1 chances and challenges of closing the material...
TRANSCRIPT
11
CHANCES AND CHALLENGES
OF CLOSING THE MATERIAL CIRCLE FOR
PASSENGER CAR TIRE RUBBER
University Twente
Engineering Technology
Elastomer Technology & Engineering
Sustainable Elastomer Systems
Enschede, the Netherlands
Tomas Bata University Centre of Polymer Systems Zlín, Czech Republic
G. HEIDEMAN
H. VAN HOEK
S. SAIWARI
W. DIERKES
J. NOORDERMEER
A. BLUME
22
CHANCES AND CHALLENGES
OF CLOSING THE MATERIAL CIRCLE FOR
PASSENGER CAR TIRE RUBBER
3
Particulate rubber
Reclaim
Devulca-nizate
Radiation
Biological
Mechanical
Thermo-mechanical
Thermo-mechanical-
spCO2
Thermo-mechanical-
chemical
As such
Compounded
Particulate rubber
Granulate
Powder
ambient
cryogenic
Introduction Types of recycled rubber
4
Particulate rubber
Granulate
Powder
ambient
cryogenic
Introduction Types of recycled rubber
Particulate rubber
Reclaim
Devulca-nizate
Radiation
Biological
Mechanical
Thermo-mechanical
Thermo-mechanical-
spCO2
Thermo-mechanical-
chemical
As such
Compounded
5
Tire parts
Tread
Sidewall
Innerliner
Carcass
Bead
Aged
Post-consumer
Factory
Degree of contamination
High
Low
https://www.futuretire.com/how-are-tires-constructed/
Whole tires
Passenger car
Truck
Off-the-road
Others
Mix
Silica
Carbon black
Introduction Feedstock
6
Tire parts
Tread
Sidewall
Innerliner
Carcass
Bead
Aged
Post-consumer
Factory
Degree of contamination
High
Low
https://www.futuretire.com/how-are-tires-constructed/
Whole tires
Passenger car
Truck
Off-the-road
Others
Mix
Silica
Carbon black
Introduction Feedstock
7
Granulometry
Fine
Coarse
Introduction
Concentration
Devulcanization aid
Processing oil
Stabilizer
Pre-treatment
Swelling time
Swelling temperature
Devulc. process type
Discontinuous
Continuous
Small scale
Larger scale
Process development
8
Granulometry
Fine
Coarse
Introduction Process development
Concentration
Devulcanization aid
Processing oil
Stabilizer
Pre-treatment
Swelling time
Swelling temperature
Devulc. process type
Discontinuous
Continuous
Small scale
Larger scale
9
Experimental Devulcanization
https://media.labcompare.com/m/1/product/13082337-400x300.jpg
Extruder process
Process temperature 220ºC
Residence time 6 min
Atmosphere Inert (N2)
Cooling Calander
Post processing Milling
Particle size feedstock 1-3 mm
Throughput Few kg/h
Internal mixer process
TCU settings 220ºC
Mixing chamber volume 50 ml
Residence time 6 min
Rotor speed 50 rpm
Atmosphere Inert (N2)
Cooling LN2
Particle size feedstock 1-3 mm
Batch size 40 g
Small scale
Larger scale
Type Screw diameter D [mm]
Flight depth[mm]
Length [mm]
Screw type
BerstorffZE 25 A UTXi
25 4.2 42DTwin screw Co-rotating
10
DEVULCANISATION:
REGENERATION:
+sol
gel
sol
Experimental Analytics Horikx-Verbruggen plot
11
Blending of 5% re-plasticized rubber with a bright white compound
Shade of grey from network detached part of the rubber
Particles non-devulcanized cores of the particles or filler clusters
White rubber compound
5% completelyre-plasticized
rubber 10% ground
rubber
Reference samples
Samples with 5% devulcanizate
Experimental Analytics White rubber test
13
Feedstock Particle size
Model compounds Fine: 0,7-2,0 mm
Coarse: 2,0-3,5 mm
Whole passenger car tire rubber
0
100
200
300
400
500
0,0
2,0
4,0
6,0
8,0
10,0
12,0
14,0
16,0
Silica -coarse
Silica -fine
Carbonblack -coarse
Carbonblack -
fine
Elon
gatio
n at
bre
ak [%
]
Tens
ile s
treng
th [M
Pa]
0
100
200
300
400
500
0,0
2,0
4,0
6,0
8,0
10,0
12,0
14,0
16,0
< 3,5 mm 2-3,5 mm 2-0,7 mm < 0,7 mm
Elon
gatio
n at
bre
ak [%
]
Tens
ile s
tren
gth
[MPa
]
14
Feedstock Whole tire - PCT
B
A
A
B
Increasing age
During service life
15
Har
dnes
s [S
hore
A] 60
40
20
0 Increasing age
ML(
1+4)
, MU 100
50
0
ΔTo
rque
[Nm
]
4
3
2
1
0
Additive phr
Devulcanizate 100
Stearic acid 0.5
Zinc oxide 1.5
6PPD 2.0
TMQ 2.0
TBBS 1.5
Sulfur 1.5
AB
Feedstock Whole tire - PCT During service life
16
Tire part - tread Carbon black versus silica
0
100
200
300
400
500
0
5
10
15
20
25
Silica/silane- virgin
Silica/silanede- and
revulcanized
Carbonblack - virgin
Carbonblack de-
andrevulcanized
Elon
gatio
n at
bre
ak [%
]
Tens
ile s
tren
gth
[MPa
]
Additive phr phr
SBR 65 65
BR 35 35
Zinc oxide 3.0 2.5
Stearic acid 2.0 1.0
TDAE 35 32.5
Carbon black N550 80
Silica Zeosil 1165MP 90
TESPT 7.2
6PPD 1.0 2.0
TMQ 2.0 2.0
TBBS 1.5 1.7
DPG 2.0
Sulfur 1.5 1.4
Model compounds (non-aged)
Batch mixer
TDAE: 6.2%
DPDS: 18 mmol
Antioxidant: 1%
Swelling: 30 minutes, 65ºC
Mixer TCU: 220ºC
Devulc, time: 6 minutes
N2 purging
Devulcanization conditions:
Feedstock
17
Silica - silane
0
20
40
60
80
100
0 0,2 0,4 0,6 0,8 1
Sol f
ract
ion
(%)
Decrease in crosslink density
Random main chain scissionCrosslink scissionUntreated TESPTTESPT 220 °CTESPT 250 °C
Additive TESPT TESPD PESPMphr
SSBR 103 103 103BR 25 25 25Zeosil 1165 80 80 80Silane 7.0 6.3 9.0TDAE 5.0 5.0 5.0ZnO 2,5 2,5 2,5Stearic acid 2,5 2,5 2,56PPD 2.0 2.0 2.0TMQ 2.0 2.0 2.0Sulfur 1,4 2.0 2.2TBBS 1,7 1,7 1,7DPG 2.0 2.0 2.0
TESPT
Devulcanization conditions:
Batch mixer
TDAE: 6.2%
DPDS: 15 mmol
Swelling: 30 minutes, 65ºC
Fill factor: 0.7
Rotor speed: 50 rpm
N2 purging
Tire part - tread Feedstock
18
Devulcanization conditions:
Batch mixer
TDAE: 6.2%
DPDS: 15 mmol
Swelling: 30 minutes, 65ºC
Fill factor: 0.7
Rotor speed: 50 rpm
N2 purging 0
20
40
60
80
100
0 0,2 0,4 0,6 0,8 1
Sol f
ract
ion
(%)
Decrease in crosslink density
Random main chain scissionCrosslink scissionUntreated TESPTTESPT 220 °CTESPT 250 °C
0
20
40
60
80
100
0 0,2 0,4 0,6 0,8 1
Sol f
ract
ion
(%)
Decrease in crosslink density
Random main chain scissionCrosslink scissionUntreated TESPDTESPD 220 °CTESPD 250 °C
0
20
40
60
80
100
0 0,2 0,4 0,6 0,8 1
Sol f
ract
ion
(%)
Decrease in crosslink density
Random main chain scissionCrosslink scissionUntreated PESPMPESPM 220 °CPESPM 250 °C
PESPM
TESPD
TESPT
Silica - silaneTire part - tread Feedstock
19
0
100
200
300
400
500
0
5
10
15
20
25
Originaltire tread
TESPT- 220 C
TESPT- 250 C
Elon
gatio
n at
bre
ak [%
]
Tens
ile s
tren
gth
[MPa
]
0
20
40
60
80
100
0
1
2
3
4
5
6
7
Originaltire tread
PESPM -220 C
PESPM -250 C
Har
dnes
s [S
hore
A]
Mod
ulus
100
% [M
Pa]
Silica - silaneTire part - tread Feedstock
20
Process development Oil swelling time
0102030405060708090
100
0 0,2 0,4 0,6 0,8 1
Sol f
ract
ion
(%)
Decrease in crosslink density
Random main chain scissionCrosslink scissionUntreated GTRD-GTRD GTR swollen 30 minsD GTR swollen 60 mins
Process conditions:
Batch mixer
Swelling temp.: 65ºC
TDAE: 5%
DPDS: 15 mmol
Antioxidant: 1%
Fill factor: 0,7
Rotor speed: 50 rpm
Mixer TCU: 220ºC
N2 purging
Screw speed: 50 rpm
Particle size: < 0,42 mm
21
Oil concentration
0102030405060708090
100
0 0,2 0,4 0,6 0,8 1
Sol f
ract
ion
(%)
Decrease in crosslink density
Random main chain scissionCrosslink scissionUntreated GTR5% TDAE15% TDAE30% TDAE50% TDAE
Process conditions:
Batch mixer
DPDS: 15 mmol
Antioxidant: 1%
Swelling: 30 min., 65ºC
Fill factor: 0,7
Mixer TCU: 220ºC
N2 purging
Rotor speed: 50 rpm
Process development
22
Oil / devulcanization aid swelling
Particle size distribution TDAE distributionAdded: 5 w%
Rubber particle
Devulc. aidOil Time
Temperature
Process development
24
Devulcanization - type of process
Process conditions: Swelling: 65ºC, 30 min.TDAE: 5%N2 purging
Batch mixerFill factor: 0,7Rotor speed: 50 rpm Mixer TCU: 220ºCScrew speed: 50 rpm
Extruder process: Screw speed varied to match residence time: 10, 20, 30 rpm
Process development
25
Compound adjustment for silica
Average composition (TGA): Silica: 42 phr
Additional silane(TESPT): 3.2 phr
Silanization: 4 minutes, 145ºCa
After-treatment
26
Summary
Upgrading of the devulcanizate by Silanization and addition of DPG for silica in the devulcanizate Continuous process (extruder) is more efficient
than batch process (internal mixer) Process is sensitive to (pre)treatment of the feedstock No influence of particle size on strength properties
if the devulcanization process is adjusted accordingly
Challenges:
Chances:
For a high quality devulcanizate Single tire parts > whole tire rubber Carbon black filled > silica filled (Type of) silane used in the original silica compound Age of the tire (part) Different devulcanization mechanisms
27
Thank you for your
attention!
Acknowledgements