE (SAN) 
Strength: Med
Strength at Elevated Temp: Low – Med
Resistance to Impact: Low
Material Flow: Med
Resistance to Shrinkage/Warpage: Med
Resistance to Flash: Med
Cost of Resin: Med
Impact on Mold (wear): Low – Med
Advantages: Good weatherability, chemical resistant, high Clarity, good processability
Disadvantages: Higher water absorption and yellowing than PS
Common Uses: Electical and Automotive applications, cosmetic Packaging, containers
Brand Examples: Absolan

Engineering Resins
ACETAL (POM) 
Strength: Med
Strength at Elevated Temp: Low – Med
Resistance to Impact: Med
Material Flow: Fair
Resistance to Shrinkage/Warpage: Fair
Resistance to Flash: Good
Cost of Resin: Med
Impact on Mold (wear): Med
Advantages: Low fatigue, low moisture sensitivity, chemical resistant, good chemical properties
Disadvantages: Poor resistance to acids, UV Degradation
Common Uses: Springs, bearings, valve parts
Brand Examples: Ashlene, Celcon, Delrin

POLYBUTYLENE TEREPHTHALATE (PBT) 
Strength: Med
Strength at Elevated Temp: Low
Resistance to Impact: High
Material Flow: Fair
Resistance to Shrinkage/Warpage: Fair
Resistance to Flash: Fair
Cost of Resin: Med – High
Impact on Mold (wear): Low – Med
Advantages: Dispersible, good electrical properties, food contact acceptable
Disadvantages: Difficult to fill thin parts, poor resistance to acid
Common Uses: Electronic components, housings, automotive connectors
Brand Examples: Celstran, Celanex, Valox

PBT / PET (GLASS FILLED) 
Strength: High
Strength at Elevated Temp: Med
Resistance to Impact: Med
Material Flow: Fair – Good
Resistance to Shrinkage/Warpage: Poor – Fair
Resistance to Flash: Fair
Cost of Resin: Med – High
Impact on Mold (wear): Med
Advantages: Low moisture absorption, high stiffness-to-weight ratio, medical and UV resistant grades
Disadvantages:  
Common Uses: Structural parts, housings, automotive components
Brand Examples: Crastin, Rynite, Makroblend

POLYETHYLENE TEREPHTHALATE (PET)
Strength: Med
Strength at Elevated Temp: Med
Resistance to Impact: High
Material Flow: Good
Resistance to Shrinkage/Warpage: Med
Resistance to Flash: Med
Cost of Resin: Med
Impact on Mold (wear): Low – Med
Advantages: Chemical resistant, clarity, easily processed
Disadvantages:  
Common Uses: Infant products, sterilizer lids, dishwasher parts
Brand Examples: Celanex, Ramapet

POLYCARBONATE (PC)
Strength: Med
Strength at Elevated Temp: Med – High
Resistance to Impact: High
Material Flow: Fair
Resistance to Shrinkage/Warpage: Fair – Good
Resistance to Flash: Good
Cost of Resin: Med – High
Impact on Mold (wear): Low
Advantages: RoHS compliant, dimensionally stable, easily Processed
Disadvantages: Fair chemical resistance, degrades during extended processing times
Common Uses: Lenses, light covers, single use containers
Brand Examples: Hopolex, Lexan, Makrolon

POLYETHER ETHER KETONE (PEEK)  
Strength: High
Strength at Elevated Temp: High
Resistance to Impact: High
Material Flow: Good
Resistance to Shrinkage/Warpage: Med
Resistance to Flash: Med
Cost of Resin: Med – High
Impact on Mold (wear): Med
Advantages: Chemical resistant, abrasive resistant, corrosive and hydrolysis resistant, can be filled with carbon fiber, graphite, molybdenum disulfide, etc. for lubricating properties and enhanced mechanical strength, food contact acceptable, good sterilizability
Disadvantages:  
Common Uses: Engineering applications, medical/healthcare
Brand Examples: Victrex

POLYETHER IMIDE (PEI) 
Strength: High
Strength at Elevated Temp: Med
Resistance to Impact: Med
Material Flow: High
Resistance to Shrinkage/Warpage: Med
Resistance to Flash: Med
Cost of Resin: Med – High
Impact on Mold (wear): Med
Advantages: Flame Retardant, good chemical resistance, good processability
Disadvantages: Notch sensitive, limited colorability
Common Uses: Medical/healthcare, automotive, aerospace, metal replacement, thin walled parts
Brand Examples: Duron, Ultem

POLYETHERSULFONE (PES) / POLYSULFONE (PSU) 
Strength: High
Strength at Elevated Temp: Med – High
Resistance to Impact: Med
Material Flow: Low – Med
Resistance to Shrinkage/Warpage: Med
Resistance to Flash: Med
Cost of Resin: High
Impact on Mold (wear): Med
Advantages: Acid resistant, thermal stability, hydrolysis resistant
Disadvantages: Poor weatherability, difficult to process, cost
Common Uses: Food service, automotive, medical/healthcare, aerospace, engineering applications
Brand Examples: HiFill, Thermocomp

POLYETHYLENE ETHER (PPE) 
Strength: Med – High
Strength at Elevated Temp: Med – High
Resistance to Impact: Med – High
Material Flow: High
Resistance to Shrinkage/Warpage: Med – High
Resistance to Flash: Med
Cost of Resin: High
Impact on Mold (wear): Med
Advantages: Excellent electrical properties, resistant to acids and bases, can be blended with PS to improve processability and toughness
Disadvantages: High viscosity, high cost, color degrades with UV
Common Uses: Automotive, electrical and industrial applications
Brand Examples: Ashlene, Norpex

POLYAMIDE (NYLON) 
Strength: Med
Strength at Elevated Temp: Low
Resistance to Impact: High
Material Flow: Good – Excellent
Resistance to Shrinkage/Warpage: Fair
Resistance to Flash: Poor
Cost of Resin: Med
Impact on Mold (wear): Low – Med
Advantages: Food contact acceptable, easily processed
Disadvantages: Degraded by UV
Common Uses: Bearings, medium stress components
Brand Examples: Akromid, Celanese, Zytel

POLYAMIDE (NYLON) – GLASS FILLED 
Strength: High
Strength at Elevated Temp: High
Resistance to Impact: Med
Material Flow: Good – Excellent
Resistance to Shrinkage/Warpage: Poor
Resistance to Flash: Fair
Cost of Resin: Med
Impact on Mold (wear): Fair
Advantages: High Strength, wear and chemical resistance
Disadvantages:  
Common Uses: Metal replacement, connectors, bushings
Brand Examples: Capron, Zytel

THERMOPLASTIC ELASTOMER (TPE) 
Strength: Low
Strength at Elevated Temp: Low
Resistance to Impact: High
Material Flow: Excellent
Resistance to Shrinkage/Warpage: Poor
Resistance to Flash: Poor
Cost of Resin: Low – Med
Impact on Mold (wear): Low
Advantages: Good weatherability, recyclable, good UV Resistance, good adhesion, good colorability
Disadvantages:  
Common Uses: Rubber replacement, bushings, seals
Brand Examples: Elastocon, Santoprene

THERMOPLASTIC POLYURETHANE (TPE/TPU) 
Strength: Med
Strength at Elevated Temp: Low   Med
Resistance to Impact: Med
Material Flow: Low
Resistance to Shrinkage/Warpage: Med
Resistance to Flash: Med
Cost of Resin: Med
Impact on Mold (wear): Low
Advantages: Wide durometer range, oil, chemical and hydrolysis resistant, good wear resistance
Disadvantages: Limited service temperature, processability
Common Uses: Gaskets, surgical instruments, sporting goods
Brand Examples: Celstran, Elastollan
 
Basic Resins Used for Plastic Injection Molding
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