Blending, Curing and Reinforcement of NR/BR/EPDM Compounds for Tire Sidewall Applications

Transcription

1 Blending, Curing and Reinforcement of NR/BR/EPDM Compounds for Tire Sidewall Applications Studies on EPDM Grafting by N-ChlorothioN Chlorothio-N-Butyl- Benzenesulfonamide DPI #356 H. Zhang, R.N. Datta, A.G. Talma and J.W.M. Noordermeer University of Twente Dutch Polymer Institute IRC 2008, Malaysia 1

2 Introduction Tire black sidewall Ozone resistance IRC 2008, Malaysia 2

3 Introduction Conventional formulation NR (50phr) BR (50phr) Carbon black Processing oil ZnO Stearic acid TMQ 6PPD Sulfur CBS CH 2 CH 3 C CH CH2 CH 2 CH CH CH 2 Anti-ozonant NH NH CH CH 2 CH CH 3 CH 3 CH 3 u Lasts not forever u Toxic u Staining IRC 2008, Malaysia 3

4 Introduction NR (50phr) (35phr) BR (50phr) (35phr) EPDM (30phr) Carbon black Processing oil ZnO Stearic acid TMQ 6PPD Sulfur CBS New formulation CH 2 CH 2 CH 2 CH x y CH 3 z UV resistance Temperature resistance Ozone resistance 30 phr of EPDM is sufficient for ozone resistance IRC 2008, Malaysia 4

5 Introduction Problems with NR/BR/EPDM blends Curatives Carbon black EPDM is not compatible with NR/BR. Cure incompatibility. Inhomogeneous filler distribution. EPDM Diene rubber Poor mechanical properties IRC 2008, Malaysia 5

6 Introduction Aim of the project To solve cure incompatibility and reinforcement problems for NR/BR/EPDM blends and improve mechanical properties. IRC 2008, Malaysia 6

7 Approaches Reactive processing Applying compatibilzing agent Modifying EPDM Introducing higher polarity and unsaturation to EPDM Curatives Carbon black EPDM Diene rubber IRC 2008, Malaysia 7 Grafted EPDM Diene rubber

8 CTBBS modification Modification agent N-Chlorothio-N-Butyl- Benzenesulfonamide (CTBBS) SO 2 N SCl CH 2 CH 2 CH 2 CH 3 Four types of EPDM Keltan 5508 (LENB-EPDM) EPDM) 4.5% ENB content 70% (wt) ethylene Keltan 4703 (HENB-EPDM) EPDM) 9% ENB content 48% (wt) ethylene Keltan 520 (DCPD-EPDM) 4.5% DCPD content 58% (wt) ethylene Nordel 1070 (HD-EPDM) 4% Hexadiene content 54% (wt) ethylene CH CH 3 Ref: HOPPER, R.J. (1976), Rubber Chemistry and Technology, 49, IRC 2008, Malaysia 8

9 CTBBS modification Dissolve EPDM in hexane Modification method 1: In solution Add Calcium stearate (Suspended in dichloromethane) Only for ENB-EPDM EPDM Add CTBBS (dissolved in dichloromethane) Flushed with N 2 Final sample Isolated by coagulation & washing with acetone. Dried in vacuum oven CTBBS-amounts added were varied respect to the available unsaturation in EPDM as relative ratios (mole%). IRC 2008, Malaysia 9

10 CTBBS modification NMR: HD-EPDM Peak area Virgin Grafted Calibration curve 14.7 Theoretical Experimental Gel 48 hours 30% CTBBS % CTBBS % CTBBS CTBBS-amount 60% 7.0 (%) Reference C H 3 IRC 2008, Malaysia 10

11 CTBBS modification NMR: DCPD-EPDM ATR/IR and NMR show no evidence of CTBBS-grafting for longer time (1week) and at higher temperature (80 o C) IRC 2008, Malaysia 11

12 CTBBS modification NMR: LENB-EPDM EPDM 25 Calibration curve Reference C H 3 Virgin Peak area CH CH 3 Theoretical Experimental 20.9 Gel 5 Grafted hours 10% CTBBS % CTBBS CTBBS-amount (%) IRC 2008, Malaysia 12

13 CTBBS modification NMR: HENB-EPDM EPDM Reference C H 3 Virgin CH CH Grafted 4 hours 10% CTBBS 14.8 IRC 2008, Malaysia 13

14 CTBBS modification Comparison EPDM types HD-EPDM LENB-EPDM HENB-EPDM DCPD-EPDM Reaction time 48 hours 4 hours 4 hours No reaction Highest CTBBS dosing without risk of gelation (mole%) No reaction The reactivity of these three EPDM with CTBBS: ENB-EPDM > HD-EPDM > DCPD-EPDM ENB-EPDM has a strong tendency towards gelation. IRC 2008, Malaysia 14

15 CTBBS modification Proposed Mechanism CH CH 3 + R SCl Cl RS CH CH 3 RS CH CH 3 Cl - DCPD-EPDM ENB-EPDM Cationic crosslinking H + Cl - + RS C CH 3 Not reactive HD-EPDM R SCl + + Cl SR RS Cl IRC 2008, Malaysia 15

16 CTBBS modification Modification method 2: In internal mixer LENB-EPDM with 20% CTBBS LENB-EPDMs Virgin LENB-EPDM Internal mixer 100 o C (10 min) Internal mixer 100 o C (15 min) Internal mixer 120 o C (10 min) Solution method Integration area of olefinic hydrogen u Gelation took place when CTBBS>25% u 20% CTBBS-grafted EPDM does not improve the mechanical properties of NR/BR/EPDM blends significantly. IRC 2008, Malaysia 16

17 Conclusions CTBBS has a different behavior with respect to grafting on various EPDM-types: ENB-EPDM has the highest reactivity, however gelation is observed at low conversions. No grafting is observed for DCPD-EPDM. The highest grafting efficiency can be reached for HD-EPDM. ENB-EPDM grafted with 20% of CTBBS is insufficient to provide significantly improved mechanical properties compared to historic data on basis of HD-EPDM. IRC 2008, Malaysia 17

18 Acknowledgement This study is part of the research programme of the Dutch Polymer Institute (DPI), project nr. #356 IRC 2008, Malaysia 18

19 IRC 2008, Malaysia 19