Thermophysical properties of conjugated soybean oil/corn stover biocomposites

Development and Characterization of Sustainable Composites from Bacterial Polyester Poly(3-Hydroxybutyrate-co-3-hydroxyhexanoate) and Almond Shell Flour by Reactive Extrusion with Oligomers of Lactic Acid

Eco-efficient Wood Plastic Composites (WPCs) have been obtained using poly(hydroxybutyrate-co-hexanoate) (PHBH) as the polymer matrix, and almond shell flour (ASF), a by-product from the agro-food industry, as filler/reinforcement. These WPCs were prepared with different amounts of lignocellulosic fillers (wt %), namely 10, 20 and 30. The mechanical characterization of these WPCs showed an important increase in their stiffness with increasing the wt % ASF content. In addition, lower tensile strength and impact strength were obtained. The field emission scanning electron microscopy (FESEM) study revealed the lack of continuity and poor adhesion among the PHBH-ASF interface. Even with the only addition of 10 wt % ASF, these green composites become highly brittle. Nevertheless, for real applications, the WPC with 30 wt % ASF is the most attracting material since it contributes to lowering the overall cost of the WPC and can be manufactured by injection moulding, but its properties are really compromised due to the lack of compatibility between the hydrophobic PHBH matrix and the hydrophilic lignocellulosic filler. To minimize this phenomenon, 10 and 20 phr (weight parts of OLA-Oligomeric Lactic Acid per one hundred weight parts of PHBH) were added to PHBH/ASF (30 wt % ASF) composites. Differential scanning calorimetry (DSC) suggested poor plasticization effect of OLA on PHBH-ASF composites. Nevertheless, the most important property OLA can provide to PHBH/ASF composites is somewhat compatibilization since some mechanical ductile properties are improved with OLA addition. The study by thermomechanical analysis (TMA), confirmed the increase of the coefficient of linear thermal expansion (CLTE) with increasing OLA content. The dynamic mechanical characterization (DTMA), revealed higher storage modulus, E’, with increasing ASF. Moreover, DTMA results confirmed poor plasticization of OLA on PHBH-ASF (30 wt % ASF) composites, but interesting compatibilization effects.

Valorization of Linen Processing By-Products for the Development of Injection-Molded Green Composite Pieces of Polylactide with Improved Performance

This work reports the development and characterization of green composites based on polylactide (PLA) containing fillers and additives obtained from by-products or waste-streams from the linen processing industry. Flaxseed flour (FSF) was first produced by the mechanical milling of golden flaxseeds. The resultant FSF particles were melt-compounded at 30 wt% with PLA in a twin-screw extruder. Two multi-functionalized oils derived from linseed, namely epoxidized linseed oil (ELO) and maleinized linseed oil (MLO), were also incorporated during melt mixing at 2.5 and 5 parts per hundred resin (phr) of composite. The melt-compounded pellets were thereafter shaped into pieces by injection molding and characterized. Results showed that the addition of both multi-functionalized linseed oils successfully increased ductility, toughness, and thermal stability of the green composite pieces whereas water diffusion was reduced. The improvement achieved was related to both a plasticizing effect and, more interestingly, an enhancement of the interfacial adhesion between the biopolymer and the lignocellulosic particles by the reactive vegetable oils. The most optimal performance was attained for the MLO-containing green composite pieces, even at the lowest content, which was ascribed to the higher solubility of MLO with the PLA matrix. Therefore, the present study demonstrates the potential use of by-products or waste from flax (Linum usitatissimum L.) to obtain renewable raw materials of suitable quality to develop green composites with high performance for market applications such as rigid food packaging and food-contact disposable articles in the frame of the Circular Economy and Bioeconomy.

The battle for the "green" polymer. Different approaches for biopolymer synthesis: bioadvantaged vs. bioreplacement

Biopolymers have been used throughout history; however, in the last two centuries they have seen a decrease in their utilization as the proliferation of inexpensive and mass-produced materials from petrochemical feedstocks quickly became better-suited to meeting society's needs. In recent years, high petroleum prices and the concern of society to adopt greener and cleaner products has led to an increased interest in biorenewable polymers and the use of sustainable technologies to produce them. Industrial and academic researchers alike have targeted several routes for producing these renewable materials. In this perspective, we compare and contrast two distinct approaches to the economical realization of these materials. One mentality that has emerged we term "bioreplacement", in which the fields of synthetic biology and catalysis collaborate to coax petrochemical monomers from sugars and lignocellulosic feedstocks that can subsequently be used in precisely the same ways to produce precisely the same polymers as we know today. For example, the metabolic engineering of bacteria is currently being explored as a viable route to common monomers such as butadiene, isoprene, styrene, acrylic acid, and sebacic acid, amongst others. Another motif that has recently gained traction may be referred to as the "bioadvantage" strategy, where the multifunctional "monomers" given to us by nature are combined in novel ways using novel chemistries to yield new polymers with new properties; for these materials to compete with their petroleum-based counterparts, they must add some advantage, for example less cost. For instance, acrylated epoxidized soybean oil readily undergoes polymerization to thermosets and recently, thermoplastic rubbers. Additionally, many plants produce pre-polymeric or polymeric materials that require little or no post modification to extract and make use of these compounds.

Synthesis and properties of a bio-based epoxy resin from 2,5-furandicarboxylic acid (FDCA)

Based on the properties comparison between FDCA-based epoxy and TPA-based epoxy, FDCA has been regarded as an ideal renewable platform chemical for the synthesis of thermosetting resins with high performance.