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

# 𝑝𝑖𝑛𝑕𝑜𝑙𝑒𝑠 = 𝑓(𝑚𝑜𝑑𝑢𝑙𝑢𝑠, 𝑖𝑚𝑝𝑎𝑐𝑡 𝑠𝑡𝑟𝑒𝑛𝑔𝑡𝑕, 𝑖𝑚𝑝𝑎𝑐𝑡 𝑠𝑡𝑟𝑒𝑛𝑔𝑡𝑕2)

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

hblom@rollprint.com

630-405-7707

Acknowledgements

Summer interns

Jocelyn Blom

Rachel Blom

Chris Girgis

Lab technician

Amelia Gonzalez