Study of silane treatment on poly‐lactic acid(PLA)/sepiolite nanocomposite thin films

Poly‐lactic acid (PLA) nanocomposite film was prepared with untreated and silane treated sepiolite through solution casting method. Sepiolite is found to be promising nano inorganic filler used to prepare biodegradable PLA nanocomposite films. The effect of sepiolite loading on the thermal, mechanical, gas permeability, and water vapor permeability (WVP) properties of the films was investigated. X‐ray diffraction analysis revealed the crystallinity index and well dispersed sepiolite in PLA/sepiolite thin films. By modifying sepiolite, depending on the nanoclay content, the mechanical properties of films were enhanced. PLA/sepiolite films exhibited improved gas barrier and WVP properties compared to neat PLA. The scanning electron microscope results demonstrated that there is a good interface interaction between sepiolite and PLA. The surface treatment of sepiolite increased the adhesion of the PLA matrix to the sepiolite nanoclay which yielded better mechanical properties of the films as compared to pure PLA. It was observed after 1.5% wt sepiolite, nano‐filler tended to agglomerate, therefore mechanical and barrier properties of films decreased. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 41428.     

Mechanical and barrier properties of cardboard and 3D packaging coated with microfibrillated cellulose

Microfibrillated cellulose (MFC) is increasingly used with cellulosic substrates and especially with paper materials. Its use with cardboard remains not reported and the study of mechanical and barrier properties of MFC‐coated cardboard has been investigated in this article. The influence of coating process as well as the effect of MFC have been highlighted by comparing different MFC‐coated cardboard samples with PE‐coated cardboard samples. MFC was coated using bar coating process. Their distribution and homogeneity onto cardboard was observed using techniques such as SEM and FE‐SEM. Tests such as oxygen and air permeability, bending stiffness, and compressive strength have been carried out. The coating process used impacts significantly cardboard properties by two opposite ways: on one hand it damages the structure cohesion of cardboard decreasing its compressive strength; on the other hand it increases its bending stiffness by increasing considerably the samples thickness. The addition of MFC counterbalances the negative effects of the coating process: bending stiffness and compressive strength are indeed improved by 30% in machine direction. On the contrary, MFC does not enhance much cardboard barrier properties, although it considerably increases their water absorption. Within a framework of packaging application, MFC will rather have consequent effects on cardboard's properties as blend or as part of the multilayer structure. Other applications have to be considered for its use as top layer. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 40106.     

Barrier properties and abrasion resistance of biopolymer‐based coatings on biodegradable poly(lactic acid) films

Coated polylactic acid (PLA) films consisting of crosslinked‐chitosan/beeswax layer were prepared to improve barrier properties and abrasion resistance of the base substrate. The effect of crosslinking the chitosan layer on durability and barrier properties of the coatings was investigated. Crosslinked samples exhibited lower degree of swelling compared to uncrosslinked samples and 50% reduction in water vapor transmission rate (WVTR) compared to neat PLA films. The beeswax coating decreased the WVTR of chitosan‐coated PLA films significantly (by 100%). However, it had a marginal effect on the oxygen transmission rate. Water vapor transmission was less affected by abrasion than oxygen transmission for both uncrosslinked and crosslinked samples. The WVTR of crosslinked samples were retained even after being subjected to abrasion, whereas WVTR of uncrosslinked samples dropped by 50%. Results obtained using the Taber test method also show that the weight loss of crosslinked coatings are about 75% less than that of uncrosslinked samples and can withstand a greater number of cycles before rupture. These translucent‐coated films retained good barrier and mechanical properties along with providing improved abrasion resistance after crosslinking. This approach provides exciting new possibilities for expanding the use of biodegradable polymers in packaging applications. POLYM. ENG. SCI., 59:1874–1881, 2019. © 2019 Society of Plastics Engineers     

Development of dual purpose,industrially important PLA–PEG based coated abrasives and packaging materials

Fabrication of industrially valuable PLA based coated abrasive and packaging products are made using bio-polymeric blends of PLA–PEG without involving the use of hazardous halogen based solvents, such as, chloroform and dichloromethane. Accordingly, an attempt has been made in our study to substitute a relatively less harmful ethyl acetate (EA) solvent in place of the toxic halogenated solvents to dissolve both PLA and PEG polymer blends to produce an environmentally safe PLA–PEG coating and film formulation in EA. This attempt in turn eliminates and replaces the use of non-degradable polymer coatings, (such as, acrylates, PVC, and synthetic latex) on Kraft paper thereby contributing to sustainability and environmental safety besides reduction in waste disposal to realize a cleaner environment. PLA is a hard and brittle polymer, which restricts its unexplored industrial user applications. On the other hand, PEG toughens the brittle PLA due to its plasticizing action. Hence, PLA–PEG polymer blends were prepared using increasing percentage of PEG content systematically from 5% to 25% and the % of PEG in PLA was optimized to 10% to get the maximum toughening effect in PLA–PEG formulation, which is ascertained by differential scanning calorimetry analysis. FTIR analysis confirmed the possible interaction that occurred between PLA and PEG, due to which a shift in vibration frequency of the PLA carbonyl group is observed. The other important test results from mechanical properties, contact angle, surface roughness, Cobb values, WVTR, and SEM analysis support to reveal that PLA–PEG (10%) blend is the best coating and film forming material on Kraft paper for the fabrication of industrially valuable both coated abrasive and packaging products to demonstrate its dual purpose applications.     

Crosslinkable poly(lactic acid)‐based materials: Biomass‐derived solution for barrier coatings

The demand for biobased barrier packaging alternatives is constantly growing. Poly(lactic acid) (PLA)‐based polymers are one of the most extensively studied biomass‐derived synthetic polymers; however, they typically lack water‐barrier properties. We synthesized a copolymer of d ,l ‐lactic acid, 1,4‐butanediol, and itaconic acid [poly(d ,l ‐lactic acid–1,4‐butanediol–itaconic acid) (PLABDIA)] via bulk polycondensation. The radical crosslinking reactions of the synthesized polymer were investigated with bulk crosslinking trials to find a formulation that was suitable for a rapidly crosslinkable barrier coating. The crosslinking efficiency was tested with methacrylate and acrylate crosslinkers together with peroxide radical initiators. Poly(ethylene glycol) diacrylate (number‐average molecular weight = 250 g/mol) together with dilauroyl peroxide proved to be the best crosslinker–initiator combination. An aqueous dispersion of PLABDIA was prepared with a thermomechanical method and applied to commercial boxboard on a pilot‐scale line coater. With a coating weight of 10 g/m², a water vapor transmission rate of 22.8 g/m²d was achieved, and this coating outperformed commercial extruded PLA coatings. The samples also showed very good grease resistance and would, therefore, be a good solution for the packaging of dry and fatty goods. © 2016 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 44326.     

Biocomposites based on renewable resource: Acetylated and non acetylated cellulose cardboard coated with polyhydroxybutyrate

Renewable resource based bilayer films were prepared from polyhydroxybutyrate film (PHB) and cellulose cardboard via compression molding, containing 5, 10, 15 and 20 wt% of PHB.The effects of PHB contents on moisture absorption, water absorption and water vapor permeation of films were investigated. All biocomposites showed improved permeation properties. As of 15% of PHB, water permeation, equilibrium moisture content and polarity showed a marked drop. It is therefore assumed that the hydrophobic PHB covered up the cellulose cardboard and formed a continuous layer. The water-polymer interactions in materials are critical to the prediction of their behavior in applications where they are exposed to water or humid environment.The elastic modulus (E), tensile strength (σ) and strain at break (?) of two-layer biocomposites depend on the PHB content. Improved uniaxial tensile behaviour was obtained in composites with more than 15% of PHB.In order to improve the adhesion between the cellulose and the PHB, the cellulose cardboard was acetylated. The percentage of moisture absorbed is less than the composites without treatment, due to the better adhesion between the PHB and the cellulose cardboard.This work showed the studies carried out to obtain and study a new biodegradable bilayer material with the needed amount of PHB to improve the barrier and the mechanical properties of cellulose cardboard. It was demonstrated that two-layer PHB-cellulose films exhibited suitable barrier and mechanical performance for packaging applications, taking advantage of the good properties of both materials. Use PHB coatings should provide an outlet for replace Tetra Pak packaging.     

New printing inks with barrier performance for packaging applications: Design and investigation

Barrier properties of packaging materials against moisture and oxygen penetration are of high relevance. Enhanced protection of existing materials against weather conditions can be achieved by application of printed coatings. To improve barrier performance of packaging materials, new inks for obtaining printed coatings with a layered structure were developed and investigated. The proposed ink compositions for flexographic printing on paper substrates are based on an environmentally friendly acrylic binder and contain inorganic fillers with platelet particles incorporated in the polymer matrix. Coatings based on the developed printing inks demonstrate significantly decreased water vapour permeability compared to traditional polymer inks. The effect of decreased permeability was investigated considering inks rheological behaviour, the coating structure, mechanical properties, surface energy and water uptake for different ink formulations. The developed inks provide variable optical properties including coatings with a relatively high transparency. The development of the functional barrier inks contributes to saving natural resources by prolonging life performance of packaging materials and goods.     

Adhesion of extrusion‐coated polymer sealing layers to a fiber‐based packaging material with an atomic layer deposited aluminum oxide surface coating

Adhesion of extrusion‐coated polymer sealing layers on an atomic layer deposited (ALD) aluminum oxide (Al₂O₃) surface coating was investigated with a view to gain information on the applicability of ALD deposited barrier layers in fiber‐based packaging materials. The polymers used for the sealing layer were low density polyethylene (LDPE), polyethylene terephthalate (PET), and polylactide (PLA). They were extrusion‐coated onto the ceramic side of paper/PET/Al₂O₃ substrates, where the Al₂O₃ layer was a few tens of nanometers thick. According to the results, good adhesion was obtained for LDPE coating, whereas the other coatings showed a considerable lack of adhesion. Presumably, the oxidation faced by LDPE in the air gap of the extrusion‐coating process was able to create an extensive number of reactive sites that strongly bonded with the hydroxyl groups on the oxide surface of the substrate. With the PET and PLA coatings, such oxidation did not occur and the adhesion obtained remained at a relatively poor level. With all of the coatings, the adhesion levels were improved using corona discharge equipment as a pretreatment prior to the extrusion‐coating process. POLYM. ENG. SCI., 52:1985–1990, 2012. © 2012 Society of Plastics Engineers     

Surface properties of new green building material after TiO2–SiO2 coatings deposition

The aim of this study was the surface functionalization of a new green ceramic material, obtained using packaging glass waste (PGW), to improve its cleanability. This objective was reached through the deposition by air-brushing of a nanostructured coating based on titania–silica sol–gel suspension. The coatings were deposited on both glazed and unglazed ceramic substrates and the thermal treatment conditions (temperature) were optimized. The obtained results suggest that the applied coatings are transparent and show a good scratch resistance and photocatalitic activity under the tested conditions. The photodegradation process and the mechanical properties are clearly affected by the thermal treatment and thus by the sample surface roughness. The best surface properties were obtained with a thermal treatment at temperature of 150 °C. These coatings do not exhibit either cracks from the substrate. All in all, the developed surface modified ceramic material is attractive as potential sustainable building material.     

High oxygen barrier property of polyethylene composite films with bilayer polyvinyl alcohol coating for emergency foods in high-humidity environments

The limited oxygen barrier of polyethylene (PE) films has restricted their further application in food packaging, like emergency foods. Although its oxygen barrier property can be improved by applying a polyvinyl alcohol (PVA) coating, the application of PVA/PE composite films in high-humidity environments is still challenging. Hence, this study aimed to enhance the oxygen barrier properties of PVA/PE composite films in high-humidity environments. Specifically, PVA coatings were modified by the itaconic acid (IA) and magnesium-aluminum layered double hydroxides (LDH), and then applied to PE films as bilayer coating. Because of the unique bilayer coating on the PE surface, the oxygen barrier property of PVA/PE composite film (IA/LDH-p) in high-humidity environments has been further improved. The results confirmed that IA/LDH-p had an oxygen permeability coefficient of 1.92 ± 0.16 × 10⁻¹⁶ cm³ cm/(cm² s Pa) under a high-humidity environment test, 82.42% better than that of single-layer coating coated on PE surface. After being stored at RH 90% for 36 h, the tensile strength and elongation at break values of IA/LDH-p were 27.20 MPa and 919.63%, respectively. Overall, this obtained PVA/PE composite films showed great potential for application in emergency foods packaging, particularly in high-humidity environments.     

A comparison of partially acetylated nanocellulose,nanocrystalline cellulose,and nanoclay as fillers for high‐performance polylactide nanocomposites

Partially acetylated cellulose nanofibers (CNF) were chemically extracted from sisal fibers and the performance of those CNF as nanofillers for polylactide (PLA) for food packaging applications was evaluated. Three PLA nanocomposites; PLA/CNF (cellulose nanofibers), PLA/CNC (nanocrystalline cellulose), and PLA/C30B (Cloisite^TM 30B, an organically modified montmorillonite clay) were prepared and their properties were evaluated. It was found that CNF reinforced composites showed a larger decrease on oxygen transmission rate (OTR) than the clay‐based composites; (PLA/CNF 1% nanocomposite showed a 63% of reduction at 23°C and 50% RH while PLA/C30B 1% showed a 26% decrease) and similar behavior on terms of water vapor barrier properties with 46 and 43%, respectively of decrease on water vapor transmission rate at 23°C and 50% RH (relative humidity). In terms of mechanical and thermomechanical properties, CNF‐based nanocomposites showed better performance than clay‐based composites without affecting significantly the optical transparency. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2016 , 133, 43257.     

High barrier sustainable co-polymerized coatings

The goal of this project was to determine the most promising co-polymerized (COP) coating for paperboard for protection against gas and water vapor transmission. The driving force for this was to create a coating that will significantly slow the permeation of water and water vapor through the paperboard, while retaining its mechanical properties. This was accomplished by creating high barrier co-polymerized coatings. This study focuses on the use of modified high shape factor engineered (HSFE) clays. In this study, acrylic co-monomers have been polymerized in the presence of three different, finely dispersed HSFE clays, to prepare the co-polymerized coatings. The wet coating structure was studied using Brookfield and Hercules Hi-Shear viscometers, water retention, and dispersion stability. The dry coating structure was studied using WYKO White Light Interferometry and burn out tests. The cylindrical laboratory coater (CLC)-coated samples were then tested for gas and water vapor permeability. Additionally, the optical and surface properties were determined. The CLC-coated board samples showed almost zero gas permeability and a significant reduction in water vapor transmission rate (water vapor permeability). The water vapor permeability was reduced up to 90% reflecting a one order of magnitude decrease in comparison to a commercially coated sample. The co-polymerized coating with high shape factor and thinner platelet clay displayed the lowest water vapor permeability and the best optical and surface properties, thereby making it the most promising barrier coating for solid bleached sulfate paperboard.     

聚乳酸水蒸气阻隔性的改性

聚乳酸(PLA)用于产品包装时不仅要满足所必需的力学性能、化学稳定性、透明性、印刷性以及热封性等,还要满足产品对阻隔性的要求.采用共混、添加助剂的方法以提高PLA对水蒸气的阻隔作用.结果显示:乙烯-乙烯醇共聚物(EVOH)、有机蒙脱土(OMMT)的加入可以降低PLA的水蒸气透过率(WVTR),且随着其含量的增加,WVTR值逐渐减小,当EVOH质量含量达到50％时,WVTR值减小了61％,OMMT含量达到9％时,WVTR值减小了58％;在OMMT/PLA共混物中加入聚癸二酸丙三醇酯(PGS)后,WVTR值增加.     

Impact of the coating process on the molecular structure of starch‐based barrier coatings

Molecular analysis of starch structure can be used to explain and predict changes in physical properties, such as water vapor and oxygen barrier properties in packaging materials. Solution casting is a widely used technique to create films from starch formulations. This study compared the molecular properties of these standard films with those of experimental coatings applied to paper in laboratory‐scale and pilot‐scale trials, with all three techniques using the same starch formulation. The results revealed large differences in molecular structure, i.e., cross‐linking and hydrolysis, between films and coatings. The main differences were due to the shorter drying time allowed to laboratory‐scale coatings and the accelerated drying process in pilot trials owing to the high energy output of infrared dryers. Furthermore, surface morphology was highly affected by the coating technique used, with a rougher surface and many pinholes occurring in pilot‐scale coatings, giving lower water vapor permeability than laboratory‐scale coatings. © 2014 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 41190.     

All starch nanocomposite coating for barrier material

Starch nanocrystals (SNC) are nanofillers of growing interest for barrier and mechanical improvement of bio‐based polymers. However, their potential use as fillers for organic coating material of industrial packaging has never been investigated. In this study, SNC processability in coating is assessed and the final properties of coated papers are measured. Coating colors composed of plasticized starch show higher Brookfield viscosity when filled with SNC even with the addition of water but rod‐coating is still possible. These diluted water‐based coatings induce paper wetting and surface crackling issues during drying as proved by drying process analysis. However no gelatinization of the SNC is observed whichever the type of drying. SNC compensate some of the water induced loss of mechanical properties of the base paper and decrease the water vapor permeability (WVP) up to 40% compared with the base paper. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39826.     

Modeling,Simulation, and Experimental Validation of Drying and Denaturation Behavior of Whey Protein Isolate–Based Coatings

Previous studies proved that heat-treated whey protein isolate (WPI)-based coatings can act as an adequate packaging material with sufficient barrier properties and producibility. These properties also depend on the degree of denaturation of the coating formulations used. This study focuses on the modeling, simulation, and experimental validation of drying and denaturation behavior of WPI-based coatings. Simulation according to existing models is able to describe denaturation and drying kinetics of WPI based coatings adequately. A degree of denaturation of about 13% was reached during coating production. Water vapor transmission rates were reduced up to 67%.     

食品软包装用透明高阻隔涂料：PVA涂料研究进展

聚乙烯醇（PVA）因其良好的透明性和成膜性以及优异的氧气和有机溶剂阻隔性，可用于透明、易回收、环境友好型的食品高阻隔软包装材料。但因其涂层对湿度敏感性差且不具备水蒸气阻隔性能而制约其发展。针对这一问题，目前主要有两种解决方法：一种是PVA化学交联，PVA能进行多元醇的酯化、醚化、缩醛化等化学反应；另一种是制备PVA-纳米复合涂料，PVA与纳米层状材料如蒙脱土（MMT）以及氧化石墨烯（GO）复合涂料的研究已取得较大进展。为此，分别从PVA的阻隔性及其影响因素、化学交联PVA涂料以及PVA-纳米复合涂料的最新研究进展进行了综述，分析了改性PVA涂料面临的问题，展望其未来研究方向。     

Comparative study of the fire protection performance and thermal stability of intumescent fire-retardant coatings filled with three types of clay nano-fillers

The fire protection and thermal stability properties of intumescent fire-retardant coatings filled with three various clay nano-fillers (layer double hydroxide [LDH], montmorillonite [MMT], and sepiolite) were compared by fire protection tests and thermo-gravimetric analysis. The fire protection tests show that the incorporation of three fillers improves the fire protection properties of the intumescent fire-retardant coatings and the addition of 1 wt% sepiolite exhibits the lowest flame spread rating of 9.9 and equilibrium backside temperature of 164.5°C at 900 seconds. TG analysis shows that the incorporation of nano-fillers imparts a considerable enhancement of thermal stability and char formation to the intumescent coatings. Especially, the coating with 1 wt% sepiolite acquires the highest residual weight of 34.2% among the samples. Char residue analysis presents that the introduction of clay nano-fillers plays a positive role in enhancing the compactness and anti-oxidation ability of the char residues, and this positive effect as well as the flame-retardant efficiency depends on the types of clay nano-fillers. The three types of layered clay nano-fillers exhibit synergistic flame-retardant effectiveness in the order of sepiolite > MMT > LDH.     

Studies on surface properties of polymeric coated paper material

Surface properties of a polymeric coating system have a strong influence on its performance and service life. However, the surface of a polymer coating may have different chemical, physical, and mechanical properties from the bulk. Significant progress has been made during the last three decades in the improvement of coating on materials. It has been established that polymeric blends have great potential in replacing economically many conventional materials because of their high specific strength. It is needed today, constantly, to improve the surface finish of any material for efficiency and shiny appearance in the severity of working environment. In packaging, materials having longer service lives and those are less corrosive are highly used. The effect of polymer based coating on the paper material improves its mechanical properties and flame resistance. Effect of flame retardant polymer coating illuminates the surface of the sheet. Important application of the material sheets will be for corrosion receptivity and humidity resistance of this material will certainly improve. Blends of PMM/PVDF are mainly used to improve piezoelectric properties of PVDF. In the present study we report the measurement of surface properties of thin layer of polymer blend coated on the cardboard sheet substrate material. Polymer blend solutions of PMMA/PVDF was prepared at 90/10 (w/w) proportions in miscible solvent of toluene and DMF. Thin film was prepared on the surface of cardboard by dipping the cardboard material in the solution. Thickness of the dried polymer coated paper sheet was measured to see uniformity of coating and for different concentrations. Surface properties such as flexibility index, yellowness, and gloss reflectance were also measured. The study on these polymer coated paper will help in improving the surface property of paper as well as its use in packaging. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 101: 4167–4171, 2006     

Anticorrosion efficiency of zinc-filled epoxy coatings containing conducting polymers and pigments

The dependence of the corrosion-inhibiting properties of zinc-filled organic coatings on the nature of the conducting polymers and conducting pigments added and on the pigment particles’ surface coating with conducting polymer layers were investigated. The following materials were selected to examine the corrosion-inhibiting properties of the conducting polymers: polyaniline phosphate (PANI), polypyrrole (PPy), natural graphite, and carbon nanotubes. Conducting pigment combinations for application in coating materials were formulated by applying pigment volume concentrations (PVC) of 0.3%, 0.5% and 1%, which were completed with Zn dust to obtain pigment volume concentrations/critical pigment volume concentrations (PVC/CPVC) = 0.64. Such conducting pigment/zinc dust combinations represented corrosion inhibitors to be used as ingredients in protective coatings. Solvent-based 2K epoxy resin based coating materials containing the corrosion inhibitors so formulated were prepared to examine their anticorrosion properties. The pigmented coatings were subjected to laboratory corrosion tests in simulated corrosion atmospheres and to standardized mechanical resistance tests. The protective coatings so obtained exhibited a higher efficiency than coating materials containing zinc dust alone. The coating material containing carbon nanotubes at PVC = 1% and the coating material containing graphite coated with polypyrrole (C/PPy) at PVC = 0.5% emerged as the best zinc-filled coating materials with respect to their corrosion-inhibiting efficiency. Treatment with the conducting polymers had a beneficial effect on the coating materials’ mechanical properties.