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Effect of bis[3-(triethoxysilyl)propyl] tetrasulfide, polyethylene glycol and polypropylene glycol on the behavior of silica filled rubber compounds based on natural rubber
Published in Bertrand Huneau, Jean-Benoit Le Cam, Yann Marco, Erwan Verron, Constitutive Models for Rubber XI, 2019
O. Kratina, P. Zádrapa, R. Stoček
In this work, investigated rubber compounds have been based on natural rubber (SVR CV60, Binh Phuoc, Vietnam) filled with 50 phr of silica (Ultrasil 7000 GR, Evonik, Germany). Bis-(triethoxysilyl) propyl tetrasulphide (Si69, Evonik, Germany), polyethylene glycol (PEG 4000) and polypropylene glycol (PPG 4000) were used as agents improving dispersibility of silica. Additionally, zinc oxide (ZnO), stearic acid and N-(1,3-Dimethylbutyl)-N‘-phenyl-p-phenylenediamine (6PPD) (all from Sigma-Aldrich Chemie, Germany) were used as additives for preparation of masterbatch. In order of preparing of final rubber compound, sulfur and accelerators N-cyklohexyl-2-benzo-thiazole-sulfenamide (CBS) and Diphenylguanidine (DPG) (all from Sigma-Aldrich Chemie, Germany) were added. Complete formulation of prepared rubber compounds is given by Table 1.
Degradation and Protection
Published in Anil K. Bhowmick, Current Topics in ELASTOMERS RESEARCH, 2008
Rabin N. Datta, Nico M. Huntink
The loss of antiozonants, either in a chemical or physical manner, appears to be the limiting factor in providing long-term protection of rubber products. That is why for new antiozonants not only the efficiency of the antiozonants must be evaluated, but one also has to watch other properties which influence their protective functions in an indifferent manner. For example, the molecule’s mobility, its ability to migrate, is one of the parameters determining the efficiency of antiozonant action. Determination of the mobility kinetics of antiozonants can be done with a gravimetric method elaborated by Kavun et al. [75]. This method was used to determine the diffusion coefficient of several substituted PPDs, in different rubbers and at different temperatures [76]. The diffusion coefficients were calculated using the classical diffusion theory: Table 15.4. The diffusion coefficients increase with increasing temperature and with decreased compatibility with the rubber. The lower diffusion coefficient observed for N-(1-phenylethyl)-N′-phenyl-p-phenylenediamine (SPPD) compared to that of IPPD and 6PPD was explained by an increased MW and/or increased compatibility with the rubbers.
Effect of filler-polymer interfacial phenomena on fracture of SSBR-silica composites
Published in Alexander Lion, Michael Johlitz, Constitutive Models for Rubber X, 2017
Mohammad Alimardani, Mehdi Razzaghi-Kashani
Rubber compounds were prepared using an internal mixer and a two roll mill. After drying silica in 80°C for two days, a master batch of rubber and silica was prepared using an internal mixer (Brabender-W50ETH). The content of filler was chosen to be 60 phr (parts per hundred of rubber). The antiozonant 6PPD (Table 1) and cure activators of zinc oxide and stearic acid were also added to the compound during this state of mixing. The resulting master batch was compounded with sulfur and accelerators (CBS N-cyclohexylbenzothiazole-2-sulfenamide & DPG diphenylguanidine) on a two roll-mill (Brabender-PM2000) operating at the friction ratio of 1:1.5 for another 15 min. Vulcanizates were finally compression molded at 160°C.
Identification and characterization of urban lakes across the continental United States
Published in Lake and Reservoir Management, 2021
Laura Costadone, Mark D. Sytsma
Urban lakes face a wide array of problems that also need to be considered in watershed management and planning programs. The EPA 303 (d) data for urban lakes indicated that they were mostly impaired by contaminants like excessive nutrients, mercury contamination, and toxic compounds that pose a serious health threat to people engaging in recreational activities in these lakes and lead to management and sustainability issues (Taylor and Owens 2009). A common compound (6PPD-quinone) found in tire chemicals and present in urban runoff has been linked to the death of coho salmon (Oncorhynchus kisutch; Stokstad 2020). Future studies should investigate interconnections between chemicals present in urban runoffs, lake food webs, and phytoplankton productivity. Continued urban development will likely exacerbate the presence of these contaminants (Li et al. 2013), and a more targeted management approach could be necessary to address the unique water quality issues in urban lakes.
Protection Mechanism of Rubbers from Ozone Attack
Published in Ozone: Science & Engineering, 2019
The antiozonants are molecules which are able to migrate, i.e. to move from the bulk of rubber compound to the surface of the rubber compound in order to be ready to react with the incoming ozone. Thus, the antiozonants must not be very soluble in the rubber and indeed the N,N’-substituted PPDs are not. Moreover, the antiozonant molecules must be very reactive with ozone to be able to scavenge ozone before it has time to attack the double bonds. For example, the antiozonant 6PPD (see Figure 1 for the chemical structure) reacts with ozone 7 × 106 M−1s−1 (Cataldo 2018). This figure should be compared with the reaction speed with ozone of the double bonds of IR which is 1.4 × 105 M−1s−1 corresponding to 50 times less than 6PPD or with the double bonds of BR and SBR i.e. 6.0 × 104 M−1s−1 corresponding to 117 times less than 6PPD. The effect of an antiozonant is to scavenge the ozone available on the surface of the rubber before it has time to react with the rubber double bonds. As the antiozonant is continuously consumed through its reaction with ozone at the rubber surface, diffusion of new antiozonant from the inner parts to the surface replenishes the surface concentration to provide the continuous protection against ozone. Blends of different PPDs antiozonants are used in the industrial practice to ensure short- and long-term protection taking advantage from the different migration ability of the various PPDs shown in Figure 1.