Photodegradation of bisphenol A polycarbonate with different types of stabilizers

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Polymer Degradation and Stability 95 (2010) 811e817

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Polymer Degradation and Stability

journal homepage: www.elsevier .com/locate /polydegstab

Photodegradation of bisphenol A polycarbonate with different types of stabilizers

Marjolein Diepens a,b, Pieter Gijsman a,b,c,*

a Laboratory of Polymer Technology, Department of Chemical Engineering, Eindhoven University of Technology, P.O. Box 513, 5600 MB Eindhoven, The NetherlandsbDutch Polymer Institute (DPI), P.O.Box 902, 5600 AX Eindhoven, The NetherlandscDSM Research, PM-CT, P.O. Box 18, 6160 MD Geleen, The Netherlands

a r t i c l e i n f o

Article history:Received 8 July 2009Received in revised form21 January 2010Accepted 2 February 2010Available online 10 February 2010

Keywords:PhotodegradationStabilizationUV-stabilizerHindered amine light stabilizerBisphenol A polycarbonate

* Corresponding author at: DSM Research, PM-CT, PThe Netherlands. Tel.: þ31 46 4761538.

E-mail address: [email protected] (P. Gijsman).

0141-3910/$ e see front matter � 2010 Elsevier Ltd.doi:10.1016/j.polymdegradstab.2010.02.005

a b s t r a c t

When unstabilized bisphenol A polycarbonate is exposed to outdoor weathering conditions, it degradesdue to irradiation, humidity and other parameters. To overcome this undesired degradation process BPA-PC can be stabilized. In this study the influence of different types of stabilizers (i.e. UV-absorbers andhindered amine stabilizers) on the photodegradation of BPA-PC were compared. It is shown that the bestway to stabilize BPA-PC is to keep the harmful UV light out. Almost all stabilizers caused a decreaseddegradation rate. The UVAs showed the best results, although radical scavengers cause a decrease indegradation too. By applying a layer of UVA-stabilized BPA-PC on top of unstabilized BPA-PC led toa decreased degradation rate of the unstabilized BPA-PC, which can quantitatively be explained bya reduction of the irradiation intensity.

� 2010 Elsevier Ltd. All rights reserved.

1. Introduction

Because of its good physical and mechanical propertiesbisphenol A polycarbonate (BPA-PC) is used in many fields ofapplications. However, one of the main disadvantages of poly-carbonate is that it degrades due to sunlight, humidity and oxygen[1]. To increase the lifetime of BPA-PCs, the undesired photo-degradation reactions (i.e. photo-Fries and photo-oxidation) [2e5]need to be overcome.

There are several ways to stabilize polymers. One can stabilizepolymers by keeping the light out, quench excited states beforephotochemistry occurs, or trap formed free radicals. This can beachieved by adding UV-absorbers, quenchers, radical scavengers, orsynergistic combinations to the polymer respectively [6]. In thenext sections the most important types of stabilizers will bediscussed.

1.1. UV-absorbers (UVAs)

To stabilize polymers against photodegradation, UV-absorberscan be used. An effective UV-stabilizer (UVA) must strongly absorb,UV light harmful for polymers, and dissipate this in a way harmless

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for the polymer. Another requirement for UVAs, especially whencolorless, transparent polymers are used, is that they most becolorless and must not scatter light. To be active, UVAs needs to bephotostable too [1,7]. When photons are absorbed by an UVA, it isexcited to the first excited singlet state. UVAs with an intra-molecular hydrogen bridge, can undergo an excited state intra-molecular proton transfer (ESIPT) [1,7]. The excited protontransferred product loses its energy by heat, fluorescence, orphosphorescence, to form the ground-state proton transferredproduct, followed by a proton shift, which leads to the UVA in theground state.

There are different groups of UVAs [1]. The most importantgroups are: hydroxybenzophenones, hydroxyphenyl benzo-triazoles, cyanoacrylates, and the more recently-commercializedhydroxyphenyl triazines. The UV absorption of these moleculesdepends on their substitution as well as on the molecule type. InFig. 1 an overview of the hydrogen transfer mechanisms of someUVAs is given.

1.2. Hindered amine light stabilizers (HALS)

Hindered amine light stabilizers (HALS) absorb no light in thewavelengths between 300 and 400 nm, and act by catalyzing thetermination step of the oxidation cycle. They can thus be activeeven at the surface of many polymers. For polyolefins this process isvery effective, however, it generally is less effective for aromaticpolymers where the rate of initiation is high and the number of

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a

b

c

d

Fig. 1. Hydrogen transfer mechanism for the class of a) hydroxybenzophenones,b) hydroxyphenylbenzotriazoles, c) cyanoacrylates, and d) hydroxyphenyltriazines [8].

Table 1Schematic overview of stabilizers and their suppliers.

AbbreviationSupplierTrade name

Chemical structure AbbreviationSupplierTrade name

Chemical structure

A1CytecCYASORBUV-531

A7BASFUVINUL3030


A8BASFUVINUL3088

A3CibaTinuvin1577

H2CytecCYASORBUV-3529


H2CytecCYASORBUV-3346


H3CibaTinuvin 770

A6BASFUVINUL3039

H4CibaTinuvin 765

M. Diepens, P. Gijsman / Polymer Degradation and Stability 95 (2010) 811e817812

propagation steps in the propagation cycle of the auto-oxidation issmall [9]. HALS stabilizers can be basic [1]. This basicity can bea concern with polycarbonate, because basic products can causedecomposition of PC upon processing and hydrolysis duringweathering [10].

It was previously shown that UVAs are more effective UV-stabilizers than HALS in stabilizing polycarbonatewhen acceleratedtests were performed with lamps which irradiates wavelengthsbelow (<290 nm) [11]. However in these conditions photo-Friesrearrangement reactions dominates the degradation mechanism,which is not the case at outdoor weathering conditions [5]. Underthese conditions oxidation is the most important degradationmechanism is oxidation, against which HALS was expected to beactive. In this study different types of stabilizers were added tobisphenol A polycarbonate and their stabilizing effect on the pho-todegradation rate was compared.

Table 2Concentration of stabilizer mixed in BPA-PC.

Sample Concentration [wt%] Sample Concentration [wt%]

A1 0.9 A7 0.7A2 1.5 A8 0.9A3 1.2 H1 0.6A4 0.6 H2 0.8A5 1.0 H3 0.7A6 1.1 H4 0.7

2. Experimental

Unstabilized bisphenol A polycarbonate (Lexan 145, SabicInnovative Plastics) was used. To stabilize the BPA-PC samples,different types of stabilizers were added to a 20 wt% polymer indichloromethane (DCM) solution. The used stabilizers and theirsuppliers are shown in Table 1. A concentration about 1 wt% of A1relative to BPA-PC was used, the concentration of the other UVstabilizers was calculated so that the amount of functional groupswas the same for each sample. The used wt% are shown in Table 2.

Films with a thickness of approximately 0.02 mmwere preparedby solution casting the BPA-PC/stabilizer solution on a glass plate.The films were dried in a vacuum oven at 60

�C for 24 h. Of each

formulation 2 films were made.

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0.5

1.0

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2.0

A8

A7

A1

A3

A2

A6A5

A4

BPA-PC

BPA-PC A1 A2 A3 A4 A5 A6 A7 A8Ab

sorb

ance

Wavelength [nm]

Fig. 2. UV absorption spectra of unirradiated stabilized BPA-PC films with differentUVAs.

300 350 400 450 0.0

0.5

1.0

1.5

2.0

Irradiation time(0 - 1035 hrs)

Abso

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Wavelength [nm]

BPA-PC

320 340 360 380 400 420 440 0.0

0.5

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1.5

2.0Irradiation time (0 - 1840 hrs)


Abso

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Wavelength [nm]

A2

280 300 320 340 3600.0

0.5

1.0

1.5

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Irradiation ti(0 - 1840 hr

Abso

rban

ce

Wavelengt

A5

a

c

e

Fig. 3. UV absorption spectra of a) unstabilized BPA-PC films and, BPA-PC stabil

M. Diepens, P. Gijsman / Polymer Degradation and Stability 95 (2010) 811e817 813

These films were aged in an Atlas Suntest XXLþ containingxenon lamps filtered by daylight filters with a wavelength rangestarting from 298 nm. The spectrum of the irradiated light can befound in our previous work [5]. The chamber and black standardtemperature were set to 40 and 60 �C respectively and the relativehumidity was set to 50%. The irradiance level was approximately0.49 W/m2/nm at l ¼ 340 nm.

UVeVis spectra were recorded on a Shimadzu UV-3102PCUVeVIS-NIR scanning spectrophotometer. Infrared spectra wererecorded using a BioRad FTS 6000 spectrometer in the attenuatedtotal reflection (ATR) mode at 200 scans at a resolution of 4 cm�1.The BioRad Merlin software was used to analyse the spectra. Allspectra were normalized using the peak located at 1014 cm�1.

3. Results and discussion

3.1. Influence of UVAs

UV-spectra of the unirradiated BPA-PC films were measured. InFig. 2 the spectra of the unstabilized and stabilized BPA-PC samples

300 350 400 450 0.0

0.5

1.0

1.5

2.0


Abso

rban

ce

Wavelength [nm]

A1

300 350 400 450 0.0

0.5

1.0

1.5

2.0


Abso

rban

ce

Wavelength [nm]

A4

380 400 420 440

mes)

h [nm]

b

d

ized with b) A1, c) A2, d) A4, and e) A5, as function of the irradiation time.

0 500 1000 1500 2000 0

2

4

6

8

10

12

Yello

win

g In

dex

Irradiation time [hrs]

BPAPC0 A1 A2 A3 A4

0 500 1000 1500 2000 0

2

4

6

8

10

12

Yello

win

g In

dex


BPAPC0 A5 A6 A7 A8

a b

Fig. 4. Calculated yellowing index for increasing irradiation times, a) BPA-PC and BPA-PC stabilized with A1 to A4, and b) BPA-PC stabilized with A5 to A8. All measurements weredone on two separately produced films. The bars show the standard deviation and the lines serve as guides to the eye. (For the interpretation of the reference to color in this figurelegend the reader is referred to the web version of this article.)

1900 1800 1700 1600 1500 1400 1300 0.00

0.05

0.10

0.15

0.20

0.25

Abso

rban

ce

Wavenumber [cm-1]

BPA-PC A1

Fig. 5. IR absorption spectra of BPA-PC, unstabilized and with A1.


are depicted. This figure shows that the UV-absorbers have noabsorbance above 400 nm. This means that the samples arecompletely colorless. In the prepared solution of A4 in DCM, whiteparticles were observed, showing that A4 was not completelysoluble in DCM, however these particles were not observed in thefinal films. The absorption spectra shows that, although its solu-bility in DCM was low, A4 was present in the BPA-PC film. It wascalculated (with 3¼ 46 800 mol/(l cm) at 348 nm) [12] that the film

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2.0

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3.0

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rban

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t 171

3 cm

-1


BPAPC A1 A2 A3 A4

a

Fig. 6. IR absorption at 1713 cm�1 for increasing irradiation times, a) BPA-PC and BPA-PC stadone on two separately produced films. The bars show the standard deviation and the line

contained only 0.15 wt%. The weight% of UVAs in BPA-PC weredifferent, see Table 2, however the amount of functional groupswasthe same for each stabilized film. Comparing the absorptionspectra, it can be observed that stabilizers A2, A3, and A8 have thehighest absorbance at wavelengths below 400 nm, which suggeststhat these stabilizers will be the most effective in absorbing theharmful UV light.

The stabilized BPA-PC films were irradiated for different irra-diation times and the UV absorption spectra were recorded. Someof the UV absorption spectra can be seen in Fig. 3.

In Fig. 3a, the absorption spectra of unstabilized BPA-PC fordifferent irradiation times are shown. It can be seen that theabsorption is increasing with irradiation times. The BPA-PC isalready showing absorptions around 400 nm, indicating that thesample is beginning to show discoloration. Fig. 3b shows that, inthe presence of A1, with increasing irradiation times the absorptionbelow 400 nm is increasing. However, this increase is limited,especially when compared to the increase found for unstabilizedBPA-PC. Fig. 3d and e show a similar behavior; increasing absor-bance below 400 nm with irradiation time and limited increaseabove 400 nm.When BPA-PCwas stabilized with A2, see Fig. 3c, theabsorption around 340 nm is decreasing whereas the absorptionabove 370 nm is increasing with increasing irradiation times. Thisindicates that the stabilizer is rearranged into another product.

To compare the effect of the added stabilizers, the yellowingindex was calculated using the data from the UV absorption spectra[13]. In Fig. 4 the delta yellowing index is shown for all the stabi-lized BPA-PC samples. From this figure it can be observed that the

0 500 1000 1500 2000 0.0

0.5

1.0

1.5

2.0

Abso

rban

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t 171

3 cm

-1


BPAPC A5 A6 A7 A8

b

bilized with A1 to A4, and b) BPA-PC stabilized with A5 to A8. All measurements weres serve as guides to the eye.

BPA-PC A1 A2 A3 A4 A5 A6 A7 A8

0

1

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7

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dex

BPA-PC A1 A2 A3 A4 A5 A6 A7 A8

0.0

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1.0

1.2

IR a

bsor

banc

e at

171

3 cm

-1

a b

Fig. 7. a) Calculated yellowing index, and b) IR absorption at 1713 cm�1 for the UVA-stabilized BPA-PC films after 870 h of irradiation. All measurements were done on twoseparately produced films. The bars show the standard deviation.

0 500 1000 1500 2000 0.0

0.2

0.4

0.6

0.8

1.0 BPA-PC without top layer BPA-PC with top layer BPA-PC with top layer x scalingfactor 0.25

UV

Abso

rptio

n at

320

nm


Fig. 8. Effect of top layer on the UV absorption at 320 nm for the degradation rate ofBPA-PC. The lines serve as guides to the eye.


BPA-PCs containing UV-absorbers show less yellowing than theunstabilized polycarbonate, except for sample A4. This is probablydue to the unsuccessful blending in BPA-PC. Stabilizer A1 shows theleast discoloration and thus the best results for stabilization againstyellowing, but good results were also obtained for stabilizers A3and A5.

To investigate the influence of UVAs on the photo-oxidation rateat the surface of the BPA-PC films, ATR infrared spectra wererecorded. It was previously reported that the absorption band at1713 cm�1 is ascribed to aliphatic acids, which are typical oxidationproducts [3]. In this study this band is used as a measure for thephoto-oxidation rate [5,14,15]. Fig. 5 shows the infrared spectra ofunirradiated BPA-PC and BPA-PC with A1. The spectra are almostsimilar. The absorption of A1 at 1713 cm�1 is negligible, so that thisband can be used as a measure of oxidation for the stabilized BPA-PC too. This was also observed for the other UVAs.

When the samples were irradiated in the XXLþ an increasedabsorbance at 1713 cm�1 was observed. The delta absorbance at1713 cm�1 for all UVA containing samples is shown in Fig. 6. Forunstabilized BPA-PC the absorption is increasing with increasingirradiation times. When the BPA-PC was stabilized with UVAs, forthe majority of the UVAs, a reduced oxidation rate was observed.However by adding A4 to BPA-PC the oxidation rate was increased.Thus the addition of A4 does not result in a good UV protection.Stabilizers A2 and A3 are showing the best results for stabilizationagainst (surface)oxidation.

In Fig. 7a and b the yellowing index and the delta IR absorbanceat 1713 cm�1 after 870 h of irradiation are shown respectively. Inthis figure it is clear that the majority of the UVAs lead to a reduceddegradation rate. As expected, stabilizer A2, A3, and A5, which havehigh UV absorbances below 400 nm, show good results. A1 issurprisingly effective against photodegradation. The UV absorbanceof the unirradiated sample below 400 nm is not very high, espe-cially compared to A2, however the addition of small amounts of A1leads to a lower yellowing index and a lower carbonyl absorption.The hydroxybenzophenone (A1) shows good results against yel-lowing. The hydroxyphenyl triazines (A2 and A3) show the bestresults for decreasing the oxidation rate, however, the differencesbetween effectiveness of the two stabilizers is small. The benzo-triazole (A5) also shows good results. The effectiveness of thecyanoacrylates (A6 and A7) is limited. A4 and A8 are not effective instabilizing the BPA-PC against photodegradation.

When the different classes of stabilizers are compared, it is clearthat the type of class is more important than the substitution of thestabilizer. In general, A1 shows the best results for stabilizing BPA-PC in the conditions used in this study.

3.1.1. Effect of UVA-containing top layer on BPA-PCThe effect of blending UVAs into BPA-PC films was also studied

by applying a second film on top of the unstabilized BPA-PC. Thissecond film was a stabilized BPA-PC film containing about 1 wt% ofA1 with a thickness of approximately 0.02 mm and was placed ontop of the unstabilized film.

In Fig. 8 it can be seen that the absorption at 320 nm forunstabilized BPA-PC is increasing with increasing irradiation times.When a UVA-stabilized film was placed on top of the unstabilizedBPA-PC film, the increased absorption at 320 nm was dramaticallyreduced. The UV absorbance of the stabilized BPA-PC top layer at340 nm is 0.62, see Fig. 2 A1. This means that at this wavelengthonly 24% of the incident light is transmitted to the underlying layer.

To determine the influence of this top layer on the actualdegradation rate, the data for the BPA-PC with the top layer werevisually superimposed on the unstabilized BPA-PC by multiplyingthe time axis with a shift factor. The results of this superimpositionare also shown in Fig. 8. The shift factorwas 0.25 used. This was alsoperformed for the IR results and the same scaling factor was found.As a result of UV absorption by A1, only 24% of the light reaches theunderlying BPA-PC film. The light intensity used was 0.49 W/m2/nm at l¼ 340 nm. As a result of the absorption, the underlying BPA-PC is only irradiated with an intensity of 0.1225 W/m2/nm atl ¼ 340 nm. Since the photodegradation corresponds to the reci-procity law [15], a 75% reduction of the light intensity should cause

300 350 400 450 0.0

0.5

1.0

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2.0


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Wavelength [nm]

H2

300 350 400 450 0.0

0.5

1.0

1.5

2.0


Abso

rban

ce

Wavelength [nm]

H3a b

Fig. 9. UV absorption spectra of BPA-PC stabilized with a) H2, and b) H3, as a function of irradiation time.


a four times longer life time (shift factor ¼ 0.25). This correspondsto the observed increase in life time. This means that by applyinga UVA-stabilized top layer the degradation chemistry is notchanged, but the overall rate of degradation is decreased and thusthe only function of A1 is absorption of the UV-light which isdifferent in other polymers [16,17].

Blending of UVAs through the bulk will increase the stability ofBPA-PC, however therewill always be a degradation layer formed atthe surface. By blending UVAs over the whole sample, the UVAswhich are located in the bulk do not contribute to a protection ofthe surface. Concentrating all UVA in a layer at the surface will leadto a better protection [18,19]. In this case the UV light is absorbedeffectively in the regions where it is most destructive, which couldlead to a better stabilization of the polymer.

3.2. Influence of HALS

As already discussed in the Introduction, adding HALS to BPA-PCdoes not lead to an initial absorption in the wavelength regime of300e400 nm. UV-absorption spectra were recorded after differentirradiation times. In Fig. 9a and b the spectra of BPA-PC containingH2 and H3 are shown.

After irradiation the absorption below 400 nm is increasing. InFig. 10a the increased absorption with irradiation times for theHALS-stabilized BPA-PCs is shown. In this figure it can be seen thatthe HALS stabilize the BPA-PC. The samples with H3 and H4 showsimilar absorptions as unstabilized BPA-PC, however after 1000 h ofirradiation these samples became very brittle and no absorptions

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1.0

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at 3

20 n

m


BPAPC H1 H2 H3 H4

a

Fig. 10. a) UV absorption at 320 nm for BPA-PC stabilized with HALS, and b) IR absorptionseparately produced films. The bars show the standard deviation and the lines serve as gu

could be measured. Because these types of stabilizers are not ableto prevent the photo-Fries rearrangement, the decreased rate ofabsorption for H1 and H2 can only be attributed to the reduction ofoxidation products formed.

Besides UV absorption spectra, ATR infrared spectra wererecorded to measure the oxidation rate. As well as for the UVA-stabilized samples, no difference between the unirradiated BPA-PCand BPA-PC with HALS was observed. Thus this band can also beused as a measure for oxidation of the HALS-stabilized BPA-PC.With increasing irradiation times the oxidation band at 1713 cm�1

becomes more pronounced, see Fig. 10b. By adding HALS stabilizersto the BPA-PC, the rate of oxidation at the surface of the film wasreduced compared to an unstabilized BPA-PC film.

In Fig. 11 an overview of the results for BPA-PC stabilized withHALS irradiated for 870 h is shown. Stabilizers H1 and H2 show thebest results concerning yellowing and oxidation rate. The yellowingof the H3 and H4 stabilized samples is similar to that of unstabilizedBPA-PC, and slightly better results were found for the oxidationrate. A major difference between H1 þ H2 and H3 þ H4 is themolecular weight of the HALS and the difference of group. H1 andH2 are oligomeric HALS types, whereas H3 and H4 are monomerictypes. An other difference is that H1 þ H2 contain amine groups,whereas H3 þ H4 contain ester groups. As the mobility in glassypolymers is almost similar for the monomeric HALS types, themobility is expected to be limited [20]. The substitution of theamine plays a minor role. Probably the difference in chemicalstructure is more important than the difference in molecularweight.

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BPAPC H1 H2 H3 H4

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at 1713 cm�1 for BPA-PC stabilized with HALS. All measurements were done on twoides to the eye.

BPA-PC H1 H2 H3 H4 0

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Fig. 11. a) Calculated yellowing index, and b) IR absorption at 1713 cm�1 for the HALS-stabilized BPA-PC films after 870 h of irradiation. All measurements were done on twoseparately produced films. The bars show the standard deviation.


4. Conclusion

In this study it is shown that by adding small amounts of UVAsand HALS to BPA-PC at room temperature, the degradation rate wasdecreased. When the results of the UVA- and the HALS-stabilizedBPA-PC samples are compared (Figs. 7 and 11) it is clear that theUV-absorbers show the best results for reducing the yellowing andthe oxidation rate.

The best results for protecting BPA-PC from the harmful irradi-ation were obtained by adding hydroxybenzophenones orhydroxyphenyl triazines. The effectiveness of the stabilizer is moreclass dependent, than substitution dependent. Upon irradiating theBPA-PC stabilized with HALS, a reduced UV absorption at 320 nm isobserved, which suggests that the increase at this wavelength is atleast partly due to oxidation.

When a top layer with UVA was applied, the degradation rateof unstabilized BPA-PC was decreased. Due to the UV absorbanceof 1 wt% UVA in BPA-PC, the irradiation intensity which reachesthe underlying unstabilized BPA-PC sample was reduced by 76%.By superimposing the UV absorption at 320 nm, a scaling factorof 0.25 was found. Since these values correspond, it is clear thatthe degradation mechanism is not changed by applyinga protective top layer. Only the irradiation intensity which rea-ches the surface of the unstabilized BPA-PC film was affected.Thus the stabilizing effect of UVAs is due to the reduction ofharmful irradiation intensity.

Acknowledgements

The authors would like to thank Sabic Innovative Plastics forsupplying the polymer samples, Cytec Industries, BASF SE and Cibafor supplying the UV-stabilizers. This research is part of theResearch Programme of the Dutch Polymer Institute (DPI) underproject nr.481.

References

[1] Zweifel H. Stabilization of polymeric materials. Berlin Heidelberg: Springer-Verslag; 1998.

[2] Rivaton A, Sallet D, Lemaire J. The photochemistry of bisphenol A poly-carbonate reconsidered. Polymer Photochemistry 1983;3:463e81.

[3] Lemaire J, Gardette JL, Rivaton A, Roger A. Dual photochemistries in aliphaticpolyamides, bisphenol A polycarbonate and aromatic polyurethanes e a shortreview. Polymer Degradation and Stability 1986;15:1e13.

[4] Torikai A, Mitsuoka T, Fueki K. Wavelength sensitivity of the photoinducedreaction in polycarbonate. Journal of Polymer Science: Part A: PolymerChemistry 1993;31:2785e8.

[5] Diepens M, Gijsman P. Photodegradation of bisphenol A polycarbonate. Poly-mer Degradation and Stability 2007;92:397e406.

[6] Heller HJ. Protection of polymers against light irradiation. European PolymerJournal e Supplement; 1969:105e32.

[7] Pickett J. Polymer photodegradation and stabilization: a tutorial. PolymerPreprints 2001;42:344e5.

[8] Wypych G. Handbook of material weathering. Toronto: ChemTec Publishing;2008.

[9] Gijsman P, Gitton M. Hindered amine stabilisers as long-term heat stabilisersfor polypropylene. Polymer Degradation and Stability 1999;66:365e71.

[10] Gaines GL. Acceleration of hydrolysis of bisphenol A polycarbonate byhindered amines. Polymer Degradation and Stability 1990;27:13.

[11] Thompson T, Klemchuck PP. Light stabilization of bisphenol A polycarbonate,advances in chemistry series 249, polymer durability, degradation and life timeprediction. Washington DC: American Chemical Society; 1996. p. 303e317.

[12] Pickett J.E. Performance of UV absorbers in plastics and coatings. In: Handbookof Polymer Degradation. 2nd ed. 2000. p. 163e190.

[13] Hunter RS, Harold RW. The measurement of appearance. John Wiley & Sons;1987. p. 95e118.

[14] Diepens M, Gijsman P. Photo-oxidative degradation of bisphenol A poly-carbonate and its possible initiation processes. Polymer Degradation andStability 2008;93:1383e8.

[15] Diepens M, Gijsman P. Influence of irradiation intensity on the photo-degradation of bisphenol A polycarbonate. Polymer Degradation and Stability2009;94:34e8.

[16] Guillory JP, Cook CF. Mechanism of stabilization of polypropylene by ultravioletabsorbers. Journal of Polymer Science and Polymer Chemistry 1971;9:1529e36.

[17] Gugumus F. The performance of light stabilizers in accelerated and naturalweathering. Polymer Degradation and Stability 1995;50:101e16.

[18] Pickett J. Calculation of the efficiency of ultraviolet screeners in plastics.Journal of Applied Polymer Science 1987;33:525e31.

[19] Nising W. Twin-wall sheets from polycarbonate. Kunststoffe 1986;76:1095e7.[20] Boersma A. Mobility and solubility of antioxidants and oxygen in glassy

polymers. I. Concentration and temperature dependence of antioxidantsorption. Journal of Applied Polymer Science 2003;89:2163e78.

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