Oxygen barrier materials from renewable sources: Material properties of softwood hemicellulose‐based films

The aim of this study was to investigate the film‐forming ability of the hemicellulose O‐acetyl‐galactoglucomannan (AcGGM) and to evaluate its potential as a barrier material. The polymer film was evaluated by measurement of its oxygen permeability (Ox‐Tran® Mocon), thermal properties (differential scanning calorimetry), and dynamic mechanical properties under a humidity scan (humidity‐scan DMA). The AcGGM was isolated from industrial process water obtained from mechanical wood pulping. The self‐supporting films were formed by solution‐casting from water. As expected, a plasticizer was needed to avoid brittleness, and glycerol, sorbitol, and xylitol were compared. However, these additives resulted in higher sensitivity to moisture, which might be less beneficial for some applications. Interesting oxygen barrier and mechanical strength properties were achieved in a film obtained from a physical blend of AcGGM and either alginate or carboxymethylcellulose, both having a substantially higher molecular weight than AcGGM. No phase separation was observed, since all the components used were rich in hydroxyl functionalities. When a plasticizer was also added to the binary mixture, a compromise between (1) low O₂ permeability, (2) high mechanical toughness, and (3) flexibility of an AcGGM‐based film was obtained. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 100: 2985–2991, 2006     

Production and characterization of films containing poly(hydroxybutyrate) (PHB) blended with esterified alginate (ALG‐e) and poly(ethylene glycol) (PEG)

Alternative materials have long been studied and developed to replace conventional skin dressings with the emergence of new biopolymers and development of polymeric film fabrication techniques. As a new material for polymeric dressings, films of poly(hydroxybutyrate) (PHB) blended with esterified alginate (ALG‐e) and poly(ethyleneglycol) was studied. The esterification of sodium alginate (ALG‐e) generated a material with some amphiphilic characteristics and increased compatibility with the PHB. PEG was added as plasticizer in PHB/ALG‐e films was also tested, since PEG is often used in blends with PHB to improve flexibility and reduce hydrophobicity. At the amounts studied, it was found that both PEG and ALG‐e increase the degree of crystallinity, but a decrease was observed in the hydrophobic nature of PHB films. At the maximum concentration of ALG‐e and PEG used an increase in water vapor permeability and a decrease in tensile strength was reached due to the synergistic effect caused by better homogenization of PEG and ALG‐e in the PHB matrix. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44362.     

Effects of plasticization conditions on the structures and properties of cellulose packaging films from ionic liquid [BMIM]Cl

By using natural softwood pulp with higher degree of polymerization (DP = 1460) as cellulose source, 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) ionic liquid as solvent and glycerol as plasticizer, a novel cellulose packaging film was prepared. The effects of plasticization conditions on the structures, mechanical properties, permeability for oxygen and water vapor were measured by Wide-angle X-ray scattering, thermogravimetric analysis, scanning electron microscopy (SEM), and other techniques. The investigations suggested that the glycerol concentration and plasticizing time had great effect on the properties of the regenerated cellulose films. The crystal transformation of cellulose I to cellulose II occurred during the dissolution and regeneration process, combining with the decrease of thermal stability. The tensile strength decreased rapidly with the addition of glycerol and prolongation of plasticizing time. However, elongation at break of the regenerated cellulose films increased at first and then decreased with increasing of glycerol concentration and plasticizing time. The morphologies for the fracture surface obtained from SEM images showed transformation of typical brittle fracture to plastic deformation with increasing of glycerol concentrations. It was also found that both water vapor permeability and oxygen permeability of the regenerated cellulose films decreased slowly with increasing of glycerol concentrations and plasticizing time, but water vapor permeability and oxygen permeability presented an almost opposite trend. The films prepared by using ionic liquid technology would be used in food packaging or other fields as a kind of green packaging material. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2012     

Edible starch sodium octenyl succinate film formation and its physical properties

Edible starch sodium octenyl succinate (SSOS) films, with or without glycerol as plasticizer, were prepared by solution‐casting method. The effect of SSOS concentration, degree of substitution (DS) of octenyl group, as well as glycerol content, on the properties of SSOS films was studied including tensile strength, water vapor permeability (WVP), and oil permeability (OP). The results indicated that the tensile strength of SSOS film was up to 39.4 ± 1.9 MPa when the concentration of SSOS was 0.05 g/mL and DS was 0.05. The increase of glycerol content resulted in a decrease of film tensile strength. WVP of SSOS films was relatively low. Meanwhile, study in OP showed that SSOS films were oilproof. © 2012 Wiley Periodicals, Inc. J. Appl. Polym. Sci., 2013     

Oxygen barrier properties of biaxially oriented polypropylene/polyvinyl alcohol blend films

The biaxially oriented PP/PVA blend film was prepared and had the higher oxygen barrier property by about 130 times than that of a biaxially oriented PP film. When the viscosity ratio (η_d(PVA)/η_m(PP)) decreased, the dispersed PVA phase was developed into platelets during stretching process. Oxygen permeability was dependent on the number and size of PVA platelet. However, the Oxygen permeability was not sensitively changed in above 25 wt% of PVA. To obtain excellent barrier property, the optimum amount of plasticizer and initiator was required. A pasticizer was related to the size and degree of crystallization of PVA platelet. An initiator played the role of a compatibilizer. The oxygen barrier was enhanced with increasing the viscosity of PP and draw ratio. The higher viscosity of PP was advantageous for preventing the delamination of a blend film, and the moisture vapor permeability was not affected with the laminar structure. As a result, the biaxially oriented PP/PVA blend film had the potential of substituting for the PVDC coated BOPP film.     

Effects of Candelilla and Carnauba Wax Incorporation on the Functional Properties of Edible Sodium Caseinate Films

The aim of this study was to evaluate the effects of candelilla (CAN) or carnauba wax (CAR) incorporation on functional properties of edible sodium caseinate (CAS) films. Glycerol and Tween-80 were used as the plasticizer and the emulsifier, respectively. The results showed that the incorporation of waxes increased film opacity, total color differences (∆E), and mechanical resistance and reduced film lightness, water vapor permeability (WVP), and elongation at break. Scanning electron microscopy showed heterogeneous structure of emulsion films with regular distribution of lipid particles. A different internal arrangement was observed as a function of the film composition with both layered and incorporated film structure. Films containing candelilla wax exhibited more regular lipid reorganization, which resulted in better water vapor barrier efficacy and mechanical resistance in comparison to control films. The presence of Tween-80 resulted in better dispersion of lipid particles in film-forming solutions and lower water solubility, lightness, film opacity, and water vapor permeability, whereas the total color differences (∆E) were significantly larger and the improvement in mechanical properties was also achieved.     

Beyond waste: Transforming wheat straw into oxygen and UV-resistant cellulose films

Regenerated cellulose membrane is a biomaterial obtained by activating, dissolving, solidifying, and regenerating cellulose powder using solvents of different polarities. It has the characteristics of high oxygen resistance and high strength. However, its low water vapor barrier and single function limit its application. In order to improve the water resistance of regenerated cellulose membranes and endow them with UV resistance, lignin was extracted from waste wheat straw using formic acid method. The extracted formic acid lignin (FAL) was added to the cellulose solution to prepare a series of regenerated lignocellulosic membranes (RC-FAL) with different lignin contents. The results indicate that lignin can not only improve the water vapor barrier, tensile strength, and water resistance of the film, but also enhance the oxygen barrier and UV absorption of the film. Compared with pure cellulose film, the contact angle of lignocellulose film can be increased by 66.2%, the UV absorption rate can reach 100%, and the oxygen transmission coefficient has no significant effect. In this paper, a new kind of biological packaging material with high oxygen resistance, strong ultraviolet absorption, and water resistance was prepared by recycling waste wheat straw, it has a broad application prospect in the industrial production of packaging materials.     

酰胺化纳米晶纤维素提高乙烯-醋酸乙烯酯共聚物薄膜阻透性的研究

合成了三种酰胺化纳米晶纤维素,并采用溶液共混成膜法制备了酰胺化纳米晶纤维素（CNC）/乙烯醋酸乙烯醋共聚物(EVA)复合膜材料。通过紫外-可见分光光度计、电子万能试验机和透湿仪研究了酰胺化CNC/ EVA复合膜的光学性能、力学性能以及水蒸气阻隔性,并通过原子力显微镜研究热压处理的EVA复合膜的表面形貌。结果表明,添加三种不同碳链的酰胺化CNC都使 EVA膜的透光率有所降低,当添加量为5 %时,EVA膜透光率仍高达90%。一定程度的热压能够让酰胺化纳米晶纤维素在EVA基体中分散更均匀,使EVA复合膜的透光率提高了2%～3%;随着纳米晶纤维素含量的逐渐增加,三种酰胺化CNC/EVA膜的拉伸强度均逐渐增强,透湿率（WVTR值）均减小;酰胺化CNC含量相同时, 十六胺改性的纳米晶纤维素(CNC-N16)/EVA复合膜的力学性能和水蒸气阻隔效果优于相应的十二胺和正辛胺。     

纳米纤维素的表面修饰及对聚乳酸膜的力学性能和阻隔性能的影响

本实验通过化学水解法从农林废弃物油茶果壳中提取出油茶果壳纳米纤维素（cellulose nanocrystals, CNC）,经丁酸酐表面修饰获得丁酸酯化纳米纤维素（butyrated cellulose nanocrystals, BCNC）后,通过溶液浇铸法制备得到了BCNC/聚乳酸（PLA）复合材料,研究了CNC改性后的形貌及性能变化,以及BCNC对PLA力学性能、阻隔性能及透光率的影响。研究结果表明,经改性后,纳米纤维素的团聚现象得到改善并能稳定的分散在非极性有机溶剂中。在PLA复合材料中,BCNC对PLA有增强增韧的效果,添加5 wt%的BCNC时,PLA膜的拉伸强度提升了30.1%。添加5 wt%的BCNC,PLA复合膜的水蒸气透过率和氧气透过率分别下降了60.0%和35.0%,且仍具有较高的透光率。由于BCNC在基体中有更好的分散性和界面结合,对提升PLA力学性能和阻隔性能的效果均优于CNC。     

纳米纤维素的表面修饰及对聚乳酸膜的力学性能和阻隔性能的影响

本实验通过化学水解法从农林废弃物油茶果壳中提取出油茶果壳纳米纤维素（cellulose nanocrystals, CNC），经丁酸酐表面修饰获得丁酸酯化纳米纤维素（butyrated cellulose nanocrystals, BCNC）后，通过溶液浇铸法制备得到了BCNC/聚乳酸（PLA）复合材料，研究了CNC改性后的形貌及性能变化，以及BCNC对PLA力学性能、阻隔性能及透光率的影响。研究结果表明，经改性后，纳米纤维素的团聚现象得到改善并能稳定的分散在非极性有机溶剂中。在PLA复合材料中，BCNC对PLA有增强增韧的效果，添加5 wt%的BCNC时，PLA膜的拉伸强度提升了30.1%。添加5 wt%的BCNC，PLA复合膜的水蒸气透过率和氧气透过率分别下降了60.0%和35.0%，且仍具有较高的透光率。由于BCNC在基体中有更好的分散性和界面结合，对提升PLA力学性能和阻隔性能的效果均优于CNC。     

High oxygen barrier materials from paper to regenerated cellulose films

A transparent, bendable, high oxygen barrier cellulose-based film was prepared, which has far better oxygen barrier properties than conventional polyethylene, polypropylene and cellophane materials. A series of regenerated cellulose films (RCs) were prepared from filter paper lacking oxygen barrier properties under different cellulose concentrations and gelation times. It was shown that the cellulose concentration and gel time had a greater effect on the oxygen barrier properties of RCs. When the cellulose concentration was 4 wt% and the gel time was 3 h, the RCs obtained the lowest oxygen permeability coefficient (OPC) down to 2.21 × 10⁻¹⁷ cm³ cm cm⁻² s⁻¹ Pa⁻¹. The films have a tensile strength of 109.5 MPa, an elongation at break of 27.3% and a light transmission rate of 89%. In further, molecular dynamics simulations showed that when the filter paper was converted to RCs, the increase in hydrogen bonding and the decrease in free volume between cellulose chains caused a decrease in the diffusion coefficient of oxygen. As a novel biobased high oxygen barrier material, the film has broad application prospect in packaging and chemical industry.     

Barrier and mechanical properties of carrot puree films

The edible films based on carrot puree, carboxylmethyl cellulose (CMC), corn starch and gelatin were developed. Glycerol was added as plasticizer. Hydrocolloids and plasticizer content effects on film properties were investigated. CMC and gelatin contents did not significantly affect film %elongation (%E), oxygen permeability (OP) and water vapor permeability (WVP) but significantly enhanced film tensile strength (TS). Corn starch content significantly enhanced film TS and WVP but not significantly affected film %E and OP. Increasing glycerol content decreased film TS and increased film %E (p < 0.05), OP and WVP. Moreover, the L, a and b values of carrot films increased with the increase of the glycerol and decreased with the increase of the corn starch.     

交联壳聚糖/聚乙烯醇/蜗牛黏液复合膜的制备及性能研究

采用延流法制备了香兰素（V）交联的壳聚糖/聚乙烯醇/蜗牛黏液（CS/PVA/SM）复合膜,并通过热重分析仪（TG）、扫描电子显微镜（SEM）和万能材料试验机等研究了不同CS/SM配比对复合膜光学性能、水蒸气和氧气阻隔能力、力学性能、热力学性能及生物降解性能等的影响。结果表明,CS/PVA/SM复合膜为可降解的亲水性薄膜,当CS溶液/SM溶液体积比为5/3时,复合膜性能优良,其抗氧化活性为87.51 %,其水蒸气透过率比纯CS膜降低了75.16 %,不透明度降低了87.74 %,拉伸强度提高了16.04 %,断裂伸长率提高了28.26倍;随着SM含量的增加,复合膜的热稳定性有所降低;CS溶液/SM溶液体积比为5/1、5/2和5/3时,复合膜表现出良好的相容性;SM的添加使复合膜具有很好的延展性和柔韧性,V的添加提高了复合膜的拉伸强度和抗氧化能力;所制备的CS/PVA/SM复合膜在食品包装领域中有潜在的应用前景。     

硬脂酸钙对大豆分离蛋白塑料结构和性能的影响

将硬脂酸钙（CaSt2）与大豆分离蛋白（SPI）以不同比例混合,丙三醇作为增塑剂,经过涂膜的方式制备了改性SPI薄膜。通过衰减全反射-傅里叶变换红外光谱、X射线衍射、热分析、力学性能测试和水蒸气透过率系数等表征手段,研究了CaSt2改性SPI薄膜的结构和性能。结果表明,CaSt2在SPI中以两种结构形式存在,其中离子形式为主。与纯SPI薄膜相比,改性SPI薄膜的结晶度提高了70.4 %,内部结构更加致密。热分析表明,改性SPI薄膜的热稳定性增强。随着CaSt2含量的增加,改性SPI薄膜的水蒸气透过系数下降,当其含量为12 %时,水蒸气阻透能力提高了40 %;同时,断裂伸长率提高了67.63 %。     

Design and mechanism of controllable respiration polyamideamine-epichlorohydrin modied sugarcane bagasse pith hemicellulose film

The major challenge in hemicellulose blend films for food packaging is to overcome the inferior wet strength and hydrophilic properties of hemicellulose-based films. Inspired by the principle of wet strength of paper, novel bio-based packaging film with high barrier and strength properties was designed via bagasse pith hemicellulose as main substrate materials and polyamideamine-epichlorohydrin (PAE) as strengthening agent. The chemical characterization showed that the mechanical and barrier properties of the blend films were found to be strongly dependent upon the amount of PAE added in the films. Compared with the film without PAE, the tensile strength of PAE-containing film with optimal amount of 1% PAE increased by 100.25%, the water vapor permeability decreased by 23.25%, and the oxygen permeability decreased by 87.18%. The results showed that the new ester bond formed between PAE and hemicellulose caused the more excellent mechanical and barrier properties of films.     

Films of chitosan and N‐carboxymethylchitosan. Part II: effect of plasticizers on their physiochemical properties

Chitosan (Ch) and N‐carboxymethylchitosan (N‐CMCh) films were prepared by the casting method at concentrations of 1% and 2% of polymer, with or without plasticizer: polyethylene glycol (PEG‐400) and glycerol (G), at 15% (w/w). The influence of composition on mechanical properties, water vapour transmission rate (WVTR), water saturation, and aqueous dissolution of the films was analysed. The thermal stability of the mixture (polymer:plasticizer, 1:1) was evaluated by thermogravimetric analysis (TGA). In general, all the properties were affected by the plasticizers. The plasticized films showed lower strength and a higher percentage of elongation (%E), in the following order: G > PEG‐400 > unplasticized film. The total WVTR increased with Ch concentration, with a different WVTR profile for Ch and N‐CMCh. While the PEG‐400 addition did not significantly modify the WVTR profile of films, the glycerol enhanced the transport of water vapour through both polymers. The plasticizer addition increased the time of water film saturation, in the following order: G > PEG‐400 > unplasticized film; this was more pronounced in the N‐CMCh films, probably due to the formation of hydrogen bonds. The solubility of the films was also affected by their composition. Copyright © 2006 Society of Chemical Industry     

Plasticized poly(lactic acid) with low molecular weight poly(ethylene glycol): Mechanical,thermal, and morphology properties

Poly(lactic acid) PLA was plasticized with low molecular weight poly(ethylene glycol) PEG‐200 to improve the ductility of PLA, while maintaining the plasticizer content at maximum 10 wt%. Low molecular weight of PEG enables increased miscibility with PLA and more efficient reduction of glass transition temperature (T_g). This effect is enhanced not only by the low molecular weight but also by its higher content. The tensile properties demonstrated that the addition of PEG‐200 to PLA led to an increase of elongation at break (>7000%), but a decrease of both tensile strength and tensile modulus. The plasticization of the PLA with PEG‐200 effectively lowers T_g as well as cold‐crystallization temperature, increasing with plasticizer content. SEM micrographs reveal plastic deformation and few long threads of a deformed material are discernible on the fracture surface. The use of low molecular weight PEG‐200 reduces the intermolecular force and increases the mobility of the polymeric chains, thereby improving the flexibility and plastic deformation of PLA. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 4576–4580, 2013     

高性能PVDC阻隔膜的制备及性能表征

通过单螺杆熔融挤出吹塑的方法制备了具有高阻隔性能的聚偏氯乙烯(PVDC)薄膜。研究了增塑剂环氧大豆油(ESBO)对PVDC薄膜结构与性能的影响。结果表明,当ESBO质量分数为3.5%时,其有效降低了PVDC薄膜的晶点尺寸和数量,并提高了薄膜的力学性能,同时使薄膜对水和氧的阻隔性能达到最佳。     

Effect of uniaxial stretching on thermal,oxygen barrier,and mechanical properties of polyamide 6 and poly(m‐xylene adipamide) nanocomposite films

In this study, the effect of uniaxial stretching on the thermal, oxygen barrier and mechanical properties of aliphatic polyamide 6 (PA6) and aromatic Poly(m‐xylene adipamide) (MXD6) nylon films as well as their in‐situ polymerized nanocomposites with 4 wt% clay were studied. Cast films were prepared by extrusion process and rapidly cooled using an air knife. The precursor films were uniaxially stretched at 110°C with draw ratios varying from 1.5 to 5. DSC results showed that the cold crystallization temperature (T_cc) of the uniaxially stretched MXD6 and MXD6/clay films drastically shifted to the lower temperatures when draw ratio increased. The aromatic nylon films had lower oxygen permeability than those of the aliphatic films, due to more rigidity and chain packing. However, the oxygen permeability of the stretched films increased with draw ratio (DR) up to a critical value for each sample, while further stretching resulted in a reduction in the oxygen permeation. This phenomenon was related to the changes in free volume upon uniaxial stretching. The ability of different geometrical models to describe the experimental relative permeability data was investigated. The Bharadwaj model that took into account clay orientation was the most successful one to predict the oxygen barrier characteristics of the stretched nanocomposites at high draw ratios. The Young's modulus and tensile strength of the aliphatic and aromatic nylons increased with uniaxial deformation, while the flexibility and elongation at break of the former decreased with increasing DR. A larger increase in the Young's modulus of the uniaxially stretched nanocomposite films compared with the neat samples was observed and could be related to the improvement in the clay orientation as well as a better alignment of the crystalline phase due to incorporating the clay platelets in the polymer matrix. In contrast, the flexibility of the stretched MXD6 improved remarkably (ca., 25 times) compared with the precursor film (DR = 1) when the draw ratio increased to 1.5. This could be related to the effect of hot stretching on the enhancement of polymer chains relaxation and mobility at low draw ratios. POLYM. ENG. SCI., 55:1113–1127, 2015. © 2014 Society of Plastics Engineers     

Mechanical properties and water vapor permeability of thin film from corn hull arabinoxylan

Isolated corn hull arabinoxylan was dissolved in water and provided a clear solution. Plasticizer (glycerol, propylene glycol, or sorbitol) was added to the arabinoxylan solution at 0–20 wt % (film dry weight), which was cast into stable films. Film thickness ranged from 22 to 32 μm. Mechanical properties, moisture content, and water vapor permeability (WVP) were studied for the arabinoxylan‐based films as a function of plasticizer concentration. Measured data for the corn hull arabinoxylan–based films were 13–18 wt % moisture content, 10–61 MPa tensile strength, 365–1320 MPa modulus, 6–12% elongation, and 0.23–0.43 × 10^?10 g m^?1 Pa^?1 s^?1 water vapor permeability. Plasticized arabinoxylan films produced in this study had lower WVPs than those of unplasticized films, which is likely attributable to the phenomenon known as antiplasticization. Scanning electron micrographs showed a homogeneous structure on film surfaces. Films containing sorbitol had the best moisture barrier properties. When grapes were coated with arabinoxylan and arabinoxylan/sorbitol films, weight loss rates of the fruit decreased by 18 and 41%, respectively, after 7 days. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 93: 2896–2902, 2004