Properties of polymer materials revealed by thermal analysis with optical observation

Yoshikazu Nishiyama1, Masayuki Iwasa1, Brian Goolsby2, Kenichi Shibata3y , y , y ,1Hitachi High-Tech Science Corp., 2 Hitachi High Technologies America, Inc.,

3 Hitachi High-Technologies Science America, Inc.

New thermal analyzers were developed that can observe samples during measurements. These systems can obtainti l i d ll t th l d t i l di DSC TG DTA DMA F th th ti l i li k d i thoptical images and collect thermal data including DSC, TG, DTA, DMA. Furthermore, the optical images are linked in the

time-scale with thermal data, so we can properly correlate the phenomena occurring during thermal analysis.We measured polyethylene terephthalate (PET) undergoing tensile stretching with this system. During glass transition, theobserved physical transformation of PET was well correlated with changes in the DSC and DMA signal. Furthermore, wefound that PET expanded unexpectedly during decomposition in air When we used aluminum pans for measuring this

Experimental

found that PET expanded unexpectedly during decomposition in air. When we used aluminum pans for measuring thisdecomposition, the aluminum pan was deformed by PET expansion, causing a dummy peak on the DTA signal. We reportthe results of various polymer samples analyzed by the new system.

Experimental

Material PET PE Rubber (NBR)

System TG/DTA DSC DMA (1 Hz oscillation) TG/DTA TG/DTA

Sample Detail 5 mg 10 mg 20 mm L x 10 mm W x 0.1 mm T 5 mg 5 mg

Heating Program 10˚C/min 10˚C/min 2˚C/min 20˚C/min(N ) to 230˚C and hold at 230˚C 20˚C/min(N ) 10˚C/min(Air)

Notes: In DSC and TG/DTA, PET sample is from a drink bottle. For DMA, PET film is a consumer product. PE sample is cut from a water pipe. NBR is a consumer product.

RealView DSC RealView TG/DTA RealView DMA

Heating Program 10 C/min 10 C/min 2 C/min 20 C/min(N2) to 230 C and hold at 230 C 20 C/min(N2) , 10 C/min(Air)

Purge Gas Air or N2 N2 N2 N2→O2 (change after temp. stability) N2→Air (change after drop to 300˚C)

The USB-linked camera can be configured to take pictures basedon various parameters (For example: every 1˚C temperaturechange every second over a range of times etc )

Results

Fig.1 Thermal analyzers with optical observation units (red arrows)by Hitachi High-Tech Science Corp.

change, every second, over a range of times, etc.).Furthermore, image data are linked to thermal analysis data, sodata and images can be overlaid using the analysis software.

#1n #1a

1000

10000

(A)crystal

10.0

5.0 #1#2

#4

#8

N2 AirDMA of PETDSC of PET

Melting

20.0

0.0

-20 0

40.0

30.0

20.0TGAir

#4a

#5a

TG/DTA of PET

#3n

#2n

#3a

#2a

E’ /

MP

a1

10

100 (B)non crystal(amorphous)

Glass transition

Cold crystallization

DS

C/

mW

0.0

-5.0

-10.0

#3

#8

#7#6

#5

Glass transition

Cold crystallization

#1 and #2 show the sample shrinks a little during glass transition. In #3 and #4 the sample is white due t ld t lli ti Th h f i h t t d #5

at 80˚C( ) ( )

at 140˚C

TG

/ %

20.0

-40.0

-60.0

-80.0

DTA

/ m

V

10.0

0.0

-10.0

-20.0

DTA

N2

#1a

#2a

#3a

#1n

#2n #4n

#5n

#3n

#6a

#6a#6a shows that the expansion of the

#4n #4a

Temperature / ˚C220.0180.0140.0100.060.020.0

0.01

0.1

Temperature / ˚C250.0200.0150.0100.050.0

-15.0

-20.0

#1 #2 #3 #4 DTA curve shows a glass transition around 70˚C, and cold crystallization around 130˚C. TGA curve

to cold crystallization. Though fusion has started, #5 does not show a liquid state. After peak apex, the sample changed to a transparent, liquid state (#7-8).

(A) (B) (A) (B)

Temperature / ˚C500.0400.0300.0200.0100.0

-100.0

-120.0

-30.0

-40.0Pt panAl pan

expansion of the sample made the Al pan deform; causing an endothermic peak.

#5n #5a

#5 #6 #7 #8

yshows that above 350˚C mass decreased by decomposition.Pictures(#2a & n) show the change in color by the decomposition occurs earlier in air.#3a & n show that gas bubbles are generated by decomposition.#4a shows that sample expands much like balloon.

Comparing amorphous to crystalline PET shows that E’ drops clearly during glass transition and rises during cold crystallization.Both materials show the same transparency at 80 ˚C. However, at 140˚C, because amorphous PET crystallizes, it becomes translucent white.

Both samples were white before melting (#1). At 140˚C (#2) they become transparentT

A /

V

0.0

-5.0

-10.0

-15.0

-20.0

TG

/ %

2.0

0.0

-2.0

-4.0

-6.0

#1

#2DTATG

OIT measurement of PEsample A sample B 1.4

1.2

1 0

20.0

0.0

-20.0

1600

1400

1200

8.3%

49.6%

TG

#1 (2min) #2 (17min)

#4a shows that sample expands much like balloon.

TG/DTA of NBR

350.0

300 0

10.0

0 0

400.0

350 0

(#2), they become transparent but keep their shape as if they are still solid.

#1(50˚C)

#2(140˚C)230˚C holdCh t

Temperature / ˚C180.0160.0140.0120.0100.080.060.040.0

DT

-25.0

-30.0

-35.0

-40.0

T

-8.0

-10.0

-12.0

-14.0

sample A

sample B

DTA

/m

V

1.0

0.8

0.6

0.4

0 2

TG

/%

20.0

-40.0

-60.0

-80.0

-100.0

Tem

pera

ture

/˚C

1200

1000

800

600

400

39.4%

Temp.

N

#5

#3 (44min)

#5 (71min)

#4 (69min)

#6 (74min)

DTA

/ m

V

300.0

250.0

200.0

150.0

100.0

TG

/ %

0.0

-10.0

-20.0

-30.0

-40.0Tem

pera

ture

/ ˚

C

350.0

300.0

250.0

200.0

150.0

TG

Temp.

sample A

sample B

#3（0min）

Change to O2

Time / min80.060.040.020.00.0

0.2

0.0

-0.2

100.0

-120.0

-140.0

400

200

0

DTA

Air

N2#1

#2

#4

#3 #6

#2 and #3 show that the volume of rubber became smaller through decomposition.

Time / min35.030.025.020.015.010.05.00.0

50.0

0.0

-50.0

-50.0

-60.0

-70.0

T

100.0

50.0

0.0

O2

#3

#4 #5 #6 #7

DTA#4（15min）

#5（20min）

Conclusion

In #5 oxidative degradation caused a decrease in carbon, and the color changes to white.Finally, #6 shows that the overall change in sample size.

#5（20min）

#6（25min）

Using thermal instruments with optical observation, we cancollect much more information about sample behavior duringanalysis.This can help explain both the expected phenomena polymers

While sample A oxidation starts before sample B, the TGA curve indicates that sample A decreases less than sample B. This result means the decomposition reaction of sample B is more drastic. In pictures #4 to #7, we can see sample B collapses and flows widely, while sample A is stable.So from the TG/DTA curve and pictures we can determine

#7（30min）

p p p p p yundergo as well as anomalous or unexpected behaviors. Thistechnology could be an important tool in education, failureanalysis, and experiment design, to name a few.

So, from the TG/DTA curve and pictures, we can determine that sample B had a more drastic decomposition reaction than sample A.