Polyhydroxyalkanoates (PHAs) are gaining increasing attention in the biodegradable polymer market due to their promising properties such as high biodegradability in different environments, not just in composting plants, and pro- cessing versatility. Indeed among biopolymers, these biogenic polyesters represent a potential sustainable replacement for fossil fuel-based thermoplastics. Most commercially available PHAs are obtained with pure microbial cultures grown on renewable feedstocks (i.e. glucose) under sterile conditions but recent research studies focus on the use of wastes as growth media. PHA can be extracted from the bacteria cell and then formulated and processed by extrusion for production of rigid and flexible plastic suitable not just for the most assessed medical applications but also considered for applications includ- ing packaging, moulded goods, paper coatings, non-woven fabrics, adhesives, films and performance additives. The present paper reviews the different classes of PHAs, their main properties, processing aspects, commercially available ones, as well as limitations and related improvements being researched, with specific focus on potential applications of PHAs in packag- ing.

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Polyhydroxyalkanoate (PHA): Review of synthesis, characteristics, processing and potential applications in packaging

The irruption of polymers from renewable resources on the scene of macromolecular science and technology

Can nanoparticles really enhance thermal stability of polymers? Part I: An overview on thermal decomposition of addition polymers

Lignin, nature’s dominant aromatic polymer, is found in most terrestrial plants in the range of 15–40% dry weight and provides structural integrity. Kraft lignin (KL) is a major by-product of pulp & paper industry where, hydrolysis lignin (HL) is the solid residue left from the enzymatic hydrolysis of wood after the pretreatment processes in cellulosic ethanol plants. Currently, most of the lignin is burned to generate heat and electricity and remaining is considered as a low value material. Only 1% of the annually produced lignin is being commercialized for its application in the preparation of bio-chemicals and to limited extent for bio-materials. Although with much lower reactivity, even crude lignin (a natural polyol) can be directly incorporated into polyurethane (PU) foam formulation due to the presence of aliphatic and aromatic hydroxyl groups in its structure as the reactive sites. However, bio-replacement ratios are usually low ~20–30% and further increasing replacement ratios results in fragile and low strength foams. Lignin depolymerization with selective bond cleavage is still a major challenge for converting it into value-added precursors especially for its utilization in the preparation of rigid PU foams. Depolymerization of these macromolecules can result in the valuable products with high hydroxyl number/functionality and low molecular weights, which in turn will increase the percentage replacement of bio-based polyols in the PU foam formulations. The technical routes/technologies for the depolymerization of lignins and their effective utilization as polyols in PU foams are summarized in this review article. These include direct utilization of lignin as well as the incorporation of depolymerized lignins, with and without modification, at high replacement ratios in PU foams. The major emphasis was given on the effective utilization of low value lignin for high value applications. Some of the associated challenges for the production of materials from lignin are also discussed.

Depolymerization of lignins and their applications for the preparation of polyols and rigid polyurethane foams: A review

Exfoliation of montmorillonite and related properties of clay/polymer nanocomposites

Relationship between morphology, properties and degradation parameters of novative biobased thermoplastic polyurethanes obtained from dimer fatty acids

Effect of clay organomodifiers on degradation of polyhydroxyalkanoates

Dimer acid-based thermoplastic bio-polyamides: Reaction kinetics, properties and structure

Bio-based TPUs from dimer acid-based polyols are synthesised by using a two-step prepolymer process including reactive processing. The effect of the polyol on the final chemical structures, morphologiesand properties ofbio-based TPUs is evaluatedby different analytical techniques. It is observed that the percentage of hard segment (HS) distributed in organised and unorganised phases is a key factor to control the materials properties. DSC reveals that the percentages of HS dispersed in the soft domains are high at low experimental HS contents. Multiscale microscopies show better defined organised structures with increasing HS content in TPUs, highlighting the importance of the distribution between hard and soft segments in the material structure.

Elodie Hablot

Papers

Relationship between morphology, properties and degradation parameters of novative biobased thermoplastic polyurethanes obtained from dimer fatty acids

Effect of clay organomodifiers on degradation of polyhydroxyalkanoates

Dimer acid-based thermoplastic bio-polyamides: Reaction kinetics, properties and structure

Structure and Morphology of New Bio‐Based Thermoplastic Polyurethanes Obtained From Dimeric Fatty Acids

Renewable biocomposites of dimer fatty acid-based polyamides with cellulose fibres: Thermal, physical and mechanical properties