Investigating the Structure–Property Relationships of Paramylon Ester/PBAT Blends for Sustainable Packaging

In this study, an ester from paramylon, paramylon propionate hexanoate (PaPrHe), was synthesized and blended with poly(butylene adipate-co-terephthalate) (PBAT). The effects of structure and morphology on the thermal and mechanical properties of the blends were investigated. Dynamic mechanical analysis showed that the blends were immiscible throughout their compositional range. After selectively etching PBAT using enzymes and conducting SEM analysis, it was found that blends with a high proportion of PaPrHe (up to 70%) had a phase-separated morphology with significant particle agglomeration, leading to inferior mechanical properties. However, when the PBAT loading was increased to 50%, a cocontinuous, weblike morphology was observed that improved the mechanical properties. Further increasing the PBAT concentration resulted in a unique submicrometer-level bead dispersion with a mean particle diameter of 0.7–1.3 μm, which enhanced the mechanical properties significantly, particularly the impact strength. The highest impact strength was exhibited by the 70% PBAT blend (54.1 kJ/m2), surpassing that of pure PBAT (37.1 kJ/m2) and PaPrHe (9.7 kJ/m2). Additionally, by uniaxial stretching at room temperature and annealing at 80 °C, blend films with tensile strengths up to 120 MPa could be obtained. Overall, PaPrHe/PBAT blends have the potential for use in mulch films and sustainable packaging applications

Long/Short Chain Mixed Cellulose Esters: Effects of Long Acyl Chain Structures on Mechanical and Thermal Properties

Long/short chain mixed cellulose esters (MCE) are practical, promising polymers with interesting properties. In the molecular design of MCE, using long acyl chains made from renewable resources is important and enhances the value of MCE as sustainable materials. In this study, we focused on two types of renewable long acyl chains for MCE: the aromatic 3-pentadecylphenoxy acetyl (PA) group derived from cardanol extracted from cashew nutshells and the aliphatic stearoyl (St) group made from vegetable oils. Using these long acyl chains and the acetyl (Ac) group as a short acyl chain, we synthesized PA/Ac MCE (P-series) and St/Ac MCE (S-series) in LiCl/DMAc medium. The thermal and mechanical analyses revealed that a mixed substitution of long and short acyl chains prevented the crystallization of the long acyl chain moieties in MCE. The P-series had slightly higher bending strength and glass transition temperature than those of the S-series but showed low impact strength because of the existence of the aromatic ring in the PA group, which caused an increase in the stiffness of the cellulose backbone and the extra intermolecular interaction. However, the S-series without aromatic rings showed remarkably improved impact strength with sufficient balanced mechanical properties for use in durable products due to its composition of low crystalline long acyl chain moieties

Morphology-Retaining Carbonization of Honeycomb-Patterned Hyperbranched Poly(phenylene vinylene) Film

Ordered porous materials are of great technological interest for use as separation, catalysis, adsorbents, and electronic devices. We report here a fabrication of honeycomb-patterned porous films from fluorescent hyperbranched poly(phenylene vinylene) (hypPPV) by breath figure method and the thermal conversion of this film to macroporous carbon. This hexagonal porous film is very thermally stable and retained its structure at up to >600 °C. After the heating, carbonization of hypPPV occurred, and black porous carbon film was obtained. Additionally, because π-conjugated hypPPV has many vinylene moieties at its terminus, the photo-cross-linking reaction easily proceeds without the collapse of the honeycomb structures. This cross-linking reaction rendered the honeycomb films completely insoluble in organic solvents. Because of the provided high thermal and chemical stability, the honeycomb films are a new class of microstructured materials that is promising for many applications such as durable electroluminescence devices, bandgap materials, adsorbents, electrodes, and solvent-resistant porous membranes

Manufacturing Low Dielectric Polysaccharide Esters with High Thermal Stability

We aimed to produce biomass-based plastics derived from polysaccharides for use in electrical devices, such as printed circuit boards (PCBs). We systematically investigated the combination of polysaccharides and side chain structures to achieve specific properties, notably a high glass transition temperature (Tg), for processes like soldering, and a low dielectric constant (Dk) to minimize electrical transmission loss. Three polysaccharides were selected as backbone structures: cellulose (β-1,4-glucan), paramylon (β-1,3-glucan), and α-1,3-glucan. Three types of side chain structures were then introduced: linear, branched, and cyclic, leading to 40 derivatives. Among them, α-1,3-glucan with cyclohexane carboxylate side chains exhibited the most promising properties combining high Tg: 205 °C and low Dk: 2.7. Additionally, improving the crystallinity resulted in a further reduction of Dk to 2.5. The high Tg and low Dk properties were comparable to, or surpassed, those of conventional polymers used in PCBs, such as epoxy and polyimide (>200 °C, 3–4). Polysaccharide esters are therefore another viable option as insulating polymers in electrical devices

Thermal Embedding of Humicola insolens Cutinase: A Strategy for Improving Polyester Biodegradation in Seawater

By thermal embedding of the commercially available enzyme Humicola insolens cutinase (HiC), this study successfully enhanced the biodegradability of various polyesters (PBS, PBSA, PCL, PBAT) in seawater, which otherwise show limited environmental degradability. Melt extrusion above the melting temperature was used for embedding HiC in the polyesters. The overall physical properties of the HiC-embedded films remained almost unchanged compared to those of the neat films. In the buffer, embedding HiC allowed rapid polymer degradation into water-soluble hydrolysis products. Biochemical oxygen demand tests showed that the HiC-embedded polyester films exhibited similar or much higher biodegradability than the biodegradable cellulose standard in natural seawater. Thermal embedding of HiC aims to accelerate the biodegradation of plastics that are already biodegradable but have limited environmental biodegradability, potentially reducing their contribution to environmental problems such as marine microplastics

Thermal Properties and Crystallization Behavior of Curdlan Acetate Propionate Mixed Esters

Curdlan, a β-1,3-glucan polysaccharide, produced by microorganisms, was used as a raw material to synthesize a completely substituted Curdlan mixed ester, Curdlan acetate propionate (CDAcPr). The degree of propionylation was changed (0.4–2.8), and the resulting thermal and crystal properties were analyzed using DSC and wide-angle X-ray diffraction (WAXD). Results showed that CDAcPr had a single Tg at all degrees of propionylation, indicating that the acyl groups were randomly distributed in its molecular chains rather than a physical blend of homoesters. Further, unlike typical mixed esters, CDAcPr also showed melting points ranging from 293 to 231 °C, with several samples showing multiple melting peaks. WAXD results suggested that CDAcPr underwent cocrystallization observed in certain copolymers, exhibiting isodimorphism. The crystal structure and melting point of CDAcPr could be controlled by changing the degree of propionylation. Such structural control greatly expanded the possibilities of biomass-based plastics derived from polysaccharides

Surface Engineering of Ultrafine Cellulose Nanofibrils toward Polymer Nanocomposite Materials

Surface grafting of crystalline and ultrafine cellulose nanofibrils with poly­(ethylene glycol) (PEG) chains via ionic bonds was achieved by a simple ion-exchange treatment. The PEG-grafted cellulose nanofibrils exhibited nanodispersibility in organic solvents such as chloroform, toluene, and tetrahydrofuran. Then, the PEG-grafted cellulose nanofibril/chloroform dispersion and poly­(l-lactide) (PLLA)/chloroform solution were mixed, and the PEG-grafted cellulose nanofibril/PLLA composite films with various blend ratios were prepared by casting the mixtures on a plate and drying. The tensile strength, Young’s modulus, and work of fracture of the composite films were remarkably improved, despite low cellulose addition levels (<1 wt %). The highly efficient nanocomposite effect was explained in terms of achievement of nanodispersion states of the PEG-grafted cellulose nanofibrils in the PLLA matrix. Moreover, some attractive interactions mediated by the PEG chains were likely to be formed between the cellulose nanofibrils and PLLA molecules in the composites, additionally enhancing the efficient nanocomposite effect

Elastic Marine Biodegradable Fibers Produced from Poly[(<i>R</i>)‑3-hydroxybutylate<b>-</b><i>co</i><b>-</b>4‑hydroxybutylate] and Evaluation of Their Biodegradability

Marine biodegradable fibers with high strength and elasticity were successfully fabricated from microbial polyesters using a melt-spinning method. Polymers were melted at temperatures lower than the constituent melting temperatures, and the obtained fibers were stretched at room temperature. The molecular weights of the fibers processed by this melt-spinning method remained unchanged, suggesting that the developed approach is very effective for polyhydroxyalkanoates, which typically exhibit low thermal stability during the melting process. The obtained fibers had tensile strengths >200 MPa and elongation at break of ∼200%, making them comparable to nonbiodegradable elastic fibers processed from polyethylene and polypropylene. It was confirmed that these fibers were completely degraded by both seawater from Tokyo Bay and freshwater from Sanshiro Pond after less than 1 month. Interestingly, periodically stacked lamellar structures of 200 nm that comprised at least 30 lamellae were generated following the biodegradation of the amorphous region of the fiber surface

DataSheet1_Marine biodegradation of poly[(R)-3-hydroxybutyrate-co-4-hydroxybutyrate] elastic fibers in seawater: dependence of decomposition rate on highly ordered structure.PDF

Here, we report the marine degradability of polymers with highly ordered structures in natural environmental water using microbial degradation and biochemical oxygen demand (BOD) tests. Three types of elastic fibers (non-porous as-spun, non-porous drawn, and porous drawn) with different highly ordered structures were prepared using poly[(R)-3-hydroxybutyrate-co-16 mol%-4-hydroxybutyrate] [P(3HB-co-16 mol%-4HB)], a well-known polyhydroxyalkanoate. Scanning electron microscopy (SEM) images indicated that microorganisms attached to the fiber surface within several days of testing and degraded the fiber without causing physical disintegration. The results of BOD tests revealed that more than 80% of P(3HB-co-16 mol%-4HB) was degraded by microorganisms in the ocean. The plastisphere was composed of a wide variety of microorganisms, and the microorganisms accumulated on the fiber surfaces differed from those in the biofilms. The microbial degradation rate increased as the degree of molecular orientation and porosity of the fiber increased: as-spun fiber < non-porous drawn fiber < porous drawn fiber. The drawing process induced significant changes in the highly ordered structure of the fiber, such as molecular orientation and porosity, without affecting the crystallinity. The results of SEM observations and X-ray measurements indicated that drawing the fibers oriented the amorphous chains, which promoted enzymatic degradation by microorganisms.</p