Rubber modification, effect

A more effective toughening of brittle thermoplastics is often achieved using rubber modification. This is discussed in more detail in Section 5. 

To demonstrate the effect of rubber modification on the impact toughness, the notched impact strength and the energy release rate were measured [14]. The results are summarized in Table 25.2. 

We have been investigating the effects of multifunctional monomers, rubber modification and light intensity upon both the rate and final degree of cure in acrylated epoxy systems. 

Within the acrylate formulations we were especially interested in the effects of acrylonitrile-butadiene rubber modification of photopolymers with varying multifunctional monomers, photoinitiator concentration and light intensity. 

The transfer constants of the EPDM elastomer are relatively low, but the rubber modifications that occur with grafting can make rubber an effective reinforcing agent for the brittle matrixes under consideration. 

Previous explanations of the impact modification effect and its phase transition like the brittle-to-tough transition have assumed a basically statistical distribution of the dispersed rubber phase in the continuous polymer matrix [139], From there the critical interparticle distance model originated [139b], which is essentially a percolation-type theoretical interpretation. Experimental results like those reported by Bucknall [139a], but also many crack surfaces published in the literature, show that more rubber phase is present in the visible area of the crack surface than would be expected from a statistical distribution, SEM evaluations are consistent with our findings of a non-statistical distribution, but a phase separation of the dispersed material into some kind of layer. 

While the polyketone terpolymer derived from carbon monoxide, ethylene, and propylene is economical with some attractive properties, such as heat, chemical, permeation, and abrasion resistance, it suffers from low-impact strength. One cost-effective approach to overcoming this shortcoming and upgrading its performance profile for automotive applications such as wheel covers, wheel caps, fuel filter necks, fuel tanks, fuel tubes, center fascias, door handles, roof rack covers, gears, junction boxes, connectors, and seat backs, as well as electric/electronic components and durable household items involves blending with polyamides including a rubber modification (Lee et al. 2013). 

Tribological characteristics confirm the influence of sulfur modification of metal counter face on lowering fiiction for the metal-polymer couples studied. In the case of ebonite, the coefficient of friction reduced significantly for the whole experimental mn, whereas application of SBR vulcanizate or polysulfide rubber was effective only during the first period of experimental cycles. Any improvement of tribiological characteristics was not assigned for polysulphone. The polymer was observed to worn the surface of iron counterface, what resulted in increase of the coefficient of friction in this case. 

H. Ismail, N. Rosnah, and U. Ishiaku, Oil palm fibre-reinforced rubber composite effects of concentration and modification of fibre surface. Polym. Int. 43(3), 223-230 (1997). 

Whilst many of these areas fall outside the scope of this chapter, particulate polymer composites are becoming increasingly complex and commonly require more than just inclusion of a filler or particle additive in order to achieve optimum properties. For example, rubber modification of mineral-filled thermoplastics to yield a balance of enhanced toughness and stiffness, is an area of commercial importance. In these ternary-phase systems, there is not only a requirement to attain good dispersion of the filler component, but also a need for breakdown of the rubbery inclusion to yield the most effective size and spatial location within the composition. Whilst this may depend to a large extent on characteristics of the material s formulation, it can also be influenced by the material s compounding route. 

Toughening epoxy matrices using liquid reactive rubbers (such as carboxyl-terminated butadiene acrylonitrile, CTBN, or the amine-terminated equivalent, ATBN) has been widely reported in the literature. Spherical rubber particles of a proper size distribution (usually 1-5 pm) can effectively enhance the toughness through crack blunting or cavitation mechanisms. However, rubber modification of epoxies becomes... 

The data also demonstrate that the addition of the thermoplastic, PMMA, does not have the significant effect on the toughness or adhesion properties as does the addition of the rubber, Vamac B-124. Clearly, the physical properties of the polymeric additive determine the magnitude of the adhesive physical property modifications, which result from their addition to an alkyl cyanoacrylate monomer. 

Biopolymers have diverse roles to play in the advancement of green nanotechnology. Nanosized derivatives of polysaccharides like starch and cellulose can be synthesized in bulk and can be used for the development of bionanocomposites. They can be promising substitutes of environment pollutant carbon black for reinforcement of rubbers even at higher loadings (upto SOphr) via commercially viable process. The combined effect of size reduction and organic modification improves filler-matrix adhesion and in turn the performance of polysaccharides. The study opens up a new and green alternative for reinforcement of rubbers. 

---