Biodegradable and Bio-based Green Blends from Carbon Dioxide-Derived Bioplastic and Poly(Butylene Succinate)

In recent year, bioplastics have become more popular resulting from the growing concerns on environmental issues and the rising fossil fuel price. However, their applications were limited by its mechanical and thermal properties. The aim of this research is thus to improve mechanical and thermal properties of PBS bioplastic films by reinforcing with silica. Due to the poor interfacial interaction between the PBS matrix and silica, glycidyl methacrylate grafted poly(butylene succinate) (PBS-g-GMA) was used as a compatibilizer in order to improve the interaction between bioplastic films and filler. PBS-g-GMA was prepared in a twin-screw extruder and analyzed by the FTIR spectrometer. PBS and silica were then mixed in a twin-screw extruder and processed into films by a chill-roll cast extruder. The effects of silica loading on thermal and mechanical properties of the prepared bioplastic films were investigated. It was found that the mechanical properties of PBS/silica composite films were improved when 1%wt of silica was added. However, the mechanical properties decreased with increasing silica loading due to the agglomeration of silica particles. The results also show that the silica/PBS films with PBS-g-GMA possessed improved mechanical properties over the films without the compatibilizer.

Novel silk/poly(butylene succinate) biocomposites: the effect of short fibre content on their mechanical and thermal properties

To improve the thermal and mechanical properties of poly(propylene carbonate) (PPC), the copolymerization of CO2 with PO was successfully carried out in the presence of a third monomer, 4,4′-diphenylmethane diisocyanate (MDI) using supported multi-component zinc dicarboxylate as catalyst. Chemical structure, the molecular weight, as well as thermal and mechanical properties of the resulting new copolymers were fully investigated. The experimental results show that the yield increases with increasing MDI feed content from 0 to 2 wt.%. The introduction of MDI leads to an increase in the molecular weight of PPC with light crosslinking. When the MDI feed content is lower than 3 wt.%, the PPC copolymers have number average molecular weight (Mn) ranging from 153 K to 424 K g/mol and molecular weight distribution (MWD) values ranging from 1.71 to 2.79. The resulting PPC copolymers show higher glass transition temperature (Tg) and decomposition temperature compared with poly(propylene carbonate) (PPC) without MDI. Considering the gel content of the resulting copolymers, the optimized MDI feed content should be smaller than 1.5 wt.% based on PO content. The introduction of small amount of MDI provides a very effective way to improve the mechanical properties and thermal stabilities of PPC due to the increase in its molecular weight.

Current research efforts in the field of poly(propylene carbonate) prepared from carbon dioxide and propylene oxide are reviewed. Interest in the polymer has been revived in light of the current discussion on sustainability and biodegradability. The progress in understanding and increasing the activity of heterogeneous zinc catalysts is steadily increasing, but without a quantum leap. The microstructure, the properties of the melt, and the solid material are given. The material property profile can be expanded through the synthesis of terpolymers based on propylene oxide, carbon dioxide and other epoxides, lactones or anhydrides etc. with the same catalyst; or the preparation of poly(propylene carbonate) blends with biodegradable or biocompatible components like calcium carbonate, wood flour, fibers, or other biodegradable polymers.

The present study aims to develop a biodegradable polymer blend that is environmentally friendly and has comparable tensile and thermal properties with synthetic plastics. In this work, microcrystalline cellulose (MCC) extracted from bamboo-chips-reinforced poly (lactic acid) (PLA) and poly (butylene succinate) (PBS) blend composites were fabricated by melt-mixing at 180 °C and then hot pressing at 180 °C. PBS and MCC (0.5, 1, 1.5 wt%) were added to improve the brittle nature of PLA. Field emission scanning electron microscopy (FESEM), scanning electron microscopy (SEM), X-ray diffraction (XRD), Fourier transform infrared spectroscope (FTIR), thermogravimetric analysis (TGA), differential thermogravimetry (DTG), differential scanning calorimetry (DSC)), and universal testing machine were used to analyze morphology, crystallinity, physiochemical, thermal, and tensile properties, respectively. The thermal stability of the PLA-PBS blends enhanced on addition of MCC up to 1wt % due to their uniform dispersion in the polymer matrix. Tensile properties declined on addition of PBS and increased with MCC above (0.5 wt%) however except elongation at break increased on addition of PBS then decreased insignificantly on addition of MCC. Thus, PBS and MCC addition in PLA matrix decreases the brittleness, making it a potential contender that could be considered to replace plastics that are used for food packaging.

The exploitation of beidellite clay (BDT), used as a nanofiller in the preparation of poly(butylene succinate) (PBS)/organoclay biodegradable nanocomposites, was investigated. A series of bionanocomposites with various loadings of the organoclay (3CTA-BDT) were prepared by in situ polycondensation reaction between succinic anhydride (SuAh) and 1,4-butanediol (1,4-BD) at atmospheric pressure in refluxing decalin with azeotropic removal of water, and the reaction was catalyzed by non-toxic bismuth chloride (BiCl3). X-ray diffraction (XRD) and scanning electron microscopy (SEM) results showed that 3CTA-BDT was likely exfoliated and well dispersed in PBS matrix. Thermal properties (TGA, DSC and thermal conductivity), contact angle measurements and water vapor sorption behavior of the corresponding nanocomposites were also discussed. Compared to pure PBS, a significant reduction of the diffusion coefficient and the water vapor permeability (WVP) by 44 and 37%, respectively, was observed by adding only 5 wt% of 3CTA-BDT. These results could make these bionanocomposites suitable materials for food packaging application.

The present study involved valorisation of rice straw (RS) in the form of rice straw flour (RSF) for the fabrication of poly (butylene succinate) (PBS) based bio-composites through a melt extrusion method, using dicumyl peroxide (DCP) as the cross-networking agent, and study of the morphological, thermal, mechanical and rheological behaviours of the extruded bio-composites. A layered like morphology with good dispersion of RSF in the PBS matrix was observed from X-ray diffraction and field emission scanning electron microscopic analysis. Thermo gravimetric analysis showed that the incorporation of RSF improved the thermal stability of PBS, whereas the value of the different thermal properties i.e. glass transition temperature (Tg), melting temperature (Tm) remained almost identical. Addition of DCP (2 wt%) into the PBS-RSF systems increased both the tensile strength and elongation at break (EB) (%) values. Rheological investigation of the bio-composites showed that the storage modulus (G') was less than the loss modulus (G") over the angular frequency (ω) range until crossover, corroborating the viscous behaviour of the samples. The complex viscosity, η' was constant when ω was less than 1 rad/s for all the samples, showing Newtonian characteristics. Shear thinning behaviour was observed when ω was greater than 1 rad/s. Furthermore, no phase separation was observed from the Han plot and good compatibility was noticed from the Cole–Cole plot, which signifies good rheological properties of the fabricated bio-composites.

In this study, for the first time, we used cyclohexane dicarboxylic anhydride (CH) as the third monomer to terpolymerize with carbon dioxide (CO2) and propylene oxide (PO) under the catalysis of zinc glutarate (ZnGA). Incorporating cis‐CH (C‐CH) and trans‐CH (T‐CH) into poly(propylene carbonate) (PPC) improved the thermal and mechanical properties and increased the polymer molecular weight and yield. T‐CH showed better improvement than C‐CH because of its twist‐chair form. PPC‐CH containing 3% T‐CH exhibits the glass transition temperature (Tg) and maximum weight thermal decomposition temperature (Tmax) at 38.6 and 263°C, respectively, and shows the Young's modulus and tensile strength about 2.9 GPa and 40.5 MPa, respectively, which has comparable mechanical properties to commercial poly(butylene succinate), polypropylene, and high‐density polyethylene. PPC‐CH may form a novel method to recover CO2 in the form of polymers for various applications.

Cellulose nanocrystals (CNCs) extracted from microcrystalline cellulose, were modified by succinic anhydride to give succinic CNCs (SCNCs). Successful surface modification of SCNCs was confirmed by results of FTIR, FE-SEM, contact angle measurement and dispersity test, and SCNCs were then subjected to melt blending with poly(butylene succinate) (PBS) to prepare nanocomposites. Meanwhile, PBS/CNC nanocomposites were also prepared through same procedure as references. The morphology, thermal and mechanical properties and crystallization properties of PBS/SCNC nanocomposites with increasing SCNCs content from 0 to 7 wt% were investigated. PBS/SCNC nanocomposites exhibit better thermal stability than that of PBS/CNCs, which is mainly ascribed to less sulfate groups on CNC surfaces and more hydrogen bond effects between PBS carbonyl groups and ester groups from SCNCs. Young’s modulus and yield strength of PBS/SCNCs are higher than that of PBS/CNC nanocomposites, which is primarily attributed to the homogeneous dispersion of SCNCs in PBS matrix, confirmed by FE-SEM images. This work is valuable for design of PBS-based nanocomposites with enhanced thermal and mechanical properties.

The gas barrier properties of poly(butylene adipate‐co‐terephthalate) (PBAT) films can be improved with poly(propylene carbonate) (PPC), but this will reduce the mechanical properties. In this work, PBAT/PPC composites and the related films were prepared by melt blending followed by film blowing process using triglycidyl isocyanurate (TGIC) as the reactive compatibilizer. Herein, the structure, thermal properties, mechanical properties, and gas barrier properties of the composites were systematically characterized via various techniques. The results indicated that the incorporation of TGIC effectively improved the interfacial compatibility between PBAT and PPC, and enhanced the thermal stability of the composites, especially for PPC. In addition, PBAT/PPC/TGIC films at 1 phr (parts per hundreds of resin) TGIC content exhibited a tensile strength of 30.8 MPa, and an elongation at break of 860%, which are 136% and 142% of those of PBAT/PPC, respectively. Meanwhile, the water vapor transmission rate dropped by 33% at this content. The improvement of mechanics and gas barrier properties makes PBAT/PPC film better meet the requirements of food preservation packaging such as fruits and vegetables.

ABSTRACTPoly(propylene carbonate) (PPC) was modified by l‐aspartic acid (Asp) and poly(butylene succinate) (PBS). To assess the effects of Asp and PBS on the thermal stability, mechanical properties of PPC, different PPC/Asp, PPC/PBS, and PPC/PBS/Asp blends were prepared by twin‐screw extruder. The results indicated that the thermal stability improved with the Asp content increasing from 0.5 to 5%. With trace presence of 2% Asp, the degradation temperature of PPC was greatly increased upon extruding and the Yield strength and Young's modulus increased 62 and 849 times, respectively, at 20°C. The flexibility of PPC was effectively improved by blending with PBS, the PBS has no significant effect on the thermal stability of PPC until PBS up to enough amount. Besides the Asp additive in PPC/PBS blends not only improved the thermal stability PPC, but improved the interfacial compatibility of the blend. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016, 133, 42970.

In this work, calcium carbonate derived from eggshell, in a form of eggshell powder (ESP) with an average particle size of 13.96 μm, was used as bio-reinforcing filler for poly (butylene succinate), (PBS). The effect of ESP content on mechanical, thermal, and morphological properties of ESP filled PBS was investigated. The ESP/PBS composites were prepared at various ESP contents of 10, 20, 30 and 40 wt.%. It was found that incorporation of ESP into PBS matrix resulted in an improvement of Youngs modulus but it resulted in a decrease of tensile stress at break, yield strength and impact strength of the composite. In addition, increasing ESP content did not significantly influence decomposition temperature and melting temperature of PBS matrix. On the other hand, with increasing ESP content, crystallization temperature of the composite decreased but degree of crystallinity increased. Fracture surface morphology of the PBS composites obtained from scanning electron microscope indicated agglomeration and poor distribution of ESP within the composite matrix. Partial adhesion between ESP surface and PBS matrix was observed as well.

The homogeneous dinuclear zinc catalyst going back to the work of Williams et al. is to date the most active catalyst for the copolymerisation of cyclohexene oxide and CO(2) at one atmosphere of carbon dioxide. However, this catalyst shows no copolymer formation in the copolymerisation reaction of propylene oxide and carbon dioxide, instead only cyclic carbonate is found. This behaviour is known for many zinc-based catalysts, although the reasons are still unidentified. Within our studies, we focus on the parameters that are responsible for this typical behaviour. A deactivation of the catalyst due to a reaction with propylene oxide turns out to be negligible. Furthermore, the catalyst still shows poly(cyclohexene carbonate) formation in the presence of cyclic propylene carbonate, but the catalyst activity is dramatically reduced. In terpolymerisation reactions of CO(2) with different ratios of cyclohexene oxide to propylene oxide, no incorporation of propylene oxide can be detected, which can only be explained by a very fast back-biting reaction. Kinetic investigations indicate a complex reaction network, which can be manifested by theoretical investigations. DFT calculations show that the ring strains of both epoxides are comparable and the kinetic barriers for the chain propagation even favour the poly(propylene carbonate) over the poly(cyclohexene carbonate) formation. Therefore, the crucial step in the copolymerisation of propylene oxide and carbon dioxide is the back-biting reaction in the case of the studied zinc catalyst. The depolymerisation is several orders of magnitude faster for poly(propylene carbonate) than for poly(cyclohexene carbonate).

Poly(ethylene- co-vinyl acetate)/clay nanocomposites: Effect of clay nature and organic modifiers on morphology, mechanical and thermal properties

In order to decrease the brittle–toughness transition temperature and increase the mechanical strength of poly(propylene carbonate) (PPC), a series of multiblock copolymers of poly(propylene carbonate)-multiblock-poly(butylene succinate) (PPC-mb-PBS) are designed and synthesized. 1H-NMR, DOSY and GPC results demonstrate the successful synthesis of PPC-mb-PBSs with designed multiblock sequence. The thermal, crystalline and mechanical properties of these PPC-mb-PBSs are evaluated by DSC, TGA, POM, tensile and tearing testing. Experiment results demonstrate that crystallinity, thermal and mechanical properties of PPC-mb-PBSs can be readily modulated by changing the composition and block length of PPC and PBS moieties. It is found that all the prepared PPC-mb-PBSs are semi-crystalline polymers with a melting temperature at 93–109 °C and a Tg at around −40 °C. Both crystallization rate and crystallinity of the multiblock copolymers increase with increasing both PBS content and PBS block length. As a consequent, the tensile strength increases with increasing PBS/PPC block ratios at room and lower temperatures. In conclusion, the amorphous PBS phase in the block copolymers acts as soft segment, endowing PPC-mb-PBS copolymers with much better flexibility than PPC at low temperature of 273 K when PPC segments are frozen.