Fire Behavior of Polyamide 12/Rubber Formulations Made by Laser Sintering

Area of Science:

• Materials Science
• Polymer Engineering
• Additive Manufacturing

Background:

• Polyamide 12 (PA12) is a common material for laser sintering (LS).
• Improving the processability and fire behavior of PA12 parts is crucial for wider applications.
• Acrylonitrile butadiene rubbers (NBRs) are explored as additives to modify PA12 properties.

Purpose of the Study:

• To investigate the effect of different NBR types on the processability and fire behavior of PA12/rubber powder blends for laser sintering.
• To evaluate powder flowability, sintering window, and thermal properties of the blends.
• To assess the fire retardancy of the modified PA12 materials.

Main Methods:

• Preparation of PA12/NBR blends with varying NBR types (different acrylonitrile contents, carboxylated rubber).
• Evaluation of powder flowability and bed homogeneity.
• Analysis of sintering behavior, including sintering window and thermal properties (crystallization and melting temperatures).
• Fire behavior assessment using cone calorimetry to measure heat release rate.

Main Results:

• Powder flowability is highly dependent on the NBR type; carboxylated rubber provided good flowability.
• NBR addition increased the sintering window and altered PA12's melting temperature.
• Formulations with 10-20 wt.% rubber were processable under standard PA12 parameters.
• Carboxylated rubber blends showed significantly improved fire behavior, with peak heat release rate reductions of 45-65% and classified as 'Good' by the Flame Retardancy Index.

Conclusions:

• NBR addition can enhance the processability and fire retardancy of PA12 for laser sintering.
• Carboxylated rubber is a promising additive for improving powder flow and fire performance.
• Amide linkage formation between PA12 and NBR likely contributes to increased melt viscosity and improved fire resistance.