Synergistic reinforcing of poly(lactic acid)-based systems by polybutylene succinate and nano-calcium carbonate

Porosity Tunable Poly(Lactic Acid)-Based Composite Gel Polymer Electrolyte with High Electrolyte Uptake for Quasi-Solid-State Supercapacitors

The growing popularity of quasi-solid-state supercapacitors inevitably leads to the unrestricted consumption of commonly used petroleum-derived polymer electrolytes, causing excessive carbon emissions and resulting in global warming. Also, the porosity and liquid electrolyte uptake of existing polymer membranes are insufficient for well-performed supercapacitors under high current and long cycles. To address these issues, poly(lactic acid) (PLA), a widely applied polymers in biodegradable plastics is employed to fabricate a renewable biocomposite membrane with tunable pores with the help of non-solvent phase inversion method, and a small amount of poly (vinylidene fluoride-co-hexafluoropropylene) (PVDF-HFP) is introduced as a modifier to interconnect with PLA skeleton for stabilizing the porous structure and optimizing the aperture of the membrane. Owing to easy film-forming and tunable non-solvent ratio, the porous membrane possesses high porosity (ca. 71%), liquid electrolyte uptake (366%), and preferable flexibility endowing the GPE with satisfactory electrochemical stability in coin and flexible supercapacitors after long cycles. This work effectively relieves the environmental stress resulted from undegradable polymers and reveals the promising potential and prospects of the environmentally friendly membrane in the application of wearable devices.

Improvement of Mechanical Property for PLA/TPU Blend by Adding PLA-TPU Copolymers Prepared via In Situ Ring-Opening Polymerization

Polylactic acid (PLA)-thermoplastic polyurethane (TPU) copolymer (PTC) was prepared by melting TPU pellets in molten lactide, followed by in situ ring-opening coordination polymerization. The results from FTIR and 1H-NMR confirmed the formation of the copolymer. PLA/TPU blends with different TPU contents were prepared by melt blending method. SEM and mechanical properties showed a conspicuous phase separation between PLA and TPU. In order to further improve the mechanical properties of the blend, PTC was used as the compatibilizer and the effects of the PTC content on the properties of the blend were investigated. The addition of PTC made TPU particles smaller in PLA matrix and improved the compatibility. With the loading of 5 wt.% PTC, the impact strength of the PLA/TPU blend reached 27.8 kJ/m2, which was 31.1% and 68.5% higher than that of the blend without PTC and pure PLA, respectively. As the content of PTC was more than 5 wt.%, the mechanical properties declined since the compatibilizer tended to form separate clusters, which could reduce the part distributed between the dispersed phase and the matrix, leading to a reduction in the compatibility of the blend. Moreover, the DMA results confirmed PTC could improve the compatibility between PLA and TPU.

Recent Trends of Foaming in Polymer Processing: A Review

Polymer foams have low density, good heat insulation, good sound insulation effects, high specific strength, and high corrosion resistance, and are widely used in civil and industrial applications. In this paper, the classification of polymer foams, principles of the foaming process, types of blowing agents, and raw materials of polymer foams are reviewed. The research progress of various foaming methods and the current problems and possible solutions are discussed in detail.

Green preparation and characterization of graphene oxide/carbon nanotubes-loaded carboxymethyl cellulose nanocomposites

In this study, a homogeneous and stable dispersion of graphene oxide (GO)/carbon nanotube (CNT) complexes (GCCs) was obtained by dispersing CNTs in an aqueous solution using GO in the absence of dispersing agents. Furthermore, carboxymethyl cellulose/GCC (CMC/GCC) nanocomposite films were prepared by a simple solution mixing-evaporation method. The dispersibility of the GCCs with different CNT contents was investigated by UV-Vis spectrophotometry. The morphological and crystalline structures of the samples were analyzed by transmission electron microscopy, scanning electron microscopy, and X-ray diffraction. X-ray photoelectron spectroscopy and Fourier-transform infrared spectroscopy were conducted to identify the chemical composition of GO, CNTs, and GCCs. These results revealed that CNTs could be stably dispersed in water using GO. In addition, when CMC/GCC nanocomposite films were prepared by mixing CMC and GCCs, CNTs were uniformly dispersed in the CMC matrix. The tensile behavior was investigated using a universal testing machine. The tensile strength and Young’s modulus of the CMC/GCC nanocomposite films were significantly improved by up to about 121% and 122%, respectively, compared to those of pure CMC because of uniform and strong π-π interfacial interactions between CNTs and CMC polymer.

Poly(lactic acid) (PLA) Based Tear Resistant and Biodegradable Flexible Films by Blown Film Extrusion

Poly(lactic acid) (PLA) was melt mixed in a laboratory extruder with poly(butylene adipate-co-terephthalate) (PBAT) and poly(butylene succinate) (PBS) in the presence of polypropylene glycol di glycidyl ether (EJ400) that acted as both plasticizer and compatibilizer. The process was then scaled up in a semi-industrial extruder preparing pellets having different content of a nucleating agent (LAK). All of the formulations could be processed by blowing extrusion and the obtained films showed mechanical properties dependent on the LAK content. In particular the tearing strength showed a maximum like trend in the investigated composition range. The films prepared with both kinds of blends showed a tensile strength in the range 12-24 MPa, an elongation at break in the range 150-260% and a significant crystallinity.