PLA Chain Mobility Research Articles

Significantly enhanced crystallization of polylactide Ingeo 4032D by polyethylene ionomer

Poly(lactic acid) (PLA) is the most important biopolymer material due to its excellent biocompatibility, biodegradability, and processability. However, its widespread applications were significantly limited by its low crystallization rate. While adding small molecule organic nucleating agents became a commonly used method in enhancing the crystallization rate, these nucleating agents generally suffer from limited solubility, which caused compromised nucleation efficiency and undesirable product appearance due to their precipitation onto the surface of the PLA products overtime. Here we report an efficient method for improving the PLA crystallization performance by using polyethylene (PE) ionomer as an additive in the PLA/TMC300 (an organic nucleating agent) nucleation/crystallization process. The added ionomer led to enhanced crystallization rate and reduced crystalline grain size. The resulting PLA from crystallization with TMC300 and ionomer showed reduced glass transition temperatures, reduced contact angles, and enhanced elastic modulus without compromising the impact strength and elongation at break. A possible mechanism was proposed for the remarkable synergistic effects of ionomer and TMC-300 in modifying the PLA crystallization process with the ionomer playing the roles of both plasticizer (enhanced PLA chain mobility and crystallization rate) and compatibilizer (enhanced dissolution and dispersion of TMC300 in the PLA matrix). This work offered a promising strategy for crystallization and modification of PLA materials.

Electrospraying poly(lactic acid) microcapsules loaded with n-hexadecane for thermal energy storage systems

Poly(lactic acid) (PLA) with good thermomechanical stability and biodegradability is selected as the shell for achieving the electro-microencapsulation of phase change materials. And, a series of n-hexadecane/PLA solutions with different compositions are electrosprayed into phase change microcapsules (mPCMs) in a green and high-efficiency way. The effects of PLA concentration and n-hexadecane addition in electrospraying solution on the microencapsulation process of n-hexadecane as well as the structures and properties of mPCMs are investigated. Experimental results indicate that spherical mPCMs with a mono-dispersed size distribution are obtained regardless of the variations in PLA concentrations and n-hexadecane additions. Encapsulated n-hexadecane tends to be randomly in the form of a poly-nuclear distribution. With increasing n-hexadecane addition, although both the mean diameter and the loading content of n-hexadecane in mPCMs increase gradually, the corresponding encapsulation efficiency of n-hexadecane decreases. And, higher loading content and higher encapsulation efficiency of n-hexadecane are obtained from higher PLA concentration solutions. When 5 wt% PLA/chloroform solution is used as matrix liquid to encapsulate n-hexadecane, the encapsulation efficiency of n-hexadecane in the mixture of 50 w/t% n-hexadecane and 50 wt% PLA can reach about 100%. Correspondingly, the phase-transition enthalpy also reaches 97 J/g. Meanwhile, because of the PLA matrix's protection, the phase-transition enthalpy of encapsulated n-hexadecane remains stable even after multiple heating-cooling processes. In addition, the cooperation of the PLA matrix with n-hexadecane chains also improves the mobility of PLA chains, resulting in a higher crystallization degree of the PLA matrix. This green, biodegradable, and durable n-hexadecane/PLA electrosprayed microcapsule can offer a new choice for the fields of thermal management and energy storage.

Thermal degradation of various types of polylactides research. The effect of reduced graphite oxide on the composition of the PLA4042D pyrolysis products

This study was aimed to investigate the effect of reduced graphene oxide (rGO) on the pyrolysis of polylactide composites (PLA4042D/rGO) prepared in solution. GC-MS analysis of PLA4042D/rGO pyrolysis products showed that introduction of rGO into the composition with PLA leads to a significant change in the ratio of main degradation products. A sharp decrease of five-membered dioxolanones accompanied by a growth in the content of lactides and cyclic oligomeric lactides was observed in PLA4042D/rGO pyrolysis products as compared with pristine PLA. DSC studies of PLA4042D crystallization in the melt showed that the adsorption of PLA macromolecules on rGO surface can cause the decrease in their segmental mobility. Apparently, a decrease in the segmental mobility of PLA chains hinders the formation of dioxolanones via the intramolecular nonradical ester interchange reaction. At the same time, the role of intermolecular reactions with the formation of cyclic oligomers of lactides increases.

Fiber-induced crystallization in polymer composites: A comparative study on poly(lactic acid) composites filled with basalt fiber and fiber powder

The poly(lactic acid) (PLA) composites with the silane coupling agent treated basalt fiber (SBF) and basalt fiber powder (SBFP) were prepared. The crystalline morphology, mechanical properties, and heat resistance of PLA/SBF/SBFP composites were investigated. The results indicated that SBF or SBFP not only acted as heterogeneous nucleating agents for PLA crystallization but also improved the mechanical properties and heat resistance of PLA. Morphological analyses showed that SBFP could play nucleating role to reduce the spherulites size of PLA, and SBF could restrict the mobility of PLA chains and construct interface crystallization for PLA during isothermal crystallization process. The composites with higher SBF loading, the “Transcrystalline-network” built in the composites significantly improved the heat resistance properties of PLA. Due to the synergistic effect of SBF and SBFP, the PLA/SBF/SBFP composites showed high heat deformation temperature (HDT), especially after isothermal crystallization, the HDT increased to 150.5 °C for the PLA/SBF/SBFP 50/10/40 composite, much higher (about 190%) than that of pure PLA (71.7 °C).

Thermal behavior of PLA plasticized by commercial and cardanol-derived plasticizers and the effect on the mechanical properties

This paper is aimed at studying the thermal properties of poly(lactic acid), PLA with different plasticizers. Plasticized PLA was obtained by mixing and extruding PLA with 20 mass% of neat cardanol, epoxidized cardanol acetate (ECA) and poly(ethylene glycol) (PEG) 400. The glass transition of completely amorphous samples, melting and crystallization behavior of plasticized PLA were analyzed by differential scanning calorimetry. Results obtained show that, below Tg, a higher enthalpy relaxation occurs for PLA plasticized by cardanol derivatives. This is indicative of a faster mobility of PLA chains below Tg, when cardanol derivatives are used as plasticizers. On the other hand, an opposite behavior was observed for the crystallization studies. In facts, a much faster crystallization was found for PLA plasticized by PEG, which in turn indicates a much higher mobility of PLA chains above Tg compared to PLA plasticized by cardanol derivatives. Mechanical properties obtained on completely amorphous samples show that PLA plasticized by ECA is characterized by lower modulus, which is indicative of a more efficient plasticization. On the other hand, the thicker crystals formed during crystallization of PLA plasticized by ECA involve a more relevant increase in the modulus in semicrystalline samples.

Thermal and Structural Analysis of Epoxidized Jatropha Oil and Alkaline Treated Kenaf Fiber Reinforced Poly(Lactic Acid) Biocomposites.

New environmentally friendly plasticized poly(lactic acid) (PLA) kenaf biocomposites were obtained through a melt blending process from a combination of epoxidized jatropha oil, a type of nonedible vegetable oil material, and renewable plasticizer. The main objective of this study is to investigate the effect of the incorporation of epoxidized jatropha oil (EJO) as a plasticizer and alkaline treatment of kenaf fiber on the thermal properties of PLA/Kenaf/EJO biocomposites. Kenaf fiber was treated with 6% sodium hydroxide (NaOH) solution for 4 h. The thermal properties of the biocomposites were analyzed using a differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA). It must be highlighted that the addition of EJO resulted in a decrease of glass transition temperature which aided PLA chain mobility in the blend as predicted. TGA demonstrated that the presence of treated kenaf fiber together with EJO in the blends reduced the rate of decomposition of PLA and enhanced the thermal stability of the blend. The treatment showed a rougher surface fiber in scanning electron microscopy (SEM) micrographs and had a greater mechanical locking with matrix, and this was further supported with Fourier-transform infrared spectroscopy (FTIR) analysis. Overall, the increasing content of EJO as a plasticizer has improved the thermal properties of PLA/Kenaf/EJO biocomposites.

Biodegradable poly (lactic acid)-poly (ε-caprolactone)-nanolignin composite films with excellent flexibility and UV barrier performance

In this work, poly(lactide-ε-caprolactone) copolymer grafted lignin nanoparticles (LNP-g-P(LA-CL) were synthesized, through a ring-open polymerization (ROP) of L-lactide and ε-caprolactone, initiated from the hydroxyl groups on LNP surface. Then PLA, PCL and various amounts of the copolymer were blended via a facile solvent casting approach. Mechanical tests showed that the addition of 6 wt% LNP-g-P(LA-CL) copolymer made a significant contribution to the toughness of PLA/PCL blend, which was enhanced by 4 folds in comparison with neat PLA. Meanwhile, the crystallization ability of both PLA and PCL were improved due to the better interfacial adhesion and mobility of PLA and PCL chains. Well-distributed elongated-fibrils and crazes, observed after tensile measurements for the nanocomposites, were responsible for absorbed energy, improved toughness and flexibility of PLA. Furthermore, UV–Vis spectroscopy measurements showed that the incorporation of 12 wt% of LNP-g-P(LA-CL) copolymer make PLA/PCL film able to shield almost 100 wt% of UV-B and UV-C irradiation. PLA/PCL-LNP nanocomposites can be used as impact resistance materials and in UV-resistance fields, such as sunshade and food packaging areas.

Impacts of cellulose nanofibril and physical aging on the enthalpy relaxation behavior and dynamic mechanical thermal properties of Poly(lactic acid) composite films

We herein report the influences of cellulose nanofibril (CNF) and physical aging on the enthalpy relaxation behavior, thermal transition, and dynamic mechanical properties of eco-friendly poly(lactic acid) (PLA) composite films with 0.5–7.0 wt% CNF loadings, which were fabricated by using a facile masterbatch-based melt-compounding process. For the purpose, melt-quenched neat PLA and PLA/CNF composite films were aged physically at 45 °C for different times. The FT-IR spectra revealed that specific hydrogen-bonding interactions exist between the carboxyl groups of PLA matrix and the hydroxyl groups of CNF fillers, and that the interactions are strengthened by the physical aging. Accordingly, the increments of the peak temperature (Tp) and area (ΔHrelax) of the endothermic enthalpy relaxation at the glass transition temperature region with the aging time were suppressed significantly for the composite films with higher CNF contents, unlike the neat PLA film. In addition, the characteristic relaxation time of PLA/CNF composite films was highly enhanced, indicating the improved enthalpy relaxation and dimensional stability. This result is associated with the fact that the CNF fillers restrict the segmental mobility of PLA chains in the composite films during the physical aging at the glassy state, which was supported by the dynamic mechanical thermal data.

Thermal, crystallization, mechanical and decomposition properties of poly(lactic acid) plasticized with poly(ethylene glycol)

In order to modify the brittleness of poly(lactic acid) (PLA), a series of PLA/poly(ethylene glycol) (PEG) blends were prepared by the solution‐cast technique using PEG as a plasticizer. The thermal, crystallization, mechanical, and hydrophilic properties of the PLA/PEG blends were compared with those of neat PLA. It is concluded that the PLA/PEG blends change from miscible to partially miscible at the critical PEG content of 10 wt%. Above 10 wt% PEG content, the miscible PLA/PEG blends occur the phase separation, and the PEG component does not co‐crystallize with PLA component with PLA and PEG crystallizing separately. The introduction of PEG reduces the intermolecular force and enhances the mobility of PLA chains, thus improving the crystallization capacity and flexibility of PLA. The PLA/PEG blends show plastic fracture behavior, yielding higher elongation and lower modulus values compared with neat PLA. Below 30 wt% PEG content, blending with PEG significantly decreases the modulus and yield stress and increases the fracture strain of PLA with an increase in the PEG content. Whereas above 30 wt% PEG content, the crystallization of PEG component results in an increase in modulus and a corresponding decrease in elongation at break of the blends. The thermal degradation temperature is in the range of 320–330°C for PLA/PEG blends, in comparison with 375°C for neat PLA. At ambient temperature, the desired mechanical properties are achieved by blending PLA with 30 wt% PEG. The PEG plasticizer is compatible with the PLA matrix and has a relatively low migration rate toward the blend surfaces with a low PEG content (≤30 wt%). J. VINYL ADDIT. TECHNOL., 24:E154–E163, 2018. © 2018 Society of Plastics Engineers

High performance poly (lactic acid)/bio-polyamide11 through controlled chain mobility

This study shows that controlled PLA chain mobility in poly (lactic acid)/polyamide11 (PLA/PA11) blends can lead to high performance materials. The addition of an appropriate amount of polyethylene oxide (PEO) or polyethylene glycol (PEG) to a PLA/PA11 blend reduces the interfacial tension and increases the interfacial interactions due to an increase in the PLA chain mobility. The mechanical properties of (PLA-PEO)/PA11 50/50 systems are highly dependent on the PEO composition and at an optimal PEO concentration show a remarkable improvement in the Izod impact strength with specimens demonstrating 17.5 times the impact strength of the neat PLA and 3 times that of neat PA11. Also, these same blends show exceptional ductility with an elongation at break of 275% as compared to 5% for the neat PLA and 6% for PLA/PA11 without added PEO. Analysis of the fracture surface of the tough blends after impact indicates controlled interfacial debonding/cavitation at the continuous PLA/PA11 interface which leads to extensive shear yielding in the surrounding matrices. An excellent correlation is found between the optimal PEO composition for high performance properties and PEO limited miscibility in the PLA phase. When PEO phase separates in the PLA it tends towards the PLA/PA11 interface and provides a locus of failure for interfacial debonding. PEG is not as effective as PEO and it has virtually no effect on the mechanical properties of the PLA/PA11 blend since it phase separates at lower concentrations, thus limiting its effect on PLA mobility and ultimately providing insufficient plastic deformation to the PLA matrix. These results indicate that controlled PLA chain mobility through the use of an optimal concentration of an appropriate plasticizer is a highly effective approach towards the development of high performance PLA/PA11 blends.

Morphology development in poly (lactic acid)/polyamide11 biobased blends: Chain mobility and interfacial interactions

In this study, the interfacial tension, morphology, PLA phase continuity and thermal behavior are studied for poly (lactic acid)/bio-polyamide11 blends. This blend combines the very unusual characteristics of high static interfacial tension, 5.8 ± 0.6 mN/m and 5.4 ± 0.4 mN/m as measured by the breaking thread (BT) and fiber retraction (FR) methods respectively, with the fine dispersed morphology and low level coalescence of a highly interacting system after melt mixing. The dispersed phase size at 1 vol% is 750 and 700 nm for dispersed PLA and PA11 respectively with no coalescence whatsoever up to 20 vol% minor phase. A coalescence study during annealing shows that the 50PLA-50PA11 blend behaves as if it were an interfacially modified system. Furthermore, the half time of crystallization of PA11 increases in the presence of PLA, an indication of significant interfacial interactions. A study using plasticizers for both PA11 and the PLA shows that this discrepancy between the static interfacial tension and the observed morphology after dynamic mixing can be attributed directly to the limited chain mobility of the stiff PLA molecule, particularly under quiescent conditions, which inhibits the available functional groups from interacting at the interface. Plasticized PLA in PLA-PA11 serves to significantly reduce the static interfacial tension as well as the phase size and coalescence in the dynamically mixed system at high concentrations of 30 and 40 vol% PLA. These results underline that the stiffness and borderline mobility of PLA chains can have a significant influence on its capacity for interfacial interactions and could be dependent on the flow conditions.

Non-isothermal kinetics of cold crystallization in multicomponent PLA/thermoplastic polyurethane/nanofiller system

The effect of platy and tubular nanofillers (NF) in combination with thermoplastic polyurethane (TPU) on cold non-isothermal crystallization (NIC) of poly(lactic acid) (PLA) was studied by differential scanning calorimetry. The data were processed using a recently proposed method of evaluating NIC kinetics. The results indicate that the NF/TPU combination leads to crystallization behaviour of the PLA matrix which is dissimilar from that of the NF-free blend and neat PLA. Addition of organophilized montmorillonite (C30) results in a dual effect on PLA crystallinity—stimulation at lower concentrations and suppression at higher loadings. In the case of halloysite nanotubes (HNT), this effect is practically absent. Crystallinity of injection-moulded samples is significantly increased by cold NIC. This indicates a synergy originating in a complex effect of NF/TPU, e.g. NF-induced changes in morphology and interphase parameters supporting the solid annealing process. TPU partially eliminates negative effect of high NF contents on cold crystallization rate. This effect is more marked in the remelted samples where the rate increases for all NF loadings. This is probably caused by absence of as-prepared crystallites in combination with higher mobility of PLA chains due to presence of TPU. The observed differences between C30 and HNT could be attributed to differences in size, shape, and specific surface. The results indicate that synergistic and antagonistic effects of NF/polymeric modifiers on mechanical and other material parameters are also significantly determined by the effects on crystallization of the matrix.

Physical ageing and molecular mobility in PLA blends and composites

Poly(lactic acid) (PLA) blends and composites were prepared from thermoplastic starch, poly(butylene-adipate-co-terephtalate), polycarbonate, wood flour and CaSO4 in a wide range of compositions. The thermal transitions of PLA were studied by differential scanning calorimetry. The detailed analysis of the transitions of PLA/thermoplastic starch blends indicated that they all are determined by the molecular mobility of PLA chains. Blending changes molecular mobility, and thus it often decreases glass transition temperature and modifies the extent of enthalpy relaxation. All other transitions and characteristics, i.e. cold crystallization, melting and the corresponding enthalpies, change accordingly. Increased molecular mobility accelerates also the physical ageing of the polymer. The interaction between PLA and the various components used for modification changed in a wide range, but no direct correlation was found between the strength of interaction and molecular mobility.

Morphology development, melt linear viscoelastic properties and crystallinity of polylactide/polyethylene/organoclay blend nanocomposites

ABSTRACTPolylactide/polyethylene blends (PLA/PE) and their nanocomposites were prepared via the melt blending process. The effects of organoclay, compatibilizer (PE‐g‐MA), and PE content on morphology, linear viscoelastic properties of the melt and cold crystallization of the samples have been studied. The Palierne model is applied to predict the rheological behavior of unfilled blends. It implies that there is a quantitative agreement between model and experimental data for low PE content blend. From WAXD and the rheological behavior, it is shown that organoclay exhibits a higher extent of intercalation and dispersion in PLA/PE/organoclay nanocomposite than in PLA/organoclay nanocomposite. The DSC results present that the addition of compatibilizer into blend nanocomposite increases cold crystallization temperature of PLA by about 3°C. This can be explained by the role of compatibilizer in transfer of a part of organoclay from PLA matrix to droplets resulting in increase of PLA chain mobility and, therefore, slightly greater cold crystallization temperature. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41300.

Adipate and Citrate Esters as Plasticizers for Poly(Lactic Acid)/Thermoplastic Starch Sheets

Poly(lactic acid) (PLA) and thermoplastic starch (TPS) sheets plasticized with different adipate and citrate esters were produced by a calendering-extrusion process. The incorporation of plasticizers significantly reduced the glass transition temperature and increased the PLA chain mobility thus improving the mechanical properties. Among the plasticizers employed, diethyl adipate significantly increased the elongation of the sheets and slightly increased the water vapor permeability. Micrographs revealed the incompatibility between starch and PLA, and there was no plasticizer phase separation, suggesting that the plasticizer concentration was adequate. The incorporation of adipate or citrate esters improves the mechanical properties and processability of PLA/TPS sheets produced by calendering extrusion at a pilot scale.

Sealability and Seal Characteristics of PE/EVA and PLA/PCL Blends

Abstract Seal strength behavior of low density polyethylene and ethylene vinyl acetate copolymer (PE/EVA) blends as well as that of blends of a seal grade PLA with aliphatic polyester (PCL) was studied. Polyethylene is commonly used for seal application in packaging multilayer structures and amorphous PLA is considered to be its counterpart for compostable and/or biodegradables ones. Incorporation of EVA in polyethylene improves its sealability in terms of a decrease in seal initiation temperature and broadness of sealability plateau. This was interpreted as due to the formation of finer crystals, a decrease in the melting point and presence of vinyl acetate polar group. These were supported by results obtained from differential scanning calorimetry (DSC) and Scanning electron microscopy (SEM). For the PLA/PCL system, the dispersed phase was stretched into elongated ellipsoidal domains. This type of morphology affected the mechanical and seal properties of the blends. As a result of blending, both hot-tack initiation temperature and strength as well as seal initiation temperature were enhanced. The enhancement in these seal properties was significant when the concentration of the dispersed phase exceeded 20 wt% in the blend. Hot-tack strength of up to twice of pure PLA was achieved through blending. This was attributed to the lower glass transition temperature of PCL, resulting in enhanced mobility of PLA chains and also the high aspect ratio of the dispersed phase. The maximum obtained hot-tack strength (1 200 g/25 mm) at 40 % dispersed content compared advantageously to commercially available polyolefin based sealant resins. The seal and hot-tack initiation temperatures were shifted to lower temperatures by as much as 30 °C, which can allow faster and more energy efficient sealing process.

Structural evolution of poly(lactic acid)/poly(ethylene oxide)/unmodified clay upon ambient ageing

ABSTRACTPoly(lactic acid) (PLA) and poly(ethylene oxide) (PEO)/unmodified clay masterbatches are compounded together in order to investigate the ambient ageing of the resulting PLA/PEO/clay ternary blends. Binary blends are miscible up to 20 wt PEO% and in ternary counterparts, clay is intercalated at a nanometric scale, similarly to the clay dispersion state in masterbatches. PEO/clay interactions are strong, as confirmed by the lower plasticization of ternary blends. Furthermore, structural modifications occurring over time are evidenced for all blends through the observation of changes in thermal responses. Over the 220‐day observation period, lower plasticized samples undergo physical ageing only whereas blends close to the miscibility limit know a rapid PLA/PEO phase separation without physical ageing. For blends with intermediate PEO concentrations, both phenomena are observed with slower PLA chain mobility transition. Remarkably clay appears to affect both phenomena, ternary blends having limited physical ageing and slower PLA/PEO segregation. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014, 131, 40426.

Strong enhancements of nucleation and spherulitic growth rates through amplified interfacial effects for immiscible linear polymer/comb-like copolymer double-layer films

Cellulose-graft-poly[poly(ethylene glycol) methyl ether acrylate] (Cell-g-PPEGA) and poly[poly(ethylene glycol) methyl ether acrylate] (PPEGA) comb-like copolymers were synthesized by electron transfer atom transfer radical polymerization (ARGET ATRP). PPEGA/PLA and Cell-g-PPEGA/PLA pairs are both immiscible as indicated by slightly decreasing glass transition temperatures of PLA in the blends measured by differential scanning calorimetry (DSC) and phase separation morphologies observed by a phase contrast optical microscope (PCOM). Cell-g-PPEGA/PLA and PPEGA/PLA double-layer films and neat PLA film were prepared to measure the nucleation and spherulitic growth rates during isothermal crystallization at various temperatures above the melting points of Cell-g-PPEGA and PPEGA layers by using a polarized optical microscope (POM). In contrast to our previous results on the miscible polymer pairs, covering the immiscible molten PPEGA layer can greatly accelerate the spherulitic growth rates for PLA and the Cell-g-PPEGA layer shows a similar but less significant effect. Nevertheless, nucleation density is much higher for the Cell-g-PPEGA/PLA film than for the PPEGA/PLA and neat PLA films. A significant finding is that although the whole double-layer film systems represent phase separated ones, the densely grafted PEGA chains in the comb-like copolymers can simultaneously take action to amplify the segmental mobility of PLA chains through local contacts at interfacial layers between phase separated domains, which significantly enhances the formation of chain folding lamellae of the PLA, resulting in obvious enhancements of the crystallization kinetics.

Mechanical, Thermal and Morphological Properties of Poly(lactic acid)/Epoxidized Palm Olein Blend

Poly(lactic acid) (PLA) is known to be a useful material in substituting the conventional petroleum-based polymer used in packaging, due to its biodegradability and high mechanical strength. Despite the excellent properties of PLA, low flexibility has limited the application of this material. Thus, epoxidized palm olein (EPO) was incorporated into PLA at different loadings (1, 2, 3, 4 and 5 wt%) through the melt blending technique and the product was characterized. The addition of EPO resulted in a decrease in glass transition temperature and an increase of elongation-at-break, which indicates an increase in the PLA chain mobility. PLA/EPO blends also exhibited higher thermal stability than neat PLA. Further, the PLA/1 wt% EPO blend showed enhancement in the tensile, flexural and impact properties. This is due to improved interaction in the blend producing good compatible morphologies, which can be revealed by Scanning Electron Microscopy (SEM) analysis. Therefore, PLA can be efficiently plasticized by EPO and the feasibility of its use as flexible film for food packaging should be considered.

A Comparative Study on the Mechanical, Thermal and Morphological Characterization of Poly(lactic acid)/Epoxidized Palm Oil Blend

In this work, poly(lactic acid) (PLA) a fully biodegradable thermoplastic polymer matrix was melt blended with three different epoxidized palm oil (EPO). The aim of this research was to enhance the flexibility, mechanical and thermal properties of PLA. The blends were prepared at various EPO contents of 1, 2, 3, 4 and 5 wt% and characterized. The SEM analysis evidenced successful modification on the neat PLA brittle morphology. Tensile tests indicate that the addition of 1 wt% EPO is sufficient to improve the strength and flexibility compared to neat PLA. Additionally, the flexural and impact properties were also enhanced. Further, DSC analysis showed that the addition of EPO results in a decrease in Tg, which implies an increase in the PLA chain mobility. In the presence of 1 wt% EPO, TGA results revealed significant increase in the thermal stability by 27%. Among the three EPOs used, EPO(3) showed the best mechanical and thermal properties compared to the other EPO’s, with an optimum loading of 1 wt%. Conclusively, EPO showed a promising outcome to overcome the brittleness and improve the overall properties of neat PLA, thus can be considered as a potential plasticizer.