Whey protein isolate coating on LDPE film as a novel oxygen barrier in the composite structure

To examine the feasibility of whey protein isolate (WPI) coating as an alternative oxygen barrier for food packaging, heat‐denatured aqueous solutions of WPI with various levels of glycerol as a plasticizer were applied on corona‐discharge‐treated low‐density polyethylene (LDPE) films. The resulting WPI‐coated LDPE films showed good appearance, flexibility and adhesion between the coating and the base film, when an appropriate amount of plasticizer was added to the coating formulations. WPI‐coated LDPE films showed significant decrease in oxygen permeability (OP) at low to intermediate relative humidity, with an Arrhenius behaviour and an activation energy of 50.26 kJ/mol. The OP of the coated films increased significantly with increasing relative humidity, showing an exponential function. Although the coated films showed a tendency to have less oxygen barrier and more glossy surfaces with increasing plasticizer content, differences in the OP and gloss values were not significant. Haze index and colour of the coated films were also little influenced by WPI coating and plasticizer content. The results suggest that whey protein isolate coating could work successfully as an oxygen barrier and have potential for replacing synthetic plastic oxygen‐barrier layers in many laminated food packaging structures. Copyright © 2004 John Wiley & Sons, Ltd.     

Evaluation of a bio‐coating as a solution to improve barrier,friction and optical properties of plastic films

The present research dealt with evaluating barrier, friction and optical properties of three different plastic films after deposition of a gelatin‐based bio‐coating. The composite films showed improved barrier properties against oxygen and UV radiation. The oxygen transmission rate decreased in the order of 73% for oriented polypropylene (OPP), 56% for low‐density polyethylene (LDPE) and 40% for polyethylene terephthalate (PET). The increased UV barrier characteristics ranged from 20% for OPP to 12% for both LDPE and PET. Static and kinetic coefficients of friction significantly decreased both in the film‐to‐film and in the film‐to‐metal tests, leading to a desirable value for many applications. However, bio‐coated films showed lower optical performances in terms of transparency and haze. Transparency decreased mainly for LDPE (36%), whereas the haze index increased especially for OPP (85%). Non‐significant differences were observed as far as the water vapour permeability was concerned, except for a slight reduction for PET (from 15.78 to 13.53 cm³/m²/day at 23°C and 90% of relative humidity), suggesting that non‐meaningful effects arose from the addition of a hydrophobic component in the original formulation. Finally, the solubility of the coating in water was around 25% for all the three plastic substrates. The obtained data suggest that the lipid protein coating tested in this study, in spite of its great potential for enhancing some characteristics of plastic packaging films, still exhibits negative aspects which necessitate further improvement. Copyright © 2008 John Wiley & Sons, Ltd.     

Development of multilayer films with improved aroma barrier properties for durian packaging application

The symmetrical A/B/A structure of multilayer blown films was fabricated in this study. The immiscible low‐density polyethylene/polylactic acid (LDPE/PLA) blend was set as a core (B) layer and LDPE was used as skin (A) layers. The compositions of PLA in the core layer were varied from 20 to 50 wt%. The thickness of each layer was 10 μm (total film thickness of ~ 30 μm). In a blown film co‐extrusion process, the morphology of the fiber/ribbon‐like structures of LDPE/PLA blend was developed. Such structures had interesting effects on gas permeability and aroma barrier properties of the films. For instance, multilayer LDPE films containing 40 and 50 wt% PLA (P40 and P50) showed the reduction of oxygen permeability (PO₂) approximately 20% and 43%, respectively, compared with the neat LDPE film. A long tortuous path for gas and aroma transportation through film thickness was created from the developed ribbon‐like structures of the PLA minor phase. For durian packaging application, fresh‐cut durian of 300 g was packed in the developed multilayer films, LDPE, and HDPE (Control), stored at 4°C for 7 days. Results demonstrated that the steady‐state condition of 10% to 13% O₂ and 8% to 10% CO₂ was achieved in all packages except in the HDPE. Moreover, the P40 and P50 films exhibited an outstanding aroma barrier property for three major durian volatiles : diethyl sulfide, ethyl propanoate, and 2‐ethyl‐1‐hexanol. Overall results clearly indicated that the multilayer LDPE films containing PLA exhibited a significantly improved aroma barrier performance with optimum gas permeability desirable for modified atmosphere packaging to retain quality of fresh‐cut durian throughout the storage period.     

Pumpkin seed oil cake/polyethylene film as new food packaging material,with perspective for packing under modified atmosphere

Biopolymer packaging materials show increasing perspective in food packaging. Main limitation remains their high water sensitivity and poor water vapour barrier properties, compared to non polar materials of synthetic origin like polyethylene. In this paper, biopolymer layer obtained from by‐product of oil industry (pumpkin seed oil cake) was laminated on polyethylene in order to obtain new packaging material that would preferably combine water barrier properties of polyethylene and oxygen barrier properties of biopolymer composite material and perform satisfactory mechanical properties. Obtained two‐layer material showed good barrier properties for water vapour (7–8 g/m² 24h), as well as oxygen (12–45 cm³/m² 24h) and light. In addition, mechanical and water sensitivity tests were performed and results showed that new material inherited biopolymer film water sensitivity and mechanical properties with slight improvement. Measured tensile strength and elongation at break was 2–4 MPa and 150–250% in transversal direction and 6–8 MPa and 100–150% in longitudinal direction. Packing in modified atmosphere assay showed that new material can be used for this purpose with good control of oxygen concentration, while packing under increased concentration of CO₂ could be performed for shorter storage period. New two layer material shows promising properties for sensitive food packing under modified atmosphere conditions with reduced use of synthetic, oil‐based materials.     

Effect of high‐pressure processing on the mechanical and barrier properties of selected packagings

This investigation focuses on the effect of high‐pressure processing (HPP) on possible changes of the mechanical properties and of the water vapour permeability of seven selected packaging materials. NOD 259 (PA‐PE), BB4L (Cryovac‐Grace packaging), PET/BOA/PE, PET/PVDC/PE, PA/SY, LDPE and EVA/PE were investigated (PET, polyester; PE, polyethylene; SY, surlyn; LDPE, low‐density polyethylene; EVA, polyethylene–vinyl acetate co‐polymer; BOA, biaxially oriented polyamide). These packaging materials were selected because of their interest to the food industry. All had an internal film of PE for food use. High‐pressure tests were realized at 10°C for 10 min at pressures of 200, 400 and 600 MPa, with water as a food‐simulating fluid. The depressurization rate was either rapid (pressure drop in <10s) or slow (20 MPa/min). Permeability to water vapour was realized using the NFF H 00 030–ASTM E96‐90 standard. Mechanical tests were carried out with a tensile testing machine (Lloyd LR5K), according to the NF 54‐102 standard. Maximal stress, rupture stress and strain at rupture were evaluated with non‐treated and treated samples. Obtained results showed that HPP minimally affects the mechanical strength of packaging material. The depressurization rate did not have any significant influence in our conditions. The barrier properties to water vapour were not significantly affected and were even slightly enhanced for LDPE, which is a packaging material commonly used for HPP applications and at least as a food contact material. Copyright © 2006 John Wiley & Sons, Ltd.     

Quality of orange juice in barrier packaging material

The vitamin C content and the colour of orange juice made from concentrate were measured during 9 months of storage at 20°C either under artificial light or in darkness. The packaging materials used were glass, standard monolayer polyethylene terephthalate (PET) and multilayer PET (PET/nylon and oxygen scavenger/PET) containers. In this experiment, all bottles were sealed with aluminium foil in order to avoid any cap effect. The results showed that in plastic packaging materials, the loss of vitamin C was related to the oxygen permeability, and that glass provided the best preservation of ascorbic acid. No statistical difference (p < 0.05) was revealed between the vitamin C content in the juice stored under artificial light or in darkness, whatever the packaging used. The modification of colour was studied with the L, a* and b* values during storage at 20°C under artificial light. L and b* decreased, revealing a reduction of lightness and yellow colour of the juice, whereas a* increased, due to the formation of brown pigments. This change in colour was partly related to the oxygen permeability of the packaging used. The losses of aroma compounds by permeation through the bottle (PET) and the cap (high‐density polyethylene, HDPE) have also been investigated. The results showed that permeation mainly took place through the cap. The use of a multilayer cap [HDPE with internal barrier layer of low‐density polyethylene (LDPE)/EvOH/LDPE] considerably limited the permeation of the aroma compounds studied, whatever the PET bottle used. Copyright © 2007 John Wiley & Sons, Ltd.     

石墨烯/低密度聚乙烯复合膜的制备及性能

目的以石墨烯/低密度聚乙烯(LDPE)复合包装材料为研究对象,讨论石墨烯、石墨烯微片对低密度聚乙烯薄膜力学性能、颜色、透光率及透氧率的影响。方法使用熔融共混方法制备不同石墨烯质量分数的石墨烯/LDPE复合材料,检测并比较其性能变化。结果石墨烯以及石墨烯微片的加入,使LDPE薄膜的弹性模量提高了9%~50%,横纵向拉伸强度提高了2%~30%,透光率降低了10%~60%,透氧率提高了10%~15%。结论由于石墨烯比表面积大、刚性高,对LDPE材料的拉伸强度、弹性模量等力学性能有明显改善,同时可提高薄膜透氧率,加深LDPE材料的颜色,降低薄膜透光率。     

LDPE/PET laminated films modified with FeO(OH) × H2O,Fe2O3, and ascorbic acid to develop oxygen scavenging system for food packaging

The iron compounds (iron(III) oxide‐hydroxide monohydrate FeO(OH) × H₂O, iron(III) oxide Fe₂O₃, and ascorbic acid) were used as oxygen scavengers modifiers in laminating of polymer films. This oxygen‐scavenging system was coated on preselected films (low density polyethylene [LDPE] and polyethylene terephthalate [PET]) from which the laminates were formed. It presents the new form of composite material packaging that has the function of oxygen scavenging, which could be suitable for food packaging. The scope of the research included studies of morphology of oxygen scavengers by scanning electron microscope and their average particle size distribution measure by particle size analyzer, the effect of type, and concentration of these substances on viscosity of adhesive and seal strength of laminates. The Fourier‐transform infrared spectroscopy (FTIR) of laminates was also performed to observe the potential interaction of functional groups of polyurethane adhesives with oxygen scavenger components. The most important ability of the developed system for oxygen scavenging was confirmed by measuring oxygen concentration (% vol) in a headspace with the prepared laminates. The concentrations of selected oxygen scavengers (4‐6 wt%) and their combinations were studied. The most effective oxygen scavenger system integrated within the PE/PET composite film consists of 6 wt% ascorbic acid and 1 wt% FeO(OH) × H₂O, where the oxygen concentration of 1.0 vol% (±0.20 vol%) was obtained after 15 days of storage. It was found that in this system the oxygen scavenging reaction occurs through ascorbate oxidation to dehydroascorbic acid, which is catalyzed by reduction of Fe³⁺ to Fe2⁺ ions.     

Studies on the oxygen barrier and mechanical properties of low density polyethylene/organoclay nanocomposite films in the presence of ethylene vinyl acetate copolymer as a new type of compatibilizer

Nanocomposite films based on low density polyethylene (LDPE), containing of 2, 3, and 4 wt.% organoclay (OC) and ethylene vinyl acetate (EVA) copolymer as a new compatibilizer were prepared and characterized using rheological tests, X-ray diffraction, differential scanning calorimetry, oxygen permeation measurements, and tensile tests. There was no exfoliation or intercalation of the clay layers in the absence of EVA, while an obvious increase in d-spacing was observed when the samples were prepared with EVA present. This issue was reflected in the properties of nanocomposites. The oxygen barrier properties of the LDPE/EVA/OC film were significantly better than those of the LDPE/OC film. The average aspect ratio of clay platelets in nanocomposites was determined from permeability measurements and using Lape–Cussler model. In addition to barrier properties, the LDPE/EVA/OC film also had better elastic modulus than their counterparts without EVA. The modulus reinforcement of nanocomposites was studied using Halpin–Tsai equations, which are universally used for composites reinforced by flake-like or rod-like fillers.     

Effect of coupling agent and nanoclay on properties of HDPE,LDPE, PP,PVC blend and Phargamites karka nanocomposite

High density polyethylene (HDPE), low density polyethylene (LDPE), polypropylene (PP) and poly(vinyl chloride) (PVC) were solution blended by using a mixture of xylene and tetrahydrofuran as solvent and polyethylene-co-glycidyl methacrylate (PE-co-GMA) as compatibilizer. The minimum ratio of solvents to obtain a homogenous solution was optimised. Wood polymer composites (WPC) were prepared by using solution blended polymer, wood flour and nanoclay. X-ray diffraction studies of WPC treated with 1 and 3 phr nanoclay showed higher exfoliation compared to WPC treated with 5 phr nanoclay. TEM study also supported the above findings. FTIR studies indicated an interaction between wood, PE-co-GMA and clay. SEM study indicated an increase in miscibility among polymers due to addition of PE-co-GMA as compatibilizer. Thermal stability improved on addition of clay to the WPC. WPC treated with 3 phr clay showed highest mechanical properties. Hardness and water absorption were improved significantly with the addition of nanoclay to wood/polymer composite.     

Fabrication and Properties of Antioxidant Polyethylene‐based Films Containing Marigold (Tagetes erecta) Extract and Application on Soybean Oil Stability

Four films were extruded in a pilot‐plant scale blown extrusion machine: a monolayer low‐density polyethylene (LDPE) film added with 2.90% of marigold (Tagetes erecta) extract, a two‐layer high‐density polyethylene/LDPE film added with 3.59% of the extract in the LDPE layer and the corresponding two control films without addition of the extract. More than 64% of astaxanthin contained in the extract was lost during the extrusion process. Spectroscopic, optical and mechanical properties of the films were affected by the addition of the marigold extract. The films showed to be light sensitive when exposed to commercial light at 25 °C; however, bags made of the films showed a positive effect on soybean oil stability when used as packaging. Copyright © 2012 John Wiley & Sons, Ltd.     

Microperforation of Three Common Plastic Films by Laser and Their Enhanced Oxygen Transmission for Fresh Produce Packaging

Three different plastic films of biaxially oriented polypropylene (BOPP), biaxially oriented polyethylene terephthalate (BOPET) and low‐density polyethylene (LDPE) were perforated using Nd‐YAG laser. Effects of laser pulse energy were examined by varying energies from 50 to 250 mJ where the pulse duration and pulse repetition were kept constant at 10 ns and 1 Hz, respectively. It was found that perforation diameters of all films increased with increasing pulse energies. Observed perforations were different among the three film types. Explanation was contributed to material inherent property and its interaction with laser. Incorporation of an inorganic filler (i.e. silica based anti‐blocking agent used in packaging film) of 0.5 wt% into the LDPE films (0.5Si‐LDPE) could improve perforation performance for LDPE. This was attributed to an increased thermal diffusivity of the 0.5Si‐LDPE film. Commercial BOPET and BOPP films containing 97 microholes/m² (hole diameter of ~100 µm) showed an improvement in oxygen transmission rates (OTR) of 18 and 5 times that of the neat films without perforation. In the case of perforated 0.5Si‐LDPE films having similar perforations of 97 microholes/m² and perforation diameter of 100 µm, a two‐fold increase of OTR was obtained. Gas transmission rates of the microperforated films were measured based on the static method. Measured OTR and CO₂TR values of the three films with varying perforation diameters in a range of ~40–300 µm were compared and discussed. Overall results clearly indicate that perforation by laser is an effective process in developing breathable films with tailored oxygen transmission property for fresh produce packaging. Copyright © 2014 John Wiley & Sons, Ltd.     

Effects of Packaging and Preservation Treatments on the Shelf Life of Murtilla Fruit (Ugni molinae Turcz) in Cold Storage

Murtilla (Ugni molinae Turcz) fruit has a unique aroma; along with its pleasant sweet flavour, this has stimulated its commercial development in international markets. This development, however, requires the application of suitable conservation methods. Five different packaging treatments for murtilla fruit (Red Pearl‐INIA variety) conservation were evaluated at 0 °C for 60 days. The treatments consisted of two types of packaging [polyethylene terephthalate (PET) punnets and low‐density polyethylene (LDPE) bags] and the application of an edible coating of carboxymethyl cellulose to the fruits. The incorporation of the aqueous extracts of murtilla leaves from the 18‐1 and 27‐1 ecotypes into the carboxymethyl cellulose edible coating was also evaluated for its antimicrobial effects. There was a significant (p < 0.05) reduction in the moisture content, a significant weight loss and an increase in soluble solids when the murtilla fruit was packed only in a PET punnet. However, with the other four treatments, in which an LDPE bag and edible coating were used, the moisture content (76.8–74.4 g/100 g) and soluble solids (15.6–17.8 ºBrix) in the fruit remained stable during storage. Low weight loss (1.64–2.25%) occurred in the fruits that received treatments with the LDPE bag and edible coating. Under experimental conditions and from operational facilities, packaging in PET punnets with an LDPE bag was the best alternative to preserve the murtilla fruit at 0 °C for 60 days. Copyright © 2013 John Wiley & Sons, Ltd.     

SiOx/PET复合薄膜的力学性能及阻隔性能

目的基于氧化硅(SiO_x)镀层优异的性能,研究不同厚度的SiO_x层对SiO_x/PET复合薄膜力学性能和阻隔性能的影响,以期得到性能较优的SiO_x/PET复合薄膜。方法以自制的聚对苯二甲酸乙二醇酯(PET)薄膜为基材,采用等离子体增强化学气相沉积法沉积得到SiO_x层厚度分别为40,150,230,320 nm的SiO_x/PET复合薄膜,并进行傅里叶变换红外线光谱分析、力学性能和阻隔性能测试,以及薄膜表观形貌分析。结果沉积SiO_x层后,SiO_x/PET复合薄膜拉伸强度和断裂伸长率随SiO_x层厚度的增大先增大后减小,氧气透过率和水蒸气透过率则出现明显衰减而后逐渐平缓的趋势。SiO_x层厚度达150~230 nm时,复合薄膜的力学性能和阻隔性能表现较优,拉伸强度、断裂伸长率、氧气透过率以及水蒸气透过率分别提高了约25.0%,20.9%,79.3%,77.3%。结论适宜厚度的SiO_x层可以使得SiO_x/PET复合薄膜同时具备较优的力学性能和阻隔性能。     

Development of an Active Thermoplastic Film with Oxygen Scavengers Made of Activated Carbon and Sodium Erythorbate

An active thermoplastic film made of low‐density polyethylene (LDPE) filled with oxygen scavengers made of powdered activated carbon (PAC) impregnated with sodium erythorbate (SE) was developed for packaging applications. Initial tests indicated that the impregnation of PAC with SE enhanced the heat resistance of SE, thereby allowing processing at temperatures typical of LDPE manufacturing. Subsequently, LDPE films with PAC/SE particles were manufactured in coupons that represented a typical juice package, and experiments indicated that these films absorbed 3.57 mg of oxygen in 11 days. This amount corresponded to 80% the concentration of oxygen in the headspace of the package. Furthermore, findings indicated that active particles alone have 10 times higher oxygen absorption capacity than the active LDPE film. Finally, the physical properties of the film were characterized by microscopy where oxygen scavengers showed a good dispersion within the matrix. However, 20 wt.% of these active particles decreased tensile strength of the film by 53%. Copyright © 2014 John Wiley & Sons, Ltd.     

包装材料对肉类食品胀袋问题的影响与分析

目的 比较分析不同种类包装材料的性能差异对所包装肉类食品胀袋问题的影响。方法 以常见的用于包装烧鸡的PA/Al/CPP、BOPA/LDPE,包装猪蹄的PET/PA/CPP、PET/PA/Al/CPP,包装肉肠的PVDC共挤膜、BOPP/PVDC/PE等6种材料为试验样品,分别测试其揉搓前后氧气透过量、拉伸性能、抗穿刺性能、热封强度、密封性能。结果 样品阻隔性由高到低依次为PET/PA/Al/CPP、PA/Al/CPP、PVDC共挤膜、BOPP/PVDC/PE、PET/PA/CPP、BOPA/LDPE;揉搓后PET/PA/Al/CPP阻隔性仍较高,PA/Al/CPP耐揉搓性差,出现贯穿性针孔,揉搓前后BOPA/LDPE、PET/PA/CPP的阻隔性相差不大;BOPP/PVDC/PE拉伸性能较差,横向断裂伸长率仅为28.4%,且热封强度低,其余样品的拉伸性能、抗穿刺性能、热封强度均较好;PA/Al/CPP,BOPP/PVDC/PE成品包装分别在袋体折皱处、袋体与热封口处漏气,其余样品均未漏气。结论 耐揉搓性差、拉伸性能差及热封强度低分别是烧鸡PA/Al/CPP包装、肉肠BOPP/PVDC/PE包装发生胀袋的主要原因;阻氧性偏低易导致由BOPA/LDPE,PET/PA/CPP,PVDC 5层共挤膜包装的烧鸡、猪蹄、肉肠在长时间存储时缓慢胀袋。上述样品存在的问题主要与材质结构、铝箔层质量、材料生产及热封工艺有关。     

Preparation and properties of polypropylene‐based nanocomposite films for food packaging

Packaging of foods in high barrier and strong materials is essential to attain food safety, and nanocomposite technology leads in search of the above kind of packaging material. The effect of compatibilizer (1.6, 5, 10, 15 and 18.4%), nanoclay (0.6, 2, 4, 6 and 7.4%) and thickness of film (35, 50, 75 100 and 120 µm) on oxygen transmission rate (OTR), water vapour transmission rate (WVTR), tensile strength and per cent elongation of polypropylene (PP)‐based nanocomposite films was studied using response surface methodology. The maximum reduction in OTR of PP‐based nanocomposite films over the control was 21.4% in treatment having 10% compatibilizer, 4% nanoclay and 120 µm thickness. A maximum of 28.1% reduction in WVTR for the treatment with 5% compatibilizer, 2% nanoclay and 100 µm thickness over the control was achieved. The regression models were developed for the prediction of OTR and WVTR of nanocomposite films. The maximum increase in the tensile strength of PP‐based nanocomposite films over the corresponding control was 71.7%. The elongation percentage of nanocomposite films was less than the control and increased with increase of thickness of film and decrease of both nanoclay and compatibilizer. Treatment having 5% compatibilizer, 2% nanoclay and 100 µm thickness of nanocomposite films showed better barrier and strength characteristics than other treatments. This paper helps to design the packaging films according to the requirement of foods to be stored using the developed regression models. Copyright © 2011 John Wiley & Sons, Ltd.     

几种食品包装用塑料膜阻透性能比较

目的研究不同厚度、不同材质的食品包装用塑料膜透氧量、透湿量的变化情况,为食品包装在阻隔性方面的选材提供依据和指导。方法采用压差法和杯式法分别测试塑料膜的透氧量和透湿量。结果单层塑料膜随厚度的增加,透氧量和透湿量均减小,阻隔性能变好。相同厚度的PE,PET,BOPP,PA这4种单层塑料膜中,PA的透氧量最小,PE的透氧量最大,BOPP的透湿量最小,PA的透湿量最大。复合膜厚度增加,其透氧量、透湿量均减小,但减小幅度逐渐变小。塑塑复合膜外层材料厚度不变时,透氧量、透湿量随总厚度变化不太明显,EVOH塑料复合膜的透氧量值和透湿量值较小,通常在5以下,铝箔塑料复合膜的透氧量值和透湿量值均小于1。结论单层塑料膜PA的氧气阻隔性最好,PE的氧气阻隔性最差,BOPP的水蒸气阻隔性最好,PA的水蒸气阻隔性最差。复合膜中,塑塑复合膜的阻隔性主要取决于外层材料,铝塑复合膜的阻隔性最好,含高阻隔材料EVOH的塑料复合膜的阻隔性比普通塑塑复合膜好,其阻隔性可与铝塑复合膜媲美。     

A comparative study of oxygen transmission rates through polymer films based on fluorescence quenching

Information on oxygen permeability through polymer films is essential for some applications, especially in food packaging where the control of oxygen levels can be critical in avoiding food spoilage. A permeability testing device using fluorescence‐based optical oxygen sensing was developed as a potential new instrument for measuring the oxygen permeability of packaging films. The fluorescence‐based permeability tester was validated against two existing commercial oxygen permeability measuring devices, the Mocon Ox‐Tran 2/20 and PBI‐Dansensor OPT‐5000. Oxygen transmission rates (OTR) of polylactide (PLA) and nanoclay‐reinforced PLA films, as well as polyethylene/poly(ethylene terephthalate) (PE/PET) and polypropylene/poly(ethylene terephthalate) (PP/PET) laminated films were determined at 23°C and 50% relative humidity using each of these instruments. No significant differences were observed between mean OTR values obtained by the fluorescence method and the corresponding values obtained using the OPT‐5000 but significantly lower values were measured when using the Mocon Ox‐Tran 2/20. In general, oxygen permeability data for the tested films were within the range of values found in the literature; however, in terms of further development, the fluorescence‐based technique gave OTR with relatively high standard deviation compared to the commercial methods and equipment modifications to address this issue are considered desirable. Copyright © 2010 John Wiley & Sons, Ltd.     

纤维素增强壳聚糖/普鲁兰多糖包装材料的研究

目的研究纤维素增强壳聚糖/普鲁兰多糖包装材料的制备及性能改善。方法采用溶液流延的方法,在壳聚糖和普鲁兰多糖溶液中,加入不同比例的微晶纤维素用于增强复合薄膜的力学、阻氧及阻湿性能。通过电子显微镜(SEM)、红外光谱(FT-IR)等手段对复合膜进行结构表征,并对复合材料的阻隔性能、拉伸性能进行测试。结果经过微晶纤维素增强的复合薄膜的拉伸强度以及断裂伸长率得到了很好的增强,阻隔性能也得到了提高。结论微晶纤维素对于PET/壳聚糖/普鲁兰多糖复合包装薄膜具有较好的增强效果。