Powerful tool for designing and developing materials

Rapid photo / thermal - oxidative degradation analysisof polymeric materials“Micro-UV Irradiator” UV-1047Xe
Japanese Patent: 4571892, US Patent: US7655185B2, EPC: EP1742035

Features of Micro-UV Irradiator (UV-1047Xe) - GC/MS System
Weather-induced degradation tests of polymeric material usually requires weeks or months to complete. Frontier
Laboratory's new Micro-UV irradiator uses a xenon lamp to provide UV light intensity about 2000 times stronger than thatof a deuterium lamp. This reduces the time necessary to acquire meaningful data reflecting the degradation of the sample.
The effects of “weather” upon exposure to the photo / thermal - oxidative
degradation process can quickly be evaluated. This information invaluably facilitate designing and developing
new materials. The same system can also be applied to other analytical areas such as elucidation of the effects
of additives on a polymer’s physical and chemical behavior (e.g. antioxidants). Photochemical reactions and UV
curing can also be examined.

UV/Py-GC/MS technique ---1) Analysis of volatiles generated from the photo / thermal - oxidative degradation process
Small amounts of photo / thermal - oxidative degradation products are generated when a polymeric material is irradiated by UV
irradiation in air while being heated. The qualitative or quantitative analysis of the degradation products can be accomplished bycryo-trapping the degradation products at the head of a separation column prior to chromatographic separation.

2) Analysis of polymeric materials degraded by exposure to a photo/thermal-oxidative environment
The irradiated polymer can be evaluated by evolved gas analysis (EGA-MS) or flash pyrolysis (Py-GC/MS).
This resulting data often provide information on the structural changes in the polymeric material.

UV/Py-GC/MS System Configuration and Basic Performance
Multi-Shot pyrolyzer

The configuration of UV/Py-GC/MS system is shown in Fig. 1.
UV light from a xenon (Xe) arc lamp is delivered via an optical fiber
cable to the center of the pyrolyzer furnace. The sample mounted in
the sample cup is directly irradiated. The sample can be heated toany desired temperature in an atmosphere (e.g. air) during UVirradiation. Photo/thermal-oxidation induced volatile degradation
products are cryo-trapped by immersing a short length of thecolumn head into liquid N2 (The Micro-Jet Cryo-Trap is alsoavailable; option). The condensed volatile components are thenanalyzed by TD-GC/MS. In addition, the residual deteriorated
polymeric material in the sample cup can be analyzed by either
EGA-MS or Py-GC/MS.

Optical fiber cable
UV light source
Xe arc lamp (with Hg)
280- 450nm

Flow switching
controller

Heating furnaceSample cupHeSeparation columnAir

Liquid nitrogen

GC ovenMSFig. 1 UV/Py-GC/MS system configuration

Analysis of the volatiles and the degraded PS after UV irradiation
1. Analysis of volatile compounds generated during UVirradiation --- Fig. 2 shows chromatograms of the volatiles
observed before and after 1 hr UV irradiation. The PS sample
was held at 60ºC under air atmosphere. UV irradiation of the PS
produced various photo / thermal - oxidative degradation
products such as benzophenone (BA) and acetophenone (AP)with reproducibility of RSD 7% or below.

In the EGA thermogram shown in Fig. 3, UV irradiation shifted
the peak top temperature for PS down by 6ºC, while the thermal
decomposition onset temperature decreased from 360ºC down
to 300ºC. This result indicates that the average molecularweight (Mn) of the base polymer is lowered after being irradiated.
The pyrograms in Fig. 4 show that the peak area value for thestyrene trimer diminished after UV irradiation, reflecting thedecreased average Mn of PS.

2. Analysis of degraded PS --- EGA and PY analyses of thedegraded PS provide information on the deterioration of PS.

566˚C
Before UV irrad.

m/z=106 m/z=120 m/z=12278 min

1234
5

0.483
0.471
0.512
0.485
0.424

0.235
0.237
0.244
0.249
0.228

0.282
0.292
0.245
0.267
0.348

Avg
RSD

0.475
6.78

0.239
3.30

0.286
13.5

Fig. 2. Chromatograms of volatile degradation products*: Analysis of volatiles produced during UV irradiation, **: Analysis of volatiles without UV irradiation

Styrene trimer

Before UV irradiation

StyrenePeak area ratio
APBAcSample : 100 µg (thin film)

Styrene dimerBA

Benzoic acid

Styrene4BenzaldehydeWith UV irrad./TD**

Table1 Reproducibility (RSD%)of the peak area ratio

Acetophenone

Without UV irrad./TD*(2,3-dicyano-2,3-dimethylbutane)

Sample: 20 µg (thin film), temp.: 60ºC, irradiation time: 1 hour, atmosphere gas: air, flow rate: 1 ml/min, split ratio: 1/10, Ultra ALLOY metal capillary column: UA+-1 30m (0.25ø) 0.5 µm, GC: 50 - 240ºC (20 ºC/min)

After UV irradiation
After UV irrad.

250 300

400500˚CFig. 3 EGA thermogram

51015 minFig. 4 Pyrograms (600ºC)
2Applications Using UV/Py-GC/MS System
Irradiation temp.: 60ºC, UV irradiation time: 3 hrs, sample size: 100 µg (powder),atmosphere gas: air, split ratio: 1/10, separation column, UA1, 30m (0.25ø) 0.5 µm, GCoven: 40 – 320ºC(20ºC/min), Thermal desorption after UV irradiation: 200ºC (5 min)1. High density polyethylene (HDPE)

EGA thermogram

4ºC

TIC of degradation productsnAfter UV irradiation

Upon UV irradiation, various aldehydes wereobservedasdegradation
products.
These
compounds are considered to have been generated
from the main chain scission of the polymer andsuccessive oxidation caused by photo / thermal oxidation. The subsequent EGA analysis of thedegraded polymer showed that the main peakascribed to the polymer backbone scission had
shifted down by 4ºC, indicating that the MW of thebase polymer had decreased.

Before UV irradiation

400500600ºC

DEP
C16-al5

C17-alWithout UV irrad./TD

C12-alC10-alC8- alC6-al

250 300

C7-al[ CH2 CH2 ]With UV irrad./TD10 minIrradiation temp.: 60ºC, UV irradiation time: 1 hr, other conditions: see those of HDPE above

2. Polypropyrene (isotactic)(PP)

EGA thermogram

2,4-Pentanedione

2-Methylpropenal

18ºC

After UV irradiation

250 300

Acetic acid

AcetoneAcetaldehyde

nAcetic acid, aldehydes, and ketones were observed
as volatile degradation products after UV irradiation.
The subsequent analysis of the degraded polymer
by EGA revealed that the main peak attributed to thescission of the polymer backbone chain had shiftedto lower temperatures, and that the decomposition
onset temperature had been lowered from 400ºC to300ºC, suggesting that the irradiation resulted in adecrease in the MW of the base polymer.

Methylene chloride

TIC of degradation products[ CH2CH(CH3) ]400500ºC

Without UV irradiation/TD

With UV irradiation/TD

3

45 minIrradiation temp.: 60ºC, UV irradiation time: 1 hr, other conditions: see those of HDPE

3. Natural rubber (polyisoprene) (NR)

EGA thermogram
TIC of degradation products

Acetaldehyde

Acetone

UV irradiation of natural rubber yielded variousaldehydes, ketones, and organic acids as volatiledegradation products. The subsequent EGA analysisof the UV-degraded polymer resulted in a shift to ahigher evolved temperature which suggests that theMW of the base polymer had increased due to acrosslinking reaction.

After UV irrad.

100

With UV irradiation/TDOCO

O

3C(CH3)3n

4 min

t-Butylphenol (an endcapping agent for PC) andbisphenol A (monomer) were observed upon UV
irradiation. This is probably caused by the repeatedscissions of carbonate bonds of the polymer. The
subsequent analysis of the degraded polymer by EGA
revealed that after UV irradiation, the main peak had
shifted to lower temperatures. This indicates that theaverage MW has decreased due to the scission of thepolymer backbone chain.

EGA thermogram
TIC of degradation products

Bisphenol A

C(CH3)2

2

UV-ON
After UVirrad.
UV-OFF250 300

p-t-Butylphenol

O

500ºC

Irradiation temperature: 60ºC, UV irradiation time: 1 hr, sample size: 10µg (thin film), thermal desorption after UV irradiation: 330ºC (5 min), forother conditions: see those of HDPE above

4. Polycarbonate (PC) (solution process)
OCO

300

Without UV irradiation/TD1(CH3)3C

Before UV irrad.

Butenal[ CH2C(CH3 ) CHCH2 ]n6ºC

Before UV irrad.

400500600ºC

Without UV irradiation/TD

With UV irradiation/TD
791113 min
3Applications Using UV/Py-GC/MS System
5. Polyacetal

Irradiation temp.: 60ºC, UV irradiation time: 1 hr, for other conditions: see those of HDPE
[Copolymer with ethylene oxide (EO)]
EO: 1.8%

EGA thermogram
TIC of degradation products

TrioxaneOOOOO

4200300400ºC

Without UV irradiation/TDO O

With UV irradiation/TD8 min

6Irradiation temp.: 60ºC, UV irradiation time: 1 hr, thermal desorption
after UV irradiation: no, other conditions: see HDPE above
EGA thermogram

50ºC
After UV irrad.

TIC of degradation products

nAcetaldehyde

Acetic acid, ethylene glycol (generated from side-chainelimination) and its formic acid ester were observed asvolatile degradation products. The subsequent EGA
analysis of the degraded polymer revealed that the peak
profile of the degraded polymer had shifted significantly
to higher temperatures, suggesting a crosslinking
reaction. This result also suggest an increase of the MWoccurring during UV irradiation.

Before UV irrad.

2500ºCO300

O

Without UV irradiation/TD

HOWith UV irradiation/TD

HO

Acetic acid

100

OH

CH2C(CH3)(COOCH2CH2OH)

O

Formic acidAcetic acid100

2

6. Polyhydroxyethylmethacrylate

After UV irrad.
Before UV irrad.

O

After irradiation, the monomer (formaldehyde), trimer(trioxane) and formic acid ester of ethylene glycol
originated from ethylene oxide units were observed.
The subsequent EGA analysis of the degradedpolymer, clearly showed a significant increase in theamount of evolved gas at temperatures below 230ºC.
Thus, the thermal stability of the degraded polymer
was proved to be lowered.

HOCH2O ] nFormaldehyde[ CH2CH2O

468 min

7. Application to photochemical reactions (Fries rearrangement of phenyl salicylate)OHO
C O

UV irradiation: 2 hours at 40ºC,
thermal desorption after UVirradiation: 40-250ºC

Phenyl salicylate
OHOC OSample size: 5 µg (thin film), atmosphere gas: He, split ratio: 1/50
Ultra ALLOY metal capillary column: UA-Fries, 15 m (0.25ø) 0.05 µm
GC oven temp.: 60 – 220ºC (20 ºC/min)Without UV irradiation/TD
Fries rearrangement

Under UV irradiation, phenyl salicylate, which is commonlyadded to cosmetics as a UV absorber, undergoes photo
Fries rearrangement to give UV-absorbing 2,2'-dihydroxybenzo-phenone and 2,4'-dihydroxybenzophenone. The
figure on the right shows the on-line analysis of thisreaction.

2,2'-DihydroxybenzophenoneOHOC

2,4'-DihydroxybenzophenoneHOOHOCOHWith UV irradiation/TD
34567 minSpecifications
 Wavelength range (at fiber end): 280 – 450 nm [Xe arc lamp (contains Hg)]
 Light intensity: >60 mW/cm2 at 365 nm, >700 mW/cm2 in wavelength range of 280 - 450 nm
 Light intensity control: 0 - 100% (1% step), irradiation time: 1 min – 999 hours (1 min step), PC controlled via RS-232C
 Supported system: Pyrolyzers manufactured by Frontier Laboratories Ltd installed on a GC/MS system(no modifications of existing pyrolyzer required)Standard accessories : UV light source, optical fiber cable/sampler, He/Air rapid pressure stabilizer, Ultra ALLOY metal capillary column,
liquid nitrogen Dewar
Options: Xe arc lamp (contains no Hg), filters: 280 – 400 nm (band pass)/350 – 400 nm (band pass), Ultra ALLOY metal capillary columns
Required utilities: Compressed air (300 - 500 kPa), liquid nitrogen, power: 100 - 240VAC (300W)

4-16-20 Saikon, Koriyama, Japan, 963-8862
TEL:81(24)935-5100 FAX:81(24)935-5102
www.frontier-lab.com/

Design and specifications are subject to change without notice.

UV1047-220208E

4