The bioeconomy at work: researchers develop 'nanohybrid' bioplastic that biodegrades much faster
Scientists in New York are reporting the development of a new biodegradable 'nanohybrid' plastic that can be engineered to decompose much faster than existing renewable plastics used in everything from soft drink bottles to medical implants. The study appears as an open access article in the journal Biomacromolecules, a publication of the American Chemical Society.
The plastic is a modified form of polyhydroxybutyrate (PHB), a promising biodegradable thermoplastic produced by the fermentation of renewable biomass by bacteria (previous post) that has been widely hailed as a 'green' alternative to petroleum-based plastic for use in packaging, agricultural and biomedical applications. Although commercially available since the 1980s, PHB has seen only limited use because of its brittleness and unpredictable biodegradation rates.
In the new study, Pralay Maiti, Carl Batt, and Emmanuel Giannelis from Cornell University's Department of Materials Science and Engineering compared the strength and biodegradation rates of raw PHB to a modified form of PHB that contains nanoparticles of clay or 'nanoclays'. One advantage of clay nanocomposites is their improved barrier properties while retaining the flexibility and optical clarity of the pure biopolymer. The use of such particles has been reported in biodegradable aliphatic polyester nanocomposites, but this is the first time they were introduced into PHB/layered silicate nanocomposites:
energy :: sustainability ::biomass :: bioenergy :: biofuels :: biopolymer :: bioplastic :: biodegradable :: nanoclay :: nanocomposite :: bioeconomy ::
The main objective of the researchers was to study the effect of nanoclays on biodegradation. Although the biodegradation of neat PHB enzymatically and in seawater was already studied, this is the first report of biodegradability of PHB nanocomposites.
Biodegradation tests were carried out at room temperature (20 C) and at 60 C. The scientists found that the modified PHB was both stronger and decomposed faster than regular PHB. The nanohybrid PHB decomposed almost completely after seven weeks, while its traditional counterpart showed almost no decomposition (image, click to enlarge). They also showed that degradation could be fine-tuned by adjusting the amount of nanoparticles added.
The study is the first report of the biodegradation of PHB nanocomposites and could lead to wider use of PHB plastics, the scientists say.
Nanotechnology and the field of nano-enhanced bioplastics is having concrete results. Recently a specialty chemicals company announced that it succeeded in embedding dispersible nanoparticles into polylactic acid (PLA) based bioplastics which makes them considerably stronger and less hazy (previous post). This is a much needed improvement, overcoming one of the key weaknesses of PLA bioplastics.
Picture: Polarizing optical images of the virgin bioplastic (PHB) and the 'nanohybrid' (PHBCN2) before and after 8 weeks of biodegradation. The samples were crystallized at 125 °C prior to composting.
References:
Pralay Maiti, Carl A. Batt, Emmanuel P. Giannelis, "New Biodegradable Polyhydroxybutyrate/Layered Silicate Nanocomposites", Biomacromolecules, 8 (11), 3393 -3400, 2007. 10.1021/bm700500t S1525-7797(70)00500-7
Biopact: Nanoparticle additive makes PLA based bioplastics stronger - July 23, 2007
Biopact: Notes on biopolymers in the Global South - March 11, 2007
The plastic is a modified form of polyhydroxybutyrate (PHB), a promising biodegradable thermoplastic produced by the fermentation of renewable biomass by bacteria (previous post) that has been widely hailed as a 'green' alternative to petroleum-based plastic for use in packaging, agricultural and biomedical applications. Although commercially available since the 1980s, PHB has seen only limited use because of its brittleness and unpredictable biodegradation rates.
In the new study, Pralay Maiti, Carl Batt, and Emmanuel Giannelis from Cornell University's Department of Materials Science and Engineering compared the strength and biodegradation rates of raw PHB to a modified form of PHB that contains nanoparticles of clay or 'nanoclays'. One advantage of clay nanocomposites is their improved barrier properties while retaining the flexibility and optical clarity of the pure biopolymer. The use of such particles has been reported in biodegradable aliphatic polyester nanocomposites, but this is the first time they were introduced into PHB/layered silicate nanocomposites:
energy :: sustainability ::biomass :: bioenergy :: biofuels :: biopolymer :: bioplastic :: biodegradable :: nanoclay :: nanocomposite :: bioeconomy ::
The main objective of the researchers was to study the effect of nanoclays on biodegradation. Although the biodegradation of neat PHB enzymatically and in seawater was already studied, this is the first report of biodegradability of PHB nanocomposites.
Biodegradation tests were carried out at room temperature (20 C) and at 60 C. The scientists found that the modified PHB was both stronger and decomposed faster than regular PHB. The nanohybrid PHB decomposed almost completely after seven weeks, while its traditional counterpart showed almost no decomposition (image, click to enlarge). They also showed that degradation could be fine-tuned by adjusting the amount of nanoparticles added.
The study is the first report of the biodegradation of PHB nanocomposites and could lead to wider use of PHB plastics, the scientists say.
Nanotechnology and the field of nano-enhanced bioplastics is having concrete results. Recently a specialty chemicals company announced that it succeeded in embedding dispersible nanoparticles into polylactic acid (PLA) based bioplastics which makes them considerably stronger and less hazy (previous post). This is a much needed improvement, overcoming one of the key weaknesses of PLA bioplastics.
Picture: Polarizing optical images of the virgin bioplastic (PHB) and the 'nanohybrid' (PHBCN2) before and after 8 weeks of biodegradation. The samples were crystallized at 125 °C prior to composting.
References:
Pralay Maiti, Carl A. Batt, Emmanuel P. Giannelis, "New Biodegradable Polyhydroxybutyrate/Layered Silicate Nanocomposites", Biomacromolecules, 8 (11), 3393 -3400, 2007. 10.1021/bm700500t S1525-7797(70)00500-7
Biopact: Nanoparticle additive makes PLA based bioplastics stronger - July 23, 2007
Biopact: Notes on biopolymers in the Global South - March 11, 2007
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