Development of Biodegradable Flame-Retardant Bamboo Charcoal Composites, Part I: Thermal and Elemental Analyses

Abstract

In this study, bamboo charcoal (BC) was used as a substitute filler for bamboo powder (BP) in a lignocellulose-plastic composite made from polylactic acid (PLA), with aluminum hypophosphite (AHP) added as a fire retardant. A set of BC/PLA/AHP composites were successfully prepared and tested for flame-retardancy properties. Objectives were to (a) assess compatibility and dispersibility of BC and AHP fillers in PLA matrix, and (b) improve flame-retardant properties of PLA composite. BC reduced flexural properties while co-addition of AHP enhanced bonding between PLA and BC, improving strength and ductility properties. Adding AHP drastically reduced the heat release rate and total heat release of the composites by 72.2% compared with pure PLA. The formation of carbonized surface layers in the BC/PLA/AHP composites effectively improved the fire performance index (FPI) and reduced the fire growth index (FGI). Flame-retardant performance was significantly improved with limiting oxygen index (LOI) of BC/PLA/AHP composite increased to 31 vol%, providing a V-0 rating in UL-94 vertical flame test. Adding AHP promoted earlier initial thermal degradation of the surface of BC/PLA/AHP composites with a carbon residue rate up to 40.3%, providing a protective layer of char. Further raw material and char residue analysis are presented in Part II of this series.

Enhancement of Flame Retardancy and Mechanical Properties of Polylactic Acid with a Biodegradable Fire-Retardant Filler System Based on Bamboo Charcoal

“…Cooperative behavior of the additives is considered to occur with the combination of BC-m and CS if Ce > 1. Since the LOI values are usually used to evaluate combustion intensity and directly correspond with UL-94 and cone calorimetry indices, LOI values were used for F p in Equation (2) [ 16 , 52 ]. Ce values were above 1 for BC-m+CS composites ( Table 6 ) suggesting a cooperative effect.…”

“…Various strategies have been proposed to improve the flame retardancy of PLA [ 14 , 15 ]. Previous work by authors include modification with aluminum hypophosphite (AHP) [ 16 , 17 ] and bamboo charcoal (BC) [ 18 ]. The flame-retardant performance was improved, but mechanical properties decreased and combustion produced toxic phosphene gas (PH 3 ).…”

Preparation of Plastics- and Foaming Agent-Free and Porous Bamboo Charcoal based Composites Using Sodium Silicate as Adhesives

“…In daily life, BC is usually made into small-size particles with various shapes for air or water purification, but its scope of use is limited due to low usage amount and dust pollution. To address the above-mentioned shortcomings, large-size BC based composites have been developed in recent years [ 10 ]. Specifically, the BC/plastics composite board is widely reported due to its high mechanical strength and ability to partially replace wood and reduce the large consumption of forest resources, showing a great potential in building materials [ 11 , 12 , 13 ].…”

“…From the above, we can see that BC mainly acts as a filler and plays a role in performance enhancement of BC/plastics; in other words, plastics could be used as adhesives to prepare BC-based composites [ 10 ]. However, plastics are suffering from these disadvantages such as flammability, easy aging, high cost, etc.…”

Advances in Wood Composites III

“…Lignocellulose plastic composites are a combination of processing techniques for filler and fiber preparation and polymer science [ 9 , 10 ]. Wang and co-workers manufacture a lignocelluloses plastic composite using polylactic acid and bamboo charcoal as a filler for bamboo powder.…”