Highly impact toughened and excellent flame-retardant polylactide/poly(butylene adipate-co-terephthalate) blend foams with phosphorus-containing and food waste-derived flame retardants.

Green polymeric foams are an important research topic for sustainable development. In this study, a natural multifunctional flame-retardant additive based on food waste was developed and evaluated for its ability to replace the commercial additives tricresyl phosphate (TCP) and trioctyl phosphate (TOP) in a polylactide/poly(butylene adipate-co-terephthalate) (PLA/PBAT) foam. A series of blend foams with additives were prepared by melt extrusion. According to the results, the blend foam with 20 phr of TCP showed the best combination of impact toughness and flame retardancy. TCP, however, poses health and environmental risks. Therefore, natural flame retardants (NFRs) were used to partially replace the commercial flame retardant (CFR). A combination of TCP and soybean residue (SB) produced an impact toughened and flame-retardant blend foam. When compared to the neat PLA/PBAT foam, the impact toughness of the best sample was increased by about 256 %. The optimal foam showed excellent flame resistance with a V-0 UL-94 rating and a high LOI value (31.8 %). SB has the potential to partially replace TCP as flame retardant and could be used in a broad range of PLA/PBAT foam applications.

Properties and flame retardancy of polylactide composites incorporating tricresyl phosphate and modified microcrystalline cellulose from oil palm empty fruit bunch waste.

One of the major environmental issues that have an impact on humans, animals, and their surroundings is plastic garbage. The use of biodegradable polymers in place of traditional plastics is one of the best solutions to this significant issue. The bio-circular-green (BCG) economic model is supported by the use of microcrystalline cellulose (MCC) as a bio-filler for polylactide (PLA) composites, which may also help to address the issue of improper plastic waste management. This study explores the chemical modification of MCC derived from oil palm empty fruit bunch waste (OPMC). Maleic anhydride-modified OPMC (MAMC) is successfully synthesized by a solvent-free and low temperature heating procedure. MAMC and tricresyl phosphate (TCP) were used as additives in PLA composites which were processed by melt extrusion and compression molding. Characterization studies confirmed the successful modification of MAMC and indicated that TCP played a crucial role as an effective plasticizer and flame retardant for PLA. All PLA/TCP composites showed significantly improved toughness and delayed ignition. The appropriate TCP level was 10 phr. The incorporation of TCP and MAMC resulted in a synergistic enhancement of impact strength and maintained excellent flame inhibition. Moreover, the thermal stability of the PLA composites increased with increments of MAMC.

Synergistic effect of microcrystalline cellulose from oil palm empty fruit bunch waste and tricresyl phosphate on the properties of polylactide composites.

Microcrystalline cellulose (MCC) was extracted from oil palm empty fruit bunch (OPEFB) waste by integrated chemical treatments of delignification, bleaching, and acidic hydrolysis. The obtained MCC (OPMC) and tricresyl phosphate (TCP) were used as additives for polylactide (PLA) composites. The influences of OPMC and TCP contents, separately and in combination, were evaluated on the properties of the composites. Characterization studies confirmed the successful extraction of OPMC from OPEFB waste. With regard to the properties of the PLA composite, the appropriate content of OPMC should be 5 phr. The good distribution of OPMC in the polymer matrix changed the failure behavior of the composite from brittle to ductile. All the PLA composites with TCP and OPMC showed flame inhibition and retarded ignition. The synergistic effect of TCP and OPMC resulted in outstanding improvement of impact strength and flame retardancy of composites. The impact toughness of PT10M5 increased to about 218.4 % and 72.3 % that of neat PLA and PT0M5, respectively. Moreover, PT10M5 achieved V-0 rating with high LOI (38.5 %). All these characteristics promise extended applications for PLA composite in bio, circular, and green (BCG) economies and electronics industries.

Toughening and thermal characteristics of plasticized polylactide and poly(butylene adipate-co-terephthalate) blend films: Influence of compatibilization.

Bio-based polylactide (PLA) derived from fermented corn starch was blended with poly(butylene adipate-co-terephthalate) (PBAT) and triethyl citrate (TEC) plasticizer using a twin screw extruder. PLA-grafted-maleic anhydride (PLA-g-MA) synthesized via reactive maleation and toluene diisocyanate (TDI) were used as compatibilizers for these blends. Improvements in the toughness, phase morphology and thermal behavior of the PLA/PBAT/TEC (PBT) blend films were evaluated in terms of compatibilization effect. The compatibilized PBT blends showed noticeably superior tensile strength, elongation, and tensile-impact toughness compared with uncompatibilized ones due to the greater compatibility of PLA and PBAT phases. Well dispersed PBAT particles and many elongated fibrils were observed on the fracture surface of the film after compatibilization. Both TDI and PLA-g-MA were effective compatibilizers for the blend at an appropriate level. The addition of PLA-g-MA to the plasticized blends not only significantly enhanced mechanical properties and phase adhesion, but also accelerated cold crystallization and formed crystal perfection, a result of improvements in chain mobility and packing efficiency. Differential scanning calorimetry (DSC) results revealed changes in Tg and melting behavior of the blends from influences of compatibilization. The different types and levels of compatibilizer affected the thermal stability of the PLA phase but did not affect char remaining.

Catalytic pyrolysis of petroleum-based and biodegradable plastic waste to obtain high-value chemicals.

The petroleum-based plastics, high-density polyethylene (HDPE), low-density polyethylene (LDPE), and polypropylene (PP), and the biodegradable plastic, polylactide (PLA) were processed by thermal and catalytic pyrolysis to investigate their suitability as feedstock for chemical recycling. The influence of pyrolysis temperature (400-600 °C) and catalyst (zeolite, spent FCC, and MgO catalyst) on the pyrolysis liquid composition and yield was studied. The studied petroleum-based plastics had similar decomposition temperature ranges but produced their highest pyrolysis yields at different temperatures. Pyrolysis liquids from thermal degradation of HDPE and LDPE consisted high yield of waxes but those of PP and PLA consisted of both waxes and liquid oil. Catalysts affected not only the pyrolysis yield, but also the proportions of liquid oil and wax in pyrolysis liquids. Alkenes, alkanes, and aromatics were the main compounds in the pyrolysis liquids. Spent FCC catalyst reduced the production of waxes and increased the production of gasoline-range hydrocarbons and aromatics. MgO catalyst led to high coke formation from polyolefins and PLA. Lactic acid, lactide and propanoic acid were examples of valuable chemicals recovered from the pyrolysis of PLA. Lactide was the main product (up to 79%) of catalytic pyrolysis with zeolite at 400 °C. Spent FCC catalyst produced mostly propanoic acid at 400 °C but at 600 °C, L-lactic acid became the most abundant compound.

Fire-extinguishing characteristics and flame retardant mechanism of polylactide foams: Influence of tricresyl phosphate combined with natural flame retardant.

Extrusion and compression molding techniques were used to process polylactide (PLA) foams using a mixture blowing agent. Tricresyl phosphate (TCP) and natural flame retardants (NFR) from pumpkin (PK) and soybean (SB) were added to rigid PLA foams and the flame retardant properties of the foams were investigated. The effects of TCP content, types and amounts of NFR, and the ratio of TCP to NFR were determined on the physical, thermal and morphological characteristics of the foams. The fire-extinguishing characteristics and flame retardant mechanism of PLA foams with TCP were studied by thermogravimetric analysis-Fourier transform infrared (TGA-FTIR), scanning electron microscope (SEM), limiting oxygen index (LOI), and UL-94 techniques. The results revealed the efficiency of TCP as a flame retardant for PLA foams. Increased TCP levels contributed to a significant enhancement in fire-extinguishing characteristics. Phosphoric acid from thermal decomposition of TCP was a key factor in the proposed mechanism of flame retardation. Flame inhibition and retarded ignition of the PLA foams were achieved at all compositions of TCP and NFR. Due to the presence of compounds such as cellulose, phosphate, and silica, both PK and SB could be used as effective NFRs for PLA foams. All these characteristics promise extended applications for PLA foam in bio, circular, and green economies.