Rubber-toughened polymers

Toughness enhancement can be realized by homogeneous rubber particles, core-shell particles, or heterogeneous modifier particles in the so-called disperse systems. The rubber content varies usually between 5 and 30 wt.%. An alternative is a network arrangement of the rubber in inclusion systems or network systems. 

100 nm thick) ultrathin sections only as cross sections, which are usually smaller than the real diameter ( tomato salad problem, see Figs. I.57-I.59 in Part I). 

Smaller core-shell particles as shown in Fig. 5.3 can be composed of different polymers and are used as modifiers for several polymers, such as PBA core-shell particles in PMMA (see Figs. 5.92-5.95) or EP copolymer particles in PP (see Fig. 5.146). A disadvantage of HIPS, ABS, and other systems containing polybutadiene rubber or PB containing copolymers is the limited weathering and aging stability that is due to their chemical double bonds. Therefore, several other rubber-like polymers without such reactive double bonds are used, such as EPR, EPDM, EVA, CPE, and PBA. 

Hgure 5.3 Core-shell particles (rubber shells with PS inclusions and SAN grafted surfaces) OSO4 stained, UDS, TEM 

Rgure 5.4 Rubber-toughened PP with EDPM (a) and EPR particles (b) stained ultrathin sections, TEM 

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The technical and commercial success of high impact polystyrene (HIPS) and acrylonitrile-butadiene-styrene (ABS) has led to a widespread research program on the use of rubbers as toughening agents for plastics. There is now an impressive 11st of rubber-toughened polymers including both amorphous and... 

Bucknall CB (2000) Deformation mechanisms in rubber-toughened polymers. In Paul DR and Bucknall CB (eds) Polymer Blends, Vol 2. Wiley, New York p 83... 

Partridge IK (1992) Rubber Toughened Polymers. In Rostami S (ed) Multicomponent Polymer Systems. Longman Scientific Technical Ltd., Essex, England, p 149... 

Distance between particles in rubber toughened polymers... 

A. Lazzeri, The kinetics of dilatational bands and the interparticle distance effect in rubber toughened polymers, in Proc. 10th International Conference on Deformation, Yield and Fracture of Polymers, Cambridge, UK, The Institute of Materials, London, 1997, p. 442. 

There is experimental evidence, for many rubber-toughened polymers, that the rubber particles cavitate early in the deformation. The degree of cross-linking is kept relatively low in the polybutadiene phase of ABS to aid cavitation, and sometimes silicone oil is added for the same reason. Figure 4.12 shows both the conventional stress-strain curve and the volumetric strain versus tensile strain for rubber-modified polystyrene. When the polystyrene yields, the volume strain increases at a higher rate. Majority of the dilatational strain is due to cavitation in the rubber phase. 

Multicomponent Polymer Systems, edited by I. S. Miles and S. Rostami, Longman Scientific and Technical, London, 1992. Three of the ten chapters of this book are devoted to blends, block copolymers and rubber-toughened polymers. 

Wu, S. (1985) Phase structure and adhesion in pol5mier blends a criterion for rubber toughening, Polymer, 26, 1855-1863. 

Cheung ME, Golovoy A, Mindroiu VE, Plummer Jr HK, van Gene H. Polysulfone and poly-(phenylene sulfide) blends 3. Rubber toughening. Polymer 1993 34(18) 3809-13. 

Williams G, Watts DC (1970) Non-symmetrical dielectric relaxation behavior arising from a simple empirical decay function. Trans Faraday Soc 66 80-85 Williams ML, Landel RR, Ferry ID (1955) The temperature dependence of relaxation mechanisms in amorphous polymers and other glass-forming liquids. J Am Chem Soc 77 3701-3707 Wood LA (1958) Glass transition temperatures of copolymers. J Polym Sci 28 319-330 Wu SH (1985) Phase structure and adhesion in polymer blends a criterion for rubber toughening. Polymer 26 1855-1863... 

Kuboky and co-workers [40] used transmission electron microscopy (TEM) to study block and white crazes in high impact polystyrene (PS). They examined the mechanism of block craze formation and found that the rubber molecules were not necessarily diffused into the entire crazes. The length of the block crazes varied before they turned to white and in some cases only white crazes were generated from the rubber particles. TEM should thus be used with caution in examining stained rubber-toughened polymers to ensure that all crazes, including the white crazes, were considered for evaluation of the extent of the deformation behaviour [41]. 

These are often referred to as rubber toughened polymers. The... 

These results show that the tensile properties of block copolsrmers, such as stif iess, tensile strength, elongation at break, and toughness, can be improved as compared to those of pure homopolymers, polymer blends, and rubber-toughened polymers. Moreover, this demonstrates the possibility of creating a new class of polymers with improved properties based on materials with structures at the nanometer scale. 

As the optimum fraction of the rubber component is rather low (0.05-0.30), the term rubber-toughened polymers (instead of blends ) is commonly used. 

Lazzeri and Bucknall [131] have proposed that the pressure dependence of yield behaviour caused by the presence of microvoids can explain the observation of dilatation bands in rubber-toughened epoxy resins [132], rubber-toughened polycarbonate [133] and styrene butadiene diblock copolymers [134]. These dilatation bands combine in-plane shear with dilatation normal to the shear plane. Whereas true crazes contain interconnecting strands, as described in Section 12.5.1 above, dilatation bands contain discrete voids that, for rubber-toughened polymers, are confined to the rubber phase. 

Additional Amorphous Rubber-Toughened Polymers (Rubber-Toughened PC, COC, Epoxy).392... 

Rubber-toughened polymers with an amorphous matrix and semicrystalline polymer matrix... 

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