Infrared Microscopy and Microanalyses for hire: Analytical Lab for small companies

Chemical Microanalysis for
Industry
State-of-the-Art Analysis for hire
Medical Device Problem Solving
Polymer Problem Solving
Industrial Problem Solving
Asbestos Analyses
etc., etc., etc.
by
John Donohue
201-294-2581
John Donohue - donohuejjp@gmail.com

Part 1: Introduction to the Technology and Method
Hello. I’m John Donohue and this is the best Infrared Microscope ever made by
any manufacturer:
Nicolet’s IR-Plan Research Microscope
mounted on a Magna 560 Mainbench
This amazing instrument allows my Lab
to obtain the Chemical Identity, via the
Infrared Spectrum, of an area as small
as 10 microns by 10 microns
(10μX10μ). That’s as small as 9 red
blood cells placed in a 3X3 square.

When you can chemically identify
objects that small you can perform such
amazing investigations that they
can often depart completely from the
expected and traditional uses of Infrared
Spectroscopy, as you will see.

John Donohue -

These documents will describe the type
of analyses I perform for Industry and
Publication using this instrument and
the other equipment in my Laboratory.
donohuejjp@gmail.com

My IR-Plan is usually set up with Two Reflachromats:
One For Reflection And Transmission, The Other Dedicated To ATR
More “Specialized Reflachromats” and Visible Light Objectives are available, if needed

Mirrored “Flying Saucer”

Mirrored “Lampshade”

… and Visible Light Objectives for
Visible and Polarized Light Microscopy
John Donohue

Hard Silicon Surface for ATR “Contact” Spectra
- donohuejjp@gmail.com

Microscope Reflection Mode
Lightpath

From Source
To Detector

The Upper Reflachromat objective
projects a conical surface of IR radiation
through the sample. It reflects off the
shiny metal beneath the sample and
follows the same conical surface up
through the sample, back to the
objective, and from there to the detector.

This mode is very fast and easy to
perform. The shiny metal substrate is
usually 0.005 inch aluminum sheet
taped onto a microscope slide. It is cut
from 5 inch by 5 inch sheet that is
cheap and disposable. It can also be
performed on any flat or curved metal
surface such as injection molding tool
surfaces, medical steel cannulas, engine
valves, gun metal, you name it.

Sample
on metal
Shiny Metal Substrate
Shiny Metal Substrate


UNIQUE ADVANTAGES OF THE FTIR MICROSCOPE
How sensitive is it? See arithmetic below.
>The FTIR Microscope increases greatly the utility of FTIR and allows the successful
use of IR in analyses that simply could not be done by a Mainbench alone.
>The Micro - ATR Objective obtains surface spectra (of the top ~micron of material)
with almost no sample prep. This is excellent for thin coatings or surface analysis.
>The FTIR Microscope can obtain useful spectra from extremely thin samples as
small as a 10μ X 10μ Square. The amount of mass providing such a signal can
approach the Detection Limits of GC/MS
>Example - FTIR Microscope’s Limit of Detection is about a 10μ X 10μ Square :
If sample is 1μ thick, 10μ X 10μ X 1μ sample of Polyethylene = how many grams?
1cc of PE = 1g = 10mm X 10mm X 10mm = 1000 cubic mm = 103 mm =>
10mm X 10mm X 10mm = 104 μ X 104 μ X 104 μ = 1012 cubic microns =>

So: 1012 cubic microns = 1g
10μ X 10μ X 1μ =100 cubic microns = 102 cubic microns
102 / 1012 = 10-10 g

So: 10μ X 10μ X 1μ sample of Polyethylene = 0.0000000001 grams of PE

So, the FTIR Microscope can ID 100 trillionths of a gram of PE

Microscope ATR Mode and Lightpath
The ATR Reflachromat objective
projects a conical surface of IR
radiation onto the inside of the ATR
Crystal’s Sample Contact Point. A
small part of the IR radiation
“tunnels” into the sample touching
this Contact Point. Some of it is
absorbed and the rest continues on
to the detector.

From Source
To Detector

This mode is particularly well-suited
to surface analysis (surfaces that are
bioactive, drug eluting, bioresorbable,
coated, “blooming” additives,
lubricious, non-thrombogenic, etc.).
It is also a good choice for highly
absorbing materials that are difficult
to get an IR beam in and out of such as
Black Rubber.

Sample

How Small Can Samples Be?
How small IS the 10μ X 10μ Limit of Detection?


Back of USA Penny
Lincoln
Memorial


Lincoln seated on Penny’s back
This image is 11.2mm X 8.5mm.


Lincoln seated on Penny’s back; mm scale to left
This image is 3.0mm X 2.3mm.


IR-Plan Visible Light 10X Objective view (Glass)
Lincoln’s Head and Shoulders
This image is 550μ X 420μ


IR-Plan IR Objective 15X Reflachromat view: Lincoln’s Head
This is the magnification at which
Knife-edge apertures are used to frame
the area to be analyzed
and FTIR Spectra are obtained.

This image is 390μ x 300μ
Limit of
Detection:
“Lincoln’s “Eye”
10μ X 10μ


Lincoln’s Face on the previous slide is about 140μ X 120μ.
The IR-Plan can obtain good spectra from much smaller
samples than this (see asbestos ribbon, below). The thin
polymer coating on Lincoln’s Face is easily IDd
as Polycarbonate.


Part 2: Asbestos Testing

Asbestos Identification
by IR Microscopy and/or
Polarized Light Microscopy


Friable Asbestos Identification by IR Microscopy of broken cementitious tile:


Zooming in on the Friable Asbestos


Microscopic amount of Asbestos squashed onto aluminum sheet


NOTE: Often Spectra are corrected for humidity in the Laboratory air


The Asbestos sample is Chrysotile


The IR Microscope is so very sensitive that even a 20μ X 65μ area
of a Single “ribbon” of Asbestos is enough for Identification


Asbestos Identification and Quantification
is routinely performed as per
EPA-600-R-93-116 using
Polarized Light Microscopy (PLM)
Examples of PLM in my Labs
Materials Analyses follow


Device Production
Restarted and Defect
Determined and Eliminated
Via Stress Birefringence
Analysis

Crack
Initiation
Point

>These barrels were for “Epinephrine
Pens” needed to counter the threat of
Nerve Gas and thus keep Saudi Arabia
from backing down to Iraq in the Gulf
War. This allowed the USA to Stage
the invasion of Kuwait.
>The barrels were breaking 100% upon
ejection from mold with undercut.
>Defect invisible until Crossed Polarizers
revealed “Knit Line” pointing to
Crack Initiation Point.
>The molten plastic was too cool when
It came squeezing around the Core Pin
for the two advancing Melt Fronts to
melt together adequately.

>I told Manufacturer to increase
Zone Temperatures by 30 degrees C
and Ejection Breakage ceased.
... and that’s how I won the war.

Injection Molding

Morphology and Physical Properties
Polypropylene Syringe Wall Cross Section
Control of Cooling Rate is a major parameter
in Determining Morphology and Properties
This type of work was very important in the
implementation of Clear Polypropylene Devices
using Milliken Clarifying Agents that have the
undesirable effect of increasing the brittleness
of Polypropylene.

Polypropylene Syringe Gate Cross Section
Control of Rheology is a major parameter
in Determining Morphology and Properties
This type of work was also very important in
the implementation of Radiation Sterilization
which also has the undesirable effect of
increasing the brittleness of Polypropylene.


Part 3: Application to Medical Device issues

Solving Medical Device problems using
IR Microscopy
Visible Microscopy


ATR Spectra of Surface of IR-Opaque Rubber

0.15
0.10
0.05

Silicone Lubricated Gasket

Abs orbanc e

0.00
-0.05
-0.10

Less Silicone After Surface Scraped

-0.15
-0.20
-0.25

No Silicone After Acetone Wash:
Silicate-filled rubber polymer

-0.30
3500

3000


2500

2000
Wavenumbers (cm-1)

1500

1000

The Technology of a Needle Point
2.3mm x 3.0mm Photos of an Insulin Needle Point

What can we learn with a fast analysis?

420μ x 550μ Photos of Needle’s three cut planes

The “subtle” cut

IR-PLAN 550μ X 420μ FOV of Point and Enhanced Image

Raw Image Obtained

Digital Enhanced Image

A “Metal Burr” is visible
on this needle point.

Infrared Microscopy Provides Chemical Identification that shows
Gelled Lubricant is used on Hypodermic Needles
3.0mm x 2.3mm

390μ x 300μ

0.012
0.011
0.010
0.009
0.008

Absorbance

0.007
0.006
0.005

Gel is Silicone

0.004
0.003
0.002
0.001
-0.000
3500

550μ X 420μ

3000


2500

2000
Wavenumbers (cm-1)

1500

1000

Engineering Resins: ESCR vs “Hoop Stress Failures”
Polyetherimide (PEI) Stopcock Outerbody resists splitting caused by fatty Feeding
Liquids but costs more than Polycarbonate (PC) (which is cracked by combination of
fats and stress). Stopcock InnerBody is pressed into Outerbody and this strong PEI
polymer can still crack if it can’t stretch enough under this “Hoop Stress”
tensile load (vs PC which is very stiff but also very TOUGH/RUBBERY).

Hoop Stress cracking

8.5mm X 11.2mm

PET Barrels That Failed At Gate
A “Cold Slug” in an Injection Molding “Gate”
can initiate breakage at unacceptably low force


Devices broke due to “Cold Slug” in Injection Molding Gate
Gate A

Ridge/Valley

Cold Slugs
Blade Striations


Gate B

Identification of PET Barrel Skirt
Contaminant by Micro-FTIR


Smudges on PET at Tip Insert of Barrels
Parting Line


PET Barrel Skirt Bloom removed for analysis
Pre-Extracted Cellulose on PET Skirt

Same Area of PET Skirt After Wiping

Cellulose

Grease about
to be removed

Streaks where Grease
was removed


PET Barrel Skirt Contaminant is Same as Found previously
The Difference Seen below is Cellulose from the Kimwipe.
The Grease is an Acid (1712 cm-1) and an Ester (1737 cm-1).
0.45

5.S il icone B B L Lube A TR,B radmons
K i mw iped B loom in P E T B B L skirt,G ri ffith,RE FL32

0.40

P E T B B L ski rt grease,K imWi ped& MC d,Castro,RE FL32,2/27/09
120a2209,MICR,CE LLU LOS E ,A CCU W IP E /A L,2/244

0.35
0.30
0.25
0.20
0.15

Log(1/ R)

0.10
0.05

Grease Found Recently

0.00
-0.05
-0.10
-0.15

Grease Found Previously

-0.20
-0.25

Cellulose

-0.30
-0.35

Silicone

-0.40
4000

3500

3000

2500

2000

Wavenumbers (c m-1)


1500

1000

Part 4: Nailing the Answer and Preventing a Recall
An unusually profitable Bioresorbable Implant with a brilliant Market-dominating future had its
Market Launch endangered by the occurrence of foreign matter inside the tiny molded
PolyLactide:Glycolide implant. A CERTAIN fix was required immediately: the cause had to be
IDd with certainty and eliminated.
Many Hypotheses were proposed:
>The Resin Supplier suggested that Residual Monomer was boiling
during molding. Extensive testing of residual monomer levels in
retained lot samples vs amount of bubbles found from molding those
lots was proposed.

Flow
Direction

>Molding Engineers suggested that the bubbles were: Shrink Voids,
Entrapped Air, Entrapped Condensation, Etc. Humidity archives were
to be examined and production areas were to be desiccated.
>”Shotgun Experiments” were about to be fired in every direction.

Instead a “RIFLE BULLET” EXPERIMENT was aimed right at the bubbles themselves.

>Contaminant was Bubbles Inflated while Flowing  “COMET”.
>Cut thin Cross-sections of the polymer through the Bubbles.
>Micro-FTIR repeatedly found a single deposit of Secondary Amide
localized in a small area on each Bubble’s inner surface.

When a thin slice of the Part, containing the Bubble, was shaved off,
the Hole in the shaving had a tiny region on its circumference
that was Hazy Translucent while the rest of the circumference and
of the part’s shaving was Clear Translucent
Clear translucent polymer slice

Hazy Translucent
Area on border of
Bubble

Cross-section of Bubble


“Zooming in” on Hazy deposit on Bubble’s circumference
Increases the Secondary Amide Absorbance Peaks relative to the PLG’S...
3.4
3.2

PLG

FTIR Microscopy

3.0
2.8

PLG

2.6
2.4

Absorbance

2.2
1648

2.0

3288

1.8

1534
3060

1.6
1.4
1.2
1.0
0.8

Zooming in

0.6
0.4
0.2
4000

3500

3000

2500
2000
Wavenumbers (cm-1)

1500

1000

...therefore the hazy area is a Secondary Amide

Three Amide deposits on Aluminum with PLG dissolved away.
Two Amide deposits squashed onto Aluminum.
Amide

Amide

Methylene Chloride removed
most of the PLG

4.0
3.5
3.0

Absorbance

2.5
2.0
1.5
1.0

Squashed onto Aluminum

0.5
0.0

Squashed onto Aluminum

-0.5
-1.0
4000

3500

3000

2500
2000
Wavenumbers (cm-1)

1500

1000

... so what is this Secondary Amide and what is it doing?

... so what is this Secondary Amide
and what did it do?

Synergistic Use of

FTIR Microscope
and
Gas Chromatograph / Mass Spectrometer
The two most powerful instruments
In Analytical Chemistry


The SIS Thermal Desorber
A Heated Inlet for GC/MS

sold by Scientific Instrument Services

Carrier Gas Flowpath to Mass Spec Detector
Pure He flowing through
glass lined steel tube
that contains sample.

Tube is injected into
GC Inlet and heated.

Volatiles separate on
column and are analyzed
by the MS.


Excised tiny intact Bubbles melted in THDSB
pop and release CO2 (and NOT O2 or N2)
PLG Hydrolysis in heated tube releases Lactide and Glycolide


Hydrolysis of PLG: The Chemistry Occurring
The moisture in the amide flakes
forms steam during injection
molding, inflating the bubbles.
The steam is consumed as it
hydrolyzes the PLG, filling the
bubbles with CO2.


as per Dr. C. C. Chu of Cornell

Spectral changes of PLG hydrolyzed on Hotplate

Carbonyl and Hydroxyl orbitals
are formed as the controls
hydrolyze on the hotplate.


Spectral changes of PLG vs proximity to amide deposit

The concentration of the same Carbonyl
and Hydroxyl orbitals is seen to increase
with increasing proximity to the bubbles
formed by the amide flakes. This large
gradient in concentration occurs across
a microscopic range of distance from the
bubbles’ walls.
It is in analyses like this one that the
FTIR Microscope is the very best tool
there is. No other instrument could
do this work: easy and exact spatial
localization of a chemical identification.


Preventing Recall - Conclusion
>Skin Flakes boiled off their water, inflating the “comets”
>As this steam inflated the PLG, it was immediately consumed by the PLG’s
Hydrolysis Reaction

>Hydrolyzing PLG emits CO2, the gas remaining inside the “comets” that was
detected by GC/MS as the “comets” melted and popped
>Hydrolyzing PLG on a hot plate using drops of water  Darkened spots ranging
from light brown to nearly black
>FTIR spectra of these darkened regions peaks appearing near 1730 cm-1 and
1620 cm-1
>FTIR spectra obtained from microscopic regions as the area examined approached
the hydrolyzed circumference of the “comet” slices  peaks appearing near 1730
cm-1 and 1620 cm-1
>The polymer pellets were protected against any further contamination by skin
flakes, there was no further problem with “comets”, the product launch was
continued, and the implant dominated its market  One Billion $ in $ales per year


Ending $100MM/yr Device Factory Shutdown
caused by “wrinkled” Injection Molded Parts
A $100MM per year device factory was shutdown because Injection
Molded parts were slightly wrinkled. No one was going to make any
money until the problem was fixed.
Possible causes that were proposed for investigation:
>Electrical supply fluctuations
>Cooling Water Heat Transfer fluctuations
>Press Horsepower fluctuations
Many “Shotgun Experiments” were about to begin with no expense to be spared

--- BUT -->The Polypropylene (PP) Resin was supposed to contain Sodium Benzoate (NaBZT), an
additive that makes the Polymer solidify at a higher temperature (faster) than normal.
>This fact suggested that the best place to look for the cause was in the PP pellets
themselves.
>I developed an Infrared analytical method that measured very quickly the NaBZT
concentrations of large numbers of individual pellet.


Plant Shutdown Ended
“Wrinkled” Injection Molded Parts caused by Resin Supplier’s Error
Analytical Method developed
to measure RAPIDLY the
Concentration of individual pellets
proving Bimodal Distribution

>The Resin Supplier by mistake had added
different pellets to the Finished Material:
pellets that contained a significantly higher
concentration of NaBZT than the correct
pellets. These wrong pellets were dumped
into the Railcar on top of the correct Resin.

FREQ

Most Pellets had
Right NaBZT amount

...but some had too much

>The resulting mixed resins received only the
little bit of blending that occurred during
transport from the Railcar to the Silo and
then to the Hoppers.
>The Parts wrinkled because the varying NaBZT
concentrations caused varying degrees of
Shrinking and Packing during molding.

NaBZT Concentration
This is one example of when to use the FTIR Mainbench instead of the Microscope:
When you want to analyze as large of an area as possible per each scan.

Part 5: Special Applications
FTIR Microscopy can do a lot more
than the simple chemical
identification of contaminants.

> It can determine the physical morphology of polymers.
> It can measure the oxidative degradation caused by
radiation sterilization (dosimetry).

> It can measure the hardness of PVCs, Polyurethanes,
and numerous other Thermoplastic Elastomers

> It can measure the Butadiene or Styrene content of Styrenics

Measuring Changes in Crystallinity:
PET Tube Turned Opaque White

Customer complained that PET catheter was opaque white instead of clear
BUT
Had the customer accidently left this catheter in a hot Autoclave overnight?

Polyethylene Terephthalate Crystal Structure


The Mettler Hotstage
Remove the glass window and insert a strip of aluminum sheet or a thin, “homemade” KBr “poker chip”.
Then you can obtain spectra while heating the sample.


Spectral Differences Between Clear And Hazy PET Tubes
Crystallinity Peaks marked in Hazy Return
Full
Spectrum

zoom in

The hazy (opaque white)
catheter had spectral
differences when
compared to the clear
catheter (crystallinity peaks
are shown at right)

Proof that Spectral Differences Between Clear and Hazy Tubes
are due to Crystallinity
The Spectra of the clear tube when
it is molten at 260C is the same as
when it is quenched from the melt
by Liquid Nitrogen.
BUT when it is quenched from the
melt by Boiling it in Water, it
anneals and grows crystals.
Crystallized in Boiling Water
When the clear tube was quenched
from the melt by Boiling it in Water,
it crystallized, turning white like the
Customer’s Hazy returned tube.
Crystallized in Boiling Water
Crystallized by Customer’s
Unknown Method


Proof that White catheter has hydrolyzed to Lower Molecular Weight
When the Clear tube, a PET control
sample, and the Hazy PET were
melted and then instantly quenched
from the melt in Liquid Nitrogen, the
Hazy sample has already Crystallized.
and the Clear tube sample has not.
The Hazy PET crystallizes much more
readily because it has Hydrolyzed to
a Lower Molecular Weight.

When the clear tube is melted and
kept (quenched) in ambient air for
4 seconds or 10 seconds before being
quenched in Liquid Nitrogen,
NO crystallization begins after the 4
seconds in air and only a tiny amount
after the 10 seconds in air.

The Hazy PET crystallizes much more readily because it has Hydrolyzed to a Lower Molecular Weight.
The Customer probably left the catheter in a hot Autoclave overnight.

Part 6: Radiation Sterilization Issues

Effects of Radiation
and Accelerated Aging


Radiation Increases PVC Blooming
Of Cytotoxic DEHP Plasticizer
The bloom visible on this catheter
was analyzed both by contacting
its surface with the ATR Objective
and by smearing the bloom onto
aluminum sheet and analyzing
the smear by Reflectance.
The smear shows only the DEHP
while the ATR sees both the
DEHP and the PVC catheter.

ATR Spectrum

Reflection from smear
on aluminum sheet

Radiation Generates Free Radicals in Polypropylene


Free Radicals Generate Carbonyl Groups in Polymers


Test Method Development
Decreased Ductility Can Cause Devices To Break During Use.
Radiation may increase the force to strain the device, but the strain
at break decreases. Devices seldom fail because they’re too stiff.
They fail because they break.
A Syringe barrel wall may be unbreakable
during use despite receiving the highest
radiation dose allowed. Syringe tips may
be much more fragile. Customer complaint
history and product history may indicate
what areas of a product are areas of concern;
what are the products’ weakest links. It is
these modes of failure that must be tested.
Testing must mimic the mode of failure
expected during customer use. Breakage
tests must be performed at a speed of
deformation similar to that experienced
by the product during customer use.
Testing samples subjected to Accelerated
Aging will provide data quickly that predicts
the future behavior of products. The Test
Protocols will define the Accelerated Aging
to be used.

Measuring Radiation Damage using Micro-FTIR
Mounting Aluminum Sheet On 3X2 Glass Slide


Shavings off Polypropylene Barrel’s Surface Analyzed Herein:
Shavings Obtained with Razor Blade


Close-ups of Polypropylene Shavings Analyzed Herein


Same Polypropylene Film Before and After 40 kGYs of Cobalt Radiation
Blue is after
2.0
1.8

1.6

Absorbance

1.4

1.2
1.0

0.8
0.6

0.4
0.2
4000

3500

3000

2500
2000
Wavenumbers (cm-1)


1500

1000

Blue is after
0.70
0.65
0.60
0.55

Absorbance

0.50
0.45

Hydroperoxides

Carbonyls

0.40
0.35
0.30
0.25
0.20
0.15
0.10
4000

3500

3000
2500
Wavenumbers (cm-1)


2000

Blue is after
0.26

Scissioned Polymer Chains Oxidize

0.24
0.22

Absorbance

0.20
0.18
0.16
0.14
0.12
0.10
0.08
2000

1900

1800
1700
Wavenumbers (cm-1)


1600

IR Spectrum Shows Radiation Induced Oxidation of Polypropylene

as per J. Donohue MDDI


Polypropylene Oxidation from 20 and 40 kGYs of Cobalt Radiation


The “Dark Reaction” of Irradiated Polypropylene
Oxidative Degradation Continues Long After Irradiation Has Ceased
This is the Reaction that is Accelerated by Accelerated Aging


Dr. Apostolou and I “wrote the book” on Accelerated Aging Methods that work


Oxygen Can More Easily Penetrate and React
with the Polymer in a Thin Film


This Post Rad Oxidation is Not Just Peroxide Scissions.
Ambient Oxygen Continues to React with the Polymer.
This is Proven by this Vacuum Oven Aging.


Polyethylene Undergoes Similar Oxidation
when Irradiated with 20 and 40 kGYs


A Carbonyl Index Can be Defined to Measure this Oxidation


Statistical Results for Micro-FTIR Dosimetry of Gamma vs Control
The Micro-FTIR Method is Accurate, Precise, and Robust


Radiation Damage (= Dose) Measured for Thin Surface
Shavings of Sterilized Polypropylene Medical Devices

Shavings of samples with 3.5 Mrads

0.30

Shavings of sterile product

Area of C=O
Absorbance
0.20
divided by X
(Carbonyl Index)

Shavings of underdosed product

Shavings of samples with 0 Mrads

0.10

0.00

0.00

0.10

0.20

0.30

0.40

X = Thickness of slice (area of 1304 cm-1 Absorbance)
FTIR Microscopy can determine a competitor’s dose or detect underdosed non-sterile devices.

Stability of Fina Syndiotactic and Isotactic
Polypropylenes to Cobalt Radiation
and Accelerated Aging


Ziegler-Natta and Metallocene Catalysts

Controlled Orientation of Monomer Approach To Active Site
Yields Controlled Stereoregularity of Polymer Chain Formed.
For Z-Ns, Solid Catalysts Control Approach to Active Site.
For Metallocenes, Molecular Structure Controls Approach.

Free Radical Degradation of Isotactic Polypropylene
Stereostructure of
Isotactic Polypropylene

Hydroperoxide Formation
by “Backbiting” Oxidation

Strings of Close, Unstable,
Pendant Hydroperoxides


Isotactic Polypropylene Before and After 38 kGy & 17 Days @ 70 C
The Isotactic Polymer is extensively Oxidized by Irradiation.
It sizzles like bacon when it is melted.
1.8
1.6

Absorbance

1.4

1.2
1.0

Hydroperoxides

Carbonyls

0.8

0.6
0.4

0.2
4000

3500

3000

2500
2000
Wavenumbers (cm-1)


1500

1000

Syndiotactic Polypropylene Before and After 38 kGy & 17 Days @ 70 C
The Syndiotactic Polymer exhibits very little Rad-induced Oxidation
2.0
1.8

1.6

Absorbance

1.4

1.2

1.0

0.8
0.6

0.4

0.2
4000

3500

3000

2500
2000
Wavenumbers (cm-1)


1500

1000

IPP & SPP: 38 kGy & 70 C Aging Study
Accelerated Aging Increases IPP Oxidation
but has Very Little Effect on SPP
0.24

0.22

IPP @ 70 C: 17 Days
88 Hrs
16 Hrs
0 Hrs

0.20

Absorbance

0.18

SPP @ 70 C:
0 to 17 Days

0.16

0.14

0.12

IPP 0 Dose
SPP 0 Dose

0.10

0.08

2000

1900

1800
1700
Wavenumbers (cm-1)


1600

IPP & SPP: 38 kGy & 40 C Aging Study
Accelerated Aging Increases IPP Oxidation
but has Very Little Effect on SPP
0.24

0.22

IPP @ 40 C: 17 Days
88 Hrs
16 Hrs
0 Hrs

0.20

Absorbance

0.18

SPP @ 40 C:
0 to 17 Days

0.16

0.14

IPP 0 Dose

0.12

SPP 0 Dose

0.10

0.08
2000

1900

1800
Wavenumbers (cm-1)


1700

1600

Carrier Gas Flowpath to Mass Spec Detector

Pure He flowing through
glass lined steel tube
that contains sample.
Tube is injected into
GC Inlet and heated.

Volatiles separate on
column and are analyzed
by the MS.


THDSB/GC/MS Analyses
of Post-Rad Volatiles

Radiation Sterilized
Syndiotactic Polypropylene
Generates an Order of
Magnitude Less Volatiles
than an Equal Mass of
Irradiated Isotactic Polypropylene


CO2
acetaldehyde

THDSB/GC/MS IDENTIFICATION
OF IPP POST-RAD VOLATILES

acetone
acetic acid

Heated Irradiated Isotactic Polypropylene Degrades
into Volatiles Based on C-C-O Units that Reveal the
Chemical Mechanisms of its Oxidation

2,4-dimethylfuran
acetoacetone
cyclopropylacetone

4-hydroxy4-methylpentanone
allylacetone
acetic anhydride
3,5,5-trimethylfuranone

The Close, Unstable, Pendant Hydroperoxides Explode Like a String of Firecrackers

THDSB/GC/IR Analyses of Post-Rad Volatiles
Thermally Degraded Post Rad Isotactic Polypropylene
Emits Low Mass Scission Products Based on C-C-O Units …
Air & Water
Desorbed Out
Of Tube
Acetone
Acetic Acid

… Because Similar Oxidized Structures Degrade into Similar Volatiles

THDSB/GC/FTIR Analyses of Post-Rad Volatiles
Thermally Degraded Post Rad Syndiotactic Polypropylene
Emits a Far More Random Mix of Scission Products …
Air & Water
Desorbed Out
Of Tube
2-Hydroxy-Propionic Acid
3-Methyl-2,4-Pentanediol

4-Butyl-Gamma-Octanolactone

… Because a More Random Dispersion of Oxidized Structures Yields
a More Random Mix of Volatile Degradation Products

John Donohue donohuejjp@gmail.com

Part 7: Additives; their Analysis and Issues
Phenolic Antioxidants Protect Against Radiation Damage by
Scavenging the Free Radicals Formed in the Polymer by Radiation


But Phenolic Antioxidants Turn Plastic Yellow When Irradiated


Hindered Amine Light Stabilizers Form Cytotoxic Hydroxylamines
as they Protect the Polymer from Radiation Damage
Without Discoloration


Millad 3988 Clarifies Polypropylene
Molding Heat Causes Hydrolysis, Releasing Benzaldehyde Derivatives
This Causes the Polymer to Emit a “Cherry Candy” Smell
Millad makes Polypropylene more brittle


Clarified Polypropylene Crystallized at 130 C from the Melt
Nucleation Determines Morphology
Not Clarified

Clarified

Millad prevents
Spherulite growth

Polypropylene Spherulites grow

Sublimation depletes Boundary of Millad


Millad Forms Thermally Unstable Precipitate if it is Overheated During
Injection Molding. Precipitate’s Sizzling Decomposition into Gaseous,
Superheated Aldehyde Strips Char out of Molding Press and Into Molded Parts.
Heated excised precipitate chunks undergoing thermal decomposition on Hotplate


Sizzling Decomposition into Aldehyde and Arylate
>Tiny orange spots were
scattered across the
Polypropylene matrix
>Any attempt to get the spectrum
of more than one orange spot at
a time yielded only a spectrum
of the Polypropylene matrix
>But the IR-Plan can can zoom in
on a single tiny orange spot to
yield the Arylate spectrum
shown …

… and Thermal Desorption of the
degrading material into the
GC/MS can show the formation
of the Aldehydes and Alcohol
Intermediates.

Thermal Decomposition of Precipitate Forms Aldehyde.
Cannizzaro Reaction of Aldehydes Forms Acid and Alcohol.
Condensation of Acid and Alcohol Forms Arylate.

Arylate Forms The Orange Spots

Thin Layer Chromatography (TLC) can Separate Chemical Mixtures that the
GC/MS can’t: Chemicals that are non-Volatile or Thermally Unstable

Liquid carries chemicals Johnspot of donohuejjp@gmail.com plate, separating them
in Donohue - extract up the

Under Visible Light

>TLC is done on a Plate Covered with
Fluorescent Silica
>UV Light makes the Separated
Chemicals from the Mixture
Visible
>The Regions of Silica Containing
these Chemicals are scraped off
the plate, separated from the Silica,
and Identified using the Analytical
Instrumentation

After Scraping

Under UV Light


Part 8: Tricks of the Trade

Measuring Durometer of FINISHED (competitive) Devices:
FTIR of DEHP Plasticized PVC Device vs Pure PVC
4.5

4.0

3.5

Absorbance

3.0

2.5

2.0

1.5

1.0

0.5
0.0
4000

Pure PVC
3500

3000

2500
2000
Wavenumbers (cm-1)

1500

1000


FINISHED Device: Measuring Plasticized PVC Durometer
2.2

Higher
PVC
conc.

2.0
1.8

Hard Endotracheal Tube

1.6
1.4

Absorbance

1.2
1.0

Soft Nasogastric Tube

0.8
0.6
0.4

DEHP

0.2
0.0
-0.2

PVC

-0.4
1600

1550

1500
Wavenumbers (cm-1)

1450

Spectra “normalized” for equal plasticizer (DEHP) content show
that the harder PVC has a higher PVC to Plasticizer Ratio
Such a test can tell the Durometer used by a Competitor

Reverse engineering competitive catheters
Micro-FTIR Spectrum of Pellethane
1.1
1.0
0.9
0.8

Absorbance

0.7
0.6
0.5
0.4
0.3
0.2
0.1
0.0
4000

3500

3000

2500
2000
Wavenumbers (cm-1)

1500

1000

zoom in here next slide

Micro-FTIR ID: FINISHED Device Pellethane Durometer
0.60

>Many catheters have tips made from a softer grade
material than the shaft.

0.55
0.50

>FTIR can measure the Durometer of finished
Polyurethane devices quickly and easily

Absorbance

0.45

>Multiple runs below show that the method is robust

0.40

80A

0.35
0.30

90A

0.25
0.20

75D

0.15
1420

1400

1380
Wavenumbers (cm-1)


1360

Micro-FTIR Spectrum of Tecothane

1.6

1.4

Absorbance

1.2

1.0

0.8

0.6

0.4

0.2

4000

3500

3000

2500
2000
Wavenumbers (cm-1)

1500

1000


Micro-FTIR ID: FINISHED Device Tecothane Durometer

0.18

0.16

74A
Absorbance

0.14

0.12

85A

0.10

0.08

0.06

55D

0.04

75D

0.02
1420

1400

1380
Wavenumbers (cm-1)


1360

Micro-FTIR Spectrum of Tecoflex with 20% BaSO4
0.80
0.75
0.70
0.65
0.60

Absorbance

0.55
0.50
0.45
0.40
0.35
0.30
0.25
0.20
0.15
0.10
0.05
4000

3500

3000

2500
2000
Wavenumbers (cm-1)

1500

1000


Micro-FTIR ID: FINISHED Device Tecoflex Durometer
NOTE:
This method is more accurate than the
manufacturer’s ability to control or measure
their Durometer. The Hardness Pucks that
were supplied by the manufacturer (after
measuring Durometer with a Hardness Tester)
and were supposed to be 60 D were instead
HARDER than the supposed 65 D pucks.

1.2

80 A
1.1
1.0
0.9

85 A

Absorbance

0.8
0.7
0.6

100 A

0.5
0.4

60 D
65 D

0.3
0.2
0.1
1400

1380

1360

1340
Wavenumbers (cm-1)


1320

1300

FTIR Shows Why High-Gloss ABS Has Less ESCR Than Low-Gloss ABS

LOW-GLOSS ABS
RESISTS CRACKING

HIGH-GLOSS
ABS CRACKS

More Styrene/Butadiene Rubber dispersed in the Acrylonitrile matrix
yields High Gloss ABS with less resistance to Environmental Stress Cracking

Packaging Materials
>There are a lot of “Tricks of the Trade” in Materials Analysis.
>For example, Most packaging films are laminates with outer
heat-sealable plies and an inner strength ply.
>The FTIR Microscope requires Liquid Nitrogen (LN2) to operate
and this LN2 can be used to cryo-fracture materials.
>Cryo-fractured laminated films can be separated easily into their
individual plies for material identification and also for accurate
thickness measurements free from thickness artifacts caused by
cutting techniques that can decrease the measured thicknesses.


Device package bottom web was
cryo-fractured with liquid N2 and
the heat seal ply was stretched over
aluminum sheet.
The film contains K-Resin…

…and the stretched Heat Seal Ply is EVA


cryo-fractured with liquid N2 and
the protruding and overhanging
plys show a Surlyn center ply
sandwiched in EVA heat seal plys.

Surlyn center ply
protruding from
fractured laminated
film

Surlyn ply and EVA heat
seal ply together

cryofractured with liquid N2 and
this two ply film separated into
a K Resin ply and a more flexible
EVA heat seal ply.

K Resin ply is stiffer

EVA heat seal ply

Part 9: UV Adhesives and the Chemical Fragility of Polycarbonate

Chemical Degradation of Polycarbonate
by Dymax Adhesive
Analysis of White Stain inside Cured Part


ABSTRACT
>Polycarbonate (PC) has poor resistance to attack by a large number of chemicals.
>Chemicals that “plasticize” PC cause problems that include clouding, warping,
crazing, cracking, breaking, falling apart, etc. For example, Formula 409 contains
about 10% “grease cutter” and will quickly destroy PC; especially when the PC has
a relatively low Molecular Weight and/or lots of molded-in-stress pulling it apart.
>Chemicals that are “Bases” (electron donators) catalyze the polymerization of PC
and therefore can also catalyze the reverse reaction, depolymerizing PC into
oligomers of Bisphenol A (BPA) monomer or the BPA monomer itself. For
example, Amines famously do this to PC.
>A major ingredient of the Dymax adhesive is N,N-Dimethylacrylamide (a base). It
is well-known that many adhesives will attack PC if they are in contact with it too
long prior to being cured. This chemical is one of the reasons for this. When the
adhesive is completely cured, this chemical is completely consumed (this fact is
demonstrated using the spectra herein).
>The white stain on the PC in contact with the “cone” of adhesive is partially
depolymerized PC. Its FTIR spectra show the presence of both PC and the
endgroups (that appear as BPA and its oligomers) are formed from the scissioning
of PC. The adhesive must be quickly and fully cured to prevent this.
>The side of the adhesive cone that was peeled free from the PC is coated with
a thin shattered film of PC. The side that was in contact with the Polyurethane
(PUR) is coated with the PUR. Thus, the adhesive is tougher and more tenacious
than either polymer.

What Happened to the Polycarbonate?


White Stain Seen Through the PC Wall Prior to Dissection
White Stain is Connected to the PC


White Stain Remains on PC After Adhesive is Peeled Back
Polycarbonate

Polycarbonate

Peeled-back
Dymax Adhesive


White Stain Remains on PC

Higher Magnification

Polycarbonate


Polycarbonate

White Stain Remains on PC


The White Stain is Partially Depolymerized Polycarbonate so FTIR shows that
it contains Absorptions for PC, Oligomers, and BPA Monomer

Polycarbonate

White Stain

Bisphenol A

The Surface of the Adhesive that was against the PC is encased
in a thin shattered PC Film that again contains Oligomers and BPA


Polycarbonate

Thin Shattered Film on Adhesive that was against the
PC contains Polycarbonate, BPA, and Oligomers

BPA

The other side of the adhesive was against the
Polyurethane and it is encased in that Polyurethane

Polyurethane Tube


What Chemical(s) Attacked
the Polycarbonate?


DYMAX Disclosed 5 Components of this Adhesive

N
O

Reactive Diluents

O

Amide

O
Isobornyl Acrylate

N,N-Dimethylacrylamide

Ketone

Photoinitiators

HO

O

Irgacure 184

HO

O

Darocur 1173

These 4 are All Ketones and one is also an Amide. Ketones can Craze and Crack
Polycarbonate and Amides can Depolymerize it to Bisphenol A.


Adhesive’s Spectrum Pre and Post Polymerization by UV
Double Bond at 1612 cm-1 Completely Consumed by Polymerization
Double Bond

Pre-UV Adhesive

Post-UV Adhesive

Adhesive Taken Off Device

N, N, Dimethylacrylamide’s Double Bond is Consumed during the Polymerization
The Two Carbons Become Part of the Cured Adhesive’s “Backbone”
The Absorption Disappears as the Adhesive Cures
This Chemical Attacks the Polycarbonate

Double Bond @ 1614 cm-1


The Isobornyl Acrylate’s Double Bond is also Consumed by the Polymerization

Double Bond


Part 10: Drug Eluting Heart Stent Coatings

Drug Eluting Coronary Stent Coatings


Angioplasty and Stenting are Competitive Procedures
Divergent processes of vascular repair after balloon angioplasty
and stenting of an atherosclerotic vessel

Edelman, E. R. et al. Circulation 1996;94:1199-1202

Copyright ©1996 American Heart Association


Edelman, E. R. et al. Circulation 1996;94:1199-1202
Divergent processes of vascular repair after balloon angioplasty and
stenting of an atherosclerotic vessel. Balloon angioplasty (top) compresses
and fractures the atherosclerotic plaque (light gray) and tunica media
(black), slightly enlarging the artery. After a few days, a thin layer of
platelet-rich thrombus (dark gray) lines the lumen and fills the dissection
plane. The lumen shrinks from combined effects of early elastic recoil and
later formation of a fibrocellular neointima (speckled area). Stent
deployment after angioplasty (bottom) compresses the dissection plane
and enlarges the lumen while stretching the artery with minimal elastic
recoil. Within hours to days after stenting, caps of thrombus infiltrated with
inflammatory cells (dark gray) form over stent struts (black rectangles),
particularly abundant at sites of deep injury. Over ensuing weeks, a
neointima forms (speckled area), thicker where injury is more severe.
Although intimal growth after stenting is greater than after balloon
angioplasty, the residual lumen is also larger, as the scaffolding of the stent
maintains luminal dimensions. Late changes in arterial size are not depicted
because the contribution of remodeling to restenosis after angioplasty or
stenting remains incompletely characterized.
(Figure prepared by James Squire.)

Stents scrape blood vessel walls. This injury causes reblockage.

Edelman and Squire

Stents scrape blood vessel walls

Edelman and Squire

Drug Eluting Coated Stent

3.0mm X 2.3mm


420μ X 550μ

300μ X 390μ

A Different Manufacturer’s

3.0mm X 2.3mm

A Different Manufacturer’s

420μ X 550μ

300μ X 390μ

Phosphatidyl Choline (PC)
coating, invented by
Biocompatibles, Ltd., used
on some Medtronic and
Abbott Drug Eluting
Coronary Stents.
Spectra of coatings obtained
off the actual stent surfaces
show the PC coating and the
anti-restenosis drug it elutes.

All drug was extracted from
the Abbott stent but PC
coating remains.
IR Spectrum of PC 1036 from Biomaterials 21 (2000) 1847-1859


IR Spectra of pure PC, PC 1036, Medtronic Stent Coating, and
Abbott Stent Coating








The Pure PC’s IR shows most of the vibrations present in the PC 1036 coating.
The PC 1036 IR was published back when Biocompatibles, Ltd. was trying to
“drum up” big company interest in their materials. *This particular spectrum is
slightly distorted (an “enlarged” 1090 vibration) because it is a surface spectrum
(obtained via ATR) of a PC polymer in which the hydrophilic PC moieties have
been rotated preferentially to the surface by contact with water. The 1090 is the
C-O-P stretching vibration.]
The Medtronic (Endeavor™) and Abbott (BiodivYsio™) stent coating spectra
were obtained by reflection off the stents’ surfaces.
The stent coatings are excellent matches to the spectrum of PC 1036. Since this
is the coating Biocompatibles, Ltd. developed for the BiodivYsio stent, I believe
it is the PC coating on the Medtronic and Abbott stents. EDAX can be run using
the SEM to see if silicon is detected from the PC 1036 TSMA component. The
literature published by Biocompatibles, Ltd. suggests a TSMA content of 3 to 5%.
At this loading EDAX should detect the silicon.


PC 1036 Biocompatibles, Ltd.
Biocompatibles, Ltd. developed the PC-coated
BiodivYsio™ stent and marketed a number of PC
polymers. One of these polymers, PC1036, appears
to be the PC coating on the BiodivYsio stent,
now a product of Abbott. It also appears to be
the coating Abbott has licensed to Medtronic for
the Endeavor stent.

PC 1036 is made using the four acrylic monomers
shown here.
>2-methacryloyloxyethyl phosphorylcholine (MPC)
>lauryl methacrylate (LMA)
>hydroxypropyl methacrylate (HPMA)
>3-trimethoxysilylpropyl methacrylate (TSMA)
MPC supplies the PC functionality to the polymer.
LMA helps the polymer adhere to metal surfaces.
TSMA makes the polymer crosslinkable, which
improves its adhesion and cohesion and helps control
its rate of drug elution.
HPMA is a co-crosslinker that, used with TSMA at 25%
loading, gave good mechanical properties.
AIBN (azoisobutyronitrile) initiates polymerization.
John Donohue - donohuejjp@gmail.comBiocompatibles,

Ltd. paper

TSMA Hydrolysis initiates the Crosslinking of the Coating
The Drug Elution Rate is determined mainly by the extent of crosslinking.
The hydroxy groups of the HPMA moiety will crosslink with TSMA also.

Biocompatibles, Ltd. paper

Part 11: Particulate Identification


Cardboard-Colored Cellulose
Organic Coating on one side


Part 12: Fish Hooks, “Bait”, and Electronics
After storage in an airtight container for more
Biodegradation of an Insect
This insect
died of
natural causes
in the spring
of 2006.

than one year, webbing is growing on it.

(No insect’s
were harmed
in the
making of
this document)

All 8.5mm X 11.2mm

Webbing at Eye
8.5mm X 11.2mm

2.3mm X 3.0mm


Views of Webbing
8.5mm X 11.2mm


550u X 420u FOVs

Spectra of Webbing on Aluminum Sheet …

1.3

Webbing placed on sheet

1.2
1.1
1.0
0.9

Abs orbanc e

0.8
0.7
0.6
0.5
0.4
0.3
0.2

Webbing squashed on sheet

0.1
0.0
-0.1
-0.2
3500

3000

2500
2000
Wavenumbers (cm-1)

1500

1000

… yields a better protein Spectrum after
it is Squashed

Inkjet Cartridge Printhead
8.5mm X 11.2mm

2.0
1.5

Epoxy

Polyimide
Polyimide

1.0

Metal
Abs orbanc e

0.5
0.0

White Epoxy

-0.5
-1.0
-1.5

Green Ink

-2.0
-2.5
-3.0
4000

Laser Cut Metal “Window”

Blue Ink
3500

3000

2.3mm X 3.0mm


2500
2000
Wavenumbers (cm-1)

1500

1000

Printhead Dismantled – Piezoelectric Ceramic Under Metal
11.2mm X 8.5mm
Cu & Glue is between PET & Polyimide
Ceramic beneath slotted Metal
3.0

PET + Butylacrylate Adhesive

2.5
2.0
1.5

Absorbance

1.0
0.5
0.0
-0.5

Butylacrylate Glue

-1.0
-1.5
-2.0
-2.5
4000

3000

2000
Wavenumbers (cm-1)

1000

Micaceous Cleavage of Ceramic

3.0mm X 2.3mm

Who made the Chip that’s encased in hard black epoxy?

Toshiba

Original Photo

Flipped Image


Fish Hook Manufacturing Processes:
Cutting, Bending, Welding, Coating

8.5mm X 11.2mm FOVs

Fish Hook’s Point and Scratched Inorganic Coating:
420u X 550u FOVs


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