Odor Barrier Characterization ofOdor Barrier Characterization of Polymer Materials Polymer Materials

MOCON 2008 Internet Seminar Series

June 11, 2008

Background Information

A company needs to contain the odor generated from a waste process.

Background Information

The company has oxygen transmission rate equipment “in house”.

They want to know if this equipment can be used to screen potential barrier materials for their odor barrier properties.

The company requested a comparative study between different polymer film types.

Background Information

The Goal:

Compare odor barrier with oxygen barrier to determine if oxygen barrier property can be used for odor barrier prediction.

What’s Smelly?

Chemical and chemical reactions are responsible for odors.

Which chemicals does one choose to represent a particular odor?

Sensory testing – can help choose a consensus of the odor (i.e. good vs. bad) and descriptors.

GC testing can quantify the chemicals comprising the odor.

What’s Smelly?

Microanalytics performed an odor characterization study of the “Smelly” material.

They utilized a Multi-dimensional Gas Chromatograph with FID / PID / Olfactory / MS Detectors

AromaTrax Approach:An Integrated Analytical Approach to Studying Flavor/Aroma Interactions

Instrumentation / Techniques: Simultaneous Olfactory and Mass Spec Detection Multidimensional Gas Chromatography - Dean

Switch.Heart Cutting (Fractions), Cryogenic Trapping, Back Flushing

Inlet sampling techniques to maximize concentrations of aroma significant compounds.

Methods: Aroma Standard Profile SPME Aroma Extract Dilution Analysis (AEDA) Headspace Aroma Dilution Analysis (HADA)

Combining human sense with instruments and methods.

FID PID SniffPort

Mass Spectrometer Open Split Interface

AromaTrax Software

Chemstation(Agilent)

MultiTraxSoftware

Injectionsystem column 1 column 2

column 2

Agilent 6890 baseddual column MDGC

Windows NT

AromaTraxModel 2100 Multidimensional GC/O-MS

col 1col 2

FIDPIDInj

Vent HCV

MScryompr

sniffport

GC ovenpre-column analytical

Optimized for trace aroma/odor analysis

Permits: Heartcutting, cryofocusing, and backflushing to ferret out aroma components hidden in non-aroma components.

Columns of different polarity

Open Split

Interface

AromaTraxModel 2100 Multidimensional GC/O-MS

MDGC MethodologySome portions of separations may not resolve well

due to complexity or some portions may mask

important odor components. Dairy Grade Polyethylene Headspace

Heart-cut Separations

Intense off-odor

Heart Cutting:

-Permits better resolution of trace or masked components..

- To resolve all components in a complex mixture by passing a portion of column effluent to a second column using flow switching

-Backflushing the uninteresting volatiles to vent, permitting the heart cut portion to resolve by itself in second column.

Back Flushing

Getting rid of uninteresting volatiles

No bake out

And

Cryotrapping

Reduce diffusional broadening.

Focus sample

Heartcut Region

ANALYTICAL Column - PID of Heartcut

PRECOLUMN-FID

2-AP -Popcorn aroma in rice

MDGC Separation of 2-AP

Rice Volatiles Continued - “Needle in the Haystack”

MDGC Heartcut permits increase resolution for the MSD and other Detectors

What’s Smelly?What’s Smelly?

Over 100 different aroma chemicals were identified from the samples.

d- limonene (terpene / essential oil family) was a prominent chemical in all of the tested samples.

Toluene (aromatic hydrocarbon) was also found in the aroma profile.

Material Selection

Barrier Name Polymer Family

OPP Poly(olefins)

PVDC Copolymer Poly(vinyls)

OPP with barrier coating Multi-layered Structure

Nylon-6 Poly(amides)

PET Poly(esters)

Odor Barrier Study

Analysis Temp: 23C Using the saturated vapor pressure of limonene and

toluene at 23C

Toluene: (25.59mmHg); Limonene: (1.84 mmHg)

Odor Barrier Study

Odor Barrier Study

0.0000

0.0020

0.0040

0.0060

0.0080

0.0100

0.0120

0.0140

0 10 20 30 40 50 60 70 80

Days

g*m

m/(

m2

*day

)

Example of Organic Transmission Rate Data

Odor Barrier Results (d- Limonene)

Material Name

Limonene-TRThickness

Normalized(g*mil)/(m2-day)

Ranking

(1 = best, 5 = worst)

OPP 5.84 5

PVDC Copolymer 0.038 3

OPP with barrier coating

1.67 4

Nylon-6 8.2 x 10-5 1

PET 1.4 x 10-4 2

Odor Barrier Results (Toluene)

Material Name

Toluene -TRThickness

Normalized(g*mil)/(m2-day)

Ranking

(1 = best, 5 = worst)

OPP 750 5

PVDC Copolymer 162 4*

OPP with barrier coating

21 3*

Nylon-6 3.8 x 10-4 2

PET 3.6 x 10-4 1

Oxygen Barrier Study

Analysis Temp: 23C Test Gas:

100% O2 (dry) Carrier Gas:

98%N2 / 2%H2 (dry) Instrument:

MOCON Oxtran® 2/21 Methodology:

ASTM D-3985

Oxygen Barrier Study

Oxygen Barrier Study

Example of Oxygen Transmission Rate Data

Oxygen Barrier Results

Material Name

Oxygen TransmissionThickness

Normalized(cc*mil)/(m2-day)

Ranking

(1 = best, 5 = worst)

OPP 1200 5

PVDC Copolymer 28 2

OPP with barrier coating

2.0 1

Nylon-6 42 3

PET 56 4

So, how do they compare?

Odor Barrier / Oxygen Barrier Comparison

Odor Barrier / Oxygen Barrier Comparison

Barrier Comparison

0.00001

0.0001

0.001

0.01

0.1

1

10

100

1000

OPP PVDC PET Nylon-6 PVDC/OPP

Sample Name

Org

anic

Per

mea

tion

g*m

il/(m

2-da

y)

1

10

100

1000

10000

Oxy

gen

Perm

eatio

n cc

/(m2*

day)

Toluene-TR

Limonene-TR

OTR

Odor Barrier / Oxygen Barrier Comparison

Material Name

Transmission Rate(Normalized)

d – Limonene(gm*mil)/(m2-day)

Toluene (gm*mil)/(m2-day)

Oxygen(cc*mil)/(m2-day)

OPP 5.84 750 1200

PVDC Copolymer 0.038 162 28

OPP with barrier coating

1.67 21 2.0

Nylon-6 8.2 x 10-5 3.8 x 10-4 42

PET 1.4 x 10-4 3.6 x 10-4 56

Odor Barrier / Oxygen Barrier Comparison

Material Name

Transmission Rate(Normalized)

d – Limonene(gm*mil)/(m2-day)

Toluene (gm*mil)/(m2-day)

Oxygen(cc*mil)/(m2-day)

OPP 5.84 750 1200

PVDC Copolymer 0.038 162 28

OPP with barrier coating

1.67 21 2.0

Nylon-6 8.2 x 10-5 3.8 x 10-4 42

PET 1.4 x 10-4 3.6 x 10-4 56

Odor Barrier / Oxygen Barrier Comparison

Material Name

Material Ranking (1 = best, 5 = worst)

d - Limonene Toluene Oxygen

OPP 5 5 5

PVDC Copolymer 3 4 2

OPP with barrier coating

4 3 1

Nylon-6 1 2 3

PET 2 1 4

ConclusionsConclusions

Oxygen transmission rate testing of different polymer families could not accurately predict or rank the organic barrier properties of the same films.

Material Name

Transmission Rate(Normalized)

d – Limonene(gm*mil)/(m2-day)

Toluene (gm*mil)/(m2-day)

Oxygen(cc*mil)/(m2-day)

PVDC Copolymer 0.038 162 28

OPP with barrier coating

1.67 21 2.0

Nylon-6 8.2 x 10-5 3.8 x 10-4 42

PET 1.4 x 10-4 3.6 x 10-4 56

Conclusions

There is no “universal” conversion factor from oxygen results to organic results

Material Name

Organic to Oxygen Ratio

d – Limonene TR Oxygen TR

Toluene TR Oxygen TR

OPP 0.0048 0.63

PVDC Copolymer 0.0014 5.79

OPP w/ coating 0.84 10.5

Nylon-6 1.95 x 10-6 9.05 x 10-6

PET 2.50 x 10-6 6.4 x 10-6

Average Ratio 0.17 3.4

Standard Deviation 0.37 4.7

Conclusions

For the same polymer material, different organics can yield different and unpredictable results. This is largely due to polymer / permeant interactions.

Material Name d – Limonene(gm*mil)/(m2-day)

Toluene (gm*mil)/(m2-day)

PVDC Copolymer 0.038 162

OPP with barrier coating

1.67 21

Conclusions

In most cases, the best way to determine whether a material is a good organic (aroma or odor) barrier, is to:

First : Determine which organics are the key players.

Second: Test the material with the proper permeant.

Even though oxygen transmission testing was a poor tool for ranking the overall organic barrier for differing materials, it may prove meaningful to use an oxygen / aroma correlation when comparing barrier properties of like polymers of different thickness, grades or added coatings.

Recommendation for a Future Study

Thank you!Thank you!

Questions, please!

Please join us next month…

Introduction to Scientific Instrument IQ/OQ/PQ Validations:

Wednesday, July 9, 2008

10 am Central