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DEGRADATION AND STABILIZATION OF POLYOLEFINSتخریب و پایدارسازی پلی اولفین ها

O. Dadgari, M. Jamali, A. Bashir, R. Bagheri

Presenter: Omid Dadgari

Paper Code: imbpa15-00180005

March 2016

Parsa Polymer Sharif

Leading manufacturer of advanced polymeric compounds in Iran

15 years of academic research experience prior to its establishment

Active professional R&D team in continuous collaboration with academic atmospheres

Innovative and Knowledge-based

Wide variety of products

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Contents

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Polymer degradation and oxidation

Stabilization strategies and mechanisms

Thermal stabilization

Light stabilization

UV radiation and measuring its effects on polymer degradation

Thermal degradation

• Happens in the absence of Oxygen

• Most polymers are thermally stable. So why degradation?

• Nature of long chains in polymers

• Structural defects

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IcosaneMP = 38 °C BP = 343.1 °C

Thermal degradation mechanisms

• Reactions including chain scission and radical formation

• Reactions including molecular rearrangements

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Oxidative Degradation

• A complex radical reaction

Termination

• Neutral products formation (may not be happened)

Propagation

• An autacceleratingchain reaction which reproduce its initiator

Initiation

• Free radical formation by light or heat

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Initiation reaction

Light

• Chromophores: Light absorbing groups

Thermal

• Polymer structure, an important parameter in controlling the relative stability

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Oxidation chain reaction in polymers

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ROOH RH

R. ROO.

O2RH

ROO. + .OH

Heat

Light

Metal ions

chain scission and

carbonyl products

hν

Δ

Bolland-Gee Mechanism

Strategies in stabilizing polymers against oxidation

ROOH RH

R. ROO.

O2RH

ROO. + .OH

Heat

Light

Metal ions

chain scission and

carbonyl products

hν

Δ

HALSHindered PhenolsAromatic Amines

Quinones

ThioethersTrialkyl Phosphites

BenzophenonesBenzotriazoles

Nickel Quenchers

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Primary antioxidants

Hindered phenols

• Mechanism: CB-A

• Wide range of temperatures

• Improvement in long-term thermal stability

• Non-regenerating mechanism:

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Secondary antioxidants

Phosphites

• Mechanism: PD

• Process stabilizer

• Stable to hydrolyze

• Stabilization byproducts are colorless

Thioethers

• Mechanism: PD

• Works in high temperatures

• Designed to protect polymers from aging in high temperatures

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UV Absorbers

Hydroxy Phenyl

Benzophenone

BP

Hydroxy Phenyl

Benzotriazolw

BTZ

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Nickel Quenchers

• Quenchers transform the radiant energy absorbed by chromophores in the polymer and prevent degradation.

• Energy absorbed by quenchers can be dissipated in the form of heat or fluorescent /phosphorescent radiation.

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Hindered Amine Light Stabilizers

• Strategy: Free radical scavenger

• Edge of polymer stabilization science

• Cyclic structure:

2,2,6,6-tetramethyl piperidine

Denisoff Cycle

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Different generations of HALS

ChimassorbTuinuvin

Cyassorb Hostavin Lowilite

• Monomeric HALS

1st generation

• Polymeric HALS

2nd generation• Non-

reactive HALS

3rd generation

• Synergistic blend of HALS & UVA

4th generation

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Solar irradiance

Solar irradiance is the power per unit area produced by the Sun in theform of electromagnetic radiation

Florida

Arizona

Bandar Abbas

Shiraz

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Outdoor Exposure

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Accelerated Weathering Testing

Fluorescent UV lamps

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Xenon Arc

What properties to measure?

Mechanical Properties

• Tensile Strength

• Elongation

• Impact Strength

Aesthetics

• Yellow Index

• Chalking

Oxidation

• Carbonyl and Hydroxyl Absorption

• Hydro-peroxide evaluation

EnEnergy for n% reduction in properties

TnTime for n% reduction in properties

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