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.

Valorization of underutilized waste biomass from invasive species to produce biochar for energy and other value-added applications.

Biochar production from invasive species biomass discarded as waste was studied in a fixed bed reactor pyrolysis system under different temperature conditions for value-added applications. Prior to pyrolysis, the biomass feedstock was characterized by proximate, ultimate, and heating value analyses, while the biomass decomposition behavior was examined by thermogravimetric analysis. The heating values of the feedstock biomass ranged from 18.65 to 20.65 MJ/kg, whereas the volatile matter, fixed carbon, and ash content were 61.54-72.04 wt %, 19.27-26.61 wt % and 1.51-1.86 wt %, respectively. The elemental composition of carbon, hydrogen, and oxygen in the samples was reported to be in the range of 47.41-48.47 wt %, 5.50-5.88 wt % and 46.10-45.18 wt %, respectively, while the nitrogen and sulphur content in the biomass samples were at very low concentrations, making it more useful for valorization from environmental aspects. The biochar yields were reported in the range of 45.36-58.35 wt %, 28.63-44.38 wt % and 22.68-29.42 wt % at a pyrolysis temperature of 400 °C, 500 °C, and 600 °C, respectively. The biochars were characterized from ultimate analysis, heating value, energy densification ratio, energy yield, pH, Fourier transform infrared spectroscopy (FTIR), and scanning electron microscopy and energy dispersive X-ray spectrometry (SEM and EDX), to evaluate their potential for value-added applications. The carbon content, heating value, energy densification ratio, and the porosity of the biochars improved with the increase in pyrolysis temperature, while the energy yield, hydrogen, oxygen, and nitrogen content of the biochars decreased. This study revealed the potential of the valorization of underutilized discarded biomass of invasive species via a pyrolysis process to produce biochar for value-added applications.