New mechanistic view on network stabilization

When sulfur vulcanized natural rubber compounds are exposed to a thermal aging environment significant change in physical properties and performance characteristics are observed. These changes are directly related to modifications of the original crosslink structure. Decomposition reactions tend to predominate and thus leading to reduction in crosslink density and physical properties as observed during extended cure and when using higher curing temperatures. The decrease in network density is common when vulcanizates are subject to an anaerobic aging process. However, in the presence of oxygen, the network density is increased with the main chain modifications playing a vital role. The stability of the network during thermo-oxidative aging is a subject matter of this paper. Additionally, the effect of para-aramide on network is described with an emphasis on possible stabilization of network changes during oxidative aging

Use of 1,3-bis(citraconimidomethyl)benzene as an antireversion agent in industrial rubber products

The following article describes the use of an antireversion agent which is useful for various applications of rubber products. 1,3-bis(citraconimidomethyl)benzene was evaluated in a series of typical applications in industrial rubber products and demonstrated advantages with regard to reversion resistance, during curing and following ageing. This improvement to the reversion resistance results in a better retention of vulcanisate properties such as tensile strength, crack growth resistance and abrasion resistance. In addition, heat evolution is significantly reduced in the presence of an anti-reversion agent

Mixing Aspects of Sulfron 3001 in Carbon Black Compounds

The mixing of Sulfron 3001 in carbon black compounds is described in this paper. The temperature-time profile of mixing between Sulfron and carbon black plays a critical role in realizing the positive effect of Sulfron on hysteresis characteristics. It has been shown that at a mixing temperature ≤140°C, there is almost no reaction between carbon black and Sulfron 3001. On the other hand, temperature above 165°C of mixing temperature, processing problems could occur because of side reactions of Sulfron 3001 on rubber. Two mixing sequences are described that provides the best results. It has been found that a temperature between 150-165°C is required to get the reaction of Sulfron 3001 and carbon black started. The time plays an important role too. It is demonstrated that time required is about 2-2,5 minutes after Sulfron and carbon blacks are added to the rubber mixes after the desired temperature (150-165°C) is reached

Improved Hysteresis and Adhesion to Steel Cord by Using Chemically Activated Aramid Fiber

This paper presents the results of studies to achieve adequate steel cord adhesion whilst seeking to improve hysteresis characteristics and to reduce compound heat generation through the use of chemically activated aramid fibers called Sulfron 3001. This unique ingredient is capable of reducing the compound hysteresis significantly. This reduction of hysteresis translates into lower heat generation and consequently better adhesion to steel cord, especially under dynamic environments

Higgs Sector of the Minimal Left-Right Symmetric Model

We perform an exhaustive analysis of the most general Higgs sector of the minimal left-right symmetric model (MLRM). We find that the CP properties of the vacuum state are connected to the Higgs spectrum: if CP is broken spontaneously, the MLRM does not approach the Standard Model in the limit of a decoupling left-right symmetry breaking scale. Depending on the size of the CP phases scenarios with extra non-decoupling flavor-violating doublet Higgses or very light SU(2) triplet Higgses emerge, both of which are ruled out by phenomenology. For zero CP phases the non-standard Higgses decouple only if a very unnatural fine-tuning condition is fulfilled. We also discuss generalizations to a non-minimal Higgs sector.Comment: brief discussion of non-minimal Higgs sectors added, journal versio

Signals of neutralinos and charginos from gauge boson fusion at the CERN Large Hadron Collider

We point out that interesting signals of the non-strongly interacting sector of the supersymmetric standard model arise from the production of charginos and neutralinos via vector boson fusion (VBF) at the Large Hadron Collider (LHC). In particular, if R-parity is violated, the hadronically quiet signals of charginos and neutralinos through direct production get considerably suppressed. We show that in such cases, the VBF channel can be useful in identifying this sector through clean and background-free final states.Comment: 10 pages Latex, 8 figures, minor changes in text and few references added, to be published in Phys. Rev.

Screening of Dirac flavor structure in the seesaw and neutrino mixing

We consider the mechanism of screening of the Dirac flavor structure in the context of the double seesaw mechanism. As a consequence of screening, the structure of the light neutrino mass matrix, m_\nu, is determined essentially by the structure of the (Majorana) mass matrix, M_S, of new super-heavy (Planck scale) neutral fermions S. We calculate effects of the renormalization group running in order to investigate the stability of the screening mechanism with respect to radiative corrections. We find that screening is stable in the supersymmetric case, whereas in the standard model it is unstable for certain structures of M_S. The screening mechanism allows us to reconcile the (approximate) quark-lepton symmetry and the strong difference of the mixing patterns in the quark and lepton sectors. It opens new possibilities to explain a quasi-degenerate neutrino mass spectrum, special ``neutrino'' symmetries and quark-lepton complementarity. Screening can emerge from certain flavor symmetries or Grand Unification.Comment: 27 pages, 3 figures; references added, discussion of the E6 model modifie

Radiatively Induced Neutrino Masses and Large Higgs-Neutrino Couplings in the Standard Model with Majorana Fields

The Higgs sector of the Standard Model with one right-handed neutrino per family is systematically analyzed. In a model with intergenerational independent mixings between families, we can account for very light neutrinos acquiring Majorana masses radiatively at the first electroweak loop level. We also find that in such a scenario the Higgs coupling to the light-heavy neutrinos and to the heavy-heavy ones may be remarkably enhanced with significant implications for the production of these heavy neutrinos at high energy colliders.Comment: Making the text of an old paper electronically availabl