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Committee F02 on
Flexible Barrier Packaging
Toward a package
durability predictive
model Dr. Henk Blom
Rollprint Packaging Products
Addison, IL USA
Outline
Review of packaging durability
A predictive model?
Preliminary data & test case
What’s next?
Package durability
Relevant across industries
Food packaging
Medical device packaging
Commercial packaging
Inadequate packaging results in:
Sterility breaches
Food spoilage
Over-concentration of medical solutions
Shortens shelf-life
Common package defects Flex fatigue pinhole
Abrasion pinhole
Abrasion pinhole
Cut
Cut/puncture
Puncture
Package durability testing
Limitations
Significant cost involved
Pass/fail testing requires large sample sizes to be statistically meaningful
Time consuming – time spent on trucks and ships
Not predictive
Gelbo is not always a good predictor of actual package performance
Process is usually iterative – may require several cycles to identify best candidate
A predictive model?
Is it possible to derive an empirical relationship between routine flexible material tests and package durability performance?
PF = a·Ex + b·Iy + c·Tz + … ???
Would an equation (or family of equations) like this… Be less expensive?
Be faster?
Enable easier screening of material candidates?
Focus design efforts?
Lead to innovative flexible package material designs?
Literature examples
Zapp – 1955 (Esso Labs)
“Abrasion of Butyl Rubber”
Studied abrasion properties of
tires using Lambourn Abrader
𝐴𝑏𝑟𝑎𝑠𝑖𝑜𝑛 𝑙𝑜𝑠𝑠 = 𝑑𝑦𝑛𝑎𝑚𝑖𝑐 𝑚𝑜𝑑𝑢𝑙𝑢𝑠 𝑥 𝑓𝑟𝑖𝑐𝑡𝑖𝑜𝑛
𝑡𝑒𝑛𝑠𝑖𝑙𝑒 𝑠𝑡𝑟𝑒𝑛𝑔𝑡
Verghese – 1992 (Texas A&M)
“Correlation of Pinhole Development Due to Flexing to Mechanical Properties of Plastic Films”
Evaluated pinhole formation in 18 commercial flexible films using custom pinhole device
# 𝑝𝑖𝑛𝑜𝑙𝑒𝑠 = 𝑓(𝑚𝑜𝑑𝑢𝑙𝑢𝑠, 𝑖𝑚𝑝𝑎𝑐𝑡 𝑠𝑡𝑟𝑒𝑛𝑔𝑡, 𝑖𝑚𝑝𝑎𝑐𝑡 𝑠𝑡𝑟𝑒𝑛𝑔𝑡2)
Tan et al – 2008 (Beijing University of Chemical Technology)
“Abrasion Resistance of Thermoplastic Polyurethane Materials Blended with Ethylene-Propylene-Diene Monomer Rubber”
Investigated abrasion resistance of TPU/EPDM blends by abrasion loss
𝑊 =𝑃
2𝐻𝑡𝑔+ 12.13𝑘
𝑃1.5𝐷𝜇2𝐻0.5
𝐾𝐼𝐶
Taber Abrasion Test
Equipment
Taber® Model 5750 Linear Abraser
Flexible Material Kit
Stylus is dragged back and forth
across a sample supported in a
holder over a mandrel
Test stops when electrical contact
is made between stylus and
mandrel - # cycles is recorded
Abrasion testing
Inputs
Material type
Film thickness
Applied load
MD / TD
Laminates
Sealant / non-sealant
Output
Cycles to failure
Oriented PET Cast Nylon Ionomer
Oriented Nylon Cast PP EVA/(L)LD
Metallocenes (L)LDPE HDPE
Total tests: > 2300
Total cycles: ~1.2 million (~650 hours)
Abrasion – variability
Considerable sample
to sample variability
Source of variation?
Technique
Material surface
???
Implication: larger
sample sizes needed
to determine
statistical
significance of
results
Abrasion – material ranking
2 mil films / 279 g
Data spans 5 orders
of magnitude
Clear differences
between types of
materials
TD is usually slightly
better than MD
What would we expect?
Abrasion – applied load
Abrasion – applied load
Various film
thicknesses plotted
at a range of applied
loads
Cycles to failure very
sensitive to applied
load
Relationship linear
on log-log plot
Does this point to
an underlying
dependence on
fundamental
material properties?
Abrasion – film thickness
Abrasion – film thickness
Materials shown
were run at various
applied loads
Linear relationship
of cycles to failure
versus film thickness
on a log-log plot
Is slope related to
modulus? Hardness?
COF? Some
combination?
Construct
mathematical
model?
What about laminates?
Laminate abrasion
properties superior
to raw material
abrasion properties!
Does the adhesive
play a role?
Is behavior related
to overall thickness
in some way?
Does the interface
in some way
produce better
abrasion resistance?
Conclusions - Abrasion
Abrasion testing has significant variability
Significant performance differences across material families
Laminate performance not as expected; further investigation required
Other areas of investigation: Extrusion coated structures; Surface treatment effects;
Variability reduction; Effect of slip; Co-extruded films
Mathematical modeling appears to have some promise relating abrasion resistance to basic material properties (for monolayer films)
Puncture properties
Many different test methods within ASTM
Spencer, dart drop, Instron slow puncture
Various puncture speeds (very slow to very fast)
Various tup diameters
Do correlations exist between any two tests?
Which is the most appropriate test? Do we
need this many tests?
Can current test methods be combined and
further standardized?
oPET puncture properties
Film thickness appears to have no effect on the Spencer impact strength of PET
Likely due to surface-initiated fracture properties
Tup geometry not adequately accounted for in Spencer method
Would other materials behave similarly?
Puncture - laminates
No obvious
correlation of raw
film properties to
laminate puncture
performance
Laminates perform
far worse than raw
films alone
Related to energy
transfer across inter-
faces?
Where do we go from here?
Abrasion
Significant work completed; additional work in progress
Puncture
Initial experiments performed; much more needs to be
done in this area
Flex pinholes
Wide open for investigation
Cut resistance
Wide open for investigation
A journey of a thousand miles…
Generate interest across the industry to advance our
understanding of package durability
Create global collaborations across companies and
industries to design and execute the next round of
experiments to build and refine models
Solicit input from other disciplines that might provide
additional skill sets
Contact information
Intrigued? Interested?
Want to get involved?
Contact Henk Blom
630-405-7707
Acknowledgements
Summer interns
Jocelyn Blom
Rachel Blom
Chris Girgis
Lab technician
Amelia Gonzalez