Additive manufacturing of fire‐retardant ethylene‐vinyl acetate

Abstract

Thermocompression (with also extrusion and injection molding) is a classical polymer shaping manufacturing, but it does not easily allow designing sophisticated shapes without using a complex mold, on the contrary to 3D printing (or polymer additive manufacturing), which is a very flexible technique. Among all 3D printing techniques, fused deposition modeling is of high potential for product manufacturing, with the capability to compete with conventional polymer processing techniques. This is a quite low cost 3D printing technique, but the range of filaments commercially available is limited. However, in some specific 3D printing processes, no filaments are necessary. Polymers pellets feed directly the printing nozzle allowing to investigate many polymeric matrices with no commercial limitation. This is of high interest for the design of flame‐retarded materials, but literature is scarce in that field. In this paper, a comparison between thermocompression and 3D printing processes was performed on both neat ethylene‐vinyl acetate (EVA) copolymer and EVA flame retarded with aluminum triHydroxyde (ATH) containing different loadings (30 or 65 wt%) and with expandable graphite (EG), ie, EVA/ATH (30 wt%), EVA/ATH (65 wt%), and EVA/EG (10 wt%), respectively. Morphological comparisons, using microscopic and electronic microprobe analyses, revealed that 3D printed plates have lower apparent density and higher porosity than thermocompressed plate. The fire‐retardant properties of thermocompressed and 3D printed plates were then evaluated using mass loss calorimeter test at 50 kW/m2. Results highlight that 3D printing can be used to produce flame‐retardant systems. This work is a pioneer study exploring the feasibility of using polymer additive manufacturing technology for designing efficient flame‐retarded materials.

Screw-assisted 3D printing with granulated materials: a systematic review

“…As will be shown in Section 4, many new experimental systems for both small- and large-scale applications appeared in the period from 2014 to 2018 [ 15 – 29 , 32 , 34 , 35 , 37 ], which can be related to the high number of publications in the same period. Although the scientific production in the last 2 years decreased, a crescent share of the research was carried out with commercial systems [ 48 , 49 , 51 , 53 , 54 , 65 – 69 , 71 – 73 , 75 ], indicating the consolidation of screw-assisted EAM in the market.…”

“…Although the first systems were mostly used in bio-AM applications [ 11 , 14 ], the concept was further developed from 2014 to 2019 to different purposes [ 17 , 18 , 37 , 39 , 40 ]. An expressive equipment variety for small-scale applications could be observed in the period, including four commercial systems (3D Discovery® [ 45 , 46 ], PAM® [ 51 ], M3DIMAKER® [ 53 ], ExAM 255® [ 54 ]). Despite the description of the first screw-assisted EAM based on a do-it-yourself (DIY) printhead kit [ 41 ], no significant equipment improvements were introduced in 2020.…”

Fire Behavior of 3D-Printed Polymeric Composites

“…A critical amount of ATH is desirable to generate an effective homogenous residue, which acts as a fire barrier layer. This barrier formation was not accomplished at low ATH concentration (i.e., 30 56) to accomplish light-weight 3D-printed parts with better flame retardancy. The design contains a core part, which was covered with an outer shell part.…”

3D printed sandwich materials filled with hydrogels for extremely low heat release rate

“…EVA/ATH (30 wt.%) pellets were then used to print 50x50x3 mm 3 EVA/ATH (30 wt.-%) polymer plates, according to a computer pattern using a Pollen (Ivry-sur-Seine, France) 3D printer, fully described elsewhere [7]. EVA/ATH (30 wt.-%) polymer pellets were incorporated on a feeder, then went through an extruder with a thermal gradient from 65°C to 130°C in the middle until 225°C at the output of extruder.…”

“…In a previous paper, it was reported that a fire-retarded formulation of an ethylene-vinyl acetate (hereafter call EVA) copolymer containing 30% weight amount of Aluminum TriHydroxide (ATH) can be processed to create flame-retardant materials by 3D-printing [7]. Following this research, an original design was elaborated and innovative sandwich multimaterials filled with a liquid phase were prepared.…”