Mechanical Properties Of PLA Research Articles

Journal Vol – 15 No -7, July 2020 Journal > Journal > Journal Vol – 15 No -7, July 2020 > Page 6 PERFORMANCE AND EMISSION CHARACTERISTICS OF GASOLINE-ETHANOL BLENDS ON PFI-SI ENGINE Authors: D.Vinay Kumar ,G.Samhita Priyadarsini,V.Jagadeesh Babu,Y.Sai Varun Teja, DOI NO: https://doi.org/10.26782/jmcms.2020.07.00051 admin July 26, 2020 Abstract: Alcohol based fuels can be produced from renewable energy sources and

Journal Vol – 15 No -7, July 2020 Journal > Journal > Journal Vol – 15 No -7, July 2020 > Page 6 PERFORMANCE AND EMISSION CHARACTERISTICS OF GASOLINE-ETHANOL BLENDS ON PFI-SI ENGINE Authors: D.Vinay Kumar ,G.Samhita Priyadarsini,V.Jagadeesh Babu,Y.Sai Varun Teja, DOI NO: https://doi.org/10.26782/jmcms.2020.07.00051 admin July 26, 2020 Abstract: Alcohol based fuels can be produced from renewable energy sources and

Effects of Filling Percentage on Mechanical Properties of PLA and PET Materials

Gerçekleştirilen çalışmada, yığma teknolojisi ile üretim yapan bir yazıcı modellemek ve modellenen üç boyutlu yazıcıda doluluk oranının mekanik özellikler üzerine etkilerinin incelenmesi amaçlanmıştır. Bu amaç kapsamında kartezyen tipi açık kaynaklı bir üç boyutlu yazıcı modellenmiştir. Prototip imalatı yapılan üç boyutlu yazıcı kullanılarak PET ve PLA malzemelerin %10, 20, 30, 40 ve %50 doluluk oranlarında mekanik test numuneleri yazdırılmıştır. Elde edilen numuneler tek eksenli çekme testleri tabi tutulmuş, sertlik ve pürüzlülük değerleri ölçülmüştür. Yapılan ölçümler neticesinde PET ve PLA malzemelerde sertlik değerinin malzemenin doluluk oranı ile doğru orantılı olduğu, doluluk oranı arttıkça malzemelerin sertliklerinin de arttığı görülmüştür. PLA ve PET malzemelerden üretilen numunelerin pürüzlülük ve çekme değerlerinin birbiriyle ters orantılı olduğu, pürüzlülük ve çekme mukavemeti değerlerinin %30 doluluk oranından itibaren %10 ve %20 doluluk oranındakinin aksi yönde seyrettiği görülmüştür.

Parametric Effects of Fused Deposition Modelling on the Mechanical Properties of Polylactide Composites: A Review

Polymers are generally inferior in mechanical properties to metals which are the current orthopaedic material for osseointegration in many parts of the world today. This assertion also applies to poly(lactic acid) (PLA), a polyester that has been recently found applicable in tissue remodelling. To improve on its mechanical properties, several processing techniques, inclusive of fused deposition modelling (FDM) also branded as fused filament fabrication (FFF), have been used. FDM has been endeared to many researchers because a range of parameters can be combined to bring about widely different mechanical properties. Although the influence of FDM parameters on the mechanical properties of PLA is clear, the tensile, compressive and flexural strengths obtained so far are inferior to human cortical bone. The need to improve on this production technique for improved mechanical properties is apparent in all the works examined in this review.

Effect of wood/basalt hybridization on crystallization and mechanical properties of PLA

In this study hybrid composites based on polylactide were reinforced with wood and basalt fibres. Composites have undergone physical and mechanical tests and the water absorption after 1 and 14 days as well as the effect of biodegradation on strength properties have been determined. Additionally the effects of annealing and temperature of tests on mechanical properties were investigated. The addition of fibres considerably increased the susceptibility of the tested composites and for composites with addition of 7.5 wt% of each wood and basalt fibres increased by more than 35% at +23°C and was by 12 times higher at 80 °C . Heat treatment of composites positively influenced the results, mainly at elevated test temperatures. For pure PLA, the increase in Young’s modulus was over 22 times (from 157 MPa to 3 473 MPa). The addition of fibres resulted in a reduction of the differences between the materials before and after annealing. Impact strength was more than double for composites after heat treatment at room temperature.

Poly(lactic acid)/thermoplasticized rice straw biocomposites: effects of benzylated lignocellulosic filler and nanoclay

The physical, viscoelastic, thermal and mechanical properties of poly(lactic acid) (PLA) as a well-known biodegradable plastics were enhanced by incorporating a chemically modified biomass without sacrificing the biodegradability of the matrix. Rice straw after milling was benzylated with NaOH and benzyl chloride solution at reflux temperature for 6 h. The weight gain percentage of benzylated rice straw (BRS) was 145% and some thermoplasticity was induced in the material. The results showed that the chemical modification successfully reduced the glass transition temperature (Tg) of rice straw to about 170 °C. By adding the benzylated rice straw at an optimal loading, the mechanical properties of PLA, i.e., Young’s modulus, tensile strength as well as toughness, were considerably improved as well as Tg, crystallinity and processability. Higher Tg, intensified non-terminal behaviour, and microscopic observations of the resultant PLA green composites demonstrated the strong interactions between PLA chains and the plasticized lignocellulosic polymers. Despite the positive effect of benzylated rice straw in PLA, compounding of the organically modified nanoclay with the biocomposites did not change the latter properties as expected due to the poor dispersion state of nanoparticles in the matrices.

Comparison of physical and mechanical properties of PLA, ABS and nylon 6 fabricated using fused deposition modeling and injection molding

The objective of this study was to compare the physical and mechanical performance of poly(lactic acid) (PLA), acrylonitrile butadiene styrene (ABS), and nylon 6 fabricated using fused deposition modeling (FDM) and conventional injection molding. It is found that different processing methods did not affect the viscosity of the samples, and the percentage difference for the density measurement is less than 4%. Water absorption of FDM samples is approximately 108% higher compared to those fabricated using the injection molding. The results also revealed that the FDM method did not strongly affect the degree of crystallinity of ABS, but it increased the degree of crystallinity of PLA and nylon 6. The tensile strength, Young's modulus, elongation at break, and impact strength of FDM samples were approximately 48%, 50%, 48%, and 78%, lower compared with the injection molded samples. The results presented can provide a guide to manufacturing the final products using FDM with the desired performance.

Improvements in the crystallinity and mechanical properties of PLA by nucleation and annealing

We develop strategies to improve the crystallinity and mechanical properties of PLA, without compromising its hydrolytic degradation behaviour. These include reactive extrusion, and addition of a novel type of cross-linked PLA-based nucleating agent (biofiller, BF). The crystallinity is further increased by annealing at temperatures between 80 and 120 °C. Maximum crystallinities of 55% were achieved in the presence of 7 wt% of the BF at 100 °C. The increases in crystallinity upon annealing translated to a 42% increase in the flexural modulus relative to the base PLA, while impact strength was maintained. Annealing temperatures of 100 °C are optimum, because of thermal degradation taking place above this temperature. Annealing also results in increases in the glass transition temperatures followed by improvements in the heat deflection temperature by as much as 7 °C. The nucleated and annealed PLA degraded to the same extent as the untreated PLA, when subjected to hydrolysis over a 12-week period.

Modeling and experimental verification of nonlinear behavior of cellulose nanocrystals reinforced poly(lactic acid) composites

In this paper, a constitutive modeling framework was introduced to characterize the time-dependent behavior in poly(lactic acid) reinforced by cellulose nanocrystals (CNCs). The mechanical properties of PLA and its corresponding nanocomposites were analyzed at three different extension rates (1, 5, 10 mm/min) using a stress relaxation test. Six hyperelastic strain energy functions were employed to describe the instantaneous mechanical behavior. The deviatoric and volumetric material constants were verified using Drucker stability criterion, and the instability limits of each model were reported. Furthermore, a hyper-viscoelastic model consisting of Neo-Hookean strain energy function and time-dependent Prony series was used to study the viscoelastic behavior of PLA and the corresponding nanocomposites. The model constants were determined using finite element (FE) simulations through an iterative process for the whole loading history of the relaxation test. Nelder–Mead Simplex method was applied to optimize the results of the FE simulations using the experimental data. The mechanical response observed for PLA and nanocomposites from model exhibited a good agreement with both short and long-term experimental data, suggesting the applicability of the estimated material parameters by this technique.

The influence of treated eucalyptus microfibers on the properties of PLA biocomposites

Eucalyptus sawdust was used for nano and microfibers preparation by a “green” process (ball milling), followed by surface treatments (alkaline and surfactant) and incorporated in PLA, from 1 to 10 wt %, aiming for the preparation of films of biocomposites. The treatments applied exposed the polar groups due to lignin removal or by the surfactant adsorption, respectively. The modification intensified the interaction in the interface region between the fibers and the PLA matrix (SEM), maintaining thermal properties (DSC results). The fibers treatments contributed to the films hydrophobicity concerning the humid environments, as evidenced by the results of moisture absorption and contact angle. However, the decrease in the crystallinity index of the biocomposites (4.2%, obtained by DSC) contributed to the increase of the water molecules diffusion (D, water absorption) caused by the structure disorder, which may favor the post-use biodegradation process. The mechanical properties of the films were promising, presenting values always above the PLA property. In general, the results suggest that the incorporation of eucalyptus fibers, mainly detergent treated, improves not only the mechanical properties of PLA but also favors properties that enhance the biodegradation process of the post-use biocomposites.

Effect of reactive group types on the properties of poly(ethylene octane) toughened poly(lactic acid)

In this work, maleic anhydride (MA) and glycidyl methacrylate (GMA) grafted poly(ethylene octane) (MPOE and GPOE) were used to toughen poly(lactic acid) (PLA). Results exhibited that the MA and GMA strongly influenced the morphology and mechanical properties of PLA. The stronger interfacial reactions between the carboxyl and/or hydroxyl of PLA and epoxy groups of GPOE induced smaller dispersed phase sizes and higher impact strength than that of PLA/MPOE blends. SEM results showed that the shear yielding properties of the PLA matrix and cavitation of rubber particles were major toughening mechanisms. Rheological investigation indicated that the PLA/GPOE blends had higher storage modulus and complex viscosity at low angular frequencies range due to the high interfacial adhesion between PLA and GPOE. The results of DMA showed that all the PLA blends had lower storage modulus due to the low stiffness of the elastomers. Compared MPOE, the addition of GPOE significantly decreased the cold crystallization and melting temperature which indicated that GPOE could enhance the crystalline ability of PLA.

Effects of walnut shell powders on the morphology and the thermal and mechanical properties of poly(lactic acid)

Poly(lactic acid) (PLA) has good environmental compatibility, however, its high brittleness, slow rate of crystallization, and low heat distortion temperature restrict its widespread use. To overcome these limitations, in this study, PLA was mixed with walnut shell (WS) powders. The effects of WS powders on the morphology and the thermal and mechanical properties of PLA were investigated. The products were characterized by differential scanning calorimetry (DSC), infrared (IR) spectroscopy, polarizing optical microscopy (POM), and various mechanical property testing techniques. The results showed that WS powders had a significant effect on the morphology and the thermal and mechanical properties of PLA. The tensile strength, impact strength, and elongation at break of the PLA/WS composites first increased and then decreased with the increasing addition of WS powders. When the addition of WS powders was about 0.5 wt%, they reached maximum values of 51.2 MPa, 23.3 MPa, and 19.0%, respectively. Compared with neat PLA, the spherulite grain size of the composites could be reduced and many irregular polygons were formed during crystallization. The melting, cold crystallization, and glass-transition temperatures of the composites were lower than those of neat PLA.

Preparation of Organo-Montmorillonite Modified Poly(lactic acid) and Properties of Its Blends with Wood Flour.

In this study, poly(lactic acid) (PLA)/wood flour (WF) composites were prepared by first blending PLA with organo-montmorillonite (OMMT) at different contents (0.5, 1, 1.5, and 2 wt %). The physical and mechanical properties of the virgin and OMMT modified PLA and its WF composites were tested. The results showed that: (1) at low OMMT content (<1 wt %), OMMT can uniformly disperse into the PLA matrix with highly exfoliated structures. When the content increased to 1.5 wt %, some aggregations occurred; (2) after a second extruding process, the aggregated OMMT redistributed into PLA and part of OMMT even penetrated into the WF cell wall. However, at the highest OMMT content (2 wt %), aggregates still existed; (3) the highly exfoliated OMMT was beneficial to the physical and mechanical properties of PLA and the WF composites. The optimal group of OMMT-modified PLA was found at an OMMT content of 0.5 wt %, while for the PLA/WF system, the best properties were achieved at an OMMT content of 1.5 wt %.

Copolycarbonate Derived from Carbon Dioxide as Toughness Improvement for Poly (lactic acid)

Abstract This work aimed to study the preparation of copolycarbonate based on carbon dioxide (CO2) and 1, 2-butylene oxide using a self-prepared zinc glutarate (ZnGA) as a catalyst. The effect of reaction time, temperature and pressure on yield of copolycarbonate products was investigated. The chemical structure was confirmed by NMR and FTIR spectra. The molecular weight and its distribution were determined by GPC. The thermal stability of copolycarbonate was measured by TGA. The synthesized copolycarbonate was melt-blended with Poly (lactic acid) or PLA to investigate the effect of copolycarbonate contents on mechanical properties of PLA. The results showed that the synthesized copolycarbonate was poly (butylene carbonate) (PBC) as indicated by NMR and FTIR results. The optimum yield of PBC was 52.21% synthesized at 95 °C, 70 bar, and 52 h of a reaction time. Based on GPC results, the molecular weight distribution of PBC was broad and no by-product such as cyclic carbonate could be detected. The TGA thermogram of PBC showed the onset temperature of 200 °C, implying the decomposition of small residual molecules. The average molecular weight was found to be 25,270 Da. The melt-blending of PLA/PBC (90/10 and 80/20 w/w) was performed with and without a reactive agent (peroxide) in an internal mixer at 190 °C and the rotor speed of 60 rpm. The torque value of reactive PLA/PBC (PLA/PBC/Per) decreased when compared to non-reactive PLA/PBC at the same blend ratio. The morphology of PLA/PBC and PLA/PBC/Per as illustrated by SEM showed that PLA/PBC was immiscible but after adding peroxide, the compatibility between PLA and PBC was improved. The elongation at break of PLA/PBC/Per (80/20/0.001phr) increased from 7.74 % to 161.38 % as well as the impact strength of PLA/PBC (80/20) increased 3 times when compared with that of neat PLA.

In situ formation of PLA-grafted alkoxysilanes for toughening a biodegradable PLA stereocomplex thin film.

Poly(lactide) (PLA) has received tremendous attention recently from researchers and industrialists due to its ability to solve environmental problems related to plastic pollution. However, PLA's brittleness, poor thermal stability, low elongation at break, and poor melt processing prevent its use in a broader spectrum of applications. Herein, we produced a very tough and thermally more stable PLA stereocomplex by simply mixing PLA with organoalkoxysilane. The stereocomplex PLA/silane (sc-PLA–silane) composite was prepared by simple mixing of three types of organoalkoxysilanes in sc-PLA followed by in situ formation of a silane-based rubbery core with a cross-linked PLA shell. Mechanical and thermal properties were improved by stereocomplexation of PLA with a small amount (1–5 wt%) of PLA-grafted silanes. The addition of organoalkoxysilane with different functional groups resulted in a plasticizer of rubbery silica-PLA core–shell gel through in situ condensation and grafting of long PLA chains at the interface between the stereocomplex and silane particles. The results revealed that the toughness of sc-PLA was improved dramatically with only a small addition (only 2.5%) of 3-(triethoxysilyl)propyl isocyanate (ICPTES). The morphology and mechanical and thermal properties of the toughened stereocomplex films were characterized. The results revealed that elongation at break was increased from 16% to 120%, while other mechanical properties such as tensile strength and modulus were retained. Surface analysis confirmed that this toughness was achieved by formation of a silica-PLA core–shell gel. The mechanical properties of PLA were improved without any significant reduction in modulus and tensile strength using this simple methodology.

Influence of Nanoparticle Pretreatment on the Thermal, Rheological and Mechanical Properties of PLA-PBSA Nanocomposites Incorporating Cellulose Nanocrystals or Montmorillonite.

Nanoparticles based on cellulose nanocrystals (CNC) and montmorillonite clay (MMT) were prepared using spray freeze-drying. The nanoparticles were then used as reinforcement to prepare nanocomposites with poly(lactic acid) (PLA) as the polymer matrix. The effect of spray freeze-dried CNC (SFD-CNC) and spray freeze-dried MMT (SFD-MMT) on the rheological and mechanical properties of PLA and its blends with poly[(butylene succinate)-co-adipate)] (PBSA) were investigated. An epoxy chain extender was used during preparation of the blends and nanocomposites to enhance the mechanical properties of the products. Different methods such as scanning electron microscopy, X-ray diffraction and adsorption/desorption analyses were used to characterize the prepared nanoparticles and their localization in the blends. Dynamic oscillatory shear behavior, elongational viscosity and mechanical characteristics of the nanocomposites of PLA and the blends were evaluated. The results obtained for nanocomposites filled with unmodified SFD-MMT were compared with those obtained when the filler was a commercial organically modified montmorillonite nanoclay (methyl-tallow-bis(2-hydroxyeethyl) quaternary ammonium chloride) (C30B), which was not spray freeze-dried.

Preparation of Polylactide Composite with Excellent Flame Retardance and Improved Mechanical Properties

Despite the good biodegradable and mechanical properties, poly(lactic acid) still suffers from a highly inherent flammability, which restricts its applications in the electric and automobile fields. In order to improve the flame retardancy of PLA, in this work, melamine polyphosphate (MPP) and zinc bisdiethylphosphinate (ZnPi) were firstly incorporated into PLA, and the synergistic effect of them on flame retardance of PLA was investigated using limiting oxygen index (LOI), UL-94 vertical measurement, scanning electron microscopy (SEM) and cone calorimeter tests etc. The results showed that PLA composite with 15 wt% of MPP/ZnPi (3:2) had the best flame-retardant efficiency with LOI value of 30.1 and V0 rating in UL-94 tests, which was far better than using MPP or ZnPi alone. What is more, although a wide range of flame retardants have been developed to reduce the flammability, so far, they normally compromise the mechanical properties of PLA. On the premise of maintaining good flame-retardant performance, we improved the toughness of flame-retardant PLA composite, and the impact strength of flame-retardant PLA composite was more than tripled (8.08 kJ/m2) by adding thermoplastic urethanes (TPU). This work offers an innovative method for the design of the unique integration of extraordinary flame retardancy and toughening reinforcement for PLA materials.

Comparison of Morphology and Mechanical Properties of Polyoxymethylene/Cellulose and Poly(Lactic Acid)/Cellulose Composites

The objective of this study is to fabricate the polyoxymethylene (POM)/microcrystalline cellulose (MCC) and poly(lactic acid) (PLA)/MCC composites, and to compare the effect of MCC on the morphology and mechanical properties of POM and PLA. The polymer composites were prepared by melt mixing in an internal mixer and molded by compression molding. The MCC concentrations were 1, 3, 5, 7, 10, 15 and 10% by weight. From scanning electron microscopy study observes the fracture surface of POM and PLA composites is much rough and the roughness increases with increasing MCC content. This observation indicates MCC induces the ductile fracture characteristic of POM and PLA. The addition of MCC can improve the impact strength of PLA composite and improve Young’s modulus of both POM and PLA composites. While the tensile strength and strain at break decrease after adding MCC. In summary, MCC can enhance the morphology and mechanical properties of PLA composites is better than POM composites.

Heat Resistant and Mechanical Properties of Biodegradable Poly(Lactic Acid)/Poly(Butylene Succinate) Blends Crosslinked by Polyaryl Polymethylene Isocyanate

ABSTRACTThis work focus on improving the heat resistant and mechanical properties of poly(lactic acid)/poly(butylene succinate) (PLA/PBS) blends using appropriate contents of polyaryl polymethylene isocyanate (PAPI). Some crosslinked structures were formed according to the gel fraction and rheological results, and the crosslinked structures played the role of nucleation site for the blends. And the Vicat softening temperature of the blends gradually increased with increasing PAPI content. Moreover, the addition of PAPI in the PLA/PBS blends produced a few PLA-PBS copolymers which acted as a compatibilizer and enhanced the interfacial adhesion. Thus, the mechanical properties of PLA were significantly improved.

Toughening of Poly(lactic acid) and Thermoplastic Cassava Starch Reactive Blends Using Graphene Nanoplatelets.

Poly(lactic acid) (PLA) was reactively blended with thermoplastic cassava starch (TPCS) and functionalized with commercial graphene (GRH) nanoplatelets in a twin-screw extruder, and films were produced by cast-film extrusion. Reactive compatibilization between PLA and TPCS phases was reached by introducing maleic anhydride and a peroxide radical during the reactive blending extrusion process. Films with improved elongation at break and toughness for neat PLA and PLA-g-TPCS reactive blends were obtained by an addition of GRH nanoplatelets. Toughness of the PLA-g-TPCS-GRH was improved by ~900% and ~500% when compared to neat PLA and PLA-g-TPCS, respectively. Crack bridging was established as the primary mechanism responsible for the improvement in the mechanical properties of PLA and PLA-g-TPCS in the presence of the nanofiller due to the high aspect ratio of GRH. Scanning electron microscopy images showed a non-uniform distribution of GRH nanoplatelets in the matrix. Transmittance of the reactive blend films decreased due to the TPCS phase. Values obtained for the reactive blends showed ~20% transmittance. PLA-GRH and PLA-g-TPCS-GRH showed a reduction of the oxygen permeability coefficient with respect to PLA of around 35% and 50%, respectively. Thermal properties, molecular structure, surface roughness, XRD pattern, electrical resistivity, and color of the films were also evaluated. Biobased and compostable reactive blend films of PLA-g-TPCS compounded with GRH nanoplatelets could be suitable for food packaging and agricultural applications.

Mechanical properties of PLA based composite filaments with surface treated oyster shell powder

Mechanical properties of PLA based composite filaments with surface treated oyster shell powder