Structure‐Property Relationships in Rubber‐Modified Styrenic Polymers

Abstract

Styrenic polymers and copolymers are often impact modified with rubber particles. The efficiency of rubber toughening depends mainly on the size of the rubber particles and the degree of cross‐linking. The deformation rate, the temperature, the orientation of the polymer molecules and the efficiency of rubber grafting also influence rubber toughening. It is thought that on impact, cavitation inside the rubber particles occurs which reduces the detrimental dilatational stress in the bulk polymer without forming cracks in the brittle matrix or at the rubber‐matrix interface. Crazing and shearing are facilitated if the rubber particles can easily cavitate. This can be achieved by either avoiding too much cross‐linking or by adding oil (silicone oil in the case of ABS) into the rubber particles, which acts as nuclei for void formation. An electron spectroscopic imaging method is described which allows visualizing the location of the oil. Already after cooling silicone oil modified ABS samples down to liquid nitrogen temperature rubber cavitation is observed. This cavitation is caused by the thermal stress developing due to the differences in thermal expansion coefficient between the rubber phase and the SAN‐matrix and is facilitated by silicone oil. Voiding also leads to an increase of light scattering, which can be detected by an optical microscope using dark field illumination.

Tough salami-inspired Cf/ZrB2 UHTCMCs produced by electrophoretic deposition

“…In these weak matrix composites (WMCs) the matrix is subjected to multiple cracking whilst the fibers provide strength and crack tolerance, in this way after the matrix is completely fractured by multiple microcracking, the total fracture occurs with the failure of the fibers [18]. A further development for UHTCMCs in terms of toughness can be borrowed from strategy behind the solution-polymerized acrylonitrile-butadiene-styrene (ABS): the salami-like particles [19,20]. The dispersed salami-like particles consist in polybutadiene particles (PB) grafted (-g-) by acrylonitrile-styrene copolymer (SAN).…”

Fractographic analysis of the crack resistance of styrene–acrylonitrile/polybutadiene‐g‐styrene–acrylonitrile blends as evaluated by the essential work of fracture method

“…For these toughened polymers, significant stress whitening occurs before fracture, and the frac-ture toughness is many times higher than that of unmodified neat polymer. For this reason, numerous studies have been conducted on ABS polymers in recent decades; they have considered the effects of different microstructural factors of the material and processing and test conditions on the phase morphology, [14][15][16][17][18][19] mechanical properties, 16,[18][19][20][21][22] and deformation behavior 3,12,16,[20][21][22][23][24][25][26][27][28][29][30] of the final product. [3][4][5][6][7][8][9][10][11] The rubber particles act as both a craze initiator and a craze terminator in the matrix.…”

“…3,12,13 Because of its chemical structure and twophase morphology, ABS represents an attractive combination of strength, toughness, chemical resistance, and thermal stability; this makes it a very suitable candidate for widespread engineering applications. For this reason, numerous studies have been conducted on ABS polymers in recent decades; they have considered the effects of different microstructural factors of the material and processing and test conditions on the phase morphology, [14][15][16][17][18][19] mechanical properties, 16,[18][19][20][21][22] and deformation behavior 3,12,16,[20][21][22][23][24][25][26][27][28][29][30] of the final product. To determine the toughness, the vast majority of the studies have focused on simple impact tests with a few reports on the application of the J-integral method as a fracture mechanics-based approach.…”

Impact behavior and fracture morphology of acrylonitrile–butadiene–styrene resins toughened by linear random styrene–isoprene–butadiene rubber

“…Therefore, the amount, structure, and types of rubber have a great effect on the properties of ABS resin. The most frequently used rubber is polybutadiene (PB).The performances of ABS toughened by PB rubber are affected by many important factors, such as the concentration of the rubber,3, 4 the size and the distribution of rubber particles,1–5 the volume fraction of the rubber phase, and the degree of grafting 1–6. In previous studies, we used lithium‐catalyzed low‐cis PB rubber (Li‐700A), nickel‐catalyzed high‐cis PB rubber (Ni‐9004), and their compounds to toughen ABS resins by bulk polymerization 7, 8.…”