The kinetics of chemical crossliniking of various Polydienes with a SEV curing system based on CBS and S was investigated. The results show a significant influence of the polymer structure on the incubation time, the network formation and the reversion. It was observed that the statistical number of 1,4-structural units or the number of protons in allyl position in the polymer are the decisive factor of these dependencies. The results are discussed in relation with the mechanism of the accelerated sulphur vulcanisation.

The kinetics of chemical crossliniking of various Polydienes with a SEV curing system based on CBS and S was investigated. The results show a significant influence of the polymer structure on the incubation time, the network formation and the reversion. It was observed that the statistical number of 1,4-structural units or the number of protons in allyl position in the polymer are the decisive factor of these dependencies. The results are discussed in relation with the mechanism of the accelerated sulphur vulcanisation.

The temperature dependent characteristics of the ultrasonic damping of various elastomers were measured by means of a prototype Ultrasonic-spectrometer. The investigation emphasizes two central aspects: the filler-effects on the ultrasonic damping in the glass transition zone and the influence of the crosslinking-density and -structure on the ultrasonic behaviour. Furthermore some improvements to the measuring method are discussed.

The longitudinal moduli of elstomers M "(f) were measured by means of a prototype ultrasonicspectrometer in a frequency range from 0,5 MHz to 2 MHz. The results are compared with the shear moduli G "(f) obtained from low frequent dynamical testing and frequency-temperature-super-position. The investigation shows that ultrasonic spectroscopy can give important indications to the correction of mastercurves.

The phase morphology and the filler distribution in polymer blends were characterized by means of a new dynamic mechanical analyzing method. Surface treatment of carbon black and silica both effects the filler distribution in polymer blends and the resulting mechanical properties too. A treatment of carbon black with zinkdimethyldithiocarbamate results in a more equal filler distribution in a NR/BR blend. In a silica filled NR/BR blend as well as for an EPDM/BR blend, going from an in situ silanisation to pre silanisation a less enlarged filled interphase is found.

The influence of the mixing order during compounding of silica filled NR-BR-SBR tread blends on the morphology and the technological properties is analysed. It showed that silanisation of the silica in the BR-SBR master batch leads to significantly improved mechanical properties with respect to tensile strength and dynamic crack propagation, albeit the filler dispersion is clearly reduced in this case. The positive effects originate from a more balanced silica distribution, which causes a reduction of the Payne effect and a modifed shape of the stress strain curves, i.e. moderate slope at the begin and steep slope at the end. As reason for a heterogeneous filler dispersion in the NR-silica master batch a premature chemical attechment of thermomechanically broken NR-chains during silanlsation of the silica is postulated, by which the NR-phase becomes strongly overloaded.

The influence of the mixing order during Compounding of silica filled NR-BR-SBR tread blends on the morphology and the technological properties is analysed. It showed that silanisation of the silica in the BR-SBR master batch leads to significantly improved mechanical properties with respect to tensile strength and dynamic crack propagation, albeit the filler dispersion is clearly reduced in this case. The positive effects originate from a more balanced silica distribution, which causes a reduction of the Payne effect and a modified shape of the stress strain curves, i.e. moderate slope at the begin and steep slope at the end. As reason for a heterogeneous filler dispersion in the NR-silica master batch a premature chemical attachment of thermomechanically broken NR-chains during silanisation of the silica is postulated, by which the NR-phase becomes strongly overloaded.

The phase morphology and the filler distribution in polymer blends were characterized by means of a new dynamic mechanical analyzing method. Surface treatment of carbon black and silica both effects the filler distribution in polymer blends and the resulting mechanical properties too. A treatment of carbon black with zinkdimethyldithiocarbamate results in a more equal filler distribution in a NR / BR blend. In a silica filled NR / BR blend as well as for an EPDM / BR blend, going from an in situ silanisation to pre silanisation a less enlarged filled interphase is found.

Considering the performance of multilayer elastomer products like tires the distribution of crosslinking chemicals caused by diffusion following the assembly step during storage and vulcanization is an interesting aspect for covulcanization, crosslink density and influences on the adhesion systems. In this manner the diffusion behavior and the equilibrium distribution of the dithiophosphate accelerator, di-(2-ethyl)hexylphosphorylpolysulfide (SDT) between different rubber compounds used in tires was investigated by means of Fourier Transform infrared spectroscopy (FT-IR spectroscopy) and swelling. The equilibrium distribution of SDT differs as a function of the rubber matrices involved, with the consequence that the concentration decreases in the direction tread -undertread - steel cord mixture.

For three different free-flowing rubber/filler-composites, based on NR/ carbon black, E-SBR/carbon black and E-SBR/silica/silane, studies are conducted on the continuous manufacture of rubber compounds. A co-rotating twin screw extruder is used for mixing. An optimum screw configuration could be found for each RFC type. To minimize the time and work expense required for a formula change a common screw configuration for all three RFC types is developed. The attained compound and vulcanizate properties are at a high level. Finally, results from the continuous rubber mixing process on a production extruder are shown.

介绍了双螺杆挤出机在2种混炼配置上所作的连续混炼的实验.通过对混炼胶的各种加工特性的分析表明,混炼元件配置越多,大体上填充剂的分散程度也越高,高水平的混炼质量不会因提高输送率而受到很大影响.2种螺杆配置获得的混炼胶的性能都优于密炼机上所获得的性能.

A comparative study of bale rubber and rubber/filler composites rubber mixing was performed with the goal of comparing the rheological behavior of the mixes and the physical properties of the corresponding vulcanizates. By varying the processing conditions, the state of the mixes was changed while maintaining the same composition. The comparison showed that free flowing rubber / filler composites provide superior quality rubber mixes after just short mixing times (lower power consumption) in discontinuous mixing processes. The state of dispersion of the filler, the viscoelastic properties of the mixes and the dynamic crack growth resistance of the corresponding vulcanizates are improved significantly.In addition, the continuous mixing process performed on a co-rotating twin screw extruder rounds off the comparison. The nearly same levels of the viscoelastic, dynamic and ultimate properties of continuously mixed compounds indicate the influence of the screw configuration and screw rotation speed. This is inasmuch of importance as the residence time of the rubber compound in the mixing zones of the TSE is very short.

The frequency dependent dynamic-mechanical properties of several elastomers(NR, BR and different SBR types) were measured by means of ultrasonic spectrometry (using a prototype ultrasonic spectrometer) and dynamic mechanical analysis. The results of the ultrasonic measurements are in agreement with the data from dynamic mechanical measurements and frequency-temperature superposition. In particular the dependence of the loss modulus G" on frequency is confirmed categorically by the ultrasonic results for the longitudinal loss modulus W. The examples shown here demonstrate the potential of the new ultrasonic spectrometer.

The influence of surface modification of precipitated silica by defined silanization on filler-rubber interaction and filler distribution in NBR/BR blends is investigated. The distribution of silica in the different phases of blends is estimated from the height of the loss modulus in the glass transition range. The linear increase of the maximum value of the loss modulus is not only caused by the increase in the volume fraction of the silica, but is also governed by the strength of the filler-matrix interaction. There is a greater linear increase with increasing phase bonding, i.e. with decreasing interface tension; more energy is dissipated in the glass transition range. It is shown that with increasing phase bonding the extent of the dependence G"=(phi) rises and, due to the surface modification, the filler distribution, the dispersion and the dynamic-mechanical properties can be selectively influenced.

The curing process of NR with different CBS/S-ratios was studied in order to get more information about the mechanism of the accelerated sulfur vulcanization. Time dependent collected extracts of the vulcanizates were analyzed by means of HPLC-MS and HPLC-UV. The MS-analysis shows the existence of dibenzothiazolyl-polysulfides during the scorch period. Quantitative analysis of the soluble reaction products demonstrates the influence of the sulfur-accelerator-ratio to the disproportion of the accelerator and the rate of the crosslinking reaction.

Thermoplastic vulcanizates (TPE-V) based on isotactic polypropylene (iPP) and polar rubbers (ENR, EVA, HNBR, NBR, ACM) were prepared by dynamic vulcanization in a laboratory internal mixer with the scope to describe the frame for further developments of oil resistant materials.At a constant iPP/rubber ratio the oil resistance increases in the sequence of increasing polarity of the rubber: EVA < ENR < HNBR < NBR < ACM. The effect is not or only slightly affected by the phase morphology. In contrary the higher crosslinking density of the rubber domains the higher the oil resistance for each system under consideration. By increasing the content of the plastic phase the oil resistance and the ultimate properties are improved. By reducing the interfacial tension between the rubber and the plastic either by properly exploiting the thermodynamic potential of the blend constituents or by incorporating phase compatibilizers the level of the mechanical properties is systematically increased. However, non-polar phase compatiblizers as used in TPE-Vs based on iPP impair the oil resistance.

In order to gain a better understanding of the reinforcement mechanism of fillers, the surface activity of a selection of industrial carbon blacks produced by different procedures with varying average particle sizes (spec. N2 surface area) and aggregate structure (DBP number) were investigated using the volumetric gas adsorption method. The adsorption isotherms for polymer-like gases were used to determine the particles’ geometrical surface roughness and the distribution functions of energetically different bonding sites for polymers on the surfaces on atomic length scales. The influence of the surface activity on the reinforcement of elastomers is demonstrated using examples of vulcanisates.

Linear polydienes differing in molecular weight as well as in konstitution (vinyl, cis-1,4-butadiene, styrene units) show significant changes in the dynamic mechanical storage and loss moduli. For a given constitution, the reptation time T rep is related to the molecular weight by a characteristic power law. The universal exponent 3.4 is understandable on basis of molecular models. With higher side group density, the plateau modulus G(N) decreases due to lower entanglement density. The plateau modulus was found to be proportional to the inverse-square of the chain cross-sectional area and also to the inverse-cubic of the packing length.

In material-sensitive recycling of crushed reclaimed rubber materials, which is achieved by admixing the recycled rubber with new rubber matrices, a drop is noted in the mechanical value level of elastomers. This drop is due to deficient grafting of the recycled rubber with the fresh rubber matrix. To improve grafting quality, the particle surfaces are modified chemically in different ways following a comprehensive morphological and chemical characterization of select types of rubber powder. Grafting with maleic anhydride and grafting of reactive silane-based coupling agents following epoxidation or hydroxylation have shown themselves to be the most promising methods. The criterion applied to evaluate the suitability and effects of the surface modification is the level of or the observable changes in the material's mechanical properties, such as, for example, fracture stress and dynamic modulus.