AUTOMATED VISCOMETERS FOR MEASURING THE DIVIDING LINES AMONG RECYCLED PLASTICS

Automated Viscometer Sets the
Grade for Recycled Plastics

CANNON Instrument Company
Main Points
• Measurements of polymer solution viscosity is a
fundamental tool for polymer characterization.
• There is a strong correlation between polymer
solution viscosity and polymer molecular size/weight.
• The measured intrinsic viscosity, 𝜂𝜂 , is used
effectively to make comparisons among recycled and
sustainable plastics.
𝜂𝜂 = 𝐾𝐾 � 𝑀𝑀𝑎𝑎
✯ properties improve at higher MWs
✯ processing is impacted by MW

Dilute Solution Viscosity (DSV)
The Concentration Continuum
zero
polymer
zero
solvent
straight
solvent
polymer
melt
𝐶𝐶∗
no chain
interactions
increasing contact
between chains
increasing extend of
chain entanglements
𝐶𝐶‡
DILUTE SEMI-DILUTE CONCENTRATED

The Utility of Intrinsic Viscosity, [η]
Mark-Houwink-Sakurada-Kuhn
𝑀𝑀 =
𝜂𝜂
𝐾𝐾
�
1
𝑎𝑎
solving for molecular weight, M
𝜂𝜂 depends on relative viscosity, 𝜂𝜂𝑟𝑟
𝜂𝜂𝑟𝑟 =
𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣
𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣𝑣
=
𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡
𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠𝑠 𝑓𝑓𝑓𝑓𝑓𝑓𝑓𝑓 𝑡𝑡𝑡𝑡𝑡𝑡𝑡𝑡
=
𝑡𝑡
𝑡𝑡𝑜𝑜

miniPV®—fully automated viscometer
great precision
• stable
• simple
time consuming
• rinsing/drying
• observing
manual viscometer automated viscometer
• speed
• safety
• range
‘+’
auto
sampler

IV is a Surrogate for MW
𝜂𝜂 = 𝐾𝐾 � 𝑀𝑀𝑎𝑎 𝑀𝑀 =
𝜂𝜂
𝐾𝐾
�
1
𝑎𝑎
K, a
Correlate processing and properties
directly with Intrinsic Viscosity.
required
to get MW
directly
measured
Target applications based on the
measured Intrinsic Viscosity.
adds a level of uncertainty

IV Ranges of PET Grades
PET grade Intrinsic Viscosity [dL/g]①
Fiber grade 0.40 – 0.70
Film grade 0.70 – 1.00
Bottle grade 0.70 – 0.78
Water and soft drink bottle grade 0.78 – 0.85
Carbonated drink bottles 0.73 – 0.80
②
①https://blog.icpg.co/the-importance-of-controlling-intrinsic-viscosity-in-extruded-pet
②Awaja F, Pavel D. Recycling of PET. Eur Polym J. 2005;41(7):1453‐1477 “However, in the last years, requirements have shifted
towards higher values.”
NOTE: In Europe and tropical areas, required IV > 0.80 dL/g.
INTRINSIC VISCOSITY is the basis for ranking PET
for processing performance and physical properties.

Study of rPET content in Bottles
Alvarado Chacon F, Brouwer MT, Thoden van Velzen EU. Effect of recycled content and rPET quality on the properties of PET bottles,
part II: Optical and mechanical properties. Packag Technol Sci. 2020;1–11
Method: ASTM D4603 | IV of PET by Glass Capillary Viscometer
9%
10%
14%
14%
NA
9%
14%
2%
IV scrutinizes blending with rPET
before
processing

Chain Extenders
Case Study | HiTerra rPET Revive
Yellow Index
Intrinsic Viscosity for
duplicate measurements
Sample - polyethylene terephthalate avg. IV std. dev. % change YI Notes
PET - Virgin 0.68 0.007 -6.96
PET - single pass 0.55 0.006 -19.1 % 0.39
PET - double pass 0.51 0.006 -25.0 % 3.2
PET - single pass + 0.5% HiTerra rPET Revive 0.63 0.002 -7.4 % 0.08
PET - double pass + 0.5% HiTerra rPET Revive 0.58 0.003 -14.7 % 2.26 No additional additive
added for this pass
Sample - polybutylene terephthalate avg. IV std. dev. YI Notes
PBT - Virgin 0.74 0.002 -0.97
PBT - single pass 0.73 0.007 -1.4 % 3.6
PBT - double pass 0.75 0.026 1.4 % 5
PBT - single pass + 0.5% HiTerra rPBT Revive 0.79 0.010
6.8 %
0.07
PBT - double pass + 0.5% HiTerra rPBT Revive 0.78 0.006
5.4 %
2.65 No additional additive
added for this pass
“Revive”
improves
IV stability
“Revive”
increases
IV
by Techmer PM

Chain Extenders
Case Study | HiTerra rPET Revive
Sample - recycled polyethylene terephthalate IV % change YI Notes
rPET 0.57 9.88
rPET - single pass + 0.5% HiTerra rPET Revive 0.61 7.0 % 9.37
Sample - polyethylene terephthalate (higher IV) IV % change YI Notes
PET - Virigin 0.84 5.35
PET - single pass 0.78 -7.1 % 14.81
PET - single pass + 2.5% HiTerra rPET Revive 0.94 11.9 % -4.16
2.5% is a higher LDR than
normally recommended,
but has dramatic
yellowness improvement
IV increases
for rPET
YI: 14.81-4.16
virgin w/Revive
at 2.5%
Significant IV increase at higher
Revive loading (let down ratio).

IV in Novel & Innovative Applications
• PVB – repurpose of laminated glass
– adhesive, paint additive, solar panel coating
• PET – Fabric Recovery
• Polymerization from Biomass
– Uses microorganisms found in the ocean to convert air and greenhouse
gas into a natural biomaterial
consolidation regeneration reintegration
end-of -life in-use product

Takeaways
direct measurement of IV
unattended & safe operation
The Fully Automated Viscometer provides:
high quality data with exceptional precision
stable design & fast results
“Owing to the superb precision of viscosity measurements, the
intrinsic viscosity can easily be measured to three significant
figures, which makes it by far the most precise polymer
characterization method.” Polymer Physics, page 35

Background
Hermann Staudinger (1930’s) performed dilute solution
viscosity (DSV) measurements to support his idea that polymers
were long sequences of covalent bonds rather than aggregates
of small molecules that formed a colloidal system.
Others have built on his ideas until we now
have an established relationship between
intrinsic viscosity and molecular weight.
𝜂𝜂 = 𝐾𝐾 � 𝑀𝑀
Staudinger index:
intrinsic viscosity:

Solution Preparation System (SPS)
Solvent Dispenser
Analytical Balance
Software for controlling
devices and calculating
concentration
Automation for Accurate Concentrations

The Solvent Motion –
Laminar Flow
stationary plate
pumping force
pulling force
Laminar flow of liquid between parallel plates:
Laminar flow of liquid pumped through tube:
y
x
x
y

The Solvent Motion –
Laminar Flow
force of gravity
Laminar flow of liquid in a vertical tube:
x
y
“particle” is
experiencing a
velocity gradient.

The Particle Motion - Rotation
Coordinate system positioned at the “particle” center.
y
x

The Macromolecular Motion
Herbert Morawetz, Macromolecules in Solution, page 291
The theories for
DSV require that
these motions
and deformations
must not be
influenced by
neighboring
polymer chains.
y
x

Molecular
Weight
Mc
c*
dilute
solution
semi-dilute & concentrated
solutions
development of
chain entanglements
Interaction Between Polymer
Chains – the Situation in Solutions
Concentration

The Meaning of Intrinsic Viscosity
The intrinsic viscosity of a polymer solution acts as a
measure of the additional energy loss due to rotation
of the macromolecule in the flowing liquid.
from Structure of Macromolecules in Solution
The macromolecule must be free to rotate:
→ cannot be encumbered by entanglements
→ only interaction is with solvent (small) molecules
“… the only way of separating them sufficiently is by
dissolution in a liquid of low molecular weight.”

Measurement of Intrinsic Viscosity
Polyphthalamide
in phenol/TCE
at 30 °C
0.72
0.77
0.82
0.87
0.92
0.97
1.02
0.00 0.50
(η
r
-
1)/c
&
ln(η
r
)/c
(dL/g)
concentration (g/dL)
H - 0.2 g/dL
K - 0.2 g/dL
H - 0.2 g/dL (dup)
K - 0.2 g/dL (dup)
H - 0.4 g/dL
K - 0.4 g/dL
H - 0.4 g/dL (dup)
K - 0.4 g/dL (dup)
H - 0.6 g/dL
K - 0.6 g/dL
H - 0.6 g/dL (dup)
K - 0.6 g/dL (dup)
H - 0.8 g/dL
K - 0.8 g/dL
H - 0.8 g/dL (dup)
K - 0.8 g/dL (dup)
Huggins
Kraemer
Mv = 20,400 Daltons
IV = 0.797 dL/gm
𝑀𝑀 =
𝜂𝜂
𝐾𝐾
�
1
𝑎𝑎
K = 0.000364
a = 0.75
Polymer Handbook,
page VII/37

Averages of the MWD
Frank McGrew, Journal of Chemical Education, vol 35, issue 4

AUTOMATED VISCOMETERS FOR MEASURING THE DIVIDING LINES AMONG RECYCLED PLASTICS

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AUTOMATED VISCOMETERS FOR MEASURING THE DIVIDING LINES AMONG RECYCLED PLASTICS