Several Factors that Influence Mechanical Properties

3 Several Factors that Influence Mechanical Properties 

The effect of the size of EPDM domains in the PP dominant matrix has been investigated since the initial study of TPV (15-19). It is well known that the size of the rubber domain affects the mechanical properties of both TPE and TPV. Wu (29) suggested that the critical mbber domain size and the critical distance between rubber domains are very important for toughness in rubber-filled nylon. This also appears to be the case of TPV. The typical stress-strain curve for TPV is shown in Fig. 8.17. 

In this curve, the symbol X represents the breaking points as a function of the EPDM domain size (dm)- The smaller EPDM domain size renders the higher tensile strength, which was first observed by Coran et al. (15). They as well as Ellul et al. (30) and Kojina (19) also showed the effect of cross-link densities of the EPDM dispersed phase on the tensile strength and tension set are shown in Fig. 8.18. The higher crosslink density in the EPDM phase was found to result in higher tensile strength and lower permanent set. 

To improve the compatibility between the PP dominant matrix and the EPDM dispersed phase, various compatibihzers have been prepared and incorporated into 

They found that the introduction of the compatibiliziler reduced the yield stress, but increased the elongation at break ratio, the results of which are shown in Fig. 8.20. 

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Considerable effort has been spent to explain the effect of reinforcement of elastomers by active fillers. Apparently, several factors contribute to the property improvements for filled elastomers such as, e.g., elastomer-filler and filler-filler interactions, aggregation of filler particles, network structure composed of different types of junctions, an increase of the intrinsic chain deformation in the elastomer matrix compared with that of macroscopic strain and some others factors [39-44]. The author does not pretend to provide a comprehensive explanation of the effect of reinforcement. One way of looking at the reinforcement phenomenon is given below. An attempt is made to find qualitative relations between some mechanical properties of filled PDMS on the one hand and properties of the host matrix, i.e., chain dynamics in the adsorption layer and network structure in the elastomer phase outside the adsorption layer, on the other hand. The influence of filler-filler interactions is also of importance for the improvement of mechanical properties of silicon rubbers (especially at low deformation), but is not included in the present paper. 

When designing biosensors, it is essential to study and tmderstand each component that constitutes this complex system as well as aU the factors that influence its unique performance and limitations [5,6]. Despite an important number of publications in the biosensor field, several aspects require further optimization and improvements many of these could be related to inadequate materials and insufiftcient understanding of the underlining mechanism. Since the properties and the type of the material used are largely connected with the transducer and the transducer/detector interface, a considerable attention must be paid to the nature of electrode material. The rapid... 

Abstract The chapter describes procedures and materials used and results obtained from several important studies of the mechanical performance of surgical sutures and the chnical factors that influence their behavior. Key features of successful suture assembly are the material used, structure of the thread, surface treatment, knot strength, and security, the in vivo environment and compatibihty of the tensile properties of the thread with those of the tissues approximated during and after surgery. To improve suture success in terms, particularly, of knot performance, couphng of thermal and chemical energies in conjunction with mechanical interlacing have been experimented with. 

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