Chemiluminescence – a tool for determination of degree of oxidation of
polymers
+
Residual service life
Jozef RychlýPolymer Institute
Dúbravská cesta 9, 843 42 Bratislava, Slovak Republic
Polyfriend workshop, september 5. 2013
What chemiluminescence is?
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Chemiluminiscencia z disproporcionácie polymérnych peroxylových radikálov
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Polyfriend workshop, september 5. 2013
Scheme of the light emission accompanying the oxidation of synthetic and natural polymers
secondary carbon atomsin the polymer chain
carbonyl, hydroxyl,carboxyl groups
oxidation
via hydroperoxides
oxidation
of their positions
terminal groups
of macromolecules
oxidation
via hydroperoxides
weak chemiluminescence from
peroxyl radicals recombination
heavily oxidized
products
bright chemiluminescence from
intermediate dioxetanes or similar
light emission precursors
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Chemiluminescence (isothermal, non-isothermal) Chemiluminescence method is one of the supporting methods of investigation of development of oxidation degradation for a large spectrum of polymers (kinetic studies). The predictions of the remaining service life becomes more and more elaborated.The most of polymers studied so far giving a bright light emission when oxidized have in the vicinity of potentially formed hydroperoxidic group carbonyl, carbamido, carboxylic, alcoholic group; isolated hydroperoxides provide only weak light emissionThe chemiluminescence from polymers is pronounced when lower molar mass compounds are either present of being formed during oxidation process.It becomes also very important method in determination degradation progress of polymers where carbonyl groups are inherent part of the chain structure.
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FTIR spectra of the polymers investigated
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Instrumentation, 1968-2013, new instrument designed at the PISAS in 1968
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Polyolefins and polydienes
CH2CH(
CH3
CH2CH
CH3
)n
polypropylene
CH2CH2CH2CH2( )n
polyethylene
CH2C CHCH2
CH3
( )n
poly(1,4-isoprene)
CH2CH CHCH2( )n
poly(1,4-butadiene)
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Tertiary carbons + double bonds C=C
>
Double bonds
>
Tertiary carbons
>
Single C-C bonds
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1000 10000 1000000
20000
40000
60000
80000
100000
120000
Inte
nsi
ty o
f CL,
cou
nts/
s/3
mg
time, s
Polyethylene
Polypropylene
Polyisoprene120 oC, oxygen
Polybutadiene
Porovnanie priebehov chemiluminiscencie z nasýtených a nenasýtených uhlovodíkových
polymérov (polyetylén a polybutadién) s polymérami majúcimi v hlavnom reťazci
terciárne uhlíky (polypropylén, polyizoprén)
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The effect of initial molar mass PP, oxygen, 120 oC
0 10000 20000 300000
40000
80000
12000040 000
80 000
180 000
CL
inte
nsity
, co
unts
/s
time, s
Polyfriend workshop, september 5. 2013
Bábika, ako model prirodzeného starnutia polymérov 13. polyurethane ether foam foot ___________________________________________________________________________
15. PMMA tray
1. polystyrene hat
6. nylon ears and nose
7. PE scarf with carbon black
2.polystyrene head
5.silicone rubber tongue
6. nylon ears and nose
.3.acrylic hair 4.polypropylene sunglasses
10. low density polyethylene arms
8.polyethylene
terephthalate (PET) body
14.polyurethane ester foam foot
9.polycarbonate hands hand
11. nylon belt 12. nylon skirt
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Polyfriend workshop, september 5. 2013
Inert atmosphere
By means of chemiluminescence we can detect the levels of hydroperoxides in polymers
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Nonisothermal experiments
Polymer is heated according to pre-set programme as in DSC measurements
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Polypropylene with fillers
50 100 150 200 250
0
500000
1000000
1500000
2000000
polypropylene(flame retardant)
polypropylene(mica reinforced)
polypropylene(talc reinforced)
polypropylene(calcium carbonatereinforced)
polypropylene(glass filled)
polypropylene(baryum sulfatereinforced)
polypropylene(homopolymer)
CL
inte
nsi
ty, c
ou
nts
/s/1
mg
temperature, oC
Polyfriend workshop, september 5. 2013
Conclusions
1. Chemiluminescence method is one of the most elegant method of investigation of development of oxidation degradation for a large spectrum of polymers (kinetic studies) and still brings to experimentators new surprises.
2. The main emphasis has been put on CL from oxidation of polyolefins and other polymers were somehow neglected.
3. The most of polymers studied so far were not characterized properly from the viewpoint of residual catalysts, defect structures, stabilizers, etc, which may be the source of conflicting data.
4. As we measure the light emission and any filter and/or absorber may modulate the observed light intensity we should be aware of some limitations; the combination with other methods is always necessary.
Polyfriend workshop, september 5. 2013