Styrenic plastics failure

Plasticizers. These materials are added to reduce the hardness of the compound and can reduce the viscosity of the uncured compound to facilitate processes such as mixing and extruding. The most common materials are petroleum-based oils, esters, and fatty acids. Critical properties of these materials are their compatibility with the rubber and their viscosity. Failure to obtain sufficient compatibility will cause the plasticizer to diffuse out of the compound. The oils are classified as aromatic, naphthenic, or paraffinic according to their components. Aromatic oils will be more compatible with styrene-butadiene rubber than paraffinic oils, whereas the inverse will be true for butyl rubber. The aromatic oils are dark colored and thus cannot be used where color is critical, as in the white sidewall of a tire. The naphthenic and paraffinic oils can be colorless and are referred to as nonstaining. 

Masterbatching of carbon black with natural rubber in latex form has never been successfully developed industrially. There are various unrelated reasons for this failure. Natural rubber latex is more variable than are styrene-butadiene rubber latexes as regards rubber content and the plasticity of the rubber. Additionally, the geographical regions in which carbon black is manufactured are far distant from those in which natural rubber is produced. A further... 

FIGURE 7. Lx)g(failure energy) vs. log(rate) curves for styrene-butadiene rubber failing cohesively (top curve) or bonded to various plastic film substrates as shown. Note vertical super-imposability. 

Figure 3.23 Stress levels for cycles to failure for different plastics polycarbonate ( ), PP ( ), acrylonitrile-butadiene-styrene (ABS) (A), HDPE ( ) [32]...

As a concluding comment it must be pointed out that, in considering styrene-based plastics for particular applications, the poor solvent resistance might be a limitation. Simultaneous application of stress, in the presence of a solvent, may give premature failure due to environmental stress cracking. These comments apply equally to PS, HIPS, ABS and the PPO-PS blends. 

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