https://cyberleninka.org/article/n/768408.pdf

Mechanical properties of graphene and graphene-based nanocomposites

Environmental, economic, and safety challenges have provoked packaging scientists and producers to partially substitute petrochemical-based polymers with biodegradable ones. The general purpose of this review is to introduce poly-lactic acid (PLA), a compostable, biodegradable thermoplastic made from renewable sources. PLA properties and modifications via different methods, like using modifiers, blending, copolymerizing, and physical treatments, are mentioned; these are rarely discussed together in other reviews. Industrial processing methods for producing different PLA films, wrappings, laminates, containers (bottles and cups), are presented. The capabilities of PLA for being a strong active packaging material in different areas requiring antimicrobial and antioxidant characteristics are discussed. Consequently, applications of nanomaterials in combination with PLA structures for creating new PLA nanocomposites with greater abilities are also covered. These approaches may modify PLA weaknesses for some food packaging applications. Nanotechnology approaches are being broadened in food science, especially in packaging material science with high performances and low concentrations and prices, so this category of nano-research is estimated to be revolutionary in food packaging science in the near future. The linkage of a 100% bio-originated material and nanomaterials opens new windows for becoming independent, primarily, of petrochemical-based polymers and, secondarily, for answering environmental and health concerns will undoubtedly be growing with time.

https://onlinelibrary.wiley.com/doi/pdf/10.1111/j.1541-4337.2010.00126.x

Poly-Lactic Acid: Production, Applications, Nanocomposites, and Release Studies.

Poly(lactic acid) crystallization

Recent advancements in supercapacitor technology

The past decade has seen the development of microporous materials (i.e., materials containing pores of dimensions <2 nm) derived wholly from organic components. Here we review this nascent area with a particular emphasis on amorphous polymers that possess intrinsic microporosity (IM), which is defined as microporosity that arises directly from the shape and rigidity of component macromolecules. Although IM can be readily identified within soluble non-network polymers and oligomers, for network polymers it is harder to differentiate IM from template effects that are responsible for the microporosity within hyper-cross-linked networks. The numerous examples of microporous polymers assembled from rigid monomers by the formation of rigid linking groups are surveyed and their IM assessed. The potential applications of these materials are highlighted.

Exploitation of Intrinsic Microporosity in Polymer-Based Materials

Recently, we reported the isothermal crystallization behaviors of poly(l-lactic acid) (PLLA) from the melt and glassy states, respectively [J. Phys. Chem. B 2004, 108, 11514; Macromolecules 2004, 37, 6433]. Surprisingly, the quite different infrared (IR) spectral evolutions occur in the two crystallization processes at different temperatures in which the same crystal modification is expected to be formed. To clarify this unusual phenomenon, the crystal modifications and thermal behavior of PLLA samples prepared under different crystallization temperatures are investigated in detail by TEM, WAXD, and FTIR techniques. On the basis of the WAXD and IR data, a new crystal modification named the α form is proposed for the crystal structure of PLLA samples annealed at temperature below 120 °C. Such crystal modification with loose 103 helical chain packing is less thermally stable than the standard α form of PLLA. This assignment can explain all the experiment observations well. Other possible mechanisms for the ...

Crystal modifications and thermal behavior of poly(L-lactic acid) revealed by infrared spectroscopy

The present study is aimed at investigating structure, dispersibility, and crystallinity of poly(3-hydroxybutyrate) (PHB) and poly(l-lactic acid) (PLLA) blends by using FT-IR microspectroscopy and differential scanning calorimetry (DSC) Four kinds of PHB/PLLA blends with a PLLA content of 20, 40, 60, and 80 wt % were prepared from chloroform solutions Micro-IR spectra obtained at different positions of a PHB film are all very similar to each other, suggesting that there is no discernible segregated amorphous and crystalline parts on the PHB film at the resolution scale of micro-IR spectroscopy On the other hand, the micro-IR spectra of two different positions of a PLLA film, where spherulite structures are observed and they are not observed, are significantly different from each other PHB and PLLA have characteristic IR marker bands for their crystalline and amorphous components Therefore, it is possible to explore the structure of each component in the PHB/PLLA blends by using micro-IR spectroscopy

Structure, Dispersibility, and Crystallinity of Poly(hydroxybutyrate)/Poly(l-lactic acid) Blends Studied by FT-IR Microspectroscopy and Differential Scanning Calorimetry

Hierarchically Porous N-doped Carbon Derived from ZIF-8 Nanocomposites for Electrochemical Applications

Poly(vinylidene fluoride) (PVDF) is one of the polymers which exhibit pronounced polymorphic crystalline forms, depending on crystallization conditions. Four different crystalline modifications, i.e., α, β, γ, and δ, have been reported so far. Among them, even though the α-form is the most common one, the β-phase is the one that has attracted the widest interest due to its extensive piezo- and pyroelectric applications. During the past few decades, a substantial amount of work has been done in attempts to characterize these crystal modifications and transformations among them. It was well documented that the α-form PVDF can be easily obtained through melt crystallization of the PVDF at atmospheric pressure. Its β-counterpart can, however, only be directly obtained by growth from solution, molecular epitaxy on the surface of potassium bromide, melt crystallization at high pressures, or by applying with a strong electric field. Transformation from its α-phase to β-phase has been achieved by mechanical defor...

On the α → β Transition of Carbon-Coated Highly Oriented PVDF Ultrathin Film Induced by Melt Recrystallization

We report an ambient pressure dried graphene aerogel (ADGA) with superelasticity (rapidly recoverable from >90% compression) and multifunctionality that could be obtained with ordinary instruments by recasting a partially reduced graphene oxide hydrogel (PRGH) with an ice-template method. This study would be a key progress for realizing cost-effective and large-scale commercial production of high-performance graphene aerogels.

Yongxin Duan

Papers

Crystal modifications and thermal behavior of poly(L-lactic acid) revealed by infrared spectroscopy

Structure, Dispersibility, and Crystallinity of Poly(hydroxybutyrate)/Poly(l-lactic acid) Blends Studied by FT-IR Microspectroscopy and Differential Scanning Calorimetry

Hierarchically Porous N-doped Carbon Derived from ZIF-8 Nanocomposites for Electrochemical Applications

On the α → β Transition of Carbon-Coated Highly Oriented PVDF Ultrathin Film Induced by Melt Recrystallization

Ambient pressure dried graphene aerogels with superelasticity and multifunctionality