Comparative study for target fragmentation in 4He and 6Li interactions with emulsion nuclei at Elab = 3.7A GeV

The multiplicity characteristics of the grey and black particles are studied in 3.7A GeV 4He and 6Li interactions with emulsion nuclei. The dependence on the system size is examined. The data are classified according the emission direction in the 4π space. The forward or backward emitted grey particle multiplicities distributions are approximated by exponential decay law. The black particle distributions also have the decay shapes, except for the CNO target nuclei; they are shoulder-shaped curves. The production probabilities and average multiplicities increase linearly with the target size. Multiplicity correlations are carried out. Regarding the nuclear limiting fragmentation hypothesis, the grey and black particle productions are independent of the projectile size.

An Investigation of the Effect of Taurit Filling of Rubber Mixes for the Coating of Radial Lorry Tyre Breakers

The results of investigating the effect of the shungite analogue Taurit (grade TSD) on the properties (measured on an RPA 2000 instrument) of a breaker rubber mix and of a rubber compound based on synthetic isoprene rubber SKI-3 are set out. Different methods of introducing Taurit have been tested: 10 parts into the rubber at the stage of its production; 10 parts into the standard rubber mix at the first stage of mixing; 10 parts into the rubber subjected to preliminary mechanical plasticisation in a laboratory internal mixer at a temperature of 100°C. The introduction of Taurit into the rubber in small quantities in order to reduce the proportion of rubber constituent in the rubber mix has also been tested. The test results have been compared with results for standard rubber mixes and rubber compounds. When Taurit is introduced into rubber at the stage of its production, the cohesive strength of the rubber mix and the rate of its vulcanisation and also the dynamic modulus components G′ and G″ are increased. When Taurit is introduced into plasticised rubber, again G′ and G″ are increased, there is an increase in plasticity, and the elastic recovery of the rubber mix is reduced. The breaker rubber compound from this mix has the best adhesion to metal cord and the highest dynamic strength. Data on the Payne effect indicate a better carbon black particle distribution when Taurit is introduced into the rubber at the stage of its production. Reduction in the proportion of rubber constituent in the rubber mix leads to a deterioration in the carbon black particle distribution.

Sensibility of grey particle production system to energy and centrality in 60A and 200A GeV 16O–Nucleus interactions

The grey particle production following 60 A and 200[Formula: see text]A GeV [Formula: see text]O interactions with emulsion nuclei is investigated at different centralities. The evaporated target fragment multiplicity is voted as a centrality parameter. The target size effect is examined over a wide range, where the C, N and O nuclei present the light target group while the Br and Ag nuclei are the heavy group. In the framework of the nuclear limiting fragmentation hypothesis, the grey particle multiplicity characteristics depend only on the target size and centrality while the projectile size and energy are not effective. The grey particle is suggested to be a multisource production system. The emission direction in the 4[Formula: see text] space depends upon the production source. Either the exponential decay or the Poisson’s peaking curves are the usual characteristic shapes of the grey particle multiplicity distributions. The decay shape is suggested to be a characteristic feature of the source singularity while the peaking shape is a multisource super-position. The sensibility to the centrality varies from a source to other. The distribution shape is identified at each centrality region according to the associated source contribution. In general, the multiplicity characteristics seem to be limited w.r.t. the collision system centrality using light target nuclei. The selection of the black particle multiplicity as a centrality parameter is successful through the collision with the heavy target nuclei. In the collision with the light target nuclei it may be qualitatively better to vote another centrality parameter.

INFLUENCE OF FILLERS ON SEMI-EFFICIENT VULCANIZED NATURAL RUBBER: DYNAMIC PROPERTIES AND HEAT BUILDUP

ABSTRACT Carbon black and silica have long been recognized as reinforcing fillers, but their effect on the dynamic properties and heat buildup of vulcanizates is rarely reported. Therefore, natural rubber composites filled by carbon black with different particle size and silica were prepared. The Payne effect and heat buildup progressively decrease with an increase of carbon black particle size because of weaker filler network structure and better dispersion, the N754 filled sample in particular shows the lowest value, only 4.7 °C. The tensile strength and tear strength of composites all increase with the reducing carbon black particle size. SiO2-filled composites exhibit obvious Payne effects and inferior mechanical properties; at high strains (>10%), tan δ of SiO2-filled composites surpasses all that of carbon black–filled composites, due to the surface silanol groups on the silica surface and due to the decreased cross-link density.

INFLUENCE OF STRAIN AMPLIFICATION NEAR CRACK TIP ON THE FRACTURE RESISTANCE OF CARBON BLACK–FILLED SBR

ABSTRACT Singularity of strain field at the crack tip of elastomeric material has recently attracted considerable attention. For SBR filled with four different types of carbon black, the strain distribution at the crack tip of the single-edge notched tension specimens are investigated using digital image correlation (DIC) and finite element analysis (FEA). Both DIC and FEA results demonstrate that the larger the carbon black particle size, the less strain amplification at the crack tip of SBR. However, the strain amplification region obtained from FEA simulation is much smaller than the strain amplification observed from DIC, and the reasons are discussed. Critical J-integral (JIC) and tearing modulus (TR) are calculated via J-integral method and are connected to crack initiation and propagation resistance of the SBR, respectively. With increasing carbon black particle size, both JIC and TR decrease. Similar trends also occur for tearing energy deduced from the dynamic mechanical thermal analysis. These results are in agreement with the prediction based on strain amplification at the crack tip.

A STUDY OF COMPOUND PARTICLES IN EMULSION

An attempt is made to study the compound particles by taking black and shower particles together. Average compound particle multiplicity is found to vary linearly with heavily ionizing particle multiplicity but with black particle multiplicity it does not show a linear dependence. Dispersion of the compound multiplicity distribution has also been studied. The ratio of the mean number of compound particles to its dispersion for different target sizes has been calculated.

Study on the Effects of Different Types of Carbon Black on the Performance of SBR2564S

The curing characteristics,crosslinking density,compressive permanent deformation,the conventional mechanical properties and dynamic mechanical properties of SBR2564S filled with different carbon black were studied.The results indicated that with the increase in specific surface area of carbon black particles，Mooney viscosity of the resulting mixture increased while the scorch time decreased.As the carbon black particle size increases, tensile strength and tear strength of SBR2564S were reduced,rebound and compressive set were increased.The kinds of carbon black had little effect on the crosslinking density of vulcanized rubber of SBR2564S.It had poor performance on dynamic mechanical properties of the resulting mixture filled with small carbon black particle size.SBR2564S vulcanizates with good comprehensive properties was obtained when N330 was used.