The Efficiency of Biobased Carbonization Agent and Intumescent Flame Retardant on Flame Retardancy of Biopolymer Composites and Investigation of Their Melt-Spinnability

Abstract

The objective of this study is to assess the efficiency of biobased carbonization agent in intumescent formulations (IFRs) to examine the flame retardant properties of polylactic acid (PLA) composites and to investigate their melt-spinnability. We used phosphorous-based halogen free flame retardant (FR) and kraft lignin (KL) as bio-based carbonization agent. After melt compounding and molding into sheets by hot pressing various fire related characteristics of IFR composites were inspected and were characterized by different characterization methods. It was fascinating to discover that the introduction of 5−20 wt% FR increased the limiting oxygen index (LOI) of PLA composites from 20.1% to 23.2−33.5%. The addition of KL with content of 3−5 wt% further increased the LOI up to 36.6−37.8% and also endowed PLA/FR/KL composites with improved anti-dripping properties. Cone calorimetry revealed a 50% reduction in the peak heat release rate of the IFR composites in comparison to 100% PLA and confirmed the development of an intumescent char structure containing residue up to 40%. For comparative study, IFR composites containing pentaerythritol (PER) as a carbonization agent were also prepared and their FR properties were compared. IFR composites were melt spun and mechanical properties of multifilament yarns were tested. The analysis of char residues by energy dispersive X-ray spectrometry (EDS) and SEM images confirmed that PLA/FR/KL composites developed a thicker and more homogeneous char layer with better flame retardant properties confirming that the fire properties of PLA can be enhanced by using KL as a carbonization agent.

Biomacromolecules and Bio-Sourced Products for the Design of Flame Retarded Fabrics: Current State of the Art and Future Perspectives

“…Lignin is the second most abundant natural material after cellulose and is easily extracted from plant cells [69]. Its structure (Figure 11) suggests that this biomacromolecule could act as a potential carbon source when combined with intumescent flame retardant additives in bulky polymers, as it bears phenylpropane units together with aliphatic/aromatic hydroxyls: this peculiarity has been clearly demonstrated in several scientific papers [70,71,72,73]. Lignin and some derivatives have also been exploited for preparing flame retardant fibers (through melt spinning) and subsequently FR fabrics.…”

Novel Bicomponent Functional Fibers with Sheath/Core Configuration Containing Intumescent Flame-Retardants for Textile Applications

“…IFRs usually contain an acid source, a carbon source and a blowing agent. The degradation of the acid source will be catalyzed by heat, resulting in a release of acid, which in turn, dilutes the gas phase and catalyze the dehydration of the carbon source [32]. The resulting char layer creates a barrier between the gas phase and the polymer, reducing heat and mass transfer, thus protecting the material from combustion [33].…”

Biodegradable Flame Retardants for Biodegradable Polymer

“…The formation of char takes place mostly in the condensed phase, and other than creating a physical barrier, it also has several other benefits, such as not allowing the passage of decomposed volatile products to the place of fire and providing insulation to the underlying material against thermal degradation [ 63 , 64 ]. Since the char forming systems tend to interrupt the burning cycle rather than working on flame poisoning mechanism therefore, regarded as more effective and less hazardous to the environment [ 65 ].…”