Toughening with rubber

We most often encounter polystyrene in one of three forms, each of which displays characteristic properties. In its pure solid state, polystyrene is a hard, brittle material. When toughened with rubber particles, it can absorb significant mechanical energy prior to failure. Lastly, in its foamed state, it is versatile, light weight thermal insulator. 

Poly(phenylene sulphide) Polypropylene Polystyrene toughened with rubber Styrene-acrylonitrile... 

Polystyrene may be extruded to produce film and other transparent articles with high gloss finish but in commercial practice the formulations toughened with rubber are used to a greater extent (extruded transparent film is toughened by stretching and orientation while it is still hot from the die). 

Figure 6. Comparison of experimental and predicted values of Youngs modulus of epoxy resin toughened with rubber particles. Finite-element predicted values were calculated using two values of the Poisson ratio of the rubber phase and the predicted bounds using the Ishai and Cohen model (26).

Bartczak, Z., Argon, A. S., Cohen, R. E., and Weinberg, M. (1999a) Toughness mechanism in semi-crystalline pol5mer blends I. High density polyethylene toughened with rubber, Polymer, 40, 2331-2346. 

Many amorphous thermoplastics are brittle, limiting their range of applications. Toughening with rubber is well known to enhance fracture resistance and toughness. Many major chemical industries are based on toughened plastics, such as ABS, HIPS and ionomers [30-34]. Important issues in the design of fracture resistant polymers are compatibility, deformation, toughening mechanisms and characterization. Particle size distribution and adhesion to the matrix must be determined by microscopy to develop structure-property relationships. 

Figure 7 shows the embrittlement filler content (f) plotted against the ratio of the strength to the draw stress Om/c dni- 4> increases with an increase in the critical volume fraction for polyvinylchloride (PVC) is less than 0.05, and is not improved by toughening with rubber particles. If a polymer does not strain-harden, even a small amount of filler leads to loss of ductility. The critical volume fractions for polypropylene (PP) and for copolymers of polyethyleneterephthalate (PET), Kodar 6763, are higher, from 0.1 to 0.2. The critical filler content of... 

Bartczak AS, Argon RE, Cohen M. Weinberg toughness mechanism in semi-crystaUine polymer blends I. High-density polyethylene toughened with rubbers. Polymer 1999 40(9) 2331-46. 

The MMA are usually toughened with rubber dissolved in the monomer (Figure 1.22) and it is these rubber particles that provide the high peel strength and toughness. 

Cyanoacrylate adhesive can be made from different acrylate monomers such as methyl, ethyl, butyl, isopropyl, and so on. These molecules differ in size and adhesives and exhibit different physical properties. Methyls are the smallest molecule and seem to work best on metal and rubber parts while ethyls work best on plastic parts. Many modifications can be made to the monomers to alter or improve their properties as adhesives. They can be toughened with rubber or formulated to have low odor, resistance to thermal cycling, or less sensitivity to surface conditions which tend to stabilize the adhesive and slow down the cure. ... 

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