Manufacturing and characterization of poly(lactic acid) composites with hydroxyapatite

Hydroxyapatite (HA), a naturally occurring calcium orthophosphate, possesses the most similar chemical composition to human bone. In this research work, composite materials were prepared using poly(lactic acid) (PLA) as a polymer matrix and HA as an osteoconductive filler for potential use in medical applications. Composites with varying HA content comprised in the 10–30 wt% range were obtained by extrusion-compounding followed by injection molding. The effect of the HA loading on overall properties was assessed by mechanical characterization using tensile, flexural, impact, and hardness standard tests. Main thermal transitions of PLA-HA composites were obtained by differential scanning calorimetry (DSC) and degradation/decomposition at high temperatures was followed by thermogravimetric analysis. Dynamical behavior was assessed by dynamic mechanical thermal analysis and the dimensional stability was studied by thermomechanical analysis (TMA). As per the results, PLA-HA composites with 20–30 wt% HA offer the best-balanced properties with a remarkable increase in the Young’s modulus. The glass transition temperature remained almost constant with slight changes of less than 1°C as measured by both DSC and TMA. TMA also revealed a remarkable decrease in the coefficient of linear thermal expansion. The overall results confirm the usefulness of these materials from a mechanical point of view for biomedical applications as they are characterized by high stiffness, tensile strength, and dimensional stability.

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Development and Characterization of Sustainable Composites from Bacterial Polyester Poly(3-Hydroxybutyrate-co-3-hydroxyhexanoate) and Almond Shell Flour by Reactive Extrusion with Oligomers of Lactic Acid

Polymers ◽

10.3390/polym12051097 ◽

2020 ◽

Vol 12 (5) ◽

pp. 1097 ◽

Cited By ~ 1

Author(s):

Juan Ivorra-Martinez ◽

Jose Manuel-Mañogil ◽

Teodomiro Boronat ◽

Lourdes Sanchez-Nacher ◽

Rafael Balart ◽

...

Keyword(s):

Lactic Acid ◽

Mechanical Characterization ◽

Linear Thermal Expansion ◽

Reactive Extrusion ◽

Thermomechanical Analysis ◽

Almond Shell ◽

Scanning Calorimetry ◽

Filler Reinforcement ◽

Lignocellulosic Filler

Eco-efficient Wood Plastic Composites (WPCs) have been obtained using poly(hydroxybutyrate-co-hexanoate) (PHBH) as the polymer matrix, and almond shell flour (ASF), a by-product from the agro-food industry, as filler/reinforcement. These WPCs were prepared with different amounts of lignocellulosic fillers (wt %), namely 10, 20 and 30. The mechanical characterization of these WPCs showed an important increase in their stiffness with increasing the wt % ASF content. In addition, lower tensile strength and impact strength were obtained. The field emission scanning electron microscopy (FESEM) study revealed the lack of continuity and poor adhesion among the PHBH-ASF interface. Even with the only addition of 10 wt % ASF, these green composites become highly brittle. Nevertheless, for real applications, the WPC with 30 wt % ASF is the most attracting material since it contributes to lowering the overall cost of the WPC and can be manufactured by injection moulding, but its properties are really compromised due to the lack of compatibility between the hydrophobic PHBH matrix and the hydrophilic lignocellulosic filler. To minimize this phenomenon, 10 and 20 phr (weight parts of OLA-Oligomeric Lactic Acid per one hundred weight parts of PHBH) were added to PHBH/ASF (30 wt % ASF) composites. Differential scanning calorimetry (DSC) suggested poor plasticization effect of OLA on PHBH-ASF composites. Nevertheless, the most important property OLA can provide to PHBH/ASF composites is somewhat compatibilization since some mechanical ductile properties are improved with OLA addition. The study by thermomechanical analysis (TMA), confirmed the increase of the coefficient of linear thermal expansion (CLTE) with increasing OLA content. The dynamic mechanical characterization (DTMA), revealed higher storage modulus, E’, with increasing ASF. Moreover, DTMA results confirmed poor plasticization of OLA on PHBH-ASF (30 wt % ASF) composites, but interesting compatibilization effects.

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Modification of Poly(lactic acid) by the Plasticization for Application in the Packaging Industry

Polymers ◽

10.3390/polym13213651 ◽

2021 ◽

Vol 13 (21) ◽

pp. 3651

Author(s):

Karolina Gzyra-Jagieła ◽

Konrad Sulak ◽

Zbigniew Draczyński ◽

Stepan Podzimek ◽

Stanisław Gałecki ◽

...

Keyword(s):

Lactic Acid ◽

Research Work ◽

Poly Lactic Acid ◽

Glass Temperature ◽

Gravimetric Analysis ◽

Green Technologies ◽

Scanning Calorimetry ◽

Melt Flow Rate ◽

Packaging Industry ◽

Molecular Compounds

Plastic products, especially in the packaging industry, have become the main commodities penetrating virtually every aspect of our lives. Unfortunately, their omnipresence is not neutral to the natural environment. Pollution in the form of microplastics is a global problem. Therefore, green technologies that enter into the circular economy become an important topic. As part of the research work, the modification of poly(lactic acid) has been studied for use in the packaging industry. Due to its intrinsic rigidity, plasticizing substances had to be introduced in PLA in order to improve its plastic deformability. Both high-molecular compounds such as ethoxylated lauryl alcohol, block copolymer of ethylene oxide and propylene oxide, and ethoxylated stearic acid as well as low-molecular compounds such as di-2-ethylhexyl adipate, di-2-ethylhexyl sebacate, and triethyl citrate were used. The samples extruded from plasticized polymers were characterized using differential scanning calorimetry, thermal gravimetric analysis, and mechanical properties including Young’s modulus. The melt flow rate (MFR) and molar mass distribution were determined. For all modified samples the glass transition temperature, depending on the plasticizer used, was shifted towards lower values compared to the base polymer. The best result was obtained for di-2-ethylhexyl adipate (ADO) and di-2-ethylhexyl sebacate (SDO). The elongation at break increased significantly for ADO at about 21%. The highest elongation was obtained for SDO (about 35%), although it obtained a higher glass temperature. The degradation of the polymer was not observed for both plasticizers. For these plasticizers (ADO and SDO) it also lowered Young’s module by about 26%, and at the infrared spectrum deformation of peaks were observed, which may indicate the interaction of the ester carbonyl group of PLA with plasticizers. Therefore it can be concluded that they are good modifiers. The selected plasticizers that are used in the production of food contact materials, in particular in the production of PVC (polyvinyl chloride) food films, also exhibited great potential to be applied to PLA food films, and exhibit better properties than the citrate, which are indicated in many publications as PLA plasticizers.

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Development of three-dimensional printing filaments based on poly(lactic acid)/hydroxyapatite composites with potential for tissue engineering

Journal of Composite Materials ◽

10.1177/0021998320988568 ◽

2021 ◽

pp. 002199832098856

Author(s):

Marcela Piassi Bernardo ◽

Bruna Cristina Rodrigues da Silva ◽

Luiz Henrique Capparelli Mattoso

Keyword(s):

Tissue Engineering ◽

Lactic Acid ◽

Fused Deposition Modeling ◽

Three Dimensional ◽

Poly Lactic Acid ◽

Scanning Calorimetry ◽

Three Dimensional Printing ◽

Fused Deposition ◽

Deposition Modeling ◽

3D Printed

Injured bone tissues can be healed with scaffolds, which could be manufactured using the fused deposition modeling (FDM) strategy. Poly(lactic acid) (PLA) is one of the most biocompatible polymers suitable for FDM, while hydroxyapatite (HA) could improve the bioactivity of scaffold due to its chemical composition. Therefore, the combination of PLA/HA can create composite filaments adequate for FDM and with high osteoconductive and osteointegration potentials. In this work, we proposed a different approache to improve the potential bioactivity of 3D printed scaffolds for bone tissue engineering by increasing the HA loading (20-30%) in the PLA composite filaments. Two routes were investigated regarding the use of solvents in the filament production. To assess the suitability of the FDM-3D printing process, and the influence of the HA content on the polymer matrix, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC) and scanning electron microscopy (SEM) were performed. The HA phase content of the composite filaments agreed with the initial composite proportions. The wettability of the 3D printed scaffolds was also increased. It was shown a greener route for obtaining composite filaments that generate scaffolds with properties similar to those obtained by the solvent casting, with high HA content and great potential to be used as a bone graft.

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Analysis of Coir Fiber Reinforced Poly-Lactic Acid (PLA) and Poly-Propylene (PP) Polymeric Composite

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.852.10 ◽

2016 ◽

Vol 852 ◽

pp. 10-15

Author(s):

Sahas Bansal ◽

M. Ramachandran ◽

Pramod Raichurkar

Keyword(s):

Lactic Acid ◽

Natural Fibers ◽

Polymeric Composite ◽

Mechanical Tests ◽

Composite Resins ◽

Poly Lactic Acid ◽

Coir Fiber ◽

Scanning Calorimetry ◽

Biodegradable Composite ◽

Poly Propylene

Green composites shaped by mixture of biodegradable polymers and natural fibers have spellbound massive interest in current years due to their environmentally valuable properties and also to decrease our dependency on the non-renewable resources. Due to the environmental advantages and light weight of natural fibers, an increasing quantity of natural fibers has been used to replace synthetic fibers composites. Coir fiber poly-lactic acid (PLA)/ poly-propylene (PP) resin reinforced polymeric composites have been developed with 90o orientation. The composition of PLA and PP for resin preparation is taken in the ratio 95:05 whereas for the composite, resins and coir fiber in 80:20. The compression molding technique is applied and then the tests are carried out. Mechanical tests (Impact and Hardness), Micro structural analysis (Fourier Transform Infrared Spectroscopy and Optical Imaging) and Differential Scanning Calorimetry are conducted. According to the investigational verification, the new biodegradable composite shows significant results on par with synthetic/ man made composites and the advantages of using bio-composites has been indicated with simplicity.

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Enhanced properties of poly(lactic acid) by concurrent addition of organo-modified Mg-Al layered double hydroxide (LDH) and triethyl citrate

Journal of Thermoplastic Composite Materials ◽

10.1177/0892705719868272 ◽

2019 ◽

pp. 089270571986827 ◽

Cited By ~ 1

Author(s):

Mehrnoush Monshizadeh ◽

Sajad Seifi ◽

Iman Hejazi ◽

Javad Seyfi ◽

Hossein Ali Khonakdar

Keyword(s):

Lactic Acid ◽

Layered Double Hydroxide ◽

Food Packaging ◽

Synergistic Effects ◽

Poly Lactic Acid ◽

Solution Casting ◽

Scanning Calorimetry ◽

Concurrent Use ◽

Triethyl Citrate ◽

Double Hydroxide

Synergistic effects of organo-modified Mg-Al layered double hydroxide (LDH) and triethyl citrate (TEC) on the properties of poly(lactic acid) (PLA) were demonstrated. PLA/LDH nanocomposites in the absence and presence of TEC were fabricated via solution casting technique. Morphological analysis revealed that as the LDH concentration increases, the number of aggregations is also increased; however, introduction of TEC considerably enhanced the dispersion quality of LDHs. Differential scanning calorimetry results showed that the addition of LDH and TEC had no significant influence on the crystallinity of nanocomposites obtained from solution casting. In contrast, once the samples were cooled from melt, the concurrent use of LDH and TEC led to a dramatic enhancement in the crystallinity of PLA ( X c = 55.5%). Moreover, the LDH nanoparticles counterbalanced the adverse effects of plasticization by TEC leading to enhanced toughness of the final nanocomposites. LDH had also a positive influence on thermal stability of PLA, indicating the heat-insulating role of LDH particles. In conclusion, the concurrent use of LDH and TEC could extend the applicability of PLA especially in food packaging applications.

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

Journal of Thermoplastic Composite Materials ◽

10.1177/0892705719828801 ◽

2019 ◽

Vol 33 (10) ◽

pp. 1383-1395

Author(s):

Hongjuan Zheng ◽

Zhengqian Sun ◽

Hongjuan Zhang

Keyword(s):

Mechanical Properties ◽

Lactic Acid ◽

Property Testing ◽

Walnut Shell ◽

Poly Lactic Acid ◽

Thermal And Mechanical Properties ◽

Scanning Calorimetry ◽

Elongation At Break ◽

Heat Distortion Temperature ◽

Testing Techniques

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.

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Hemp Fibre Reinforced Poly(Lactic Acid) Composites

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.29-30.337 ◽

2007 ◽

Vol 29-30 ◽

pp. 337-340 ◽

Cited By ~ 21

Author(s):

M.A. Sawpan ◽

K.L. Pickering ◽

Alan Fernyhough

Keyword(s):

Lactic Acid ◽

Degree Of Crystallinity ◽

Poly Lactic Acid ◽

X Ray Diffraction ◽

Scanning Calorimetry ◽

X Ray ◽

Hemp Fibre ◽

Reinforcing Material ◽

Fibre Loading ◽

The Degree Of Crystallinity

The potential of hemp fibre as a reinforcing material for Poly(lactic acid) (PLA) was investigated. Good interaction between hemp fibre and PLA resulted in increases of 100% for Young’s modulus and 30% for tensile strength of composites containing 30 wt% fibre. Different predictive ‘rule of mixtures’ models (e.g. Parallel, Series and Hirsch) were assessed regarding the dependence of tensile properties on fibre loading. Limited agreement with models was observed. Differential scanning calorimetry (DSC) and x-ray diffraction (XRD) studies showed that hemp fibre increased the degree of crystallinity in PLA composites.

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Multifunctional PLA Blends Containing Chitosan Mediated Silver Nanoparticles: Thermal, Mechanical, Antibacterial, and Degradation Properties

Nanomaterials ◽

10.3390/nano10010022 ◽

2019 ◽

Vol 10 (1) ◽

pp. 22 ◽

Cited By ~ 8

Author(s):

Agueda Sonseca ◽

Salim Madani ◽

Gema Rodríguez ◽

Víctor Hevilla ◽

Coro Echeverría ◽

...

Keyword(s):

Thermal Stability ◽

Silver Nanoparticles ◽

Lactic Acid ◽

Food Packaging ◽

Synthesis Method ◽

Crystallization Rate ◽

Poly Lactic Acid ◽

Scanning Calorimetry ◽

The Matrix ◽

Degradation Properties

Poly(lactic acid) (PLA) is one of the most commonly employed synthetic biopolymers for facing plastic waste problems. Despite its numerous strengths, its inherent brittleness, low toughness, and thermal stability, as well as a relatively slow crystallization rate represent some limiting properties when packaging is its final intended application. In the present work, silver nanoparticles obtained from a facile and green synthesis method, mediated with chitosan as a reducing and stabilizing agent, have been introduced in the oligomeric lactic acid (OLA) plasticized PLA in order to obtain nanocomposites with enhanced properties to find potential application as antibacterial food packaging materials. In this way, the green character of the matrix and plasticizer was preserved by using an eco-friendly synthesis protocol of the nanofiller. The X-ray diffraction (XRD) and differential scanning calorimetry (DSC) results proved the modification of the crystalline structure as well as the crystallinity of the pristine matrix when chitosan mediated silver nanoparticles (AgCH-NPs) were present. The final effect over the thermal stability, mechanical properties, degradation under composting conditions, and antimicrobial behavior when AgCH-NPs were added to the neat plasticized PLA matrix was also investigated. The obtained results revealed interesting properties of the final nanocomposites to be applied as materials for the targeted application.

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Improved Weathering Performance of Poly(Lactic Acid) through Carbon Nanotubes Addition: Thermal, Microstructural, and Nanomechanical Analyses

Biomimetics ◽

10.3390/biomimetics5040061 ◽

2020 ◽

Vol 5 (4) ◽

pp. 61

Author(s):

Thevu Vu ◽

Peyman Nikaeen ◽

William Chirdon ◽

Ahmed Khattab ◽

Dilip Depan

Keyword(s):

Carbon Nanotubes ◽

Lactic Acid ◽

Uv Light ◽

Degradation Mechanism ◽

Decomposition Temperature ◽

Poly Lactic Acid ◽

Accelerated Weathering ◽

Degradation Behavior ◽

Scanning Calorimetry ◽

Norrish Type

To understand the interrelationship between the microstructure and degradation behavior of poly(lactic acid) (PLA), single-walled carbon nanotubes (CNTs) were introduced into PLA as nucleating agents. The degradation behavior of PLA-CNT nanocomposites was examined under accelerated weathering conditions with exposure to UV light, heat, and moisture. The degradation mechanism proceeded via the Norrish type II mechanism of carbonyl polyester. Differential scanning calorimetry (DSC) studies showed an increase in glass transition temperature, melting temperature, and crystallinity as a result of the degradation. However, pure PLA showed higher degradation as evidenced by increased crystallinity, lower onset decomposition temperature, embrittlement, and a higher number of micro-voids which became broader and deeper during degradation. In the PLA-CNT nanocomposites, CNTs created a tortuous pathway which inhibits the penetration of water molecules deeper into the polymer matrix, making PLA thermally stable by increasing the initial temperature of mass loss. CNTs appear to retard PLA degradation by impeding mass transfer. Our study will facilitate designing environmentally friendly packaging materials that display greater resistance to degradation in the presence of moisture and UV light.

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Rice Bran/Poly(lactic acid) Composites in Packaging Product

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.931-932.57 ◽

2014 ◽

Vol 931-932 ◽

pp. 57-62

Author(s):

Rapeephun Dangtungee ◽

Rapeeporn Srisuk ◽

Suchart Siengchin

Keyword(s):

Mechanical Properties ◽

Compressive Strength ◽

Lactic Acid ◽

Rice Bran ◽

Food Packaging ◽

Pressure Range ◽

Research Work ◽

Magnesium Stearate ◽

Poly Lactic Acid ◽

Molding Process

This research work was carried out on the production of rice bran/poly (lactic acid) (PLA) composites. The composition during the batch molding process included rice bran, PLA, glycerol, and magnesium stearate (mold released agent). Afterwards, the composition was molded by bio-compression at temperature of 170°C for 5 min, and a pressure range of 50-100 kg/cm3. The result showed that the composition of rice bran, PLA, and glycerol could be used in the formation of food packaging. Also the mechanical properties, such as compressive strength and hardness, were investigated. It could be concluded that the most appropriate formulation of rice bran packaging was 5 phr PLA and 3 phr glycerol and 2 phr magnesium stearate. Moreover, FTIR results indicated the non-toxic nature of this method of food packaging.

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