Thermal stability and miscibility of poly(hydroxybutyrate) and soda lignin blends

Industrial Crops and Products (Impact Factor: 2.84). 11/2010; 32(3):656-661. DOI: 10.1016/j.indcrop.2010.08.001


The thermal properties and miscibility of poly(hydroxybutyrate) (PHB) and soda lignin blends were investigated by thermogravimetry analysis (TGA), differential scanning calorimetry (DSC), scanning electron microscopy (SEM) and Fourier transform infra-red spectroscopy (FTIR) over the entire range of composition. Although the addition of soda lignin shifts the onset of PHB decomposition to lower temperatures, the PHB/lignin blends are thermally more stable than PHB over a wider temperature range. The thermal behaviour of these blends as measured by TGA suggests compatibility for the blends containing up to 40 wt% soda lignin. These results correlate well with the glass transition temperature (Tg) data where a single Tg was obtained for these blends. At higher lignin to PHB ratios, two Tgs depicting immiscibility were obtained. The infra-red data show that the miscibility of the blends containing up to 40 wt% soda lignin is associated with specific hydrogen bonding interactions between the reactive functional groups in lignin with the carbonyl groups of PHB.Research highlights▶ PHB/soda lignin blends are miscible up to 40 wt% lignin so that the Gordon–Taylor and Kwei equations are obeyed. ▶ The miscibility of PHB/soda lignin blends are due to the association between the OH groups of lignin and the carbonyl groups of PHB. ▶ Soda lignin reduces the initial PHB decomposition temperature though it stabilises PHB decomposition.

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    • "Depending on the source and extraction method used, the physico-chemical characteristics are different and influence the properties of materials in which are embedded. The effective use of lignin in composites with various biopolymers like PHB [12] [13], starch [14], cellulose [15], chitosan [16] has been also reported in literature. Sahoo et al. [17] achieved the incorporation of up to 65 wt% lignin in polybutylene succinate (PBS) matrix and proved the reinforcing effect of lignin. "
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    ABSTRACT: Two types of lignin obtained from softwood (LB) and hardwood (LO) were employed for manufacturing polylactic acid (PLA) – based composites. The morphological changes, mechanical and thermal properties, as well as water uptake of composites were evaluated before and after accelerated weathering. The chemical structure of lignin has an important influence on the composite properties. The addition of lignins to PLA matrix determined an increase of the impact strength and thermal stability of PLA, a good adhesion being observed in SEM micrographs. After accelerated weathering, tensile and impact strength decreased for all samples, but slightly for PLA/lignin composites, while all composites recorded an increase of water sorption capacity, especially for PLA/LB material. The free surface energy increased after weathering for all materials. The obtained results offer an opportunity to design environmentally friendly materials containing lignin that present higher values than the raw material itself.
    Full-text · Article · Feb 2015 · Composites Part B Engineering
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    • "The problem of PHB stability can be solved (or at least limited) by making use of stabilizers, such as anti-oxidants, plasticizers, thermal stabilizers, processing aids [16] [17] [18] [19] [20] [21] [22] [23] [24] [25]. The choice of the proper stabilizing system for PHB is a relevant issue. "
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    ABSTRACT: Poly(3-hydroxybutyrate) (PHB) is a biodegradable polymer, whose applicability is limited by its relatively poor mechanical properties and narrow processing window. In this paper, a natural polyphenolic additive, tannic acid (TA) was used as thermal and processing stabilizer for PHB. The thermal stability of both neat and TA-doped PHB samples was studied by rheology and calorimetry. The experimental results show that the neat PHB massively degrades and that the addition of tannic acid enhances the thermal stability of PHB, thus widening the processing window of the polymer. Physical and chemical interactions between the polymer and the additive were considered as key factors to interpret the experimental data. The described results are of interest for the development of sustainable alternatives to synthetic polymer additives, by increasing the applicability of bio-based materials.
    Full-text · Article · Dec 2014 · European Polymer Journal
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    • "Infrared spectroscopy can provide information on the development of weak bonds and interactions such as hydrogen bonding between matrix and filler. Mousavioun et al. [25] observed a shift in the carbonyl absorption for melt extruded blends of PHB and soda lignin, which was ascribed to hydrogen bonding interactions of the reactive functional groups of lignin with the carbonyl oxygen in PHB. FTIR-ATR experiments were carried out on cross-sections cut from plate sample in order to investigate on the interactions between PHB and LRR. "
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    ABSTRACT: A Lignin Rich Residue (LRR) obtained as a by-product from the fermentative bioethanol production process, and commercial alkali lignin (AL), were used as fillers for the preparation of bio-based blends and composites with poly(3-hydrobutyrate) (PHB). Chemical characterization of LRR demonstrated that the filler contained sugar residues. Rheological and thermal characterization of the blends demonstrated that LRR did not affect thermal stability of PHB, while AL had a strong pro-degrading effect. Addition of suitable amounts of LRR dramatically affected the rheological behavior of the polymer melt, suggesting that the additive can modify polymer processability. LRR was also a heterogeneous nucleating agent, potentially able to control the physical aging of PHB. Lower resilience and elongation at break values were found for the biocomposites, due to the poor interfacial adhesion between filler and matrix. Biodegradation behavior of the composites was qualitatively assessed by analyzing the surface of soil buried films. Significant surface degradation was observed for PHB, while the process was retarded at high filler concentration, as LRR inhibited hydrolytic and biotic polymer degradation. The reported results demonstrated the feasibility of the conversion of an agro-industrial by-product into a bio-resource in an environmentally friendly and cost-effective way.
    Full-text · Article · Jul 2014 · International Journal of Biological Macromolecules
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