Biodegradation Behavior Of Poly Research Articles

Biodegradation study of poly(hydroxybutyrate-co-hydroxyvalerate)/halloysite/oregano essential oil compositions in simulated soil conditions

The aim of this work was to evaluate the influence of halloysite clay nanoparticles – unmodified (Hal) and organically modified (mHal) – and oregano essential oil (OEO), used as an antimicrobial agent in active packaging, on the biodegradation behavior of poly(hydroxybutyrate-co-hydroxyvalerate) (PHBV) films. Five samples were prepared by melt mixing using 3 wt% clay, and 8 wt% and 10.4 wt% OEO. PHBV compositions containing OEO presented the highest rate of biodegradation, achieving 46% of mass loss after aging for 12 weeks in simulated soil. The addition of clay nanoparticles reduced the polymer's biodegradation to 32%. The compositions containing OEO showed a rough and layered surface with visible cracks, indicating degradation occurring through layer-by-layer erosion from the surface. This degradation was confirmed by the chemical changes on the surface of all samples, with a slight decrease in molar masses. The composition containing 8 wt% OEO presented an increase in the crystallization degree as a result of the preferential consumption of amorphous phase, whereas for the compositions containing clay nanoparticles, both crystalline and amorphous regions were degraded at similar rates. Therefore, the combination of additives allows the biodegradation process of PHBV to be controlled for use in the production of active packaging.

Biodegradation behavior of poly (glycolic acid) (PGA) and poly (butylene adipate-co-terephthalate) (PBAT) blend films in simulation marine environment

Polyglycolic acid (PGA) and poly (butylene adipate-co-terephthalate) (PBAT), as widely applied biodegradable polymers, the degradation behavior of their blends in marine environments has not been proven. This study investigated the changes of macroscopic and microscopic morphology, thermal properties, crystalline and chemical structure, degradation rate of PGA/PBAT blends with different ratios in the simulation marine environment containing sediments and marine organisms. The results showed that degradation primarily occurred due to ester bond breakage, and PGA exhibited a faster degradation rate than PBAT films. The amorphous region degraded more rapidly than the crystalline region, and the thermal stability of the materials decreased. The degradation of PGA and PBAT blends followed their respective single degradation laws and the compatibility of blend samples decreased after degradation. The degradation rate of the samples was obtained by measuring the biochemical oxygen demand, which indicated that a higher PGA content could result in a faster degradation rate for PGA/PBAT films. This study provides an efficient method for constructing materials with controlled biodegradability.

Biodegradation behavior of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) containing phenolic compounds in seawater in laboratory testing conditions

Biodegradation in marine medium of PHBV films with or without 5 % wt. of phenolic compounds (catechin, ferulic acid, and vanillin) was assessed at laboratory scale. Respirometric analyses and film disintegration kinetics were used to monitor the process over a period of 162 days. Structural changes in the films were analyzed throughout the exposure period using FESEM, DSC, Thermogravimetric analyses, XRD, and FTIR spectra. Respirometric tests showed complete biodegradation of all materials during the exposure period (the biodegradation half-time ranged between 63 and 79 days) but at different rates, depending on the phenolic compound incorporated. Ferulic acid and vanillin accelerate the PHBV biodegradation, whereas catechin delayed the process. Disintegration kinetics confirmed these results and showed that degradation occurred from the surface to the interior of the films. This was controlled by the degradation rate of the polymer amorphous phase and the formation of a biomass coating on the film surface. This is the result of the compounds generated by polymer degradation in combination with excretions from microorganisms. This coating has the potential to affect the enzyme diffusion to the polymer substrate. Moreover, the cohesion forces of the amorphous phase (reflected in its glass transition temperature) affected its degradation rate, while the slower degrading crystalline fragments were released, thus contributing to the disintegration process on the film's surface. Ferulic acid, with its hydrolytic effect, enhanced degradation, as did vanillin for its plasticizing and weakening effect in the amorphous phase of polymer matrix. In contrast, catechin with cross-linking effect hindered the progress of the material degradation, considerably slowing down the process rate.

Biodegradation behavior of poly (lactic acid) samples obtained by three‐dimensional printing: Influence of temperature and pigment presence

AbstractIn this study, the biodegradation behavior in the soil of natural and pigmented poly (lactic acid) (PLA) plates obtained by three‐dimensional (3D) printing or by compression molding was evaluated by the respirometry method at three different temperatures: 21, 28, and 35°C. PLA samples before and after aerobic biodegradation tests were characterized by Fourier transform infrared spectroscopy, differential scanning calorimetry (DSC), thermogravimetric analysis (TG), and size exclusion chromatography analysis. The increase in test temperature enhanced the biodegradation process. At a test temperature of 35°C, the maximum biodegradation rates of natural PLA and pigmented PLA were 65% and 68% higher, respectively, compared to the maximum biodegradation rate observed at 21°C. DSC and TG analysis indicate that pigmented PLA samples were more susceptible to degradation by hydrolysis. However, the rate of biodegradation efficiency was lower in pigmented PLA samples, with a decrease of 16%, 24%, and 14% at 21, 28, and 35°C, respectively, compared to natural PLA. This behavior indicated that pigment hindered the hydrolysis by‐products absorption by microorganisms. Additionally, the presence of micro voids in PLA samples obtained through 3D printing accelerated the rate of biodegradation efficiency by 32% at 28°C compared to pressed samples.Highlights Poly (lactic acid) (PLA) plate biodegradation in soil was analyzed using respirometry method. Temperature, pigment presence, and sample preparation method were considered. Higher temperatures enhanced both natural and pigmented PLA biodegradation. Pigments appeared to act as antimicrobial agents, slowing down the process. Water presence in the micro voids accelerated hydrolysis and biodegradation.

Biodegradation Behavior of Poly(Butylene Adipate-Co-Terephthalate) (PBAT), Poly(Lactic Acid) (PLA), and Their Blend in Freshwater with Sediment.

Poly(butylene adipate-co-terephthalate) (PBAT) and poly(lactic acid) (PLA) are well-known biodegadable polyesters due to their outstanding performance. The biodegradation behavior of PLA/PBAT blends in freshwater with sediment is investigated in this study by analyzing the appearance, chemical structure and aggregation structure of their degraded residues via SEM, TG, DSC, gel permeation chromatography (GPC) and XPS. The effect of aggregation structure, hydrophilia and biodegradation mechanisms of PBAT and PLA on the biodegradability of PLA/PBAT blends is illuminated in this work. After biodegradation, the butylene terephthalate unit in the molecular structure of the components and the molecular weight of PLA/PBAT blends decreased, while the content of C-O bond in the composites increased, indicating that the samples indeed degraded. After 24 months of degradation, the increase in the relative peak area proportion of C-O to C=O in PLA/PBAT-25, PLA/PBAT-50 and PLA/PBAT-75 was 62%, 46% and 68%, respectively. The biodegradation rates of PBAT and PLA in the PLA/PBAT blend were lower than those for the respective single polymers.

Biodegradation Behavior of Poly (Lactic Acid) (PLA), Poly (Butylene Adipate-Co-Terephthalate) (PBAT), and Their Blends Under Digested Sludge Conditions

This paper presents a study on the degradation of Poly (lactic acid) (PLA), Poly (butylene abdicate—terephthalate) (PBAT) and their blends with different proportions in the environment of digested sludge. The degradation rates of PLA and PBAT were obtained through anaerobic reaction device. The samples obtained at regular intervals were measured and analyzed by differential scanning calorimeter (DSC), infrared spectrometer (FTIR) and scanning electron microscope (SEM) respectively. The results showed that the degradation rate of PLA was higher than that of PBAT under the same degradation environment and degradation time. DSC results showed that the degradation rate of PLA in the amorphous phase was slowed by the influence of PBAT. The characteristic peaks of the materials on the infrared spectrum shifted after degradation which implicit the degradation occurs. At the microscopic level, numerous protruding ribs in the material can be seen in the electron micrograph. Obviously, the samples can be degraded under the environment of digested sludge.

Effect of silica resources on the biodegradation behavior of poly (lactic acid) and chemical crosslinked poly (lactic acid) composites

Biodegradation tests of PLA and chemically crosslinked PLA (CrPLA) filled with two different types of SiO2 (RSiO2 and CSiO2) that were surface-treated with stearic acid were studied using a CO2 detection technique. Triallyl isocyanurate (TAIC) in the presence of dicumyl peroxide (DCP) was selected as a chemical crosslinking agent. The incorporation of SiO2 fillers altered the peak of the TAIC-carbonyl functional group at 1685 cm−1 by interfering with the chemical crosslinking reaction, which affected the crystallinity and melting behaviors of SiO2/CrPLA composites, as observed by DSC thermograms. The FTIR spectra of surface-treated RSiO2 and CSiO2 showed that RSiO2 was significantly changed, with the silanol vibration peak observed at 960 cm−1, which indicated a strong reaction with stearic acid. The addition of SiO2 resulted in more water absorption with extensive surface erosion, and eventually, faster biodegradation and faster rates of composited samples were discovered. The higher content of loaded SiO2 was also found to improve the amount of water absorption, which accelerated biodegradation. However, CSiO2 is more effective at accelerating biodegradation than RSiO2 is for PLA and CrPLA because of its greater hydrophilicity.

Effect of Commercial SiO2 and SiO2 from rice husk ash loading on biodegradation of Poly (lactic acid) and crosslinked Poly (lactic acid)

In this work, biodegradation behavior of poly (lactic acid) (PLA) and crosslinked PLA filled with two types of SiO2, precipitated SiO2 (commercial SiO2) and SiO2 from rice husk ash, were studied. Rice husks were first treated with 2 molar hydrochloric acid (HCl) to produce high purity SiO2, before burnt in a furnace at 800°C for 6 hours. All components were melted bending by an internal mixer then hot pressed using compression molder to form tested specimens. FTIR spectra of SiO2 and PLA samples were investigated. The results showed the lack of silanol group (Si-OH) of rice husk ash after steric acid surface modification, while the addition of particles can affect the crosslinking of the PLA. For biodegradation test by evaluating total amount of carbon dioxide (CO2) evolved during 60 days incubation at a controlled temperature of 58±2°C, the results showed that the biodegradation of crosslinked PLA occurred slower than the neat PLA. However, SiO2 incorporation enhanced the degree of biodegradation In particular, introducing commercial SiO2 in PLA and crosslinked PLA tended to clearly increase the degree of biodegradation as a consequence of the more accelerated hydrolysis degradation.

Biodegradation behavior and modelling of soil burial effect on degradation rate of PLA blended with starch and wood flour

The biodegradation behavior of Poly (lactic acid) (PLA) blended with starch and wood flour in outdoor soil was investigated comprehensively. As a result, starch provided a biological fuel for the growth of microorganisms in the soil which accelerated the degradation rate of PLA more obviously than wood flour. With the increase of starch content, the weight loss increased and the morphology exhibited more gullies and cavities. X-ray Photoelectron Spectroscopy (XPS) analysis indicated that the variation of O/C ratio was controlled by starch biodegradation and PLA hydrolysis and they were a concomitant process. The mechanical strengths of all the blends showed similar trend and fitted a first-order exponential decay model. The model is shown in good agreement with experimental results as the correlation coefficient is higher than 0.99, and the model can support an efficient method to estimate the durability of starch/wood flour/PLA blends.

Biodegradation behavior of poly(butylene adipate-co-terephthalate) (PBAT), poly(lactic acid) (PLA), and their blend under soil conditions

Poly(lactic acid) (PLA) and poly(butylene adipate-co-terephthalate) (PBAT) were mixed at a ratio of 40:60, extruded to form granules and cast into film; then, the PLA, PBAT, and PBAT/PLA film samples were buried in real soil environments. The residual degraded samples were taken regularly from the soil and analyzed by SEM, DSC, TGA, IR spectroscopy and elemental analysis. The analyses showed that PBAT and PLA had different biodegradation mechanisms. Further, the melting temperature and the melting point change of the various components in the PBAT/PLA blend before and after the biodegradation essentially followed the process of the changes in the respective single polymers. After biodegradation, the carbon atom content in the molecular structure of the PBAT, PLA, and PBAT/PLA samples decreased, while the oxygen atom content increased, indicating that the samples indeed degraded. The biodegradation rates of PBAT and PLA in the PBAT/PLA blend were not the same as those for the single materials.

Biodegradation behaviour of poly(lactic acid) and (lactic acid-ethylene glycol-malonic or succinic acid) copolymers under controlled composting conditions in a laboratory test system

(Lactic acid, ethylene glycol, malonic or succinic acid) copolymers [(LA–EG–MA) and (LA–EG–SA) copolymers] were synthesized with different monomer feed ratios by direct polycondensation. The copolymers were characterized in terms of various properties such as acid value and number average molecular weight. The aerobic biodegradation under controlled composting conditions of commercially available and laboratory synthesized poly(l-lactic acid) (PLA) and synthesized copolymers was carried out according to ISO 14855-1:2005. The biodegradability of tested materials was found to be strongly dependent on the lactic acid content, ranging from 94% (method A) and 104% (method B) to 43% (method A) and 46% (method B) over the 110-days of the 50 °C composting.

Understanding the mechanical and biodegradation behaviour of poly(hydroxybutyrate)/rubber blends in relation to their morphology

AbstractIn this work poly(hydroxybutyrate/poly(vinyl butyral)‐ co‐(vinyl alcohol)‐co(vinyl acetate) (or ethylene propylene diene monomer rubber) blends were prepared by conventional processing techniques (extrusion and injection moulding). A droplet type morphology was obtained for P(3HB)/PVB blends whereas P(3HB)/EPDM blends presented some extent of co‐continuous morphology. In addition, rubbery domains were much smaller in the case of PVB. These differences in morphology are discussed taking into account solubility parameters and rheological behaviours of each component. For both blends, the increase of elastomer ratio led to a decrease of Young's modulus but an increase in elongation at break and impact strength. The latter increased more in the case of P(3HB)/EPDM blends although the rubbery domains were larger. These results are explained in the light of the glass transition of the rubber and the presence of plasticizer in the case of PVB. The addition of elastomer also resulted in an increase of P(3HB) biodegradation rate, especially in the case of EPDM. It is assumed that, in this case, the size and morphology of the rubbery domains induce a geometrical modification of the ‘erosion front’ which leads to an increase of the interface between P(3HB) phase and the degradation medium and consequently to an apparently faster biodegradation kinetics of PHB/rubber blends. Copyright © 2011 Society of Chemical Industry

Biodegradation behavior of PHAs with different chemical structures under controlled composting conditions

Polyhydroxyalkanotes (PHAs) are biobased and biodegradable polymers, of which poly(hydroxybutyrate- co-hydroxyvalerate) (PHBV, 3 %mol HV) and poly-3-hydroxybutyrate-co-4-hydroxybutyrate [P(3HB,4HB), 10 %mol 4HB] are currently commercialized. To understand the influence of chemical structure on the biodegradability of PHA, the biodegradation behavior of poly(hydroxybutyrate) (PHB), PHBV (40 %mol HV), PHBV (20 %mol HV), PHBV (3 %mol HV) and P(3HB,4HB) (10 %mol 4HB) were investigated under the controlled composting conditions according to ISO 14855-1. It was found that PHAs with different chemical structures can be biodegraded under the controlled composting conditions. The order of biodegradability was P(3HB, 4HB) (40 %mol 4HB) ≈ PHBV(40 %mol HV) >PHBV(20 %mol HV) >PHBV(3 %mol HV) >PHB.

Study on development and in vitro biodegradation behaviour of poly(D, L-lactide-co-glycolide) 75/25 bioscaffolds

Three-dimensional porous scaffolds based on biodegradable polymers are widely researched for applications to replace and restore the functions of diseased or damaged organs. The requirements for the scaffolds include: highly interconnected pore structures to facilitate cell adhesion for tissue regeneration, maintenance of mechanical properties and structural integrity until cells adapt to its environment and biodegradability with a controlled degradation rate. This paper focuses on the development and in vitro biodegradation behaviour of poly (D,L-lactide-co-glycolide acid) (PLGA) 75/25 and changes on pore morphology affected by initial pore sizes and degradation media. The pore morphology, mechanical properties, and geometric transformation were examined over the course of 13 weeks. It is concluded that the PLGA 75/25 scaffolds degraded after seven weeks and completely degraded after 13 weeks. The degradation time of scaffolds with small pores and in distilled water was comparatively shorter due to poorer interconnectivity of the pores and a more aggressive environment.

Oxo-biodegradable polymers – Effect of hydrolysis degree on biodegradation behaviour of poly(vinyl alcohol)

Poly(vinyl alcohol) (PVA) is considered to be one of the very few vinyl polymers soluble in water and susceptible to biodegradation in aqueous media by specific microorganisms, implying oxidation of the carbon backbone followed by a random endocleavage of the polymer chains. The overall process does not appear to be appreciably affected by either degree of polymerization (DPn) or degree of hydrolysis (HD) of PVA at least in the 100–1000 and 80–100% ranges, respectively. In order to assess the effect of HD on the biodegradation propensity of PVA, different PVA samples having similar DPn and noticeably different HD values were synthesized by controlled acetylation of commercial PVA (HD = 99%) and submitted to biodegradation tests in aqueous medium, mature compost and soil by using respirometric procedures. Re-acetylated PVA samples characterized by HD of between 25 and 75% underwent extensive mineralization when buried in solid media, whilst PVA (HD = 99%) showed recalcitrance to biodegradation under those conditions. An opposite trend was indeed observed in aqueous solution, thus suggesting that biodegradation is not an absolute attribute directly related to structural features of the substrate under investigation. Boundary conditions related to the framework under which the biodegradation assessment is undertaken have to be taken into account and specifically well defined.

Biodegradable polymers based on renewable resources. V. Synthesis and biodegradation behavior of poly(ester amide)s composed of 1,4:3,6‐dianhydro‐D‐glucitol, α‐amino acid, and aliphatic dicarboxylic acid units

AbstractA series of poly(ester amide)s were synthesized by solution polycondensations of various combinations of p‐toluenesulfonic acid salts of O,O′‐bis(α‐aminoacyl)‐1,4:3,6‐dianhydro‐D‐glucitol and bis(p‐nitrophenyl) esters of aliphatic dicarboxylic acids with the methylene chain lengths of 4–10. The p‐toluenesulfonic acid salts were obtained by the reactions of 1,4:3,6‐dianhydro‐D‐glucitol with alanine, glycine, and glycylglycine, respectively, in the presence of p‐toluenesulfonic acid. The polycondensations were carried out in N‐methylpyrrolidone at 40°C in the presence of triethylamine, giving poly(ester amide)s having number‐average molecular weights up to 3.8 × 104. Their structures were confirmed by FTIR, 1H‐NMR, and 13C‐NMR spectroscopy. Most of these poly(ester amide)s are amorphous, except those containing sebacic acid and glycine or glycylglycine units, which are semicrystalline. All these poly(ester amide)s are soluble in a variety of polar solvents such as dimethyl sulfoxide, N,N‐dimethylformamide, 2,2,2‐trifluoroethanol, m‐cresol, pyridine, and trifluoroacetic acid. Soil burial degradation tests, BOD measurements in an activated sludge, and enzymatic degradation tests using Porcine pancreas lipase and papain indicated that these poly(ester amide)s are biodegradable, and that their biodegradability markedly depends on the molecular structure. The poly(ester amide)s were, in general, degraded more slowly than the corresponding polyesters having the same aliphatic dicarboxylic acid units, both in composted soil and in an activated sludge. In the enzymatic degradation, some poly(ester amide)s containing dicarboxylic acid components with shorter methylene chain lengths were degraded more readily than the corresponding polyesters with Porcine pancreas lipase, whereas most of the poly(ester amide)s were degraded more rapidly than the corresponding polyesters with papain. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 81: 2721–2734, 2001

A novel evaluation method for biodegradability of poly(butylene succinate-co-butylene adipate) by pyrolysis-gas chromatography

Biodegradation behavior of poly(butylene succinate-co-butylene adipate) (PBSA) film samples during the soil burial degradation test was studied by pyrolysis-gas chromatography (Py-GC). In the pyrograms of the PBSA film sample residues, various ester compounds containing succinate and/or adipate units were observed as the main pyrolysis products along with some minor pyrolyzates such as fatty-acid esters comprising propionates and valerates which might be formed mostly from carboxyl end-groups existing in PBSA molecules. Although the relative yields of the major pyrolyzates were almost unchanged before and after the soil burial test, those of the fatty-acid esters decreased with the soil burial time almost correlating with the decrease in recovery as residue. Thus, the variation of the relative yields of the fatty-acid esters proved to be a good measure to evaluate the degree of PBSA biodegradation. Furthermore, the local structural changes for the biodegraded PBSA film samples were also evaluated from the relative yields of these specific esters observed on the pyrograms for tiny pieces of analyte (ca. 0.1 mg) sampled from local points.

Biodegradation behaviour of poly(lactide-co-glycolide) induced by microorganisms

The effect of microorganisms on degradation of PLLA was compared by using different kind of fungus in vitro. Fusarium L023 showed the strongest activity in accelerating the degradation of PLLA. Therefore, the in vitro degradation of PLGA copolymers was examined by immersing PLGA(50/50) and PLGA(70/30) films in media with or without Fusarium L023. Degradation of the polymeric films was monitored by measuring inherent viscosity and weight loss, as well as using techniques such as GPC, 1H NMR, DSC and SEM. In this case, the degradation of PLGA copolymers could be markedly accelerated by Fusarium L023. The microorganism assimilated the released oligomers as carbon-source, and this could explain why the inherent viscosity decreased more slowly for inoculated samples at the later stage than those in the controlled medium. Moreover, the Fusarium L023 would favor the degradation of PLGA copolymers by destroying the crystallization of PLLA segments at the later stage, which was caused by the preferential loss of glycotyl unit in the case of hydrolysis, for Fusarium L023 was more effective on accelerating the degradation of PLLA than PGA.

Thermal, Crystallization, and Biodegradation Behavior of Poly(3-hydroxybutyrate) Blends with Poly(butylene succinate-co-butylene adipate) and Poly(butylene succinate-co-ε-caprolactone)

Morphologies, some physical properties, and biodegradability were investigated for the binary blends of natural poly(3-hydroxybutyrate) [P(3HB)] with chemosynthetic poly(butylene succinate-co-butylene adipate) (PBSA) and poly(butylene succinate-co-ε-caprolactone) (PBSC) prepared using a simple casting procedure. The DSC thermogram of each blend system revealed two distinct glass transitions independent of blend composition. The radial growth rate of P(3HB) spherulite in the blends, observed on a polarizing microscopy, almost kept constant in the blends with P(3HB) content ranged from 50 wt% to 100 wt%. These results indicate that P(3HB) and PBSA, and P(3HB) and PBSC are immiscible in the amorphous state. The enzymatic degradation of blend film was carried out in phosphate buffer (pH 7.5) at 37°C in the presence of P(3HB) depolymerase purified from Alcaligenes faecalis T1. The degradation behavior of blends was monitored by observing UV spectra, measurement of weight-loss and NMR analysis. As a general, the weight-loss rates of blends increased with the increase of P(3HB) content except the blends contained 90 wt% P(3HB) in which a weight-loss was about three times faster than that of pure P(3HB) films. After the beginning of degradation, the content of P(3HB) in films decreased faster than those of blend partners. The biodegradability of aliphatic polyester is suggested to be controllable by blending.

Synthesis and characterization of biodegradable poly(1,4‐butanediol succinate)

AbstractBiodegradable poly(1,4‐butanediol succinate) was synthesized from 1,4‐butanediol and succinic anhydride. The synthesized polymer was identified by 1H‐NMR spectrometer and FT‐IR spectrophotometer. The weight average molecular weights were between 4,600 and 29,000, and molecular weight distributions were in the range of 1.7 and 1.9. The glass transition temperature of poly(1,4‐butanediol succinate) was revealed at 73°C. The crystallization and cold crystallization of the polymers were investigated as a function of heating rate, cooling rate, reheating rate, and molecular weight. The biodegradation behavior of poly(1,4‐butanediol succinate) in micro‐organisms such as fungi, actinomycetes, and bacteria was studied by using modified ASTM method. Based upon visual observation, the crystalline structure of films composed of larger molecular weight polymers retained their crystallinity longer than similar structures in low molecular weight samples. © 1995 John Wiley & Sons, Inc.