The present work studies the influence of thermal aging behaviour of rubber compounds based on natural rubber (NR), styrene butadiene rubber (SBR) and their blend NR/SBR 60/40 on dynamic-mechanical and fatigue crack growth properties. The thermal ageing at the temperatures 70 and 110 degrees C has been applied, which closely simulates the real service conditions of tires. Dynamic mechanical analysis (DMA) and fatigue crack growth (FCG) properties were characterised for the aged samples. The loss compliance J" has been determined as a parameter, which effectively is detecting the embrittlement or softening/hardening behaviour of the aged rubber. Finally, the FCG studies revealed that increase in aging temperature has deleterious effect on crack growth resistance as was reflected in all the aged materials.

The study deals with the influence of mineral fillers surface modification on properties of some filled elastomer systems. The mineral fillers (calcined kaolin and precipitated silica) were tested in styrene-butadiene rubber compounds. For surface treatment of both fillers two types of organic acids were used as modification agents (stearic and benzoic acid). In this work the influence of fillers surface modification on vulcanization characteristics, gas permeability and physical-mechanical properties of SBR rubber compounds was measured and evaluated. Obtained results indicate improvement in some properties by used mineral filler surface modification, which could be result of better filler surface/polymer matrix interaction.

The intercalation of organic compound is necessary to functionalize the montmorillonite surface. So, the intercalation of diethylene glycol and polyethylene glycol and the influence of plasticizer, namely tricresyl phosphate and isodecyldiphenyl phosphate as co-intercalating agents were studied. For the PVC/clay nanocomposites the suspension type of PVC was used and the compound was prepared by the melt intercalation method. Two kinds of MMT (Cloisite (R) Na(+), Cloisite (R) 30B) and laboratory modified MMT by intercalation (diethylene glycol, polyethylene glycol) and co-intercalation (tricresyl phosphate and isodecildifenyl phosphate) agents were used for the set of nanocomposite samples. The thermal stability of nanocomposite specimens was tested using of thermo gravimetric analysis, DMA and pH method.

In this research, the effect of modified filler on mechanical properties of polymer/clay composite was studied. Firstly, the filler - vermiculite was modified by two methods. Former one was done by hexadecyltrimethylammonium bromide, the latter by maleic anhydride. The level of clay modification was determined by X-ray diffraction and Fourier transform infrared spectroscopy. Further, the fillers were compounded with the polymer matrix Surlyn 8920. The level of filler dispersion in polymer was studied by X-ray diffraction and their influence on physical properties was found by mechanical test. Their results showed that tensile modulus increased, while the tensile stress decreased for treated filler compounds.

Most rubber articles are prepared from filler-elastomer compounds and dynamic mechanical data can give valuable insight into behavior of such systems. The aim of this study was to compare complex tensile modulus E* and complex shear modulus G* using seven types of vulcanized filled rubbers and two testing devices.Carbon black and clay filled styrene butadiene rubber (SBR) compounds were tested. The E* value was measured using a dynamic mechanical analyzer (DMA DX04T from R.M.I.) and the G* value using a rubber process analyzer (RPA 2000 from Alpha Technologies) at 1 Hz, 30 degrees C and at small deformation amplitudes common to both devices. For characterization of tested materials absolute values of complex modulus \E*\ and \G*\ were used together with values of loss factor tan delta.The highest values of \E*\, \G*\ and tan delta in tested carbon blacks were obtained for type N330. The highest values of \E*\, \G*\ and tan delta in tested clay fillers were found for organoclay Cloisite 93A.Maximum at the dependence tan delta/amplitude, obtained in a broader shear amplitude range, was found to be smaller for carbon black filled compounds than expected and maximum at this dependence for clay filled compounds was not observed.The amplitude dependences of analogous dynamic mechanical characteristics from dynamic mechanical analysis (DMA) and rubber process analysis (RPA) measurements seem to be similar. Between the analogous dynamic mechanical characteristics from DMA and from RPA usually a linear relationship exists with high correlation coefficient.Conclusions derived from DMA and RPA testing on the same series of rubber compounds seem to be the same. Copyright (C) 2006 John Wiley & Sons, Ltd.

The paper concentrates on poly(vinyl chloride) – PVC – from the point of view of structural characterisation of PVC/clay nanocomposites through X-ray diffraction, thermogravimetric analysis and dynamic rheometric analysis. PVC plasticizer was mixed with clay, natural and organophilic, and the suspension was then compounded with other components. Two factors were followed: effect of shearing alone, and in combination with temperature. The type of filler and the method of composite preparation affect the mechanical and thermal properties of the composite, through delamination and exfoliation levels. The results showed that the thermal degradation is shifted towards higher temperatures for organophilic clays, compared to chemically untreated natural clay.

Small deformations of hard materials are characterized by elastic modulus E. For characterization of elastomers a stress at given strain is commonly used. This value is obtained from one measured point on the stress–strain curve. For characterization of tensile behaviour of elastomers we have used here a specific deformation energy in tension between zero and the chosen strain. The coefficients of variation of the measured specific deformation energies were reasonably low. The main advantage of using the specific deformation energy (instead of stress at given strain) is the fact that this value is obtained directly from all measured data between zero and the chosen strain. Specific deformation energy should be therefore more sensitive to differences in behaviour of elastomers than the stress at given strain.

In this paper poly(vinyl chloride)/clay nanocomposites were prepared by melt intercalation using a single screw extruder. Problems with thermal stability of these nanocomposites during compounding were largely eliminated by pre-treatment of the organoclay with plasticizer (dioctyl phthalate), which created a barrier between polymer and quaternary amine. These nanocomposite materials were analyzed with respect to their morphology. The intercalation, exfoliation, nano-phase dispersion and orientation were investigated using Transmission Electron Microscopy (TEM), Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM) and X-ray diffraction (XRD). Moreover, different types of sample preparation for these techniques were tested as well. It was found that partially intercalated and disordered structure arose in poly (vinyl chloride) composites containing sodium type of montmorillonite, while a fine dispersion of partial to nearly full exfoliation of individual montmorillonite layers in poly (vinyl chloride) matrix was observed when this clay was organically modified. Finally, the influence of different mixing time (in extruder) on nano-phase morphology was surveyed.

Abstract Polyvinylchloride compositions have been prepared by the melt intercalation method using a single screw extruder. Different types of nanofiller based on natural sodium montmorillonite were tested. In particular, intercalating agents containing amine groups combined with co-intercalating agent (low or high molecular weight plasticiser) were examined to determine which is the most suitable not only for producing the largest basal spacing and subsequently the best exfoliation of clay tactoids in polymer matrix, but also for the highest beneficial influence on mechanical properties. In the case of improved exfoliation, the effect of compounding was investigated. Therefore, three values of screw speed were studied and some blends were compounded twice to study the retention time in a single screw extruder and the influence on orientation, dispersion and exfoliation of clay particles in the PVC matrix. Moreover, the effect of different types of plasticiser on mechanical properties was also studied. Bis(2-ethylhexyl) phthalate, Bis(2-ethylhexyl) adipate and Lankroflex epoxy plasticiser were tested. Dynamical thermo-mechanical properties were examined and the tensile properties of thin PVC sheets prepared by calendaring. Using X-ray diffraction and transmission electron microscopy, it was found that partially intercalated and disordered structures arose in polyvinylchloride composites containing sodium montmorillonite, while a fine dispersion of partial exfoliation of individual montmorillonite layers in polyvinylchloride matrix was observed when this clay was organically modified. Finally, the value of the tensile modulus for PVC nanocomposites containing as little as 5 wt-% montmorillonite was increased three times provided that the optimum melt processing conditions were used.

Sodium montmorillonite (MMT Na+) was modified by co-intercalation, i.e. simultaneous action of octadecylamine and stearic acid in different ratios. The amount of MMT Na+ was calculated as 5 wt % to the weight of PP. Co-intercalation was carried by the mechanism of ion-dipole reaction and the achieved result was measured by XRD technique. The modified MMT and polypropylene (PP) were mixed on a one screw KO Kneader Buss with maleic-anhydride-modified PP (PPMa) as a compatibilizer. The content of PPMa in mixtures was 5 wt % to the weight of PP. The level of MMT exfoliation in the nanocomposite systems was also studied by SEM technique. The properties of samples were evaluated by the measurement of mechanical properties (break point and break strain). To assese the systems' morphology SEM technique was used. The influence of different ratios of the individual components on the properties of polypropylene nanocomposites is discussed. The improvement of PP nanocomposite was achieved in the mechanical properties measurement and confirmed by SEM also, but only for lower value of ODA/STA concentrations.