Crystallization Of Polylactic Acid Research Articles

Used of Chemically Modified Titanium Dioxide Particles to Mediate the Non-isothermal Cold Crystallization of Poly(latic acid)

In this work, the effect of the chemical modification of titanium dioxide particles on the non-isothermal crystallization process of polylactic acid (PLA) was studied. Cold crystallization in some polymers occurs above the glass transition temperature (Tg) when the polymer chains gain sufficient mobility to organize themselves into the ordered structure (i.e. the crystal structure) by folding the chains. Cold crystallization in general is caused by the ordering of the molecular chains in the crystalline PLA due to the increased mobility during heating. Through an analysis of the cool crystallization process in DSC at different cooling rates, it was observed that the behavior of PLA and its composites made with titanium dioxide, neat and functionalized with dicarboxylic acids, can be described through the models used for crystallization of the polymer carrying out during cooling, such as Mo’s and Jeziorny’s model. In addition, it was determined that the chemical modification of TiO2 performed with silane increases the crystallization rate in the last step of the process; while the chemical modification with dicarboxylic acid has an accelerated effect on the crystal formation process attributed to the affinity between the aliphatic part of this group and the polymer chains. Also, it was shown that the inclusion of the silanized particles has no effect on the energy requirement compared to the pure PLA process; however, the addition of particles with the dicarboxylic acid decreases the energy value required to complete the crystalline state due to affinity at the surface to immobilize the polymer chains. Finally, it is emphasized that the activation energy required to perform the crystallization of PLA and its composites has positive values, which is an indicator that the crystallization was performed while heating, after reaching and passing the glass transition temperature and before melting.

The Effect of Different Acrylic-Based Rubbers on the Crystallization Behavior of PLA/PDLA Stereocomplex

This study investigated the performance of two acrylic rubbers on the improvement of mechanical and thermal properties of polylactic acid (PLA)/ poly(D-lactide) (PDLA) stereocomplex. The selected acrylic-based rubbers consisted of a commercial acrylic rubber (ACM) and acrylic core–shell rubber (CSR). In this work, 5 wt% PDLA was melt-blended with PLA to form PLA/PDLA stereocomplex (ST) in the presence of a 15 wt% acrylic-based rubber in an internal mixer at 180 °C and 50 rpm. It was found that the small amount of PDLA could successfully form stereocomplex crystals with PLA during melt mixing. The addition of acrylic-based rubbers not only increased the impact strength of the blends but also assisted PLA in forming more perfect crystals. This is because the rubbers could act as nucleation sites for PLA crystallization leading to smaller spherulite size than that of neat unmodified PLA. Comparatively, CSR could provide much higher %crystallinity with quicker nucleation onset than ACM in both PLA and ST systems, even though the crystallization rate was lower. In terms of mechanical properties, CSR also contributed to the highest impact strength due to the smaller size of CSR than ACM in both PLA and ST systems.

Structure and evolution of multiphase composites for 3D printing

Ethylene-vinyl acetate–glycidyl methacrylate random terpolymer (EVM–GMA, VA = 60 wt%, GMA = 2.9%) was used as a polymeric plasticizer replacing the traditional dioctyl phthalate (DOP) to prepare a polyvinyl chloride (PVC) masterbatch. Polylactic acid (PLA) was applied to blend with the PVC masterbatch in melt to examine the epoxy ring-opening reactions between epoxy groups in EVM–GMA and end carboxyl groups in PLA in order to construct a special phase structure in PVC/PLA improving the mechanical properties and 3D printing performance. The formation and evolution of phase structures were revealed by aids of the unique rheological responses of multi-component composite system. The results showed that with the increase in EVM–GMA content, the phase morphology of PVC/PLA was refined from co-continuous phase structure to denser one and then evolved to sea-island structure. It was also found that the addition of EVM–GMA inhibited the crystallization of PLA and the cold crystallization as well. When PVC/EVM–GMA/PLA was incorporated in weight ratio of 45/5/50, the denser co-continuous phase structure with smaller domain imparted the composite a highest zero shear viscosity and viscous flow activation energy. This unique structure existed stably when the shear rate was less than 230 s−1 or below 180 °C. Consequently, it endowed composite the highest impact strengths and smoothest appearance of 3D printed specimens. Therefore, moderate EVM–GMA is not only a reliable alternative plasticizer for PVC, but also an ideal modifier for the compatibility of PVC/PLA blends which presented an excellent performance in 3D printing.

Morpho-Structural, Thermal and Mechanical Properties of PLA/PHB/Cellulose Biodegradable Nanocomposites Obtained by Compression Molding, Extrusion, and 3D Printing.

Biodegradable blends and nanocomposites were produced from polylactic acid (PLA), poly(3-hydroxybutyrate) (PHB) and cellulose nanocrystals (NC) by a single step reactive blending process using dicumyl peroxide (DCP) as a cross-linking agent. With the aim of gaining more insight into the impact of processing methods upon the morphological, thermal and mechanical properties of these nanocomposites, three different processing techniques were employed: compression molding, extrusion, and 3D printing. The addition of DCP improved interfacial adhesion and the dispersion of NC in nanocomposites as observed by scanning electron microscopy and atomic force microscopy. The carbonyl index calculated from Fourier transform infrared spectroscopy showed increased crystallinity after DCP addition in PLA/PHB and PLA/PHB/NC, also confirmed by differential scanning calorimetry analyses. NC and DCP showed nucleating activity and favored the crystallization of PLA, increasing its crystallinity from 16% in PLA/PHB to 38% in DCP crosslinked blend and to 43% in crosslinked PLA/PHB/NC nanocomposite. The addition of DCP also influenced the melting-recrystallization processes due to the generation of lower molecular weight products with increased mobility. The thermo-mechanical characterization of uncross-linked and cross-linked PLA/PHB blends and nanocomposites showed the influence of the processing technique. Higher storage modulus values were obtained for filaments obtained by extrusion and 3D printed meshes compared to compression molded films. Similarly, the thermogravimetric analysis showed an increase of the onset degradation temperature, even with more than 10 °C for PLA/PHB blends and nanocomposites after extrusion and 3D-printing, compared with compression molding. This study shows that PLA/PHB products with enhanced interfacial adhesion, improved thermal stability, and mechanical properties can be obtained by the right choice of the processing method and conditions using NC and DCP for balancing the properties.

Preparation of polylactic acid/TEMPO-oxidized bacterial cellulose nanocomposites for 3D printing via Pickering emulsion approach

The aim of this study is to produce a novel TEMPO-oxidized bacterial cellulose (TOBC) reinforced Polylactic acid (PLA), fully biodegradable composites for fused deposition molding (FDM). In order to get uniform dispersion of BC in PLA matrix, TEMPO-mediated oxidation reaction and Pickering emulsion were used. The PLA composite microspheres were found uniformly coated by TOBC, via Pickering emulsion approach. And screw extrusion was used to prepare PLA/TOBC filaments for FDM. The mechanical properties, crystallinity, fluidity and thermal stability of PLA/TOBC nanocomposites were systematically investigated. It was found that the addition of a small amount of TOBC could effectively improve the mechanical properties and crystal properties of PLA. Uniform dispersion of TOBC in PLA matrix is helpful for forming a three-dimensional network and cross-linking structure which acts as a nucleating agent to promote the crystallization of PLA. In this paper, the mechanical properties and crystallization properties of the composites were optimized when TOBC content up to 1.5 wt%, and with further increasing TOBC, TOBC accumulates were found in PLA matrix, which were defects for PLA composites, the mechanical properties and crystallinity of the nanocomposites were reduced. • Pickering emulsion approach can achieve good dispersion of BC in PLA. • TEMPO-mediated oxidation to improve the compatibility of BC with PLA matrix. • The addition of BC improves the crystallinity PLA nanocomposites. • 3D printed PLA/BC nanocomposites have good mechanical properties and designability.

Effects and mechanism of cellulose acetate butyrate on the crystallization of polylactic acid

The effect of cellulose acetate butyrate (CAB) on the crystallization kinetics of polylactic acid (PLA) has been investigated by means of differential scanning calorimetry (DSC), polarized optical microscopy (POM) and scanning electron microscopy (SEM). CAB is essentially immiscible with PLA, as CAB spherical particles with average diameters in the range of 140–185 nm dispersed uniformly in PLA matrix. The incorporation of CAB effectively reduces the crystallization rate of PLA even at a low loading of 0.2 wt%. Moreover, it is particularly interesting to find a critical CAB content (about 5 wt%) which further increase in CAB concentration doesn’t bring significant influence on the PLA crystallization rate. Combined with the results of POM, SEM, DSC and selective dissolving experiment, it is proposed that the coating of CAB on the nuclei which enhanced by the nano-scaled CAB structure could strongly inhibit the nucleation, and thereby reduce the overall crystallization rates of PLA.

Lignin: A Biopolymer from Forestry Biomass for Biocomposites and 3D Printing.

Biopolymers from forestry biomass are promising for the sustainable development of new biobased materials. As such, lignin and fiber-based biocomposites are plausible renewable alternatives to petrochemical-based products. In this study, we have obtained lignin from Spruce biomass through a soda pulping process. The lignin was used for manufacturing biocomposite filaments containing 20% and 40% lignin and using polylactic acid (PLA) as matrix material. Dogbones for mechanical testing were 3D printed by fused deposition modelling. The lignin and the corresponding biocomposites were characterized in detail, including thermo-gravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, X-ray diffraction analysis (XRD), antioxidant capacity, mechanical properties, and scanning electron microscopy (SEM). Although lignin led to a reduction of the tensile strength and modulus, the reduction could be counteracted to some extent by adjusting the 3D printing temperature. The results showed that lignin acted as a nucleating agent and thus led to further crystallization of PLA. The radical scavenging activity of the biocomposites increased to roughly 50% antioxidant potential/cm2, for the biocomposite containing 40 wt % lignin. The results demonstrate the potential of lignin as a component in biocomposite materials, which we show are adequate for 3D printing operations.

Isolation and characterisation of nanofibrillated cellulose from waste cotton: effects on thermo-mechanical properties of polylactic acid/MA-g-SEBS blends

In garment industry, cotton waste is the major threat for disposal or waste management due to environmental issues. Nanofibrillated cellulose (NFC) from waste cotton was isolated by steam explosion technique, an eco-friendly method in comparison with chemical methods. Nanocellulose was characterised by different analysis techniques like TEM, SEM and XRD. The crystallinity index of nanocellulose was found to be 66% based on Seigel’s empirical method. SEM micrographs showed highly entangled nanofibrils with diameters ranging from 67 to 70 nm. TEM results revealed reduction in the size of fiber from micro to nano upon mild acid treatment along with steam explosion. Bionanocomposites of maleated styrene ethylene butylene styrene (MA-g-SEBS) toughened polylactic acid (PLA) reinforced with nanocellulose were fabricated by twin screw extruder and tested for thermo-mechanical behaviour using injection molded specimen. Mechanical property evaluation showed that the composites containing nanocellulose exhibited higher modulus compared to virgin PLA and PLA binary blend system containing SEBS or MA-g-SEBS. The elongations of bionanocomposites were substantially increased, possibly due to good dispersion of nanocellulose and its plasticizing effect. Morphological studies were also carried out to investigate the effect of nanocellulose on toughened PLA. The impact strength was also found to be higher compared to virgin PLA by the incorporation of nanocellulose to SEBS toughened PLA. Differential scanning calorimetry measurements observed an increase in crystallization of PLA by heterogeneous nucleation effect of NFC.

Morphology Evolutions and Mechanical Properties of In Situ Fibrillar Polylactic Acid/Thermoplastic Polyurethane Blends Fabricated by Fused Deposition Modeling

AbstractThere are many studies devoted to conquer the strength–ductility trade‐off dilemma of polylactic acid (PLA) by flexible elastomer blending, like thermoplastic polyurethane (TPU), but little is known about the effects of the fused deposition modeling (FDM) process on the in situ morphology evolution of the elastomers. In this work, the effects of the three successive drawing processes in FDM on the morphology evolution of the dispersed TPU in the PLA matrix, and the toughening behavior of FDM‐printed PLA/microfibrillar‐TPU blends, are systematically studied. The results manifest that the average length of the TPU microfibrils can be turned precisely from 67.24 to 103.72 µm. The in situ microfibrillation process can remarkably improve the PLA crystallization capability and interfacial interaction. More interestingly, the inevitable decrease of impact strength of FDM‐printed part induced by the voids is compensated by the network‐like TPU microfibrils formed during the layer‐by‐layer printing. These inspiring findings suggest that the in situ fibrillation process can conquer the inherent weaknesses of both FDM process and PLA materials, providing facile and efficient method for fabricating high toughness PLA parts.

Influence of graphene nanoscrolls on the crystallization behavior and nano‐mechanical properties of polylactic acid

Graphene nanoscrolls (GNS), one‐dimensional carbon‐based nanomaterials, have been predicted to possess extraordinary characteristics due to their unique open topology with scrolled graphene monolayers. In this study, the conversion of planar 2‐D graphene nanoplatelets (GNPs) to tubular and scrolled 1‐D GNSs is described. The effects of GNS as a nucleating agent to modulate the morphology, crystallization, and nano‐mechanical properties of polylactic acid (PLA) were studied. The nucleating effect of GNS and its unique topological characteristics proves to influence the crystallization of PLA. Fourier transform infrared (FTIR) spectroscopy indicated nonpreferential interactions of PLA chains around GNS due to the bulky and helical PLA macromolecular chains. Superior interfacial interactions and strain in GNS provide better load transfer between GNS and PLA matrices, resulting in higher modulus and hardness. This study is the first detailed analysis to elucidate the role of unique GNS to favorably modulate the properties of a polymer.

Strong and thermal-resistance glass fiber-reinforced polylactic acid (PLA) composites enabled by heat treatment.

Polylactic acid (PLA) is a biodegradable polymer derived from renewable resources, showing potentials in replacing traditional petroleum-based polymers, yet its brittleness and low thermal-resistance limits its applications. Thus, glass fibers (GF) combined with heat treatment were used to prepare high-performance PLA. Differential scanning calorimetry (DSC) and X-ray diffraction (XRD) were employed to analyze crystallization behavior of PLA/GF composite. Tensile, flexural and impact tests were conducted to investigate mechanical properties, and heat deflection temperature was measured to evaluate thermal resistance. GF can coincidently enhance strength, rigidity, and toughness of PLA. Isothermal heat treatment can further improve the mechanical properties regardless of GF content. Compared with neat PLA, the tensile strength, flexural modulus, and impact strength can be increased by 162.5%, 266.4%, 232.5%, respectively, in the presence of 20 wt% GF after isothermal heat treatment, and meanwhile heat deflection temperature can be increased from 50.6 °C to 148.8 °C. Both DSC and XRD analysis results indicated that GF can significantly enhance crystallization of PLA. Thus, not only GF but also enhanced crystallization led to the outstanding mechanical performance of PLA/GF composites. While GF shows little effect on thermal resistance, heat treatment can remarkably improve thermal stability, in particular for PLA/GF composites.

Water–soluble extracts from banana pseudo–stem as functional additives for polylactic acid: Thermal and mechanical investigations

Water–Soluble Extracts (WSE) were obtained from Banana Pseudo–stems (BPS) using a simple and robust deconstruction procedure. WSE were characterized by FTIR, WAXS, TGA–DTG analysis. With the objective of developing fully bio–based polymer formulations, WSE fillers were blended to Poly Lactic Acid (PLA) using a solution blending, casting and thermocompression process. Thermal and mechanical properties were investigated by Differential Scanning Calorimetry (DSC), Dynamic Mechanical Analysis (DMA) and uniaxial tensile tests on neat–PLA (n–PLA) and PLA/WSE blends at various filler contents. Thermal DSC investigations established that WSE act as a plasticizer on PLA. This was further confirmed by DMA by the shift of the loss factor (tan δ) peak maximum towards lower temperatures. WSE also significantly impacted the thermally induced crystallization of PLA and the nucleating power of WSE was assessed by isothermal and non–isothermal studies. WSE had a detrimental effect on PLA brittleness and a slightly positive influence on its stiffness in the glassy state, whereas the drawability remained fairly acceptable when PLA–based materials where drawn at 75 °C above Tg. Moreover, WSE induced an earlier strain–hardening of the composite films as compared to neat PLA. These results underline the valorization potential of such agricultural by–products for sustainable polymer applications in the packaging industry.

Enhancement in Thermal Stability of Polyoxymethylene (POM)-Based Biopolymer Blend Materials

In this study, we demonstrate the enhancement in thermal stability of polyoxymethylene (POM)-based biopolymer blend materials. Polyoxymethylene (POM)/Polylactic acid (PLA) blends have been used as alternative biopolymer materials for supporting environmental problems with thermal stability feature. The effects on POM biopolymer blend materials with a controlled PLA amount in their compositions under various injection conditions, were investigated by thermogravimetric analysis, dynamic mechanical analysis, and differential scanning calorimetry. The POM/PLA biopolymer blend materials showed POM phase acted as a homogeneous nucleating site for increasing PLA crystallization, which improves storage modulus of the blend materials. The decomposition temperatures of POM/PLA biopolymer blends tend to shift around 30˚C - 50˚C lower compared to the decomposition temperatures of PLA. Thus, the decomposition temperature behavior of POM/PLA blends seems to be closer to POM. The suitable ratio in POM70/PLA30 resulted in the high strength of the blend materials. The POM/PLA biopolymer blend material was tested at various injection speeds and good miscibility was obtained at an injection speed of 100 mm/s. This enhancement of thermal stability in POM/PLA blend materials should be useful in the development of high-performance bio-based thermoplastic materials.

Manufacture of a hydrophobic CaO/polylactic acid composite

ABSTRACTIn this study, the surface of calcium oxide (CaO) was modified with n-octadecyltrichlorosilane [CH3(CH2)16CH2SiCl3] to obtain modified calcium oxide (CaO-M). CaO and CaO-M were melt-blended with polylactic acid (PLA) to prepare PLA/CaO and PLA/CaO-M, respectively. Moisture absorption measurement showed that the surface of modified CaO was changed from hydrophilic to hydrophobic. CaO and PLA had a tendency to agglomerate after blending, whereas the blend of CaO-M and PLA showed no signs of agglomeration, and the distribution of CaO-M in PLA was homogeneous. In addition, CaO-M had a heterogeneous nucleation effect on PLA, which effectively inhibited cold crystallization and promoted crystallization of PLA. In conclusion, CaO-M can be used as a nucleating agent of PLA.

The New Generation from Biomembrane with Green Technologies for Wastewater Treatment.

A biopolymer of polylactic acid (PLLA)/polypropylene carbonate (PPC)/poly (3-hydroxybutrate) (PHB)/triethyl citrate (TEC) blends was prepared by the solution-casting method at different proportions. The thermal characteristics were studied by differential scanning calorimetry (DSC) and thermogravimetry (TG). PHB and TEC were added to improve the interfacial adhesion, crystallization behavior, and mechanical properties of the immiscible blend from PLLA and PPC (20%). The addition of more than 20% of PPC as an amorphous part hindered the crystallization of PLLA. PPC, PHB, and TEC also interacted with the PLLA matrix, which reduced the glass transition temperature (Tg), the cold crystallization temperature (Tcc), and the melting point (Tm) to about 53, 57 and 15 °C, respectively. The Tg shifted from 60 to 7 °C; therefore, the elongation at break improved from 6% (pure PLLA) to 285% (PLLA blends). In this article, biomembranes of PLLA with additives were developed and made by an electrospinning process. The new generation from biopolymer membranes can be used to absorb suspended pollutants in the water, which helps in the purification of drinking water in the household.

The effect of a small amount of modified microfibrillated cellulose and ethylene–glycidyl methacrylate copolymer on the crystallization behaviors and mechanical properties of polylactic acid

With the purpose of improving the crystallization rate and toughness of polylactic acid (PLA) comprehensively, chemical modified microfibrillated cellulose (MMFC) and ethylene–glycidyl methacrylate copolymer (EGMA) were used in the preparation of the PLA/MMFC/EGMA composite. After controlled acetylation using acetic anhydride, MMFC exhibited an improved hydrophobicity, resulting in a much better dispersion in PLA matrix. To clarify the impact of MMFC on the crystallization behaviors and mechanical properties of PLA, PLA/MMFC composites with 1–20 wt% of MMFC were characterized using differential scanning calorimetry (DSC) analysis and stress–strain curves. It was revealed that in the presence of only a small amount of MMFC (3 wt%), the crystallization rate of PLA was enlarged for seven times when the crystallization occurred at 120 °C, and the tensile modulus and tensile strength were both increased by 25% compared with pure PLA. The effect of EGMA component on the crystallization and mechanical properties of PLA was considered based on the characterization of the PLA/MMFC/EGMA composite. It was confirmed from DSC thermograms that a small amount of EGMA (5 wt%) did not exhibit any negative impact on the crystallization of PLA in the case of PLA/MMFC-3 wt%/EGMA-5 wt% composite. Meanwhile, in the presence of the EGMA, PLA/MMFC-3 wt%/EGMA-5 wt% composite showed an obvious increase of elongation-at-break from 9.1 to 20.8 compared with pure PLA. A remarkable improvement of crystallization behavior and toughness of PLA was achieved due to cooperative effect of the small amount of MMFC and EGMA in the PLA composite.

Condensed Tannin-Based Polyurethane as Functional Modifier of PLA-Composites

ABSTRACTNovel polylactic acid-based composites were prepared for the first time by melt-blending urethanization using bark polyflavonoids, and polymeric methyl diisocyanate. Rheological, morphological, structural, thermal, and mechanical properties were studied. Polymerization between polyflavonoids and isocyanate during the melt-blending was demonstrated by spectroscopy, confocal microscopy, and thermal analysis. Polyflavonoids improved the blend processability and affected the polylactic acid-crystallization, blend-urethanization, and flexural features. Polyphenols act as nucleating agent, and the effect was highly influenced by the polymeric methyl diisocyanate-charge, and the polyflavonoids-content. Low polymeric methyl diisocyanate-loading (10 wt%) degrades the elasticity modulus (E), while the highest polymeric (20 wt%) improved the miscibility between the polylactic acid polymer-matrix and the polyflavonoids.

Effect of flax fiber content on polylactic acid (PLA) crystallization in PLA/flax fiber composites

Crystallization of polylactic acid (PLA) has a profound effect on its thermal stability and mechanical properties. However, almost no crystallization occurs in actual injection molding process due to rapid cooling program. In this paper, flax fiber was employed as nucleator to enhance the crystallization capability of PLA. Effects of flax fiber content on cold crystallization, melt crystallization, crystallinity, crystal form, morphologies, and size of spherulites of PLA/flax fiber composites were investigated. Dynamic mechanical analysis was innovatively employed to study cold crystallization temperature of PLA/flax fiber composites under dynamic force, and the relationship between cold crystallization temperature (y) and flax fiber content (x) data was fitted by the function y = 34.1 × exp (−x/5.7) + 78.0. The differential scanning calorimetry results showed that the cold crystallization temperature of composites dropped, the melt crystallization temperature of composites increased, and the crystallinity of composites improved with increasing of flax fiber content. Using polarized optical microscopy, it has been found that the spherocrystal size of composites was much smaller than that of neat PLA, and flax fiber induced transcrystallization on the flax fiber surfaces. Wide-angle X-ray diffraction was applied to reveal that flax fiber significantly enhanced the formation of α-form PLA crystals.

Improvement of thermal and mechanical properties of composite based on polylactic acid and microfibrillated cellulose through chemical modification

Polylactic acid (PLA) is the most representative sustainable and bio-based polymer environmentally friendly that has a great potential to replace petroleum-based plastics. However, brittleness, low heat resistance, and slow crystallization limit the wide application of PLA. One of strategies to improve PLA properties is by reinforcing with microfibrillated cellulose (MFC). Unfortunately, the hydrophilic properties of MFC make it difficult to attain good dispersion in a hydrophobic PLA matrix. Therefore, modification of MFC was needed to increase its compatibility with PLA in the composite formation. In this experiment, MFC was modified with partial acetylation (degree of substitution: 1) and further grafted with lactide monomers through ring-opening polymerization using Sn(Oct)2 catalyst. The result of acetylation and grafting were verified by infrared spectra. Composites were prepared by mixing PLA (molecular weight of 200,000) and the modified MFC at 9:1 ratio through organic solvent method. Followed by 8 min-kneading and hot pressing at 180°C, the resulted composites were evaluated for their mechanical and thermal properties. Thermal characterization carried out using differential scanning calorimetry measurements showed that the presence of modified MFC increased the temperature of glass transition and accelerated the crystallization of PLA. Mechanical properties measurement showed that the presence of modified MFC enhanced the elongation at break (1.1 to 1.8%), tensile strength (14.9 to 25.7 MPa), and modulus of elasticity (1.7 to 2.1 GPa). These results demonstrated that the modified MFC could extend the application of PLA in industry.

PLA/PBAT Bionanocomposites with Antimicrobial Natural Rosin for Green Packaging.

The use of biodegradable polymers is of great importance nowadays in many applications. Some of the most commonly used biopolymers are polylactic acid (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) due to their superior properties and availability. In this manuscript, we use a facile and green modification method of organoclay (OC) by antimicrobial natural rosin which is considered as a toxicity-free reinforcing material, thus keeping the green character of the material. It increases the interlayer spacing between the clay platelets. This was proven by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) and found to impart antimicrobial properties to PLA/PBAT blends. The morphology of the resulting blends was conducted using scanning and transmission electron microscopies (SEM and TEM), and evidence of exfoliation and intercalation was observed. The thermal properties of the blends were studied using differential scanning calorimetry (DSC), and a detailed study of the crystallization of both PLA and PBAT was reported showing cold crystallization behavior of PLA. The final effect on mechanical and antimicrobial properties was also investigated. The obtained results reveal excellent possibility of using expanded OC modified PLA/PBAT polymer blends by adding a green material, antimicrobial natural rosin, for food packaging and biomembranes applications.