Studies on the Reaction of Acrylonitrile Butadiene Styrene to Melt Processing Conditions

Abstract

Acrylonitrile butadiene styrene (ABS) was investigated for its reaction to melt processing. Studies were done in a lab scale micro extruder and injection molder. It was found that during typical processing times, the ABS begins to undergo a hydrogen abstraction reaction in the presence of oxygen in its polybutadiene (PB) phase. This leads to a crosslinking of the PB chains, which in turn can have an effect on the performance of the polymer. The ABS also was shown to undergo chain scission, opposing the crosslinking effect on the viscosity of the polymer. With higher temperatures, it was found that the crosslinking occurred earlier and at a faster rate. Crosslinking preceded chain scission such that the higher temperatures had the highest peak viscosities. Ultimately, chain scission became the dominant mechanism, decreasing the viscosity. Similar results were seen with changing retention time. Higher retention times in the melt increased the viscosity to a point before decreasing again. During processing, it was found that temperature and shearing both have an effect in progressing the reaction.

Molecular Pathways for Polymer Degradation during Conventional Processing, Additive Manufacturing, and Mechanical Recycling

“…During (additive) manufacturing, the most common degradation route for ABS is proposed to be thermal oxidation [104][105][106]. An interesting off-line study has been performed by Shimada and Kabuki [107], mentioning the three stages of initiation, propagation, and termination, as included in the auto-oxidative cycle in Figure 5.…”