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The spherulite dimensions of neat PLA, PLA/ADR, PLA/α-cellulose, and PLA/PMMA/α-cellulose composites isothermally crystallised at 135 °C for 10 min. The spherulite dimensions for a neat PLA, b PLA/ADR, c PLA/α-cellulose, d PLA/PMMA/α-cellulose (90/10), e PLA/PMMA/α-cellulose (80/20) composites are approximately 46, 32, 26, 23, and 19 μm, respectively
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Polylactide (PLA)/polymethylmethacrylate (PMMA)/α-cellulose composites were fabricated using a twin-screw extruder. During fabrication, α-cellulose short fibres were incorporated for improving the toughness of the brittle PLA and a chain extender was used for reducing PLA hydrolysis. Highly transparent PLA and PMMA were blended to obtain miscible a...
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Rare earth luminescent material CaAlSiN3:Eu2+ (CEu) was applied and modified with (3-Aminopropyl) triethoxysilane (KH550) to obtain two types of rare earth conversion agents, CEu and KH550-modified CEu (KCEu). Two kinds of polylactide (PLA) conversion films were successfully prepared through solution blending. The results showed that the addition o...
Citations
... In order to obtain information about the optical properties of the films, clarity and haze were measured. These two properties describe the transparency and scattering of light of the material respectively [43,44]. Clarity and haze are significantly different for the two samples. ...
Over the last years, bio-based and biodegradable alternatives have gained considerable attention both of academic and of packaging industrial communities, driven by recent legislation and increasing awareness concerning environmental issues related to traditional plastic. However, it is often observed that packaging products made from bioplastics do not exhibit comparable performance to those produced using common non-biodegradable ones. The presence of long chain branching improves the processing behavior under elongational flow and, then, the filmability of low viscosity polymers such as polyesters. In this work it has been demonstrated that the presence of long chain branching in a bio-co-polyester, induced by the use of pentaerythritol in the synthesis a of poly(butylene adipate-co-butylene terephthalate), is able to dramatically change the rheological behavior of the linear chain polyester improving its filmability. The addition of branching lead to an increase of the elastic modulus and the tensile strength in branched polyester films if compared to the linear ones, while the elongation at break decreased. This is due to the answer of the branched polyester to the non-isothermal elon- gational flow that allows a better orientation of the macromolecules of the branched polyester. The film obtained with the branched polyester showed a decrease in clarity and a slight increase in haze if compared to linear one due to differences in the morphology of the two samples.
... Poly(methyl methacrylate) (PMMA) is a visible-light transparent synthetic polymer that can be used as a substitute for inorganic glass since its discovery on account of its transparency, high impact strength, dimensional stability, and weather resistance [13]. Nowadays, worldwide spread applications of PMMA range from packaging to biomedical implants [14], optic [15], cosmetic, and construction materials [16]. In addition to these applications, PMMA can be used for the development of multicomponent polymeric material via the incorporation of inorganic fillers, such as carbon nanotubes [17], clays [18], metals, and semiconductor particles [19,20]. ...
Cellulose is a class of biopolymers that prominently contributes to developing lightweight, eco-friendly, and biodegradable plastics. Among them, nanofibrillated cellulose (NFC) is one of the most interesting due to its mechanical behavior. Mixing it with synthetic plastic such as poly(methyl methacrylate) (PMMA) reduces synthetic polymer usage, agro-industrial residue and develops fiber-reinforced composites. NFC was prepared from residual biomass and oxidized with TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl radical). Herein, NFC was incorporated (25, 50 and 75 wt%) in a colloidal emulsion of PMMA, with PMMA particle size control (50 and 175 nm). The investigation of this system on the PMMA/NFC transparency was addressed here. FTIR and SEM demonstrated effective incorporation of NFC and interaction with the PMMA. The increment of NFC increased the water contact angle and improved film transparency. Paired with PMMA particle size control, particularly at 50 nm, this favored composite transparency, becoming close to or even greater than pure NFC.
Graphical abstract
... In the same study a decreased crystallinity is reported 295 . Poly(2-ethyl-2-oxazoline) 296 , poly(ethylene-co-vinyl acetate) 297 , PMMA [298][299][300][301] and ionomers 302 are shown to hinder PLA crystallinity in respective blends, while preserving overall transmittance (T400-800 >70 %, T400-800 >80 %, T400-800 >80 %, T400-800 >80 %, respectively). T400-700 >50 % is reported for blend of PLA and poly(ethyleneco-vinyl alcohol) modified by reactive compatibilization 303 . ...
Due to environmental concerns, interest in bioplastics is rising. For optical applications, materials have to meet high requirements. Polylactide (PLA), a known bioplastic, is already applied in high tech applications such as medicine. The material shows favorable optical properties and excellent resistance against photodegradation. However, the material turns hazy due to crystallization when exposed to temperatures above 55-60 °C. This renders it useless for optical applications. Clouding might be avoided by influencing PLA’s crystallization behavior. In this critical review the broad use of PLA is discussed. It is also shown, that currently no material is commercially available that meets all requirements set while being biodegradable and exclusively based on renewable feedstocks. Finally, an overview of the current state in research is provided, considering PLA-based materials with adapted crystallization behavior under the aspect of transparency. At last, recommendations for the goal of achieving highly sustainable PLA-based optical components are given.
... There are steps available in improvising PLA such as polymer-polymer blending, polymerfillers and polymer plasticizer blending [7]. Polymer are usually blended with other polymer to improve mechanical properties, like what have been done by Yen et al., [8] in blending PLA with poly methyl methacrylate (PMMA) in order to improve the toughness of the brittle PLA. While addition of fillers contributes in the reduction of cost and increase flexibility of the composites. ...
Nowadays, the usage of plastic packaging raises environmental concern as they
accumulated on landfill. Hence, biodegradable polymer is introduced to substitute
conventional plastic in the packaging industry. Currently, biopolymers are studied
extensively and some of them shows potential to substitute non-degradable plastic,
but one biopolymer (polylactic acid (PLA)) in particular stands out as it possesses the
same properties as conventional plastic like polystyrene and polyester. Though, PLA’s
slow degradation rate and brittleness limit its application. Therefore, this study aims
to overcome the limitations of PLA and widen its application by modifying them. In
this study, algae is used as a filler to lower the cost and increase degradation rate
while epoxidized palm oil (EPO) is used as plasticizer to increase the flexibility of PLA.
Plasticized PLA (PLAEPO) is mixed using 5 wt% of algae filler content. The composite is
prepared by two methods; solvent casting and melt mixing. For solvent casting, PLA
and algae are dissolved in chloroform and casted by evaporation whereas for melt
mixing, all materials are melt blended using an internal mixer. Characterization for
the flexibility, thermal, mechanical and morphological properties of PLAEPO/algae
composite is conducted by using flexibility test, differential scanning calorimetry
(DSC), tensile testing and scanning electron microscopy respectively. After further
discussion and consideration, it is decided that PLAEPO/ALG-5 is best prepared by
solvent casting method.
Poly(lactic acid) (PLA)/cellulose nanocrystal (CNC) nanocomposites with 1 or 3 phr of CNC were prepared by melt mixing and compression molding then their % crystallinities as well as crystallization and melting behavior during the first heating/cooling/second heating process were investigated by differential scanning calorimetry (DSC). Isothermal crystallization at 80–130°C for 5 min was performed during the cooling process to see how the isothermal crystallization affects % crystallinity at 25°C. The % crystallinity at 25°C as well as the crystallization rate of the nanocomposite increased with CNC content and showed a maximum at the isothermal crystallization temperature of 105°C regardless of CNC content. The bimodal DSC melting peaks observed during the second heating process were considered due to the crystals with many defects (α′) and the crystals with more perfect structure (α), respectively. Isothermal crystallization kinetic analysis by Avrami equation showed that the Avrami exponents of the nanocomposites were about 1, meaning a rod‐ or disc‐shaped crystal growth mechanism. Improving the mechanical properties of the PLA/CNC nanocomposite would be possible because the % crystallinity at 25°C could be effectively increased by changing CNC content and cooling history.
Highlights
PLA/CNC nanocomposites.
Crystallization and melting behavior analysis of the nanocomposites by DSC.
Isothermal crystallization at 80–130°C for 5 min during cooling by DSC.
Crystallization degree was maximum for the isothermal crystallization at 105°C.
Isothermal crystallization kinetic analysis by Avrami equation.
In the present investigation, we have successfully fabricated and characterized modified Poly(methyl methacrylate) (PMMA)/Cellulose acetate (CA) nano blends as a function of graphene oxide (GO) loading. These nano blends were systematically characterized using x-ray diffraction (XRD), Fourier transforms infrared spectroscopy (FTIR), FT-Raman spectra, Ultraviolet and visible spectroscopic technique (UV-vis), Thermogravimetric analysis (TGA). The weak interfacial interaction between the polymer blend system and GO influenced on the mechanical stress-strain behavior of the polymer blend. Scanning electron microscopic (SEM) study reveals the entanglement of polymer network and existence of occupied GO network. Topographic two (2D) and three (3D)dimension micrographs recorded by Atomic force microscopy (AFM) technique estimate the decreased surface roughness due to the presence of carbon. Dielectric performances were carried out using impedance analyzer as a function of frequency (10 Hz to 1 MHz) and temperature (30°C-150 °C). The dielectric constant for the pure blend (ε′ = 2.25) was appreciably improved to three fold (ε′ = to 2.25 × 10³) for 2 wt% GO loaded polymer blend system. The modified nano blends may be suitable for various electronic and electrical device applications.
The hydrolytic degradation of poly(L‐lactic acid)/poly(methyl methacrylate) (PLLA/PMMA) blends was carried out by the immersion of thin films in buffer solutions (pH=7.24) in a shaking water bath at the temperature of 60 °C for 38 days. The PLA/PMMA blends (0/100; 30/70;50/50; 70/30; 100/0) were obtained by melt blending using a Brabender internal mixer and shaped into thin films of about 150 μm thickness. Considering that PMMA does not undergo hydrolytic degradation, the PLLA hydrolytic degradation was followed via evolution of PLA molecular weight (recorded by size exclusion chromatography (SEC)), thermal parameters (differential scanning calorimetry (DSC)) and morphology of the films (scanning transmission electron microscopy (STEM)). The results revealed, a completely different degradation pathway of the blends depending on the polymethacrylate/polyester weight ratio. DSC data let suggest that, during the hydrolysis, at higher PMMA content, the polyester amorphous chains, more sensitive to water, is degraded before to able to crystallize while with higher PLLA content, the crystallization is favoured leading to more resistant sample to hydrolysis. In other words, and quite unexpectedly, increasing the content of water‐sensitive PLLA in the PLLA/PMMA blend does not mean de facto faster hydrolytic degradation of the resulting materials.
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In current study, cellouronic acid sodium (CAS), obtained from bagasse pith, has been introduced into poly(acrylamide-co-diallyldimethylammonium chloride) (poly(AM-co-DAC)) network to form novel thermo-sensitive semi-IPNs. The structure and morphology of the hydrogels were proved by Fourier transformation infrared spectroscopy (FT-IR), X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM). The effects of CAS content, initiator charge, cross-linker dosage and swelling-medium property on the thermo-responsive water absorptivity were investigated in detail. The results elucidated that the prepared gels exhibited a thermo-sensibility with an upper critical solution temperature (UCST) and a high water-absorbency. And the values of UCST and equilibrium swelling ratio largely depended on the inner structure of the semi-IPNs and the external solvent property. It was also revealed that the swelling process conformed to the Schott’s pseudo second order model and diffusion type was non-Fickian diffusion. The value of activation energy for this polyelectrolyte was found to be 8.74 kJ/mol.
