BARRIER PROPERTY AND STRUCTURE OF ACRYLONITRILE/ACRYLIC COPOLYMERS

A series of acrylonitrile (AN) copolymers with methyl acrylate (MA) or ethyl acrylate (EA) as comonomer (5-23 wt%) was prepared by free-radical copolymerisation. The permeability coefficients of the copolymers to oxygen and carbon dioxide were measured at 1.0 MPa and at 30 degrees C, and those to water vapor also measured at 100% relative humidity and at 30 degrees C. All the AN/acrylic copolymers are semicrystalline. As the acrylate content increase, the permeability coefficients of the copolymers to oxygen and carbon dioxide are increased progressively, but those to water vapor are decreased progressively. The gas permeability coefficients of the polymers were correlated with free-volume fractions or the ratio of free volume to cohesive energy.

Effect of sterilization on barrier property of BOPET used in film-laminated steel

High-temperature sterilization is applied when film-laminated steel is used as food-can packaging material. To study the effect of this sterilization on the barrier property of biaxially oriented polyester （BOPET） film,the water vapor transmission, thermal properties, and microstructure of BOPET that had undergone different sterilization time were analyzed. Results show that water vapor transmission is decreased by sterilization, and that with increased sterilization treatment time,the melting point and melting enthalpy of BOPET increases. Moreover, the microstructure of BOPET film also can be improved by sterilization ,in which the quantity of crystal nuclei and the crystallization density increase to form a network-like structure, which is beneficial to the barrier property of BOPET film.

Research Status and Prospects of Bio-based Materials for Grease Barrier Coatings on Paper Food Packaging

Increased environmental and health concerns over the use of plastic packaging or fluorine-containing coatings,in combination with increased market demand for products with a longer shelf life,make bio-based materials one of the most important research candidates for alternative paper packaging materials for oil resistance.These bio-based materials have excellent oxygen and oil barriers,which are critical for food packaging.Moreover,they are biodegradable,naturally renewable,and safe.In this artical,two main groups of bio-based oil repellents for paper food packaging,including polysaccharide-based biopolymers and protein-based biopolymers,are enumerated,and the advantages and weaknesses of bio-based oil repellents are discussed,and effective solutions are proposed.Finally,research status and prospects on the development of bio-based oil-resistant coatings for the food packaging industry are presented.

Synergism of Zinc Oxide/Organoclay-Loaded Poly(lactic acid) Hybrid Nanocomposite Plasticized by Triacetin for Sustainable Active Food Packaging

The synergistic effect of organoclay(OC)and zinc oxide(ZnO)nanoparticles on the crucial properties of poly(lactic acid)(PLA)nanocompositefilms was systematically investigated herein.After their incorporation into PLA via the solvent casting technique,the water vapor barrier property of the PLA/OC/ZnOfilm improved by a maximum of 86%compared to the neat PLAfilm without the deterioration of Young’s modulus or the tensile strength.Moreover,thefilm’s self-antibacterial activity against foodborne pathogens,including gram-negative(Escherichia coli,E.coli)and gram-positive(Staphylococcus aureus,S.aureus)bacteria,was enhanced by a max-imum of approximately 98–99%compared to the neat PLAfilm.Furthermore,SEM images revealed the homo-geneous dispersion of both nano-fillers in the PLA matrix.However,the thermal stability of thefilm decreased slightly after the addition of the OC and ZnO.Thefilm exhibited notable light barrier properties in the UV-Vis range.Moreover,the incorporation of a suitable biodegradable plasticizer significantly decreased the Tg and notably enhanced theflexibility of the nanocompositefilm by increasing the elongation at break approxi-mately 1.5-fold compared to that of the neat PLAfilm.This contributes to its feasibility as an active food packa-ging material.

Deposition of SiOx barrier films by O2/TMDSO RF-PECVD

This paper reports that the SiOx barrier films are deposited on polyethylene terephthalate substrate by plasmaenhanced chemical vapour deposition （PECVD） for the application of transparent barrier packaging. The variations of 02/Tetramethyldisiloxane （TMDSO） ratio and input power in radio frequency （RF） plasma are carried out to optimize barrier properties of the SiOx coated film. The properties of the coatings are characterized by Fourier transform infrared, water vapour transmission rate （WVTR）, oxygen transmission rate （OTR）, and atomic force microscopy analysers. It is found that the 02/TMDSO ratio exceeding 2：1 and the input power over 200 W yield SiOx films with low carbon contents which can be good to the barrier （WVTR and OTR） properties of the SiOx coatings. Also, the film properties not only depend on oxygen concentration of the inlet gas mixtures and input power, but also relate to the surface morphology of the coating.

Effects of Si/Al,Na/Al and H_(2)O/Na_(2)O molar ratios on formaldehyde barrier properties of inorganic aluminosilicate coatings

Wood-based panels containing urea-formaldehyde resin result in the long-term release of formaldehyde and threaten human health.In this study,inorganic aluminosilicate coatings prepared by combining metakaolin,silica fume,NaOH,and H_(2)O were applied to the surfaces of wood-based panels to obstruct formaldehyde release.The Si/Al,Na/Al,and H_(2)O/Na_(2)O molar ratios of the coatings were regulated to investigate their effects on the structure and formaldehyde-resistant barrier properties of coatings.Results showed that the cracks in the coatings gradually disappeared and the formaldehyde resistance rates of the barrier increased as the Si/Al molar ratio was increased from 1.6 to 2.2.This value also increased as the Na/Al molar ratio was increased from 0.9 to 1.2 because of the improvement of the degree of polymerization.As the H_(2)O/Na_(2)O molar ratio was increased from 12 to 15,the thickness of the dry film decreased gradually and led to the reduction in the formaldehyde resistance rate.When the Si/Al,Na/Al,and H_(2)O/Na_(2)O molar ratios were 2.2,1.2,and 12,respectively,the inorganic aluminosilicate coating showed good performance as a formaldehyde-resistant barrier and its formaldehyde resistance rate could reach up to 83.2%.

Different Kinds of Microfibrillated Cellulose as Coating Layers Providing Fiber-based Barrier Properties

In this study,we investigated the barrier properties of different kinds of microfibrillated cellulose(MFC)coating layers.The air,oxygen,and water vapor permeability,as well as the water contact angles(WCA),were measured to quantify the barrier efficacy of the applied coatings.The WCA data showed that the surfaces of MFC-coated cardboards are more hydrophilic than those of uncoated cardboards.However,different MFC coatings realize different oxygen transmission rates(OTRs)and water vapor transmission rates(WVTRs).The MFC coating derived from bleached bamboo pulp subjected to carboxyethylation pretreatment(MFCCBP)gave the best oxygen and water vapor barrier performances.The OTR of the virgin cardboard(>16500 cm^(3)/(m^(2)·24 h))decreased to 4638 cm^(3)/(m^(2)·24 h)after coating with the MFCCBP.The WVTR similarly decreased from 1016.7 g/(m^(2)·24 h)to 603.2 g/(m^(2)·24 h).

BARRIER PROPERTIES OF VINYLIDENE CHLORIDE/METHYL ACRYLATE COPOLYMER

A series of vinylidene dichloride (VDC) copolymers with methyl acrylate (MA) as comonomer (3-12wt%), was prepared by free-radical suspension copolymerization. The permeability coefficients of the copolymers to oxygen and carbon dioxide were measured at 1.0 MPa and at 30 degrees C, and those to water vapor were measured at 30 degrees C and 100% relative humidity. All the VDC/MA copolymers studied are semicrystalline. As the MA content increases, the permeability coefficients of the copolymers to oxygen, carbon dioxide, and water vapor are progressively increased, caused by decrease in crystalline fraction and increase in free volume of VDC/MA copolymers.

The influence of the structures and compounds of DLC coatings on the barrier properties of PET bottles

To reduce the oxygen transmission rate through a polyethylene terephthalate （PET） bottle （an organic plastic） diamond-like carbon （DLC） coatings on the inner surface of the PET bottle were deposited by radio frequency plasmaenhanced chemical vapour deposition （RF-PECVD） technology with C2H2 as the source of carbon and Ar as the diluted gas. As the barrier layer to humidity and gas permeation, this paper analyses the DLC film structure, composition, morphology and barrier properties by Fourier transform infrared, atomic force microscopy, scanning electron microscopy and oxygen transmission rate in detail. From the spectrum, it is found that the DLC film mainly consists of sp3 bonds. The barrier property of the films is significantly relevant to the sp3 bond concentration in the coating, the film thickness and morphology. Additionally, it is found that DLC film deposited in an inductively coupled plasma enhanced capacitively coupled plasma source shows a compact, homogeneous and crack-free surface, which is beneficial for a good gas barrier property in PET bottles.

Silica-Based Nanocoating Doped by Layered Double Hydroxides to Enhance the Paperboard Barrier Properties

Paperboard is an environment-friendly multi-layer material widely used for packaging applications. However, for food packaging paperboard lacks essential barrier properties towards oxygen and water vapor. Conventional solutions to enhance these barrier properties (e.g. paperboard film coating with synthetic polymers) require special manufacturing facilities and difficult the end-of-life disposal and recycling of the paperboard. Paperboard coating with silica-based formulations is an eco-friendly alternative hereby disclosed. Silica-nanocoatings were prepared by sol-gel synthesis, with or without the addition of Zn(2)-Al-NO3 layered double hydroxides (LDHs), and applied on the surface (ca 2 g/m2) of industrial paperboard samples by a roll-to-roll technique. The physicochemical features of silica-nanocoatings were studied by FTIR-ATR, SEM/EDS, XRD analysis and surface energy measurements. The barrier properties of uncoated and silica-coated paperboard were accessed by water vapor transmission rate (WVTR) and oxygen permeability (Jo2) measurements. The best barrier results were obtained for paperboard coated with a mixture of tetraethoxysilane (TEOS) and 3-aminopropyltriethoxysilane (APTES), with and without the incorporation of LDHs.

A Brief Analysis on The Influencing Factors of Net Content Loss of Household Liquid Detergents

Through tracking the net content of household liquid detergent under different experimental conditions,it was found that the storage temperature,the storage humidity,the packing material,the thickness of the packing material and the inner-packing detergent all had some effects on the net content,and there is a certain relationship between the mass loss and time in a certain storage period.It was found that the higher the temperature and the lower the humidity,the greater the mass loss of the household liquid detergent;and The barrier property of the PE bottle is better than that of the PET bottle.In the case of the same material,the thinner the material is,the greater the mass loss will be;Different liquid household detergents have different mass loss under the same storage temperature and humidity conditions,and due to different composition and proportion of the contents,the mass loss of liquid household detergents was different too.

Investigation of Microwave Surface-Wave Plasma Deposited SiO_x Coatings on Polymeric Substrates

In this paper, we reported nano-scale SiOx coatings deposited on polyethylene terephthalate （PET） webs by microwave surface-wave assisted plasma enhanced chemical vapor deposition for the purpose of improving their barrier properties. Oxygen （O2） and hexamethyl- disiloxane （HMDSO） were employed as oxidant gas and Si monomer during SiOx deposition, re- spectively. Analysis by Fourier transform infrared spectroscope （FTIR） for chemical structure and observation by atomic force microscopy （AFM） for surface morphology of SiO~ coatings demon- strated that both chemical compounds and surface feature of coatings have a remarkable influence on the coating barrier properties. It is noted that the processing parameters play a critical role in the barrier properties of coatings. After optimization of the SiOx coatings deposition conditions, i.e. the discharge power of 1500 W, 2 ： 1 of O2 ： HMDSO ratio and working pressure of 20 Pa, a better barrier property was achieved in this work.

Development and Physical Properties of Film of Wheat Gluten Cross-linked by Transglutaminase

Films were developed from the modified wheat glutens by microbial transglutamina se(MTGase, [E/S]=10u/g,15u/g and 20u/g) in order to improve physical and barri er properties of the films.Glycerol was used as a plasticizer.The films prepared from the modified-glutens by MTGase show a lower elongation at break(E) and a water vapor permeability(WVP), and a higher tensile strength(TS) than the nati ve gluten films.When the modified gluten films by different concentrations of MT Gase are immersed in water at 25℃,their weight losses decreased significantly, and their water resistance increases obviously as expected, compared with the c ontrol gluten films. Moreover, an addition of glycerol as plasticizer greatly mo dified water vapor barrier and mechanical properties of the films.

Biopolymer Films and Coatings in Packaging Applications--A Review of Recent Developments

This review covers the recent developments in the field of biobased packaging materials. Special emphasis is placed on the barrier properties, which are crucial in terms of food packaging. The state-of-the-art of several biopolymers including pectin, starch, chitosan, xylan, galactoglucomannan, lignin and cellulose nanofibrils is discussed. As in most cases the packaging related properties of single layer biopolymer films are inadequate, the thin film coatings, such as sol-gel and ALD (atomic layer deposition), as well as the multilayer coatings are also briefly touched.

Formulation and Characterization of Film Based on Gum Exudates from Brea Tree （Cercidium praecox）

In the present study, films and coatings for food applications based on a gum exudate from Brea tree （Cercidium praecox） were formulated and the influence of plasticizer content on their functional properties was evaluated. Brea gum is a renewable resource available in semi-desert areas, extracted by native people. Films were produced by casting method and characterized through water vapour permeability, mechanical （tensile strength and elongation at break）, morphological and optical properties. Glycerol was used as plasticizer. Brea gum films presented good visual aspect, transparency and amber colour. Microscopic observation showed a dense and homogeneous structure. Film wettability increased with glycerol content due to hydrophilic nature of the plasticizer. Solubility of films in water increased with temperature. Water sorption isotherms of films at 25 ~C showed that at high aw （above 0.50）, the film matrix swells altering its structure and properties. Water vapour permeability remained practically constant up to 20% of glycerol content and then increases linearly with the plasticizer. The addition of glycerol decreased the opacity and tensile strength. The best film properties were obtained at 20% of glycerol concentration.

Effect of substitution group on dielectric properties of 4H-pyrano [3,2-c] quinoline derivatives thin films

The AC electrical conductivity and dielectrical properties of 2-amino-6-ethyl-5-oxo-4-（3-phenoxyphenyl）-5,6-dihydro-4H-pyrano[3, 2-c]quinoline-3-carbonitrile（Ph-HPQ） and 2-amino-4-（2-chlorophenyl）-6-ethyl-5-oxo-5,6-dihydro-4H-pyrano [3, 2-c] quinoline-3-carbonitrile（Ch-HPQ） thin films were determined in the frequency range of 0.5 k Hz–5 MHz and the temperature range of 290–443 K. The AC electrical conduction of both compounds in thin film form is governed by the correlated barrier hopping（CBH） mechanism. Some parameters such as the barrier height, the maximum barrier height, the density of charges, and the hopping distance were determined as functions of temperature and frequency. The phenoxyphenyl group has a greater influence on those parameters than the chlorophenyl group. The AC activation energies were determined at different frequencies and temperatures. The dielectric behaviors of Ph-HPQ and Ch-HPQ were investigated using the impedance spectroscopy technique. The impedance data are presented in Nyquist diagrams for different temperatures. The Ch-HPQ films have higher impedance than the Ph-HPQ films. The real dielectric constant and dielectric loss show a remarkable dependence on the frequency and temperature. The Ph-HPQ has higher dielectric constants than the Ch-HPQ.

Study on the barrier properties and antibacterial properties of cellulose-based multilayer coated paperboard used for fast food packaging

Some petroleum-based packaging materials have a series of safety issues,and as a result,people are more inclined to use biodegradable and nontoxic packaging materials for foods.However,biodegradable alternatives often need to be modified to overcome their own shortcomings.In this paper,carboxymethyl chitosan(CMCS)/carboxymethyl cellulose sodium(CMC)+polylactic acid(PLA)nano zinc oxide(ZnO)nanoparticles(CMCS/CMC+PLA/ZnO NPs)multilayer coated paperboard was prepared to explore its potential use in food package applications.The multilayer CMCS/CMC+PLA coating reduced the oxygen transmission rate by 99%and doubled the barrier properties for soybean oil penetration and water vapor compared with a single PLA coating layer in a 23℃/50 RH environment.The oil resistance time of the multilayer CMCS/CMC+PLA coating also increased 28 times,and the water vapor barrier properties increased twofold compared to a single CMCS/CMC coating layer.The water vapor barrier properties increased by a factor of 3 even at 38℃/90 RH.Compared with the CMCS/CMC+PLA coating without nanoparticles,the barrier performance of the CMCS/CMC+PLA/ZnO NPs coating was further improved.The oxygen,water vapor,and heptane vapor barrier properties all doubled,and the oil resistance time reached 235 h.While a corona treatment reduced the polar component content in the CMCS/CMC coating and led to a slight decrease in the barrier properties of the coating to heptane,it was still a good oil-repellent coating overall.The antibacterial activity(A)toward Escherichia coli and Staphylococcus aureus exceeded 2,which meant that the multilayer coating with 1.5%added ZnO NPs reduced the growth of bacteria by more than 99%.The multilayer coated paperboard created here with the blended and modified materials significantly improved the barrier and antibacterial properties,suggesting that multilayer coatings prepared from degradable materials have good commercial prospects as fast food packaging.

Biodegradable Poly(propylene carbonate)/Layered Double Hydroxide Composite Films with Enhanced Gas Barrier and Mechanical Properties

Relatively well crystallized and high aspect ratio Mg-Al layered double hydroxides（LDHs） were prepared by coprecipitation process in aqueous solution and further rehydrated to an organic modified LDH（OLDH） in the presence of surfactant. The intercalated structure and high aspect ratio of OLDH were verified by X-ray diffraction（XRD） and scanning electron microscopy（SEM）. A series of poly（propylene carbonate）（PPC）/OLDH composite films with different contents of OLDH were prepared via a melt-blending method. Their cross section morphologies, gas barrier properties and tensile strength were investigated as a function of OLDH contents. SEM results show that OLDH platelets are well dispersed within the composites and oriented parallel to the composite sheet plane. The gas barrier properties and tensile strength are obviously enhanced upon the incorporation of OLDH. Particularly, PPC/2%OLDH film exhibits the best barrier properties among all the composite films. Compared with pure PPC, the oxygen permeability coefficient（OP） and water vapor permeability coefficient（WVP） is reduced by 54% and 17% respectively with 2% OLDH addition. Furthermore, the tensile strength of PPC/2%OLDH is 83% higher than that of pure PPC with only small lose of elongation at break. Therefore, PPC/OLDH composite films show great potential application in packaging materials due to its biodegradable properties, superior oxygen and moisture barrier characteristics.

Superior Ductile and High-barrier Poly(lactic acid)Films by Constructing Oriented Nanocrystals as Efficient Reinforcement of Chain Entanglement Network and Promising Barrier Wall

It is a daunting task to develop a promising strategy at an industrial scale for simultaneously ameliorating ductility and gas barrier performance of poly(lactic acid)(PLA)films in the application of green packaging.In this work,biaxial stretching and constrained annealing were employed to prepare transparent PLA films with superior ductility and barrier properties.The oriented nano-sized crystals induced by biaxial stretching were developed into regularαform during constrained annealing,which could not only serve as“nano-barrier wall”to impede the diffusion and dissolution of gas molecules,but also strengthen amorphous chain entanglement network as physical crosslink to enhance ductility.As a result,the as-prepared PLA films exhibited an outstanding comprehensive performance with a low oxygen and water vapor permeability coefficient of 0.733×10^(-14) cm^(3)·cm·cm^(-2)·s^(-1)·Pa^(-1) and 3.82×10^(-14) g·cm·cm^(-2)·s^(-1)·Pa^(-1),respectively,outstanding ductility with elongation at break of 66.0%,high yield strength of 84.2 MPa,and good transparency of more than 80%at 550 nm.The new insight in the relationship between microscopic amorphous and crystalline structure and macroscopic performance is conducive to alleviating the intrinsic defects of brittle and insufficient barrier PLA films without the aid of any heterogenous modifiers,facilitating their widespread commercialization in the booming sustainable packaging market.

Multifunctional Polypyrrole-silver Coated Layered Double Hydroxides Embedded into a Biodegradable Polymer Matrix for Enhanced Antibacterial and Gas Barrier Properties

In this study,polypyrrole-silver coated layered double hydroxides(LDHs@PPy-Ag)was prepared by chemical polymerization of pyrrole(Py)with silver ions.Silver nanoparticles(AgNPs)could be uniformly reduced onto PPy coatings in situ by redox reaction during simultaneous polymerization process.And LDHs@PPy-Ag/poly(ε-caprolactone)(PCL)nanocomposites were fabricated by solution casting method.It is revealed that spherical AgNPs are loaded on PPy coatings uniformly.Particularly,compared with pure PCL,LDHs@PPy-Ag/PCL nanocomposites with incorporation of only 1 wt%LDHs@PPy-Ag show a 17%increase in tensile strength(36.5 MPa)and a 29%increase in elongation at break(822%).Upon PPy-Ag coatings onto original LDHs,oxygen relative permeability of LDHs@PPy-Ag/PCL nanocomposites decreases to 52%with the same addition.Meanwhile,due to the double antibacterial activity of PPy and AgNPs,the antibacterial rate of LDHs@PPy-Ag reaches 100%.And the corresponding LDHs@PPy-Ag/PCL nanocomposites also show outstanding antibacterial activity.Considering the superiority of their comprehensive performance,antibacterial LDHs@PPy-Ag/PCL nanocomposites can be used further for the application as biodegradable polymeric active packaging materials.