Improved Thermal Processing of Polylactic Acid/Oxidized Starch Composites and Flame-Retardant Behavior of Intumescent Non-Wovens

Abstract

Thermoplastic processing and spinning of native starch is very challenging due to (a) the linear and branched polymers (amylose and amylopectin) present in its structure and (b) the presence of inter-and-intramolecular hydrogen bond linkages in its macromolecules that restrict the molecular chain mobility. Therefore, in this study, oxidized starch (OS) (obtained after oxidation of native starch with sodium perborate) was melt-blended with polylactic acid (PLA) polymer to prepare PLA/OS blends that were then mixed together with ammonium polyphosphate (APP), a halogen-free flame retardant (FR) used as acid donor in intumescent formulations on twin-screw extruder to prepare PLA/OS/APP composites. OS with different concentrations also served as bio-based carbonic source in intumescent formulations. PLA/OS/APP composites were melt spun to multifilament fibers on pilot scale melt-spinning machine and their crystallinity and mechanical properties were optimized by varying spinning parameters. The crystallinity of the fibers was studied by differential scanning calorimetry and thermal stabilities were analyzed by thermogravimetric analysis. Scanning electron microscopy was used to investigate the surface morphology and dispersion of the additives in the fibers. Needle-punched non-woven fabrics from as prepared melt-spun PLA/OS/APP fibers were developed and their fire properties such as heat release rate, total heat release, time to ignition, residual mass % etc. by cone calorimetry test were measured. It was found that PLA/OS/APP composites can be melt spun to multifilament fibers and non-woven flame-retardant fabrics produced thereof can be used in industrial FR applications.

Influence of Myrrh Extracts on the Properties of PLA Films and Melt-Spun Multifilament Yarns

“…The decrease in the Tc1 can be attributed to greater molecular chain mobility in PLA modified with aqueous myrrh extract. M. Maqsood [32] estimated that the increase in the Tc of melt-spun PLA fibers due to higher concentration of oxidized starch can be correlated with quite high agglomeration of the additives which decreases the molecular chain mobility. Analyzing plasticized PLA films with different epoxidized karanja oil content [33] was concluded Meanwhile, the films made from modified PLA with myrrh extracts (B and C films) are opaque and also have almost uniform reflectance, but approximately 15% lower, in spectral range from 800 nm to 550 nm.…”

An overview of the recent advances in flame retarded poly(lactic acid)

“…Generally, IFR consists of acid source (such as phosphorus-based compounds), carbon source (such as polyatomic alcohols), and blowing agent (such as nitrogen-based compounds). 29,30,[85][86][87][88][89][90][91][92][93][94][95][96][97] Table 3 shows the types of IFR used for PLA.…”

Biodegradable Flame Retardants for Biodegradable Polymer

“…Both itaconic acid and tartaric acid are used as a raw material for the development of flame retardants [ 84 ]. Maqsood et al [ 56 , 85 ] studied the effect of cornstarch as a bio-based carbonization agent in intumescent formulations as a potential biodegradable substitute for pentaerythritol and PLA/starch composites. The mechanism of intumescence indicating catalytic phosphorylation to produce phosphate esters, which eventually dehydrated the starch and formed char structure containing residue up to 43%, was studied.…”