Friction characteristics of 20 x 4.4, type 7, aircraft tires constructed with different tread rubber compounds

A test program was conducted at the Langley aircraft landing loads and traction facility to evaluate the friction characteristics of 20 x 4.4, type, aircraft tires constructed with experimental cut-resistant, tread rubber compounds. These compounds consisted of different blends of natural rubber (NR) and an alfin catalyzed styrene-butadiene copolymer rubber (SBR). One tire having a blend of 30 SBR and 70 NR and another having a blend of 60 SBR and 40 NR in the tread were tested together with a standard production tire with no SBR content in the tread rubber. The results of this investigation indicated that the test tires constructed with the special cut-resistant tread rubber compositions did not suffer any significant degradation in tire friction capability when compared with the standard tire. In general, tire friction capability decreased with increasing speed and surface wetness condition. As yaw angle increased, tire braking capability decreased while tire cornering capability increased. Tread-wear data based on number of brake cycles, however, suggested that the tires with alfin SBR blends experienced significantly greater wear than the standard production tire

Rolling friction for hard cylinder and sphere on viscoelastic solid

We calculate the friction force acting on a hard cylinder or spherical ball rolling on a flat surface of a viscoelastic solid. The rolling friction coefficient depends non-linearly on the normal load and the rolling velocity. For a cylinder rolling on a viscoelastic solid characterized by a single relaxation time Hunter has obtained an exact result for the rolling friction, and our result is in very good agreement with his result for this limiting case. The theoretical results are also in good agreement with experiments of Greenwood and Tabor. We suggest that measurements of rolling friction over a wide range of rolling velocities and temperatures may constitute an useful way to determine the viscoelastic modulus of rubber-like materials.Comment: 7 pages, 6 figure

Dynamic Soft Elasticity in Monodomain Nematic Elastomers

We study the linear dynamic mechanical response of monodomain nematic liquid crystalline elastomers under shear in the geometry that allows the director rotation. The aspects of time-temperature superposition are discussed at some length and Master Curves are obtained between the glassy state and the nematic transition temperature Tni. However, the time-temperature superposition did not work through the clearing point Tni, due to change from the ``soft-elasticity'' nematic regime to the ordinary isotropic rubber response. We focus on the low-frequency region of the Master Curves and establish the power-law dependence of the modulus G' ~ omega^a. This law agrees very well with the results of static stress relaxation, where each relaxation curve obeys the analogous power law G' ~ t^{-a} in the corresponding region of long times and temperatures.Comment: Latex, [epj]{svjour} style, 9 pages 11 figures submitted to Euro. Phys. J.

Synthesis of siliceous fillers based on waste of silicon plant in Karaganda

This work is devoted to the synthesis of the silica filler- fumed silica based on various liquid glass (sodium and potassium) for further out of the use in the rubber industry. We obtained water glass was heated to 70 degrees with constant stirring. Selection by us revealed that for every 50 ml needed water glass 5 ml of hydrochloric acid to precipitate a white termination loss - white carbon. The hallmark of this study is that the raw material for fumed silica is a waste of Karaganda silicon plant - microsilica does not require energy - costs compared to analogical ways

In situ characterisation of dispersion processes of silica in an elastomer matrix under shear, impact of a filler treatment

International audienceThe dispersion of a filler immersed in a polymer flow submitted to shear is the result of the counterbalance between hydrodynamic forces acting on the agglomerate and its cohesive forces. The nature of the filler, its surface treatment or its degree of infiltration by the polymer should impact its cohesivity. To better understand the influence of these parameters on dispersion, direct observations of dispersion mechanisms under shear were carried out on raw silica, silica treated with a covering agent and fully infiltrated silica agglomerates. Dispersion mechanisms and critical stresses for dispersion were determined and found to be different in those three cases

Characterization of dispersion mechanisms of agglomerated fillers in an elastomer matrix under shear by in-situ observations

International audienceThe mixing of carbon black or silica fillers and a polymer matrix in an internal mixer implies two processes: dispersion and distribution. To disperse implies to reduce the filler initial size (a hundred microns) down to the aggregate size (a few tens of nanometers). This size is necessary to ensure the reinforcement of the matrix. Although the mixing of a filler and a matrix is an usual operation, elementary mechanisms and key parameters responsible for the size reduction of the filler are not fully understood. The rheo-optical technique (counter-rotating shear cell coupled with an optical microscope) is an efficient technique to observe in-situ during shear the filler dispersion mechanisms. Kinetics and criteria of dispersion mechanisms such as erosion or rupture can be determined. The present work compares the shear-induced dispersion mechanisms and criteria of different grades of carbon black and silica in a common polymer matrix (styrene-butadiene rubber). The objective was to determine the role of the intrinsic parameters of the filler (specific area) on dispersion. This study shows differences in the dispersion mechanisms of silica and carbon black. The data will be discussed in terms of internal organisation of the fillers

Deformation and recovery behaviour of thermoplastic vulcanisates

The purpose of this study was to identity key elements in the microstructure of thermoplastic vulcanisates (TPVs) in order to understand better the deformation and recovery characteristics of thermoplastic vulcanisate blends. Thermoplastic vulcanisates based on natural rubber and a thermoplastic (polypropylene) were studied. The rubber was dynamically crosslinked during melt-blending and test specimens were produced by injection moulding and extrusion. Morphological analysis and tensile stress–strain studies were used to investigate the effect of composition, processing and microstructure on the deformation and recovery behaviour of thermoplastic vulcanisate blends. [Continues.

Pengaruh Konsentrasi Anhidrida Maleat Dan Peroksida Benzoil Terhadap Persen Pencangkokan Pada Sintesis Kompatibilizer Polyethylene-Graft-Maleic Anhydride

Telah dilakukan sintesis Linear Low Density Polyethylene- graft-Maleic Anhydride (LLDPE-g-MA) untuk mengetahui pengaruh konsentrasi anhidrida maleat dan peroksida benzoil terhadap persen pencangkokan. Sintesis dilakukan dengan cara mencangkokkan monomer anhidrida maleat ke dalam Linear Low Density Polyethylene (LLDPE) dengan bantuan peroksida benzoil sebagai inisiator dan xylene sebagai pelarut. Reaksi dilakukan dalam reaktor stainless steel pada suhu 120°C selama 5 jam dengan bantuan gas nitrogen. Konsentrasi anhidrida maleat divariasikan antara 10-40 per seratus resin, sedangkan variasi BPO dilakukan pada 0,5-2 per seratus resin. Persen pencangkokan ditentukan dengan menghitung monomer anhidrida maleat yang tercangkok ke dalam LLDPE. Analisis Fourier Transform Infra Red (FTIR) dilakukan untuk mempelajari gugus fungsi yang terbentuk dalam LLDPE-g-MA. Hasil penelitian menunjukkan bahwa persen pencangkokan tertinggi sebesar 9,2598% dihasilkan pada penggunaan anhidrida maleat sebesar 40 per seratus resin dan BPO sebesar 2 per seratus resin

Recycling of Pretreated Polyolefin-Based Ocean-Bound Plastic Waste by Incorporating Clay and Rubber

Plastic waste found in oceans has become a major concern because of its impact on marine organisms and human health. There is significant global interest in recycling these materials, but their reclamation, sorting, cleaning, and reprocessing, along with the degradation that occurs in the natural environment, all make it difficult to achieve high quality recycled resins from ocean plastic waste. To mitigate these limitations, various additives including clay and rubber were explored. In this study, we compounded different types of ocean-bound (o-HDPE and o-PP) and virgin polymers (v-LDPE and v-PS) with various additives including a functionalized clay, styrene-multi-block-copolymer (SMB), and ethylene-propylene-based rubber (EPR). Physical observation showed that all blends containing PS were brittle due to the weak interfaces between the polyolefin regions and the PS domains within the polymer blend matrix. Blends containing clay showed rough surfaces and brittleness because of the non-uniform distribution of clay particles in the polymer matrix. To evaluate the properties and compatibility of the blends, characterizations using differential scanning calorimetry (DSC), scanning electron microscopy (SEM), and small-amplitude oscillatory shear (SAOS) rheology were carried out. The polymer blend (v-LDPE, o-HDPE, o-PP) containing EPR showed improved elasticity. Incorporating additives such as rubber could improve the mechanical properties of polymer blends for recycling purposes