two compounding additives to improve tire reversion
TRANSCRIPT
Two Compounding Additives to Improve Tire Reversion ResistanceDr Hermann-Josef Weidenhaupt Joel Neilsen LanxessCorporationPresented at ITEC 2018 Akron Ohio
Challenge
2
Challenge
bull Large tires such as TruckBus Aircraft and tires used on giant loadingdump trucks have a large percentage of natural rubber in their compounds NR is necessary due to its toughness and lower hysteretic properties
3
Challenge
bull Large tires such as TruckBus Aircraft and tires used on giant loadingdump trucks have a large percentage of natural rubber in their compounds NR is necessary due to its toughness and lower hysteretic properties
bull It is well known that natural rubber will revert heat from vulcanization and heat from severe service will cause natural rubber to lose its physical properties (tensile modulus tear etc) This reversion can reduce the service life of large tires
4
Challenge
bull Large tires such as TruckBus Aircraft and tires used on giant loadingdump trucks have a large percentage of natural rubber in their compounds NR is necessary due to its toughness and lower hysteretic properties
bull It is well known that natural rubber will revert heat from vulcanization and heat from severe service will cause natural rubber to lose its physical properties (tensile modulus tear etc) This reversion can reduce the service life of large tires
bull Natural rubber reversion is primarily due to the breakdown of poly sulfidic crosslinks into shorter fewer crosslinks
5
Challenge
bull Large tires such as TruckBus Aircraft and tires used on giant loadingdump trucks have a large percentage of natural rubber in their compounds NR is necessary due to its toughness and lower hysteretic properties
bull It is well known that natural rubber will revert heat from vulcanization and heat from severe service will cause natural rubber to lose its physical properties (tensile modulus tear etc) This reversion can reduce the service life of large tires
bull Natural rubber reversion is primarily due to the breakdown of poly sulfidic crosslinks into shorter fewer crosslinks
bull The tires of focus tend to be far more expensive vs standard street tires so extending their service life is greatly desired and thus increasing reversion resistance is an important goal
6
Challenge
bull Large tires such as TruckBus Aircraft and tires used on giant loadingdump trucks have a large percentage of natural rubber in their compounds NR is necessary due to its toughness and lower hysteretic properties
bull It is well known that natural rubber will revert heat from vulcanization and heat from severe service will cause natural rubber to lose its physical properties (tensile modulus tear etc) This reversion can reduce the service life of large tires
bull Natural rubber reversion is primarily due to the breakdown of poly sulfidic crosslinks into shorter fewer crosslinks
bull The tires of focus tend to be far more expensive vs standard street tires so extending their service life is greatly desired and thus increasing reversion resistance is an important goal
bull We will present features and performance of two Rhein Chemie products designed to reduce reversion Perkalinkreg900 and Vulcurenreg
7
8
Properties of Crosslink Structure
Advantages of short crosslinks (C-C- or C-S-C-bridges)minus Reversion stabilityheat stabilityminus Compression setpermanent set at elevated temperatures
Advantages of long crosslinks (C-Sx-C-bridges)minus Tensile strengthminus Rebound elasticityminus Tear resistanceminus Fatigue resistanceminus Dynamic damping
Figure 1 Sulfur Crosslinking of Polyisoprene
Sulfur Crosslinks Form at the Allylic Hydrogen Atoms
Figure 2 Changes in network structure during reversion
S
SS
SS
S
SS
S
AccS
S SSSS
S
S
AccS
S
S
SSSS
AccS S
S
SS S
S
S
bullBreakage of crosslinks
bullRearrangement Cyclisation
bullShortening of crosslinks
bullIsomerisation conjugated double bonds
bullNew crosslinks
SSSS
Reversion process
SS
SS
SxS
S
SS S
SxSy-ACC
type of sulfur bridge bonding energy (kJmol)- C - SX - C - (x gt 2) lt 268- C - S2 - C - 268- C - S - C - 285- C - C - 352
Figure 3 Crosslink Bonding Energy
Torq
ueS
lsquo [s
tand
ardi
zed]
07
08
09
10
0 50 100 150
VSL 5025-0 (SSBR)
VSL 2525-0 (SSBR)
CB 24 (BR)
Natsyn 2200
NR (Crepe)
SL 25-0 (SSBR)
160degC
Figure 4 Influence of polymer on reversion
Figure 5 Structure of Perkalinkreg900
N
O
O
N
O
O
13-Bis(citraconimidomethyl)benzenePerkalinkreg 900 (CIMB)
Figure 6 CIMB Crosslink Formation- Diels-Alder Mechanism
N
O
O
N
O
O
+ +
N
O
O
N
O
O
Figure 7 Distribution of Crosslinks in Vulcanizates+
CompoundCureConditions
Total CrosslinksX 105
PolysulfidicCrosslinksX 105
Di SulfidicCrosslinksX 105
Mono SulfidicX 105
Carbon-CarbonX 105
Control150deg Ct90 502 318 187 - -
170deg C30rsquo205 004 006 193 -
Perkalinkreg 900 15 phr
150deg Ct90 504 294 210 - -
170deg C30rsquo254 003 010 088 153
Concentration of Crosslinks gram-molegram hydrocarbon
+ ldquoA New Concept for Reversion Protection of Accelerated Sulfur Systemsrdquo
Presented at The ACS Rubber Division Meeting October 1994 Authors
RN Datta amp MS Ivany
Figure 8 High Level Natural Rubber Compound
NR 80 phr BR 20 phr carbon black N539 40 phr silica 80 phr oil 30 phr IPPD 18 phr TMQ 12 phr ZnO RS 100 phr stearic acid 075 phr resin 20 phr
Cohedurreg RS (resorcinolstearic acid 21) 12 phr HMT 06 phr
Vulcanization system with Perkalink
CBS 07 07MBTS 03 03Sulfur 3 3CIMB 0 1
Reference
min
Figure 9 Rheometer (MDR 2000E 180degC)
reference
reference + 10 phr CIMB