Biodegradable Blends Of Poly Research Articles

Antistatic and antimicrobial packaging of PLA/PHBV blend‐based graphene nanoplatelets nanocomposites

AbstractGraphene nanoplatelets (GNP) were used as a filler for the preparation of antistatic and antimicrobial packaging based on biodegradable blends of poly(acid lactic)/poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PLA/PHBV) for the electronic components industry. These packages must have low electrical resistivity and mechanical resistance. The use of biodegradable polymers helps to reduce waste and the addition of GNP can also contribute to antimicrobial activity. In this work, the effect of the addition of GNP on the thermal, mechanical, electrical, electromagnetic properties, and antimicrobial activity of the PLA/PHVB blend was evaluated. PLA/PHBV (80/20) blends with the addition of 1, 3, and 5 wt% of GNP were prepared by melt mixing using extrusion and injection‐mold processes. The samples were characterized by mechanical tests (tensile test, and Shore D hardness), thermal (differential scanning calorimetry and thermogravimetric analysis), impedance spectroscopy, electromagnetic interference shielding efficiency (EMI SE), antimicrobial activity, and field emission gun scanning electron microscopy. In general, the addition of GNP contributes to the increase in elastic modulus and Shore D hardness. The percolation threshold was obtained with the addition of 3 or 5 wt% of GNP in the PLA/PHBV blend with a reduction of 3 orders of magnitude in the electrical resistivity, which can be applied to antistatic packaging. All the nanocomposites exhibited antimicrobial activity, and the addition of 5 wt% GNP inhibited 86% of the growth of Escherichia coli. The PLA/PHBV blend‐based GNP nanocomposite with the addition of 5 wt% of GNP presents the best balance of mechanical properties, with low electrical resistivity, greater total shielding effectiveness of EMI SE, and antimicrobial activity.

Biodegradable blends of poly(butylene succinate-co-terephthalate) and stereocomplex polylactide with enhanced rheological, mechanical properties, heat resistance and hydrolytic degradation

Biodegradable blends of poly(butylene succinate-co-terephthalate) and stereocomplex polylactide with enhanced rheological, mechanical properties, heat resistance and hydrolytic degradation

Characterization of a new bio‐based and biodegradable blends of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) and poly(butylene‐co‐succinate‐co‐adipate)

AbstractMelt blending of poly(3‐hydroxybutyrate‐co‐3‐hydroxyvalerate) (PHBV) and poly(butylene‐co‐succinate‐co‐adipate) (PBSA) was investigated by means of batch mixing at different weight ratios (100:0, 70:30, 50:50, 30:70, and 0:100). PHBV and PBSA were immiscible. PBSA formed small nodules in PHBV, while PHBV formed large inclusions in PBSA. In 50/50 wt% blends, a co‐continuous structure was obtained. The crystallization rate of PHBV and PBSA increased in the blends, most probably due to mutual nucleation, except at the later stages, where PHBV crystallization rates slowed down inside the nodules and in the co‐continuous structure. The mechanical properties were successfully modeled with the EBM model, including parallel and serial resistances and show that the rigidity of the material can be modulated using PBSA. The elongation at break is however governed by PHBV. The blends featured brittle fracture even if PBSA was the continuous phase. The analysis of the stress at break showed that the fracture could be ascribed to debonding at the interfaces and the fracture behavior of PHBV.

Blends of biodegradable poly(ε-caprolactone) and sustainable poly(propylene carbonate) with enhanced mechanical and rheological properties

Blends of biodegradable poly(ε-caprolactone) and sustainable poly(propylene carbonate) with enhanced mechanical and rheological properties

Manipulating Crystallization for Simultaneous Improvement of Impact Strength and Heat Resistance of Plasticized Poly(l-lactic acid) and Poly(butylene succinate) Blends.

Crystalline morphology and phase structure play a decisive role in determining the properties of polymer blends. In this research, biodegradable blends of poly(l-lactic acid) (PLLA) and poly(butylene succinate) (PBS) have been prepared by melt-extrusion and molded into specimens with rapid cooling. The crystalline morphology (e.g., crystallinity, crystal type and perfection) is manipulated by annealing the molded products from solid-state within a short time. This work emphasizes on the effects of annealing conditions on crystallization and properties of the blends, especially impact toughness and thermal stability. Phase-separation morphology with PBS dispersed particles smaller than 1 μm is created in the blends. The blend properties are successfully dictated by controlling the crystalline morphology. Increasing crystallinity alone does not ensure the enhancement of impact toughness. A great improvement of impact strength and heat resistance is achieved when the PLLA/PBS (80/20) blends are plasticized with 5% medium molecular-weight poly(ethylene glycol), and simultaneously heat-treated at a temperature close to the cold-crystallization of PLLA. The plasticized blend annealed at 92 °C for only 10 min exhibits ten-fold impact strength over the starting PLLA and slightly higher heat distortion temperature. The microscopic study demonstrates the fracture mechanism changes from crazing to shear yielding in this annealed sample.

Biodegradable blends of poly(butylene adipate‐co‐terephthalate) and polyglycolic acid with enhanced mechanical, rheological and barrier performances

AbstractBlends of poly(butylene adipate‐co‐terephthalate)/polyglycolic acid (PBAT/PGA) were prepared by melt blending, in which PGA was used as reinforcing component. Impacts of PGA content on tensile property, microstructure, crystallization property, melt viscosity, barrier performance of the blends were researched. Compared with very soft behavior of PBAT, the tensile yield strength and modulus of PBAT/PGA (65/35) sample increased from 7.67, 62.6 MPa of neat PBAT to 12.05, 158.9 MPa, respectively. However, owing to poor PBAT/PGA interface compatibility, its elongation at break decreased significantly from 1082.1% to 88.7%. An epoxy chain extender (ADR) was used as reactive modifier to improve its interface compatibility and rheological property. The related physical properties of PBAT/PGA/ADR (65/35/x) samples with various ADR contents were evaluated in detail. It was found that ADR exerted relatively complex influences on the properties. Overall, compared with neat PBAT and PBAT/PGA (65/35) sample, the PBAT/PGA/ADR (65/35/x) samples exhibited better stiffness‐ductility balance and higher processing stability.

Morphological and mechanical properties of biodegradable poly(glycolic acid)/poly(butylene adipate-co-terephthalate) blends with in situ compatibilization.

In the present work, the biodegradable blends of poly(glycolic acid) (PGA) and poly(butylene adipate-co-terephthalate) (PBAT) with in situ compatibilization using 4,4′-methylenebis(phenyl isocyanate) (MDI) were prepared. The combined results of FTIR, DSC, SEM, DSC, POM, TGA and rheology demonstrated that the MDI was successfully reacted with PGA/PBAT, the complex viscosity and storage moduli (G′) of the blends were increased. Melt elasticity and viscosity of the blends were also increased on increasing the concentration of PBAT. SEM results indicated that the compatibility was improved by in situ compatibilization. Due to the apparent differences in melting temperature (Tm) between PGA and PBAT, the morphology of the dispersed phase evolved from a spherical structure to in situ microfiber when the content of PBAT was up to 60% during injection molding. The interfacial adhesion between PGA and PBAT was strengthened, consequently, the impact strength of the blend was sharply increased from 9.0 kJ m−2 to 22.2 kJ m−2. On account of the chain extension effect, the crystallinity, crystallization temperature and crystallization size were decreased, which was also of benefit for the improvement of toughness. Meanwhile, the thermal stability of the PGA was improved through blending with PBAT. A novel biodegradable blending material with enhanced toughness and thermal stability was prepared.

Development of Essential Oil Incorporated Active Film Based on Biodegradable Blends of Poly (Lactide)/Poly (Butylene Adipate-co-Terephthalate) for Food Packaging Application

Active packaging improves the food safety and quality with the incorporation of certain additives such as antimicrobial agents. The PLA/PBAT films were prepared with two essential oils—eucalyptus oil and cinnamon oil of various concentrations (1%, 5% and 10% w/w) and characterised their optical and mechanical properties, surface hydrophobicity, chemical composition and antimicrobial activity. Cinnamon oil composite films were observed as thicker film (88.88 µm) than the eucalyptus oil films (54.46 µm). The highest UV-blocking properties were observed in cinnamon oil films. However, transparency and tensile properties of the cinnamon oil films decreases as the concentration increases. The tensile strength of the eucalyptus oil film decreased by 17%, while for cinnamon by 42%. The cinnamon oil (10% w/w) film showed ≈ 5% higher biofilm inhibition than eucalyptus oil (10% w/w). The PLA/PBAT–cinnamon oil films with potent antimicrobial and UV-blocking properties can be used in food packaging to improve the quality and increase the shelf-life of foods.

Influence of aging on molecular motion in PBAT-thermoplastic starch blends studied using solid-state NMR

The influence of seven-month aging on molecular motion in blends of biodegradable poly(butylene-adipate-co-terephthalate) (PBAT) and corn starch plasticized with water, urea (U) and/or glycerol (G) was studied using solid-state 1H and 13C NMR spectroscopy. Changes in 1H and 13C NMR spectra due to aging in G-containing blends are explained by starch retrogradation. The increasing number of urea-glycerol interactions in the aged UG-containing blend can be deduced from the 1H NMR spectra. The formation of a crystalline phase was not observed in the U-containing blends. The 13C spin-lattice relaxation times and scanning electron microscopy support this interpretation of the NMR spectra.

Biodegradable blends of poly(butylene adipate-co-terephthalate) and stereocomplex polylactide with enhanced rheological, mechanical properties and thermal resistance

The aim of this study was to prepare a new blend system by blending equimolar poly(L-lactic acid) (PLLA) and poly(D-lactide acid) (PDLA) with poly(butylene adipate-co-terephthalate) (PBAT) and to form stereocomplex polylactide (sc-PLA) during blending process. Then, sc-PLA would improve the performance of PBAT without compromising its biodegradability. Torque-time curve, differential scanning calorimetry (DSC), and wide angle X-ray diffraction (WAXD) measurements indicated that only sc-PLA formed in PBAT matrix. The phase morphology showed that sc-PLA particles were uniformly dispersed in PBAT matrix, and the sizes were independent of their contents. The rheological properties of PBAT were significantly enhanced by addition of sc-PLA, especially after the formation of a percolation network structure. With the increase of sc-PLA content, the blends displayed increased yield strength and modulus and decreased elongation at break and tensile strength. The sc-PLA particles could reinforce PBAT matrix. Compared with pure PBAT, the heat resistance of PBAT/sc-PLA blends was improved.

Blends of poly(butylene adipate-co-terephthalate) (PBAT) and stereocomplex polylactide with improved rheological and mechanical properties.

Biodegradable blends of poly(butylene adipate-co-terephthalate) (PBAT) and stereocomplex polylactide (sc-PLA) were prepared herein via a melt blending method at various sc-PLA loadings. Wide-angle X-ray diffraction and differential scanning calorimetry results verified that complete stereocomplex polylactide crystallites in the PBAT could be achieved. Scanning electron microscopy observation indicated that sc-PLA was dispersed in the PBAT matrix as spherical particles; the dispersed size of the sc-PLA did not display a pronounced increase once the content of sc-crystallites reached a critical gel point. As solid fillers, sc-PLA could reinforce the PBAT matrix in a relatively wider temperature region and accelerate the non-isothermal crystallization of PBAT. The properties of PBAT were greatly improved after blending with sc-PLA, particularly when a percolation network structure of spherical filler had formed in the blends. In addition, all the blends showed higher yield stresses and moduli than those of the neat PBAT but exhibited reduction in elongations in tensile mechanical tests. These results would be interesting to the industrial polymer materials community, and may be of significant use and importance for the wider practical application of PBAT.

Blends of biodegradable poly(butylene adipate-co-terephthalate) with poly(hydroxi amino ether) for packaging applications: Miscibility, rheology and transport properties

The improvement of the properties of biodegradable poly(butylene adipate-co-terephthalate) (PBAT) through the addition of poly(hydroxi amino ether) (PHAE) is investigated. Analysis by means of DSC, DMTA, FTIR and TEM reveals that blends are partially miscible, with finely dispersed droplet/matrix morphology. Besides of morphology, hydrogen bonds between both, hydroxyl groups and tertiary amines in neat poly(hydroxi amino ether), and with carbonyl groups of poly(butylene adipate-co-terephthalate) in the blends, work out the linear viscoelastic properties and the time relaxation spectrum. Blends rich in poly(hydroxi amino ether) show the highest relaxation times and consequent strain hardening behaviour, which facilitates film elaboration for packaging.Permeability to water vapour, limonene and carbon dioxide is measured obtaining a great reduction on PBAT permeability with the addition of poly(hydroxi amino ether), specially for carbon dioxide. The mechanical properties of the blends are similar to the polymer that forms the matrix. Overall, this work aims to shed light on the effect of a second component on the properties of a biodegradable polymer in order to design suitable materials for packaging applications.

Biodegradable Compatibilized Poly(l-lactide)/Thermoplastic Polyurethane Blends: Design, Preparation and Property Testing

Biodegradable blends of poly(l-lactide) (PLL) toughened with a polycaprolactone-based thermoplastic polyurethane (TPU) elastomer and compatibilized with a purpose-designed poly(l-lactide-co-caprolactone) (PLLCL) copolymer were prepared. Both 2-component (PLL/TPU) and 3-component (PLL/TPU/PLLCL) blends of various compositions were prepared by melt mixing, hot-pressed into thin films and their properties tested. The results showed that, although the TPU could toughen the PLL, the blends were immiscible leading to phase separation with the TPU domains distributed in the PLL matrix. However, addition of the PLLCL copolymer could partially compatibilize the blend by improving the interfacial adhesion between the two phases. Biodegradability testing showed that the blends were biodegradable and that the PLLCL copolymer could increase the rate of biodegradation under controlled composting conditions. The 3-component blend of composition PLL/TPU/PLLCL = 90/10/10 parts by weight was found to exhibit the best all-round properties.

Nanofibrous poly(3-hydroxybutyrate)/poly(3-hydroxyoctanoate) scaffolds provide a functional microenvironment for cartilage repair.

Articular cartilage defects, when repaired ineffectively, often lead to further deterioration of the tissue, secondary osteoarthritis and, ultimately, joint replacement. Unfortunately, current surgical procedures are unable to restore normal cartilage function. Tissue engineering of cartilage provides promising strategies for the regeneration of damaged articular cartilage. As yet, there are still significant challenges that need to be overcome to match the long-term mechanical stability and durability of native cartilage. Using electrospinning of different blends of biodegradable poly(3-hydroxybutyrate)/poly(3-hydroxyoctanoate), we produced polymer scaffolds and optimised their structure, stiffness, degradation rates and biocompatibility. Scaffolds with a poly(3-hydroxybutyrate)/poly(3-hydroxyoctanoate) ratio of 1:0.25 exhibit randomly oriented fibres that closely mimic the collagen fibrillar meshwork of native cartilage and match the stiffness of native articular cartilage. Degradation of the scaffolds into products that could be easily removed from the body was indicated by changes in fibre structure, loss of molecular weight and a decrease in scaffold stiffness after one and four months. Histological and immunohistochemical analysis after three weeks of culture with human articular chondrocytes revealed a hyaline-like cartilage matrix. The ability to fine tune the ultrastructure and mechanical properties using different blends of poly(3-hydroxybutyrate)/poly(3-hydroxyoctanoate) allows to produce a cartilage repair kit for clinical use to reduce the risk of developing secondary osteoarthritis. We further suggest the development of a toolbox with tailor-made scaffolds for the repair of other tissues that require a 'guiding' structure to support the body's self-healing process.

Solid-State NMR Study of Poly(3-Hydroxybutyrate) and Ecoflex reser Blends

Biodegradable blends of poly(3-hydroxybutyrate) and aromatic-aliphatic co-polyester Ecoflex® were studied by means of basic solid-state NMR techniques. C NMR spectra pointed at existence of individual components in blends, however, existence of regions in which components affect each other was also deduced from changes of shape of some spectral lines. Analysis of proton spin–lattice relaxation process in laboratory frame running in blends with different fractions of components revealed poor miscibility of these polymers. The domain size of components was calculated based on the values of spin–lattice relaxation times in laboratory frame. Spin–lattice relaxation process in the rotating frame of Ecoflex® proton spin system was only slightly influenced by the blending. Incompatibility of these polymers was confirmed by all realized experiments.

A fully biodegradable patent ductus arteriosus occlude.

The purpose of this study was to develop a fully degradable occluder for the closure of PDA, which can be deployed percutaneously. The blends of biodegradable poly(ε-caprolactone) and poly(L-lactide-co-ε-caprolactone) with various compositions were studied as the potential material. The mechanical properties, i.e. elastic modulus and strain recovery, of the blends could be largely tailored by changing the continuous phase component. Moreover, the suitable blends were selected to fabricate a prototype and its in vitro biodegradation rate and blood compatibility, was evaluated. The current results indicate that no adverse effect on the platelet and leukocyte components of the blood. Biocompatibility implantation studies of the device showed acceptable tissue response. Finally, an artificial PDA conduit was created in a pig, and the device deployment was tested from a sheath: the device recovered within 2-3min of unsheathing and fully sealed the conduit.

Biodegradable Plasticized Blends of Poly(L-lactide) and Cellulose Acetate Butyrate: From Blend Preparation to Biodegradability in Real Composting Conditions

Biodegradable blends of poly(L-lactide) (PLL) and cellulose acetate butyrate (CAB) were prepared as 40–60 µm thick films cast from solution using chloroform as a solvent. Both poly(ethylene glycol) (PEG) and a polyester adipate (Paraplex G40) were used as plasticizers to decrease the PLL/CAB blends’ glass transition temperature and make them more flexible. Ternary PLL/CAB/PEG blends showed only partial compatibility due to phase separation of crystalline PLL-rich and CAB-rich domains. In contrast, when Paraplex G40 was used as the plasticizer, it produced PLL/CAB/Paraplex G40 blends with stable morphology over an extended period of time with much reduced phase separation. The PLL/CAB/plasticizer blend films all degraded in real composting conditions at PLL contents of over 50 wt%. Moreover, the PEG-plasticized ternary blend films showed complete degradability at PLL ≥ 70 and CAB ≤ 30 wt%. These results suggest that the CAB content and plasticizer type can be used to tune polymer blend compatibility and biodegradability. The most promising formulations were found to be PLL/CAB/Paraplex G40 blends with compositions of PLL ≥ 70, CAB ≤ 30 and Paraplex G40 = 20 parts by weight, combining good polymer compatibility and biodegradability with a suitable balance of mechanical properties.

The mechanical behavior and biocompatibility of polymer blends for Patent Ductus Arteriosus (PDA) occlusion device

Patent Ductus Arteriosus (PDA) is a cardiovascular defect that occurs in 1 out of every 2000 births, and if left untreated, may lead to severe cardiovascular problems. Current options for occluding utilize meta scaffolds with polymer fabric, and are permanent. The purpose of this study was to develop a fully degradable occluder for the closure of PDA, that can be deployed percutaneously without open-heart surgery. For percutaneous deployment, both elasticity and sufficient mechanical strength are required of the device components. As this combination of properties is not achievable with currently-available homo- or copolymers, blends of biodegradable poly(ε-caprolactone) (PCL) and poly(L-lactide-co-ε-caprolactone) (PLC) with various compositions were studied as the potential material for the PDA occlusion device. Microstructures of this blend were characterized by differential scanning calorimetry (DSC) and tensile tests. DSC results demonstrated the immiscibility between PCL and its copolymer PLC. Furthermore, the mechanical properties, i.e. elastic modulus and strain recovery, of the blends could be largely tailored by changing the continuous phase component. Based on the thermo-mechanical tests, suitable blends were selected to fabricate a prototype of PDA occluder and its in vitro performance, in term of device recovery (from its sheathed configuration), biodegradation rate and blood compatibility, was evaluated. The current results indicate that the device is able to recover elastically from a sheath within 2–3min for deployment; the device starts to disintegrate within 5–6 months, and the materials have no adverse effects on the platelet and leucocyte components of the blood. Biocompatibility implantation studies of the device showed acceptable tissue response. Finally, an artificial PDA conduit was created in a pig model, and the device deployment was tested from a sheath: the device recovered within 2–3min of unsheathing and fully sealed the conduit, the device remains stable and is completely covered by tissue at 1 month follow up. Thus, a novel prototype for PDA occlusion that is fully degradable has been developed to overcome the limitations of the currently used metal/fabric devices.

Preparation and Characterization of Biodegradable PLA/PCL Polymeric Blends

In this study, blends of biodegradable Poly (lactic acid) (PLA) and Polycaprolactone (PCL), were prepared using Hakee Rheomix and characterized for rheological, thermal, mechanical and viscoelastic properties. Morphology of tensile fractured surfaces was examined through scanning electron microscopy (SEM). The blends of PLA/PCL exhibited an increase in percentage of elongation, impact toughness, loss factor and decrease in strength and modulus, when compared to that of neat PLA. Among the various blend proportions considered in this work, 80/20% PLA/PCL blend exhibited the highest elongation and impact strength. Differential scanning calorimetry (DSC) showed the influence of PCL content on glass transition temperature (Tg), melting temperature and degree of crystallinity of PLA/PCL blends.

TOUGHENING AND STRENGTHENING OF POLY(PROPYLENE CARBONATE) BY 1,6-BIS(HYDROXYISOPROPYL URETHANE)HEXANE

采用非异氰酸酯路线合成了1,6-六亚甲基二氨基甲酸羟异丙酯(BPU),分子量为320.利用熔融共混方法制备了聚碳酸1,2-丙二酯(PPC)/BPU共混物.研究发现BPU与PPC间有较好的相容性,随着BPU含量的增加,共混体系的起始热分解温度(Td,5%)可分别增加24~33℃,共混物韧性也显著提高,断裂伸长率最大可增至53.4%,为纯PPC的4倍,且共混物的强度和模量仍维持在较高的数值;BPU含量不超过10 wt%时,可以同时实现共混体系的增韧和增强.剪切屈服和银纹化是PPC/BPU体系得以增韧的最主要机理,而空洞化现象起辅助作用.