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David Vroom Consultant

Development of Advanced Development of Advanced Development of Advanced Development of Advanced CrossCrossCrossCross----linking Materialslinking Materialslinking Materialslinking Materials

Scope of the PresentationScope of the PresentationScope of the PresentationScope of the Presentation

Materials designed for radiation processing• Cross-linking of Polymers – Industrial

applications- wire and cable insulation - elastic memory products- circuit protection devices - positive temperature coefficient (PTC)

heaters

Scope of the PresentationScope of the PresentationScope of the PresentationScope of the Presentation

• Industry oriented – non-academic- complex, proprietary formulations

• No trade secrets, formulations• Product oriented

- market pull• Emphasis on e-beam irradiated

materials

TodayTodayTodayToday’’’’s Split Markets Split Markets Split Markets Split Market

• High performance / high cost / niche- aerospace - defense- marine - ferries- medical- mass transit- energy generation / distribution- telecommunications – outside plant- circuit protection - telecommunications - industrial heating

TodayTodayTodayToday’’’’s Split Markets Split Markets Split Markets Split Market

• Required performance / low cost / pseudo commodity- automotive- commercial electronics- commercial general- circuit protection – batteries - non-industrial heating

TodayTodayTodayToday’’’’s markets markets markets market

• Green- bio-degradable- recyclable formulations- use of recycled materials

• RoHS- reduce / eliminate heavy metals- lead free (soldering)

TodayTodayTodayToday’’’’s markets markets markets market

• Higher operating / maximum temperatures

• Small dimensions• Light weight• More aggressive solvents• Extended life

TodayTodayTodayToday’’’’s Realitys Realitys Realitys Reality

• Reformulation- raw materials obsolescence

- edge materials- changing regulations- challenge all components availability

• Materials allocation- fluoropolymers

High Performance MaterialsHigh Performance MaterialsHigh Performance MaterialsHigh Performance Materials

• Higher cost acceptable• High quality• Meet or beat the spec.• Higher operating temperatures

- lead free soldering applications- engine compartments

High Performance MaterialsHigh Performance MaterialsHigh Performance MaterialsHigh Performance Materials

• Superior mechanical properties- defense applications

• Superior chemical properties- NBC (nuclear, biological, chemical)

• Acceptable manufacturability• Acceptable delivery – longer lead times• Generally lower volumes

Acceptable Performance Acceptable Performance Acceptable Performance Acceptable Performance MaterialsMaterialsMaterialsMaterials• Lowest possible cost or lower• High quality• Meet the spec.• Appropriate operating temperature• Appropriate mechanical properties• Appropriate chemical resistance

Acceptable Performance Acceptable Performance Acceptable Performance Acceptable Performance MaterialsMaterialsMaterialsMaterials• Environmentally acceptable

- RoHS, halogen free• Superior manufacturability• Superior delivery – off-the-shelf,

scheduled deliveries• Generally higher volumes

Materials CharacteristicsMaterials CharacteristicsMaterials CharacteristicsMaterials Characteristics

High performance and acceptable performance crosslink-able polymeric

materials are complex and require significant development.

Materials Development ProcessMaterials Development ProcessMaterials Development ProcessMaterials Development Process

• Needs / specification from customer• Product design – specification

refinement• Formulation – choose polymer(s),

modifier(s), additives – iterative process, pass the tests

• Compounding – scaling issues• Manufacturability

Choosing the right componentsChoosing the right componentsChoosing the right componentsChoosing the right components

• Market needs drive choice of components- low cost – polyolefin co-polymers- high temperature – fluoropolymers, - high expansion ratio – highly branched

polyolefins- oil resistance – fluoropolymers- chemical resistance – fluoropolymers,

fluoroelastomers, polyesters


• Market needs drive the choice of components- abrasion resistance – fluoropolymers, - cut through resistance - nylons- lubricity – fluoropolymers- biocompatibility - flame retardants – brominated

compounds, red phosphorous, water releasing compounds (Mg(OH)2, Al2O3


• Chemistry helps guide components choice- compatibility of components- cross-linking stabilization of quasi-

compatible components- material interaction with the

environment – substrate


• Chemistry helps guide components choice- adhesive bond to jacket - substrate- crosslink / degradation dose matching

- multiple layer products- temperature matching – jacket,

adhesive- e-beam vs. Co-60 irradiation – dose

rate issues

Commonly Used PolymersCommonly Used PolymersCommonly Used PolymersCommonly Used Polymers

Little change over the past 25 years• Polyolefins

- polyethylene – HD, LD, LLD, VL, UL- co-polymers – EMA, EBA, EVA (modifiers)

• Fluoropolymers- ETFE, PVDF, PFA/MFA,

(PTFE)

Commonly Used PolymersCommonly Used PolymersCommonly Used PolymersCommonly Used Polymers

• Elastomers- EPDM, fluoroelastomers (modifiers)

• Polyesters – PBT, Hytrel• Nylons – 11, 12• Polyamides (adhesives)

Additives Additives Additives Additives

List of 35 types of additives• Antioxidants• Biocides• Blowing agents

- Physical blowing agents (compressed gases, volatile liquids)

- Chemical blowing agents (solid compounds that decompose to evolve gas)

AdditiveAdditiveAdditiveAdditive

• Conductive fillers – for PTC heaters, circuit protection devices, high voltage stress grading, EMI shielding, induction heating - carbon blacks- metal powders- ferromagnetic materials

AdditivesAdditivesAdditivesAdditives

• Cross-linking enhancers - radiation• Cross-linking inhibitors - radiation• Chemical curing agents (peroxides)• Degradability agents (to promote bio- or

photo- degradation)• Fiber (glass, graphite, metal, etc) for

reinforcing

AdditivesAdditivesAdditivesAdditives

• Flame retardants- Halogenated- Halogen free- Synergists

• Inert fillers (low cost)• Pigments• Recyclate additives (to boost properties

of recycled plastics)• UV stabilizers

Formulation ConsiderationsFormulation ConsiderationsFormulation ConsiderationsFormulation Considerations

• Meet the customer needs / specificationMarket drives choices - use temperature / maximum

temperature- flame retarded- low smoke- electrical properties- solvent resistance


• Meet the customer needs / specificationMarket drives choices - mechanical properties- installation methods / concerns- cost- weight- product size range


• Choose base polymer(s)- determines main features of material

- operating temperature range- gross mechanical and chemical properties

- effects of crystallinity – additives contained in amorphous regions only


• Choose base polymer(s)- average molecular weight

- crosslink-ability vs. melt process-ability

- molecular weight distribution- crosslink-ability vs. melt process-

ability


• Choose polymer modifiers- reduce crystallinity – important if high

additive levels required in highly crystalline materials like HD polyethylene

- increase flexibility- lower cost


• Choose polymer modifiers- compatibility of polymers and other

additives- quasi compatibility – use radiation to

lock components together - materials that are designed to absorb

and coat other materials- improve manufacturability –

processing speed, drool, clogs


• Additives- complex formulations – in excess of 10

components in some cases- high solids (non-melting) content – can

be over 50%- green anti-oxidant and flame

retardant packages - particle size – small tubing, conductive

polymers


• Additives- green cross-linking promoters

- phasing out traditional types like tri-chlorobenzene (TCB)

- pigments – heavy metals, radiation bleaching / color change

- compatibility - bleeding


• One formulation may not pass all tests in product size range- cost- VW1 flame test – UL test- chemical resistance- titrate the formulation to fine tune- should look and feel the same


The effects of radiation on all components must be

understood

Elastic Memory Elastic Memory Elastic Memory Elastic Memory –––– Market Needs, Market Needs, Market Needs, Market Needs, Materials SolutionsMaterials SolutionsMaterials SolutionsMaterials SolutionsHigh Performance – Energy production /

distribution – splices / terminations• Needs

- high voltage insulation – up to 69KV- acceptable shrink time- cable type specific – oil filled / solid


distribution, tubing / molded parts• Needs

- moisture proof- stress grading- no arc-tracking - charring- rodent / insect proof- minimal uv degradation (30 yr. life)


distribution, tubing / molded parts• Solutions

- product design- thick wall product / shrink time / dual /

multi-layer wall thermoplastic / elastomer product

- Co-60 irradiation – thick / rigid


distribution, tubing / molded parts• Solutions

- polyolefin or fluoropolymer holdout layer – EPDM inner layer

- conductive additives for stress grading

- additives to eliminate arc tracking –diatomaceous earth

Elastic Memory Elastic Memory Elastic Memory Elastic Memory –––– Market Needs, Market Needs, Market Needs, Market Needs, Materials SolutionsMaterials SolutionsMaterials SolutionsMaterials Solutions

Elastic Memory Elastic Memory Elastic Memory Elastic Memory –––– Market Needs, Market Needs, Market Needs, Market Needs, Materials SolutionsMaterials SolutionsMaterials SolutionsMaterials SolutionsAcceptable performance – Automotive

tubing / molded parts• Needs – a demanding market

- low cost- delivery, delivery, delivery – line down

considerations- high quality- cable systems protection - moisture

sealing


tubing / molded parts• Needs

- chemical resistance – brake fluids, coolants, oils, fuel

- abrasion resistance- higher temperature jackets and

adhesives


tubing / molded parts• Needs

- rapid, reliable, foolproof installation- color matching - beautification - generally green


tubing / molded parts• Solutions

- single and dual wall requirements- polyolefin HDPE, LDPE /

fluoropolymers based outer jacket- adhesive / blocking material inner wall

- matched to jacket and substrate


tubing / molded parts• Solutions

- metal filled material – induction heating sensitive additives in jacket and adhesive / blocking layers –induction heating for installation

• Reliable components supply and manufacturing process

Circuit Protection Circuit Protection Circuit Protection Circuit Protection –––– Market Needs, Market Needs, Market Needs, Market Needs, Materials SolutionsMaterials SolutionsMaterials SolutionsMaterials Solutions

High and acceptable performance• Needs

- Low resistance – milli-Ohms for small components

- Low cost- Smaller, smaller and smaller – battery

pack surface mounted down to 0.5 mm by 0.5 mm


High and acceptable performance• Needs

- Reliability, reliability, reliability- telecommunications - long- cell phone – two year lifetime- automotive – ten year life time


High and acceptable performance• Solutions

- PE, PE co-polymers and fluoropolymers- Carbon black most common conductive filler- New products using metal powder

conductive fillers are being introduced- Processing is as important as the material

formulation – orientation- Co-60 and e-beam processing

PTC Heaters PTC Heaters PTC Heaters PTC Heaters –––– Market Needs, Market Needs, Market Needs, Market Needs, Materials SolutionsMaterials SolutionsMaterials SolutionsMaterials Solutions• Needs

- range of auto- regulating temperatures

- range of power outputs (watts/meter)- longer lengths between power points- solvent resistance- abrasion resistance, indoor / outdoor

applications

PTC Heaters PTC Heaters PTC Heaters PTC Heaters –––– Market Needs, Market Needs, Market Needs, Market Needs, Materials SolutionsMaterials SolutionsMaterials SolutionsMaterials Solutions• Solutions

- Carbon black conductive filler- Olefin based heaters - 85° C shut off- PVDF based heaters - 110° C shut off- PFA / MFA based heaters - 121° C

shut off- product design – outer jackets / braids

PTC Heaters PTC Heaters PTC Heaters PTC Heaters –––– Market Needs, Market Needs, Market Needs, Market Needs, Materials SolutionsMaterials SolutionsMaterials SolutionsMaterials Solutions

Concluding RemarksConcluding RemarksConcluding RemarksConcluding Remarks

• Materials development market driven• Both high performance and acceptable

performance materials are complex and require significant development

• Product designers and materials formulators must work together

• Shift toward smaller product sizes, light weight and green

Concluding RemarksConcluding RemarksConcluding RemarksConcluding Remarks

• Available number of cross-linking polymers and additives is extensive

• Compounding route is a crucial part of the development process

• Small variations in composition, compounding can result in failure to qualify

• Education / experience concerns

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