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1.
Biocomposite films were prepared by incorporating different concentrations of beet root residue powder (BRP) (2, 4, 8, and 12 g BRP/100 g water) into films based on residues of gelatin capsules (GCR) (40 g GCR/100 g water). Control films had no BRP added. A complete mechanical, physicochemical, barrier, optical, and antioxidant characterization of all films was performed. Among all the films considered, BRP12 was found to present the most adequate properties and was further investigated. SEM micrographs showed that BRP12 presented a less homogeneous surface in comparison with the control film, but they showed similar thermal stability. After 15 days of soil degradation, the films lost over 75% of weight. The films were effective on protecting sunflower oil from primary oxidation process, and BRP12 showed higher protection than control film. Therefore, this study suggests that the formulated films could act as promising antioxidant materials and contribute to environmentally friendly technologies. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43094.  相似文献   

2.
Sophorolipids (SL; microbial glycolipids) were used as additives in solvent‐cast short‐chain polyhydroxyalkanoate (sc‐PHA) films to enhance surface roughness and porosity. Poly‐3‐hydroxybutyrate (PHB), poly‐(6%)‐3‐hydroxybutyrate‐co‐(94%)‐3‐hydroxyvalerate (PHB/V), and poly‐(90%)‐3‐hydroxybutyrate‐co‐(10%)‐3‐hydroxyhexanoate (PHB/HHx) films were evaluated with up to 43 wt % of SL. Sophorolipid addition caused surface dimples with maximum diameters of 131.8 µm (PHB), 25.2 µm (PHB/V), and 102.8 µm (PHB/HHx). A rise in the size and number of pores in the polymer matrix also occurred in PHB and PHB/V films. Surface roughness and film porosity were visualized by scanning electron microscopy and quantitated using confocal microscopy by correlating the surface area (A′) to the scanned area (A) of the films. The phenotypic alterations of the films caused a gradual decline in tensile strength and modulus and increased the elongation to break. Reductions in the enthalpies of fusion (ΔHf) in both the PHB (41% reduction) and PHB/HHx (36% reduction) films implied diminished crystallinity as SL concentrations increased. Over the same SL concentrations the Tan δ maxima shifted from 4 to 30°C and from 2 to 20°C in these respective films. These results provide a novel means by which sc‐PHA properties can be controlled for new/improved applications. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40609.  相似文献   

3.
The effect of freeze‐thaw pretreatment on the thermal drying process and physicochemical properties of chitosan was investigated in this study. Results showed that the freeze‐thaw treatment changed the form of chitosan paste and reduced 75.6–77.7% of the water content. The freeze‐thaw treatment decreased the drying time of chitosan from 16–19 h to 2.75–4 h and the dried product was loosely packed powder. After freeze‐thaw treatment, the molecular weight of chitosan was unchanged during the thermal drying. The heat‐induced browning effect of chitosan during drying was greatly alleviated by the pretreatment. Furthermore, the pretreatment increased the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) radical‐scavenging activity of dried product by 40.4–59.8%. The molecular weight, color, and DPPH radical‐scavenging activity of the pretreated dried chitosan product were close to those of freeze‐dried product. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41017.  相似文献   

4.
This study examined the effect of storage time at room temperature on the melt viscosity, thermal, and tensile properties of epoxidized soybean oil plasticized poly(lactic acid) (PLA) films manufactured through a cast extrusion process. Infrared results indicate that plasticizer migration to the surface of the film occurred after only 30 days of storage, which significantly affected the performance of plasticized films. While the melt viscosity, glass transition temperature, degree of crystallinity, tensile strength, and modulus increased, the elongation at break and energy to break decreased with storage time up to 30 days and all properties remained constant thereafter. However, the ability of stored plasticized film to cold crystallize remained unaffected since both the cold crystallization temperature and melting temperature were not affected during storage. Although plasticized film lost some flexibility after only 30 days of storage due to plasticizer migration to the surface of the film, sufficient plasticization performance still remained in plasticized PLA films for flexible packaging application even after a long storage period at ambient conditions. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43201.  相似文献   

5.
Concern about environmental issues has motivated research into the development of biodegradable packaging from renewable sources. Natural polymers such as starch constitute a good alternative for diminishing the use of nonbiodegradable and nonrenewable components in the packaging industry. However, depending on the botanical source, films with different properties are formed. The aim of this study was to evaluate the film‐forming capacity of different starch sources (cassava, corn, potato, and wheat) by casting with starch contents from 2 to 6%. Principal component analysis methodology was used to evaluate the correlation between the formulations and their physicochemical and mechanical properties. It was not possible to produce continuous films based on potato starch, probably because of its very low amylose content (10%). The corn‐, cassava‐, and wheat‐starch‐based films were characterized by their thicknesses (0.06–0.22 mm), moisture contents (19–26%), water solubilities (13.7–26.5%), water‐vapor permeabilities (WVPs; 0.19–0.48 g mm h?1 m?2 kPa?1), wettabilities (35–106°), biodegradabilities in soil, and thermal and mechanical properties (tensile strength = 1.9–6.7 MPa, elongation = 41–166%, and Young's modulus = 8–127 MPa). The wheat starch films presented higher WVPs and lower mechanical properties. The cassava starch films presented lower wettabilities and good mechanical properties; this suggested that their use in packaging for products, such as fruits and vegetables, with higher water activities could be feasible. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46564.  相似文献   

6.
Active and biodegradable materials have great potential in food packaging applications, improving the safety and quality of products. The objective of this study was to develop a new material based on buriti oil incorporated into a chitosan film. Different concentrations of buriti oil in dried films (2.1 g/m2, 10.4 g/m2, 20.8 g/m2, and 31.3 g/m2) were added into a chitosan matrix (41.7 g/m2). The chitosan/buriti oil films were characterized by water‐vapor barrier properties, total water‐soluble matter (TSM), tensile properties, thermogravimetric analysis, microstructure, microbial permeation properties, and biodegradation estimation. The higher oil concentration improved the water‐vapor barrier and the buriti oil acted largely as a plasticizer and increased the elongation at break, and decreased the tensile strength (TS) of chitosan films. The total water‐soluble matter of chitosan films decreased in function of the buriti oil concentration, but the biodegradation and thermal stability increased. The chitosan films presented a microbial barrier against Escherichia coli, Staphylococcus aureus, and Pseudomonas aeruginosa. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43210.  相似文献   

7.
Biodegradable materials as polylactide (PLA) are very interesting for cosmetic packaging application. However, these polymers, under environmental conditions or/and chemical treatments, can undergo “aging,” compromising their performances such as container. The aim of this study was the evaluation of mechanical, physicochemical, and organoleptic properties of PLA bottles present in the cosmetic market. In particular, mechanical tests and thermal analyses were applied to study the PLA container degradation under stressed physicochemical conditions. Calorimetric and morphological analyses were applied to evaluate differences between internal and external surface of containers. Results highlighted that the heating process together with chemical treatment determined a significant modification on polymer, leading to a more resistant and fragile material, whereas the only physical or chemical treatment alone showed a plasticizing effect. In conclusion, this study represents a start point to evaluate content–packaging interactions to optimize the choice of PLA polymer as cosmetic packaging. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40067.  相似文献   

8.
The biopolymer poly‐3‐hydroxybutyrate‐co‐3‐hydroxyvalerate (PHBV) is a promising material for packaging applications but its high brittleness is challenging. To address this issue, PHBV was blended with nine different biopolymers and polymers in order to improve the processing and mechanical properties of the films. Those biopolymers were TPS, PBAT, a blend of PBAT + PLA, a blend of PBAT + PLA + filler, PCL and PBS, and the polymers TPU, PVAc, and EVA. The extruded cast films were analyzed in detail (melting temperature, crystallinity, mechanical properties, permeation properties, and surface topography). A decrease in crystallinity and Young's modulus and an increase in elongation at break and permeability were observed with increasing biopolymer/polymer concentration. In PHBV‐rich blends (≥70 wt % PHBV), the biopolymers/polymers PCL, PBAT, and TPU increased the elongation at break while only slightly increasing the permeability. Larger increases in the permeability were found for the films with PBS, PVAc, and EVA. The films of biopolymer/polymer‐rich blends (with PBAT, TPU, and EVA) had significantly different properties than pure PHBV. A strong effect on the properties was measured assuming that at certain biopolymer/polymer concentrations the coherent PHBV network is disrupted. The interpretation of the permeation values by the Maxwell–Garnett theory confirms the assumption of a phase separation. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46153.  相似文献   

9.
The present work focuses on the microwave synthesis of lactic acid‐grafted‐gum arabic (LA‐g‐GA) by polycondensation reaction and its influence as an additive to improve the gas barrier properties of poly(lactic acid) (PLA) films, prepared by solution casting method. It is observed that during the synthesis of LA‐g‐GA, hydrophilic gum is converted into hydrophobic due to grafting of in situ grown hydrophobic oligo‐(lactic acid). Subsequently, PLA/LA‐g‐GA bionanocomposite films are fabricated and characterized for structural, thermal, mechanical and gas barrier properties. Path breaking reduction in oxygen permeability (OP) of ~10 folds is achieved in case of PLA films containing LA‐g‐GA as filler. However, water vapor transmission rate (WVTR) is reduced up to 27% after 5 wt % addition of filler. Reduction in OP of this order of magnitude enables the PLA to compete with PET in term of enhancing shelf life and maintaining the food quality. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43458.  相似文献   

10.
Mushroom polysaccharides (MP), including white MP, brown MP, and enoki MP, were incorporated into cellulose nanofiber (CNF). Studies on thermal property, structure, crystallinity, and morphology of CNF‐MP films revealed that MP was well interacted with and adsorbed onto CNF. Incorporation of MP significantly (P < 0.05) increased tensile strength and reduced water vapor permeability of CNF film. CNF‐MP films possessed higher antioxidant activity than CNF only or CNF‐chitosan film, and the antioxidant activity of released components from CNF‐MP films immersed in water was higher than that released from films immersed in methanol. Radical scavenging activity and reducing ability were major antioxidant mechanisms of CNF‐MP films. These trends were consistent with the results of total phenolics content released from films and the antioxidant activity of MP themselves. This study demonstrated CNF‐MP films may be used as packaging material for preventing oxidation and/or dehydration of food during storage. © 2017 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018 , 135, 46166.  相似文献   

11.
Plasma polymerized γ‐terpinene (pp?GT) thin films are fabricated using RF plasma polymerization. MIM structures are fabricated and using the capacitive structures dielectric properties of the material is studied. The dielectric constant values are found to be in good agreement with those determined from ellipsometric data. At a frequency of 100 kHz, the dielectric constant varies with RF deposition power, from 3.69 (10 W) to 3.24 (75 W). The current density–voltage (J?V) characteristics of pp–GT thin films are investigated as a function of RF deposition power at room temperature to determine the resistivity and DC conduction mechanism of the films. At higher applied voltage region, Schottky conduction is the dominant DC conduction mechanism. The capacitance and the loss tangent are found to be frequency dependent. The conductivity of the pp?GT thin films is found to decrease from 1.39 × 10?12 S/cm (10 W) to 1.02 × 10?13 S/cm (75 W) and attributed to the change in the chemical composition and structure of the polymer. The breakdown field for pp–GT thin films increases from 1.48 MV/cm (10 W) to 2 MV/cm (75 W). A single broad relaxation peak is observed indicating the contribution of multiple relaxations to the dielectric response for temperature dependent J?V. The distribution of these relaxation times is determined through regularization methods. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42318.  相似文献   

12.
Freezing/thawing is used as a new method to elaborate exfoliated gelatin‐Montmorillonite (MMT) bionanocomposites. The data of X‐ray diffraction and transmission electron microscopy indicate that freezing/thawing is an effective approach to exfoliate the clay for concentrations higher than 5 mass% in gelatin matrix. In addition, after freezing/thawing process to introduce, the crystallinity (triple‐helix content) of gelatin‐MMT bionanocomposites is improved, revealing that freezing/thawing method has the advantages for gelatin molecules to renature into triple‐helix. Specially, the data of Fourier transform infrared indicate that freezing/thawing may be induce more hydrogen bond interactions in gelatin‐MMT bionanocomposites due to the better dispersion of MMT. The mechanical measurements and thermogravimetric analysis show that gelatin‐MMT bionanocomposites prepared by freezing/thawing display enhanced mechanical properties and thermal stability in comparison with the ones prepared by conventional blending at the same clay content. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013  相似文献   

13.
Bio‐nanocomposite films based on polyvinyl alcohol/chitosan (PVA/CS) polymeric blend and cellulose nanocrystals (CNC) were prepared by casting a homogenous and stable aqueous mixture of the three components. CNC used as nanoreinforcing agents were extracted at the nanometric scale from sugarcane bagasse via sulfuric acid hydrolysis; then they were characterized and successfully dispersed into a PVA/CS (50/50, w/w) blend to produce PVA/CS–CNC bio‐nanocomposite films at different CNC contents (0.5, 2.5, 5 wt %). Viscosity measurement of the film‐forming solutions and structural and morphological characterizations of the solid films showed that the CNC are well dispersed into PVA/CS blend forming strong interfacial interactions that provide an enhanced load transfer between polymer chains and CNC, thus improving their properties. The obtained bio‐nanocomposite films are mechanically strong and exhibit improved thermal properties. The addition of 5 wt % CNC within a PVA/CS blend increased the Young's modulus by 105%, the tensile strength by 77%, and the toughness by 68%. Herein, the utilization of Moroccan sugarcane bagasse as raw material to produce high quality CNC has been explored. Additionally, the ability of the as‐isolated CNC to reinforce polymer blends was studied, resulting in the production of the aforementioned bio‐nanocomposite films with improved properties. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42004.  相似文献   

14.
Environmental and economic reasons make the use of bioplastics and biocomposites increasingly coveted in sectors other than packaging. Recycling of all wasted or rejected durable plastics is highly desired and biobased plastics are no exception. Therefore, the investigation of pre‐ and post‐consumer recycling of products made from biobased plastics is of great interest. Polylactic acid (PLA) and its blends have been chosen for this study because it is an excellent representative of mass‐produced bioplastics for industrial applications. As part of the “Sustainable Recycling of ‘Green’ Plastics” project, the current study addresses the durability issues related to the reprocessing and post‐consumer recycling of a PLA virgin resin and two commercially available blends of PLA namely one with polycarbonate (PC) and one with polyethylene (PE). The materials were investigated using methods that simulate post‐processing and post‐consumer recycling. Accelerated ageing was performed at elevated temperature and humidity to simulate the usage period of the materials. The materials were analyzed using differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and their mechanical strength was evaluated by tensile and impact testing. The flow properties of the materials were characterized by the melt flow index (MFI). Multiple processing of pure PLA did not affect the impact strength or the glass transition temperature (Tg), but caused crystallization and increase in the MFI, indicating that degradation occurred during processing. DSC thermograms of the blends revealed that the components in the blends were not miscible. Multiple processing of the blends did not significantly affect the elastic modulus of the materials, but affected the elongation at break. The results indicated that multiple processing of the PLA/HDPE blend caused increased dispersion and thus increased elongation at break, while the dominating mechanism in the PLA/PC blend was degradation that caused a decrease in elongation at break. Post‐consumer recycling of the PLA/PC blend was simulated and the results clearly showed that ageing corresponding to one year of use caused a significant degradation of PLA. Pure PLA was severely degraded after only one ageing cycle. Although the PLA/PC blend showed some improved mechanical properties and resistance to degradation compared with pure PLA, one ageing cycle still caused a severe degradation of the PLA and even the PC was degraded as indicated by the formation of small amounts of bisphenol A. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43916.  相似文献   

15.
This article reports for the first time the results about the use of inertized fly ash from municipal solid waste incineration as a filler for polypropylene (PP). An innovative process based on the stabilization with colloidal silica has been used for fly ash inertization. Polymer–filler composites containing different filler amounts up to 30 wt % have then been formulated and prepared by means of melt compounding process. Structural, morphological, mechanical, and thermal characterization of their properties has been performed and discussed in detail. Remarkable enhancements of tensile (+ 93%) and flexural (+ 107%) elastic moduli if compared to pristine PP, together with enhancements of flexural resistance (+ 36%) and deflection temperature under load (+ 50%), have been observed when adding filler 30 wt % in suitable processing conditions. Moreover the filler has been shown to interact with polymer crystalline structure and positively influence the thermal‐oxidative stability. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4157–4164, 2013  相似文献   

16.
Thermal processing of two potato protein isolates (PPIs) with glycerol as a plasticizer was explored in this study. The PPIs were pretreated by alkali or alkali under reducing conditions. The PPIs before and after pretreatment were analyzed by sodium dodecyl sulfate polyacrylamide gel electrophoresis, differential scanning calorimetry, and Fourier transform infrared spectroscopy. The effects of plasticizer content and pretreatment on mechanical and thermo‐mechanical properties of the compression‐molded biopolymers were studied. The highest tensile strengths obtained were 20–25 MPa and the biopolymer can be brittle or ductile depending on the plasticizer contents. The molecular weight and protein structure of the PPIs markedly affected the resultant biopolymers’ static and dynamic mechanical properties. The pretreatment of PPIs caused distinctly different changes in the mechanical properties of the two PPIs. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42723.  相似文献   

17.
An acrylate‐modified tung‐oil waterborne insulation varnish was synthesized from tung oil, maleic anhydride, and acrylates via a Diels–Alder reaction and free‐radical polymerization, and the varnish could be solidified at a relatively low temperature with blocked hexamethylene diisocyanate as a curing agent. The resulting films were characterized by Fourier transform infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The insulation properties (electrical insulation strength, volume resistivity, and surface resistivity) of the varnish films were tested, and the resistances of films to salted water were evaluated. With an increase in the maleic anhydride content, the thermal stability of the film was improved, whereas the electrical insulation strength, volume resistivity, and surface resistivity decreased. The electrical insulation strength of the film after it was immersed in the NaCl solution was lower than that in dry state, and it decreased as the immersed time was prolonged. In particular, the electrical insulation strength loss of the film increased significantly at maleic anhydride contents beyond 25 wt %. Furthermore, the hardness of the film increased with increasing methyl methacrylate/N‐butyl acrylate ratio, whereas the flexibility and adhesion of film decreased to a certain degree at the same time. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41608.  相似文献   

18.
To fully explore the influences of saturated fatty acids (SFAs) on the properties of sweet‐potato‐starch (SPS)‐based films, five SFAs were chosen to add to SPS. The SPS‐based films were prepared by casting. The microstructure, mechanical, optical, water vapor barrier, and thermal properties of the films were investigated. The 2.0% (w/w, on the basis of starch) SFA significantly changed the SPS pasting characteristics in the peak viscosity, breakdown, and other feature point viscosity values as determined by a Rapid Visco Analyser. The amylose molecular weights decreased as measured by high‐performance size exclusion chromatography. A thermal study with differential scanning calorimetry suggested that the addition of SFA increased the onset temperature and peak temperature. Scanning electronic microscope (SEM) images showed a continuous and uniform structure in the films with SFA. The SPS–SFA composite films showed lower light transmission and elongation at break than the control. Compared with the control films, the addition of SFA increased the tensile strength and decreased the water vapor permeability of the films. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41380.  相似文献   

19.
The objective of this work was to characterize the moisture sorption and water vapor permeation behavior of edible films made from sodium caseinate and chitosan for future applications as protective layers on foods. Glycerol was used as a plasticizer, and the films were obtained by a casting/solvent‐evaporation method. The moisture sorption kinetics and water vapor permeability (WVP) were investigated. The effect of the addition of glycerol on the WVP characteristics of the films was determined at 25°C with a relative humidity (RH) gradient of 0–64.5% (internal to external). Experimental data were fitted with an exponential function with two fitting parameters. WVP increased with increasing glycerol content in both films, chitosan samples being much more permeable than caseinate ones at any glycerol content. WVPs of sodium caseinate, chitosan, and chitosan/caseinate films with 28 wt % glycerol were also determined for two RH gradients, 0 to 64.5% and 100 to 64.5%, higher WVPs being measured at higher RHs. The moisture sorption kinetics of caseinate films prepared with various glycerol contents were determined by the placement of the films in environments conditioned at 20°C and 75% RH. Peleg's equation and Fick's second law were used to predict the moisture sorption behavior over the entire time period. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2009  相似文献   

20.
Collagen, a prominent biopolymer, which is famous for its excellent biological activity, has been used extensively for tissue engineering applications. In this study, a novel solvent system for collagen was developed with an ionic liquid, 1‐ethyl‐3‐methylimidazolium acetate ([EMIM][Ac]), solvent system. A series of sodium salts were introduced into this solvent system to enhance collagen's dissolution procedure. The results show that the solubility of collagen was significantly influenced by the temperature and sodium salts. The solubility reached up to approximately 11% in the [EMIM][Ac]/Na2HPO4 system at 45°C. However, the structure of the regenerated collagen (Col‐regenerated) may have been damaged. Hence, we focused on the structural integrity of the collagen regenerated from the [EMIM][Ac] solvent system by the methods of sodium dodecyl sulfate–polyacrylamide gel electrophoresis, Fourier transform infrared spectroscopy, ultrasensitive differential scanning calorimetry, atomic force microscopy, X‐ray diffraction, and circular dichroism because its signature biological and physicochemical properties were based on its structural integrity. Meanwhile, a possible dissolution mechanism was proposed. The results show that the triple‐helical structure of collagen regenerated from the [EMIM][Ac] solvent system below 35°C was retained to a large extent. The biocompatibility of Col‐regenerated was first characterized with a fibroblast adhesion and proliferation model. It showed that the Col‐regenerated had almost the same good biological activity as nature collagen, and this indicated the potential application of [EMIM][Ac] in tissue engineering. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 2245–2256, 2013  相似文献   

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