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1.
Polylactic acid (PLA) films containing 1 wt % and 3 wt % of lignin nanoparticles (pristine (LNP), chemically modified with citric acid (caLNP) and acetylated (aLNP)) were prepared by extrusion and characterized in terms of their overall performance as food packaging materials. Morphological, mechanical, thermal, UV–Vis barrier, antioxidant and antibacterial properties were assayed; appropriate migration values in food simulants and disintegration in simulated composting conditions were also verified. The results obtained indicated that all lignin nanoparticles succeeded in conferring UV-blocking, antioxidant and antibacterial properties to the PLA films, especially at the higher filler loadings assayed. Chemical modification of the fillers partially reduced the UV protection and the antioxidant properties of the resulting composites, but it induced better nanoparticles dispersion, reduced aggregates size, enhanced ductility and improved aesthetic quality of the films through reduction of the characteristic dark color of lignin. Migration tests and disintegration assays of the nanocomposites in simulated composting conditions indicated that, irrespectively of their formulation, the multifunctional nanocomposite films prepared behaved similarly to neat PLA.  相似文献   

2.
Innovations in food and drink packaging result mainly from the needs and requirements of consumers, which are influenced by changing global trends. Antimicrobial and active packaging are at the forefront of current research and development for food packaging. One of the few natural polymers on the market with antimicrobial properties is biodegradable and biocompatible chitosan. It is formed as a result of chitin deacetylation. Due to these properties, the production of chitosan alone or a composite film based on chitosan is of great interest to scientists and industrialists from various fields. Chitosan films have the potential to be used as a packaging material to maintain the quality and microbiological safety of food. In addition, chitosan is widely used in antimicrobial films against a wide range of pathogenic and food spoilage microbes. Polylactic acid (PLA) is considered one of the most promising and environmentally friendly polymers due to its physical and chemical properties, including renewable, biodegradability, biocompatibility, and is considered safe (GRAS). There is great interest among scientists in the study of PLA as an alternative food packaging film with improved properties to increase its usability for food packaging applications. The aim of this review article is to draw attention to the existing possibilities of using various components in combination with chitosan, PLA, or bacteriocins to improve the properties of packaging in new food packaging technologies. Consequently, they can be a promising solution to improve the quality, delay the spoilage of packaged food, as well as increase the safety and shelf life of food.  相似文献   

3.
Poly lactic acid (PLA) is a compostable, as well as recyclable, sustainable, versatile and environmentally friendly alternative, because the monomer of PLA-lactide (LA) is extracted from natural sources. PLA’s techno-functional properties are fairly similar to fossil-based polymers; however, in pristine state, its brittleness and delicacy during processing pose challenges to its potential exploitation in diverse food packaging applications. PLA is, therefore, re-engineered to improve its thermal, rheological, barrier and mechanical properties through nanoparticle (NP) reinforcement. This review summarises the studies on PLA-based nanocomposites (PLA NCs) developed by reinforcing inorganic metal/metallic oxide, graphite and silica-based nanoparticles (NPs) that exhibit remarkable improvement in terms of storage modulus, tensile strength, crystallinity, glass transition temperature (Tg) value, antimicrobial property and a decrease in water vapour and oxygen permeability when compared with the pristine PLA films. This review has also discussed the regulations around the use of metal oxide-based NPs in food packaging, PLA NC biodegradability and their applications in food systems. The industrial acceptance of NCs shows highly promising perspectives for the replacement of traditional petrochemical-based polymers currently being used for food packaging.  相似文献   

4.
The development of biodegradable materials for tailored applications, particularly in the field of polymeric films and sheets, is a challenging technological goal as well as a contribution to help protect the environment. Poly(lactic) acid (PLA) is a promising substitute for several oil-based polymers; however, to overcome its thermal and mechanical drawbacks, researchers have developed solutions such as blending PLA with polybutylene adipate terephthalate (PBAT), which is capable of increasing the ductility of the final material. In this study, PLA/PBAT binary blends, with minimum possible content of nonrenewable materials, were examined from processing, thermal, morphological, and rheological perspective. An optimized PLA/PBAT ratio was chosen as the polymeric basis to obtain a biodegradable formulation by adding a biobased plasticizer and appropriate fillers to produce a micrometer film with tailored flexibility and tear resistance. The processing technology involved flat-die extrusion, followed by calendering. The tearing resistance of the produced film was investigated, and the results were compared with literature data. A study on the essential work of fracture was implemented to explore the mode III out-of-plane fracture resistance starting from a trouser tear test.  相似文献   

5.
PLA nanocomposite films with multifunctional characteristics such as mechanical, anti-UV, antibacterial, electrical, gas barrier properties are potentially of high interest as packaging biomaterials. Occasionally, desired and beneficial effects obtained by addition nanofillers come along with some drawbacks, leading to the sharp drop in the molecular weights of the polyester chains, and consequently an important loss of mechanical and thermal properties. Novel PLA-ZnO nanocomposite films were produced by melt-compounding PLA with 0.5–3% ZnO rod-like nanoparticles. The surface treatment of nanofiller by silanization (with triethoxy caprylylsilane) was necessary to obtain a better dispersion and to limit the decrease of molecular mass of PLA. The morphology, molecular, thermo-mechanical and transport properties to water vapor of PLA-ZnO films were analyzed with respect to the neat PLA. According to DSC and to XRD, the produced films were essentially amorphous. The changes in PLA permeation properties were strongly dependent on temperature and nanofiller loading. The well dispersed ZnO nanoparticles within the polyester matrix were effective in increasing the tortuosity of the diffusive path of the penetrant molecules. The activation energy remained similar for PLA and PLA-1% ZnO, but was found greater at higher loading of ZnO (3%), confirming the increased difficulty of travelling molecules to diffuse through PLA. In comparison to the neat PLA (presenting no antimicrobial efficacy), the nanocomposites were active against both Gram-positive and Gram-negative bacteria, stronger antibacterial activity being evidenced after 7 days elapsed time. By considering the multifunctional properties of PLA-ZnO nanocomposites, the films produced by extrusion can be considered a promising alternative as environmental-friendly packaging materials.  相似文献   

6.
Antimicrobial active films based on poly(lactic acid) (PLA) were prepared with poly(ε‐caprolactone) (PCL) and thymol (0, 3, 6, 9, and 12 wt%) by solvent casting methods. The films were characterized by thermal, structural, mechanical, gas barrier, and antimicrobial properties. Scanning electron microscopy analysis revealed that the surface of film became rougher with certain porosity when thymol was incorporated into the PLA/PCL blends. Thymol acted as plasticizers, which reduce the intermolecular forces of polymer chains, thus improving the flexibility and extensibility of the films. The addition of PCL into the pure PLA film decreased the glass transition temperature of the films. The presence of thymol decreased the crystallinity of PLA phase, but did not affect the thermal stability of films. Water vapor barrier properties of films slightly decreased with the increase of thymol loading. The antimicrobial properties of thymol containing films showed a significant activity against Escherichia coli and Listeria monocytogenes. The results indicated the potential of PLA/PCL/thymol composites for applications in antimicrobial packaging. Copyright © 2014 John Wiley & Sons, Ltd.  相似文献   

7.
张会良 《高分子科学》2015,33(12):1702-1712
Poly(propylene carbonate)(PPC) was blended with polylactide(PLA) and poly(1,2-propylene glycol adipate)(PPA) using a twin screw extruder. Then the PPC/PLA/PPA films were prepared using the blown film technique. DMA results showed that PPA could act as a plasticizer and improve the miscibility between PPC and PLA. Crystal morphology displayed that blending PLA with the amorphous PPC led to a decrease of the spherulite size of PLA. The results of mechanical tests indicated that PPC-rich films showed high elongation at break and PLA-rich films showed high tear strength and good optical properties. The content of PPC and PLA significantly affected the physical properties of the films. With increasing PPC content, the melt strengths of the PPC/PLA/PPA films were enhanced. These findings contributed to the biodegradable materials application for designing and manufacturing polymer packaging.  相似文献   

8.
Antimicrobial nanocomposite films containing oregano essential oil (EO) were prepared by solvent casting. Film matrix was composed of supramolecular poly(lactic acid)–cellulose nanocrystals (PLA–CNC) nanocomposite. Bioactive PLA–CNC–oregano films were prepared by incorporating oregano EO as an antimicrobial agent. Resulting films were then converted into packaging applied on mixed vegetables as a food model and stored for 14 days at 4 °C to determine their antimicrobial capacity against Listeria monocytogenes, their physico-chemical/structural properties and their total phenols (TP) release during storage, in order to evaluate the effect of oregano EO. It was observed the addition of oregano EO did not affect the water vapor permeability (WVP) of films, but increased their elongation at break (Eb) and reduced their tensile strength (TS) and tensile modulus (TM) at day 0. However, TS, TM, Eb and WVP values of control and bioactive films were increased slightly after 14 days of storage. FTIR analysis allowed characterizing the molecular interactions of oregano EO with PLA–CNC matrix via the identification and interpretation of their respective vibration bands. Microbiological analysis of mixed vegetables inoculated with L. monocytogenes (3 log CFU g?1) indicated that PLA–CNC–oregano films induced a quasi-total inhibition of bacteria in vegetables at day 14 and therefore demonstrated a strong antimicrobial capacity in situ. The percentage of TP release from bioactive films was determined by Folin–Ciocalteu’s method and results showed that TP release increased continuously from day 0 to day 14, up to 16.6 % at day 14. These results allowed demonstrating the strong antimicrobial capacity of PLA–CNC–oregano films for food packaging applications in vegetable produce.  相似文献   

9.
Polylactide polymers have gained enormous attention as a replacement for conventional synthetic packaging materials in the last decade. By being truly biodegradable, derived from renewable resources and by providing consumers with extra end-use benefits such as avoiding paying the "green tax" in Germany or meeting environmental regulations in Japan, polylactides (PLAs) are a growing alternative as a packaging material for demanding markets. The aim of this paper is to review the production techniques for PLAs, summarize the main properties of PLA and to delineate the main advantages and disadvantages of PLA as a polymeric packaging material. PLA films have better ultraviolet light barrier properties than low density polyethylene (LDPE), but they are slightly worse than those of cellophane, polystyrene (PS) and poly(ethylene terephthalate) (PET). PLA films have mechanical properties comparable to those of PET and better than those of PS. PLA also has lower melting and glass transition temperatures than PET and PS. The glass transition temperature of PLA changes with time. Humidity between 10 and 95% and storage temperatures of 5 to 40 degrees C do not have an effect on the transition temperature of PLA, which can be explained by its low water sorption values (i.e. <100 ppm at Aw = 1). PLA seals well at temperatures below the melting temperature but an appreciable shrinking of the films has been noted when the material is sealed near its melting temperature. Solubility parameter predictions indicate that PLA will interact with nitrogen compounds, anhydrides and some alcohols and that it will not interact with aromatic hydrocarbons, ketones, esters, sulfur compounds or water. The CO2, O2 and water permeability coefficients of PLA are lower than those of PS and higher than those of PET. Its barrier to ethyl acetate and D-limonene is comparable to PET. The amount of lactic acid and its derivatives that migrate to food simulant solutions from PLA is much lower than any of the current average dietary lactic acid intake values allowed by several governmental agencies. Thus, PLA is safe for use in fabricating articles for contact with food.  相似文献   

10.
Active packaging materials are the subject of research because their performance exceeds that of traditional packaging. From this class, antimicrobial materials extend the shelf-life of products and reduce the risk of contamination by pathogens. In this paper, new composite materials with antimicrobial properties are obtained by using polyvinyl alcohol and bacterial cellulose powder. Potassium (2E,4E)-hexa-2,4-dienoate was used as the antimicrobial agent. The films thus obtained were characterised using Fourier-transform infrared spectroscopy and scanning electron microscopy. Mass transfer phenomena concerning the release of potassium (2E,4E)-hexa-2,4-dienoate were investigated. The results indicated that the new biocomposite films could be used as antimicrobial packaging materials.  相似文献   

11.
Functional inorganic nanofillers for transparent polymers   总被引:6,自引:0,他引:6  
The integration of inorganic nanoparticles into polymers has been used for the functionalization of polymer materials with great success. Whereas in traditional polymer composites, micron sized particles or agglomerates typically cause significant light scattering hampering optical applications, in nanocomposites the particle dimensions are small enough for the production of highly transparent composites. A challenge for the generation of such materials is to develop an integrated synthesis strategy adapting particle generation, surface modification and integration inside the polymer. Surface grafting using polymerizable surfactants or capping agents allows for linking the particles to the polymer. Novel techniques such as in situ polymerization and in situ particle processing are beneficial to avoid aggregation of inorganic particles inside the polymer matrix. The functions associated with inorganic fillers are widespread. Layered silicates and related materials are nowadays commercially available for improving mechanical and barrier properties in packaging. With the availability of highly transparent materials, the focus has shifted towards optical functions such as luminescence and UV-protection in transparent polymers. IR-active fillers are used in laser-holography for transparent poly(methyl methacrylate) (PMMA) nanocomposites. Refractive index modulation and ultrahigh refractive index films were developed based on inorganic materials such as PbS. The integration of magnetic nanoparticles has a great potential for applications such as electromagnetic interference shielding and magneto-optical storage.This tutorial review will summarize functions associated with the integration of inorganic nanofillers in polymers with a focus on optical properties.  相似文献   

12.
《先进技术聚合物》2018,29(6):1706-1717
Biodegradable poly(lactic acid) (PLA)/poly(butylene adipate‐co‐terephthalate) (PBAT) blends and films were prepared using melt blending and blowing films technique in the presence of chain extender‐Joncryl ADR 4370F. The ADR contains epoxy functional groups and used as a compatibilizer. The morphological, mechanical, rheological, thermal, and crystalline properties of the PLA/PBAT/ADR blown films were studied. Scanning electron microscopy micrographs of the films revealed more ductile deformation with increasing PBAT content. The addition of PBAT enhanced the toughness of the PLA film. Tensile tests indicated that the elongation at break increased from 20.5% to 334.6% in the machine direction and from 7.1% to 715.9% in the transverse direction. The Young modulus increased from 2690.5 to 395.6 MPa in the machine direction and from 2623.5 to 154.0 MPa in the transverse direction. The sealing strength of 40/60/0.15 PLA/PBAT/ADR film was the highest among all the samples up to 9.4 N 15 mm−1. These findings gave important implications for designing and manufacturing polymer packaging materials.  相似文献   

13.
Antimicrobial packaging protects the product from the external environment and microbial contamination, conferring numerous advantages on human health. Interest in biopolymers as packaging materials has considerably increased recently. Bacterial cellulose is an interesting biomaterial produced as nanofibrils by Acetobacter xylinium and is a promising candidate due to its remarkable properties. New composite materials with antimicrobial properties were developed in this work, containing poly(vinyl alcohol) (PVA) as polymer matrix and ground bacterial cellulose (BC) as reinforcing fibres. Sorbic acid was used as an antimicrobial agent because it is a preservative recognised in the food industry. The materials obtained were studied using Fourier-transformed infrared spectroscopy (FTIR). The swelling rate of the composites was also measured. Release experiments of sorbic acid from the composite films into water were performed and the mass transfer phenomena were investigated using Fick’s law of diffusion. The antimicrobial effect was tested against Escherichia coli K12-MG1655. The results obtained indicated that the new biocomposite films could be promising antimicrobial food packaging materials.  相似文献   

14.
In this work, the modification process of poly(lactic acid) (PLA) with metal-based nanoparticle (NPs) additives (Ag, ZnO, TiO2) at different loading (0.5, 1.0, and 2.5 wt%) and by melt-mix extrusion method followed by film formation as one of the advantageous techniques for industrial application have been investigated. PLA nanoparticle composite films (PLA-NPs) of PLA-Ag, PLA-ZnO, PLA-TiO2 were fabricated, allowing convenient dispersion of NPs within the PLA matrix to further pursue the challenge of investigating the surface properties of PLA-NPs reinforced plastics (as films) for the final functional properties, such as antimicrobial activity and surface mechanical properties. The main objective was to clarify how the addition of NPs to the PLA during the melt extrusion process affects the chemistry, morphology, and wettability of the surface and its further influence on the antibacterial efficiency and mechanical properties of the PLA-NPs. Therefore, the effect of Ag, ZnO, and TiO2 NPs incorporation on the morphology (SEM), elemental mapping analysis (SEM-EDX), roughness, surface free energy (SFE) of PLA-NPs measured by goniometry and calculated by OWRK (Owens, Wendt, Rabel, and Kaelble) model was evaluated and correlated with the final functional properties such as antimicrobial activity and surface mechanical properties. The developed PLA-metal-based nanocomposites, with improved mechanical and antimicrobial surface properties, could be used as sustainable and biodegradable materials, offering desirable multifunctionalities not only for food packaging but also for cosmetics and hygiene products, as well as for broader plastic products where antimicrobial activity is desirable.  相似文献   

15.
Aliphatic polyesters, especially those derived from lactide (PLA), glycolide (PGA) and ε-caprolactone (PCL), are being investigated worldwide for applications in the field of surgery (suture material, devices for internal bone fracture fixation), pharmacology (sustained drug delivery systems), and tissue engineering (scaffold for tissue regeneration) [1,2]. This is mainly due to their good biocompatibility and variable degradability. These polymers present also a growing interest for environmental applications in agriculture (mulch films) and in our everyday life (packaging material)as the development of biodegradable materials is now considered as one of the potential solutions to the problem of plastic waste management.For both biomedical and environmental applications, it is of major importance to understand the degradation characteristics of the polymers. The hydrolytic degradation of aliphatic polyesters has been investigated by many research groups. Our group has shown that degradation of PLAGA large size devices is faster inside than at the surface. This heterogeneous degradation is due to the autocatalytic effect of carboxylic endgroups formed by ester bond cleavage. Moreover,degradation-induced morphological and compositional changes were also elucidated. In the case of PCL, the hydrolytic degradation is very slow due to its hydrophobicity and crystallinity.The enzymatic degradation of these polymers has been investigated by a number of authors. A specific enzyme, proteinase K, has been shown to have significant effects on PLA degradation. This enzyme preferentially degrade L-lactate units as opposed to D-lactate ones, amorphous zones as opposed to crystalline ones [3]. The enzymatic degradation of PCL polymers has also been investigated. A number of lipase-type enzymes were found to significantly accelerate the degradation of PCL despite its high crystallinity. In the case of PLA/PCL blends, the two components exhibited well separated crystalline domains. The selective degradation of PCL or PLA components by enzymes revealed the inner morphology of the blends with formation of microsphere-like or island-like structures [5].  相似文献   

16.
Here we introduce a new method aiming the immobilization of bioactive principles onto polymeric substrates, combining a surface activation and emulsion entrapment approach. Natural products with antimicrobial/antioxidant properties (essential oil from Syzygium aromaticum—clove and vegetal oil from Argania spinosa L—argan) were stabilized in emulsions with chitosan, a natural biodegradable polymer that has antimicrobial activity. The emulsions were laid on poly(lactic acid) (PLA), a synthetic biodegradable plastic from renewable resources, which was previously activated by plasma treatment. Bioactive materials were obtained, with low permeability for oxygen, high radical scavenging activity and strong inhibition of growth for Listeria monocytogenes, Salmonella Typhimurium and Escherichia coli bacteria. Clove oil was better dispersed in a more stable emulsion (no separation after six months) compared with argan oil. This leads to a compact and finely structured coating, with better overall properties. While both clove and argan oils are highly hydrophobic, the coatings showed increased hydrophilicity, especially for argan, due to preferential interactions with different functional groups in chitosan. The PLA films coated with oil-loaded chitosan showed promising results in retarding the food spoilage of meat, and especially cheese. Argan, and in particular, clove oil offered good UV protection, suitable for sterilization purposes. Therefore, using the emulsion stabilization of bioactive principles and immobilization onto plasma activated polymeric surfaces we obtained a bioactive material that combines the physical properties and the biodegradability of PLA with the antibacterial activity of chitosan and the antioxidant function of vegetal oils. This prevents microbial growth and food oxidation and could open new perspectives in the field of food packaging materials.  相似文献   

17.
Biocomposites were fabricated using poly(propylene) carbonate as matrix and cellulosic polysaccharide banana (Musa acuminate) peel powder as filler in varying concentrations (5–25?wt.%) and were characterized for their functional properties. Microscopic analysis indicated the uniform distribution and existence of microfibrils in the filler. The thermal stability of the composites was lower than the matrix till 320?°C, beyond which it increased. The visco-elastic and mechanical behavior of the biocomposites was found to be enhanced with the addition of fillers. Thus, with better thermal, visco-elastic, and mechanical properties, the biocomposite films can be a replacement for the non-biodegradable polymers for packaging applications.  相似文献   

18.
The development of biodegradable packaging materials, especially from renewable resources is a constant preoccupation of nowadays, because of the environmental problems caused by synthetic polymers. The combination of cellulose with other polymeric materials could be an ecologic alternative and a way to use renewable resources for food packaging. Bacterial cellulose which is produced by microbial fermentation is also a promising material which can be used not only in biomedical application, but also as food packaging material. In this research different composite films between poly(vinyl alcohol)-bacterial cellulose (PVA-BC) were obtained by casting method. The obtained films were UV irradiated for different periods of times from 1 to 10 hours, using a mercury lamp, Philips TUV-30, emitting light mainly at 254 nm. Changes in FT-IR spectra before and after UV irradiation and the modification of transparency and of the swelling characteristics of the films were observed. As it was expected the composites materials are sensitive at UV exposure.  相似文献   

19.
Recently, biocomposites have emerged as materials of great interest to the scientists and industry around the globe. Among various polymers, polylactic acid (PLA) is a popular matrix material with high potential for advanced applications. Various particulate materials and nanoparticles have been used as the filler in PLA based matrix. One of the extensively studied filler is cellulose. However, cellulose fibres, due to their hydrophilic nature, are difficult to blend with a hydrophobic polymer matrix. This leads to agglomeration and creates voids, reducing the mechanical strength of the resulting composite. Moreover, the role of the various forms of pure cellulose and its particle shape factors has not been analyzed in most of the current literature. Therefore, in this work, materials of various shapes and shape factors were selected as fillers for the production of polymer composites using Polylactic acid as a matrix to fill this knowledge gap. In particular, pure cellulose fibres (three types with different elongation coefficient) and two mineral nanocomponents: precipitated calcium carbonate and montmorillonite were used. The composites were prepared by a melt blending process using two different levels of fillers: 5% and 30%. Then, the analysis of their thermomechanical and physico-chemical properties was carried out. The obtained results were presented graphically and discussed in terms of their shape and degree of filling.  相似文献   

20.
Casein (and its sodium salt, sodium caseinate, SC) is an inexpensive natural milk protein that is used as a biodegradable biomaterial, especially to produce packaging films. However, to enhance some of its properties, it needs to be blended with other polymers, which should preferably be biodegradable such as poly lactic acid (PLA) and poly ε-caprolactone (PCL). New SC-g-PLA and SC-g-PCL graft copolymers have been prepared and unambiguously characterized, in particular by 1H and DOSY NMR. The grafting degrees are high (between 24 and 35% by weight) and result in variations of properties, such as hydrophobicity and thermal properties. The microstructures of SC/PLA and SC/PCL blends were studied and compared, with and without the addition of the SC-g-PLA and SC-g-PCL copolymers to test the compatibilization capacity of these new biodegradable copolymers.  相似文献   

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