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why use additives, reinforcements, and fillers
- to improve processability (lubricant)
- to reduce materials costs (talc filler)
- to reduce shrinkage (wood flour)
- to improve surface finish
- alter thermal properties: expansion coeff,flammability, heat transfer
- to improve electrical properties
- to prevent degradation during processing
- for color or tint
- to improve mechanical properties (modulus,strength, etc)
- to lower the coefficient of friction
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additives
- may be distributed in matrix (ex. color)
- may bloom to surface (ex. antistat, slip)
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additives for processing
- antioxidants – prevent chain scission
- heat stabilizers – prevent degradation
- processing aids – increase productivity
- lubricants – allow processing
- coupling agents – improve performance
- curing agents – allow/improve productivity
- foaming / blowing agents – shape modifiers
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additives ‐ performance
- flame retardants – various techniques
- antistatics – various techniques
- impact modifiers – ‘rubber’ modified
- plasticizers – rigid to flexible
- UV stabilizers ‐ consumable
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thixotropic additive
- fluid when agitated,thickens at rest
- ex. paint
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LETDOWN
= ratio used in coloring plastics with coloring concentrates
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tracer additives
anti-counterfeit taggants = uniquely encoded particles for each customer or app
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WPC = wood plastic composites
=> wood flour + plastic granules = pallwood
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additives - appearance
- colorants – tricky area
- nucleating agents ‐ clarifiers
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Fillers
= main purpose cost reduction (i.e. dollar store)
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additives – unintended outcomes
- loss of FDA
- impaired sealability / weldability
- impaired printability
- loss of physical properties
- new processability limitations
- can conflict when used simultaneously
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