scholarly journals Properties and Degradation Performances of Biodegradable Poly(lactic acid)/Poly(3-hydroxybutyrate) Blends and Keratin Composites

Polymers ◽  
2021 ◽  
Vol 13 (16) ◽  
pp. 2693
Author(s):  
Martin Danko ◽  
Katarína Mosnáčková ◽  
Anna Vykydalová ◽  
Angela Kleinová ◽  
Andrea Puškárová ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Microbial Growth ◽  
Hydrolytic Degradation ◽  
Gel Permeation Chromatography ◽  
Poly Lactic Acid ◽  
Environmental Aspects ◽  
Scanning Calorimetry ◽  
Biodegradable Poly ◽  
Basic Hydrolysis

From environmental aspects, the recovery of keratin waste is one of the important needs and therefore also one of the current topics of many research groups. Here, the keratin hydrolysate after basic hydrolysis was used as a filler in plasticized polylactic acid/poly(3-hydroxybutyrate) blend under loading in the range of 1–20 wt%. The composites were characterized by infrared spectroscopy, and the effect of keratin on changes in molar masses of matrices during processing was investigated using gel permeation chromatography (GPC). Thermal properties of the composites were investigated using thermogravimetric analysis (TGA) and differential scanning calorimetry (DSC). The effect of keratin loading on the mechanical properties of composite was investigated by tensile test and dynamic mechanical thermal analysis. Hydrolytic degradation of matrices and composites was investigated by the determination of extractable product amounts, GPC, DSC and NMR. Finally, microbial growth and degradation were investigated. It was found that incorporation of keratin in plasticized PLA/PHB blend provides material with good thermal and mechanical properties and improved degradation under common environmental conditions, indicating its possible application in agriculture and/or packaging.

scholarly journals Glycerolysis of Poly(lactic acid) as a Way to Extend the “Life Cycle” of This Material

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 1963 ◽  
Author(s):  
Marcin Borowicz ◽  
Joanna Paciorek-Sadowska ◽  
Marek Isbrandt ◽  
Łukasz Grzybowski ◽  
Bogusław Czupryński
Keyword(s):  
Lactic Acid ◽  
Life Cycle ◽  
Raw Materials ◽  
Gel Permeation Chromatography ◽  
Acid Value ◽  
Economic Losses ◽  
Poly Lactic Acid ◽  
Scanning Calorimetry ◽  
Economic Point

The article concerns the use of glycerolysis reaction as an alternative method of processing post-production and post-consumer waste from poly(lactic acid) (PLA). Management of waste is a very important issue from an environmental protection and economic point of view. Extending the “life cycle” of PLA is extremely important because it allows to make the most of this material. It also limits economic losses resulting from its disposal in the biodegradation process at the same time. This paper presents a method of glycerolysis of poly(lactic acid) waste using various amounts of anhydrous glycerol (mass ratio from 0.3 to 0.5 parts by weight of glycerol per 1.0 part by weight of PLA). This process was also carried out for pure, unmodified PLA Ingeo® (from NatureWorks) to compare the obtained results. The six liquid oligomeric polyhydric alcohols were obtained as a result of the synthesis. Then, they were subjected to physicochemical tests such as determination of color, smell, density, viscosity, and pH. In addition, the obtained raw materials were subjected to analytical tests such as determination of the hydroxyl value, acid value, water content, and elemental composition. The average molecular weights and dispersity were also tested by gel permeation chromatography (GPC). The assumed chemical structure of the obtained compounds was confirmed by spectroscopic methods such as FTIR, 1H NMR, 13C NMR. Glycerolysis products were also subjected to differential scanning calorimetry (DSC) to determine thermal parameters. The obtained research results have allowed the precise characterization of newly obtained products and determination of their suitability, e.g., for the synthesis of polyurethane (PUR) materials.

scholarly journals Effects of Inorganic Fillers on the Thermal and Mechanical Properties of Poly(lactic acid)

2014 ◽  
Vol 2014 ◽  
pp. 1-8 ◽  
Author(s):  
Xingxun Liu ◽  
Tongxin Wang ◽  
Laurence C. Chow ◽  
Mingshu Yang ◽  
James W. Mitchell
Keyword(s):  
Mechanical Properties ◽  
Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Mechanical Analysis ◽  
Poly Lactic Acid ◽  
Inorganic Filler ◽  
Homogeneous Distribution ◽  
Thermal And Mechanical Properties ◽  
Scanning Calorimetry ◽  
Tensile Tester

Addition of filler to polylactic acid (PLA) may affect its crystallization behavior and mechanical properties. The effects of talc and hydroxyapatite (HA) on the thermal and mechanical properties of two types of PLA (one amorphous and one semicrystalline) have been investigated. The composites were prepared by melt blending followed by injection molding. The molecular weight, morphology, mechanical properties, and thermal properties have been characterized by gel permeation chromatography (GPC), scanning electron microscope (SEM), instron tensile tester, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and dynamic mechanical analysis (DMA). It was found that the melting blending led to homogeneous distribution of the inorganic filler within the PLA matrix but decreased the molecular weight of PLA. Regarding the filler, addition of talc increased the crystallinity of PLA, but HA decreased the crystallinity of PLA. The tensile strength of the composites depended on the crystallinity of PLA and the interfacial properties between PLA and the filler, but both talc and HA filler increased the toughness of PLA.

scholarly journals Simultaneous Enhancement of Strength and Toughness of PLA Induced by Miscibility Variation with PVA

Polymers ◽  
2018 ◽  
Vol 10 (10) ◽  
pp. 1178 ◽  
Author(s):  
Yanping Liu ◽  
Hanghang Wei ◽  
Zhen Wang ◽  
Qian Li ◽  
Nan Tian
Keyword(s):  
Mechanical Properties ◽  
High Performance ◽  
Fracture Strain ◽  
Electrospun Fiber ◽  
Structural Evolution ◽  
Amorphous Structure ◽  
Poly Lactic Acid ◽  
Poly Vinyl Alcohol ◽  
Scanning Calorimetry ◽  
Strength And Toughness

The mechanical properties of poly (lactic acid) (PLA) nanofibers with 0%, 5%, 10%, and 20% (w/w) poly (vinyl alcohol) (PVA) were investigated at the macro- and microscale. The macro-mechanical properties for the fiber membrane revealed that both the modulus and fracture strain could be improved by 100% and 70%, respectively, with a PVA content of 5%. The variation in modulus and fracture strain versus the diameter of a single electrospun fiber presented two opposite trends, while simultaneous enhancement was observed when the content of PVA was 5% and 10%. With a diameter of 1 μm, the strength and toughness of the L95V5 and L90V10 fibers were enhanced to over 3 and 2 times that of pure PLA, respectively. The structural evolution of electrospun nanofiber was analyzed by differential scanning calorimetry (DSC) and Fourier transform infrared spectroscopy (FTIR). Although PLA and PVA were still miscible in the concentration range used, the latter could crystallize independently after electrospinning. According to the crystallization behavior of the nanofibers, a double network formed by PLA and PVA—one microcrystal/ordered structure and one amorphous structure—is proposed to contribute to the simultaneous enhancement of strength and toughness, which provides a promising method for preparing biodegradable material with high performance.

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

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.

scholarly journals Poly(lactic acid) polymer stars built from early generation dendritic polyols

2013 ◽  
Vol 91 (6) ◽  
pp. 392-397 ◽  
Author(s):  
Genny E. Keefe ◽  
Jean-d'Amour K. Twibanire ◽  
T. Bruce Grindley ◽  
Michael P. Shaver
Keyword(s):  
Molecular Weight ◽  
Ring Opening ◽  
Gel Permeation Chromatography ◽  
Poly Lactic Acid ◽  
Reactive Site ◽  
Scanning Calorimetry ◽  
Early Generation ◽  
Sequential Reaction ◽  
Cyclic Esters ◽  
Total Molecular Weight

A family of polymer stars has been prepared from early generation dendritic cores with four, six, and eight arms. Four dendritic cores were prepared from the sequential reaction of a multifunctional alcohol with a protected anhydride, followed by deprotection to afford two or three new alcohol functionalities per reactive site. These cores were used as initiators for the tin-catalyzed ring-opening polymerization of l-lactide and rac-lactide to afford isotactic and atactic degradable stars, respectively. Two series of stars were prepared for each monomer, either maintaining total molecular weight or number of monomer units per arm. The polymers were characterized by NMR spectroscopy, light-scattering gel-permeation chromatography, differential scanning calorimetry, and thermogravimetric analysis. Our results support previous work that suggests that the length of the arms dictates thermal properties rather than the total molecular weight of the star. Little effect was noted between aromatic and aliphatic cores, presumably due to the flexibility of the rest of the core molecule. We have shown that early generation dendrimers can serve as excellent core structures for building core-first polymer stars via the ring-opening of cyclic esters.

scholarly journals Analysis of the Degradation During Melt Processing of PLA/Biosilicate® Composites

2019 ◽  
Vol 3 (2) ◽  
pp. 52 ◽  
Author(s):  
Eduardo H. Backes ◽  
Laís de N. Pires ◽  
Lidiane C. Costa ◽  
Fabio R. Passador ◽  
Luiz A. Pessan
Keyword(s):  
Molecular Weight ◽  
Gel Permeation Chromatography ◽  
Melt Processing ◽  
Poly Lactic Acid ◽  
Processing Route ◽  
Mechanical Resistance ◽  
Scanning Calorimetry ◽  
Oxidative Reactions ◽  
Bioactive Composites ◽  
Internal Mixer

Poly (lactic acid) (PLA)/bioactive composites are emerging as new biomaterials since it is possible to combine stiffness, mechanical resistance, and bioactive character of the bioglasses with conformability and bioabsorption of the PLA. In this study, PLA/Biosilicate® composites were prepared using a melt-processing route. The processability and properties were evaluated aiming to produce composites with bioactive properties. Two different PLA (PLA 2003D and PLA 4043D) were tested with the addition of 1 wt. % of Biosilicate®. Both materials presented a huge reduction in melt viscosity after internal mixer processing. The degradation effects of the addition of Biosilicate® in the PLAs matrices were evaluated using zeta potential tests that showed a very high liberation of ions, which catalyzes PLA thermo-oxidative reactions. To understand the extension of degradation effects during the processing, the composites were characterized using thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), gel permeation chromatography (GPC), and rheological tests. GPC results showed that PLA with the lowest residual acid content (RAC), PLA 2003D, presented higher thermal stability, higher molecular weight, and viscosity baseline compared to PLA 4043D. The composites showed a significant decrease in molecular weight for both PLA with the addition of Biosilicate®. TGA results showed that Biosilicate® might have reduced the activation energy to initiate thermodegradation reactions in PLAs and it occasioned a reduction in the Tonset by almost 40 °C. The DSC results showed that severe matrix degradation and the presence of bioglass did not significantly affect glass transition temperature (Tg), melting temperature (Tm) and crystallinity of PLAs, but it influenced cold crystallization peak (Tcc). In this way, the type of PLA used influences the processability of this material, which can make the production of filaments of this material for 3D printing unfeasible.

Mechanical properties and hydrolytic degradation of methoxy poly(ethylene glycol)-b-poly(DL-lactide-coglycolide- co-ε-caprolactone) diblock copolymer films

e-Polymers ◽  
2008 ◽  
Vol 8 (1) ◽  
Author(s):  
Nongnit Morakot ◽  
Jirasak Threeprom ◽  
Yodthong Baimark
Keyword(s):  
Mechanical Properties ◽  
Weight Loss ◽  
Ethylene Glycol ◽  
Diblock Copolymers ◽  
Hydrolytic Degradation ◽  
Size Exclusion ◽  
Block Length ◽  
Poly Ethylene Glycol ◽  
Scanning Calorimetry ◽  
Poly Ethylene

AbstractBiodegradable films of methoxy poly(ethylene glycol)-b-poly(DL-lactideco- glycolide-co-ε-caprolactone) diblock copolymers (MPEG-b-PDLLGCL) were prepared by solution casting method. Effects of MPEG block length and DLL:G:CL ratio of the MPEG-b-PDLLGCL films on their mechanical properties and hydrolytic degradation were studied and discussed. It was found that the mechanical properties of films were strongly dependent on glass transition temperatures (Tg) of the diblock copolymers. The hydrolytic degradation was investigated in phosphatebuffered solution at 37°C. The degraded films were characterized using gravimetry (%water uptake and %weight loss), 1H-NMR spectroscopy, differential scanning calorimetry and size exclusion chromatography. The %weight loss of the degraded films increased and molecular weight decreased on increasing the MPEG block length and incorporating the G and CL units, according to their %water uptakes. The MPEG content of the degraded film decreased and the Tg increased with hydrolytic degradation time.

scholarly journals Feasibility of Reprocessing Natural Fiber Filled Poly(lactic acid) Composites: An In-Depth Investigation

2017 ◽  
Vol 2017 ◽  
pp. 1-10 ◽  
Author(s):  
Sujal Bhattacharjee ◽  
Dilpreet S. Bajwa
Keyword(s):  
Lactic Acid ◽  
Natural Fiber ◽  
Environmental Concern ◽  
Wood Flour ◽  
Gel Permeation Chromatography ◽  
Thermomechanical Properties ◽  
Poly Lactic Acid ◽  
Filler Concentration ◽  
Scanning Calorimetry ◽  
Abrupt Decrease

Poly(lactic acid) (PLA) based composites are biodegradable; their disposal after single use may be needless and uneconomical. Prodigal disposal of these composites could also create an environmental concern and additional demand for biobased feedstock. Under these circumstances, recycling could be an effective solution, since it will widen the composite service life and prevent the excessive use of natural resources. This research investigates an in-depth impact of recycling on the mechanical and thermomechanical properties of oak wood flour based PLA composites. Two composite formulations (30 and 50 wt% filler), each with 3 wt% coupling agent (PLA-g-MA), were produced and reprocessed six times by extrusion followed by injection molding. Measurements of fiber length and molecular weight of polymer were, respectively, carried out by gel permeation chromatography (GPC). Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and Fourier transform infrared spectroscopy (FTIR) tools were used to study morphological and molecular alterations. With consecutive recycling, PLA composites showed a gradual decrease in strength and stiffness properties and an increase in strain properties. The 50% and 30% filler concentration of fibers in the composite showed an abrupt decrease in strength properties after six and two reprocessing cycles, respectively.

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