Natural Antimicrobial – Containing EVOH Coatings on PP and PET Films: Functional and Active Property Characterization

Natural antimicrobials are currently being tested by many researchers for active packaging applications as a response to consumer demands for safer food products. In previous work, several packaging materials consisting of ethylene vinyl alcohol (EVOH)‐coated polypropylene (PP) films containing essential oils or their constituents as active agents were successfully developed and tested for antimicrobial activity. In this work, selected films from those materials, namely EVOH coatings with carvacrol, citral, marjoram essential oil, or cinnamon bark essential oil, on PP and polyethylene terephthalate (PET) substrates, were subjected to diverse physicochemical analyses in order to assess their suitability for food packaging applications. Concretely, the investigated properties were the stability of EVOH coatings on PP and PET substrates, the retainability of EVOH matrices for active compounds, the mechanical, optical, surface and barrier properties of the final active films and the effects of a matrix modification based on the addition of bentonite nanoclay on the performance of PP/EVOH active packages studied in actual working conditions. Results showed that the application of corona discharge followed by a polyethyleneimine‐based primer was the best anchorage treatment available to stabilize EVOH coatings on PP and PET substrates. Furthermore, they demonstrated that the retention of active agents into EVOH matrices ranged from low to moderate, depending on the embedded substance, and that their presence into an EVOH coating in the final multilayer films did not noticeably affect their mechanical, optical or barrier properties, although it considerably improved their wettability. They also indicated that the inclusion of bentonite nanoparticles into their carrier layers substantially enhanced the performance of the final packages, while maintaining or slightly improving their other physical properties. Hence, as a conclusion, all the assayed multilayer films were considered perfectly valid for food packaging applications, and the incorporation of bentonite nanoclay to their carrier layers was also highly recommended. Copyright © 2014 John Wiley & Sons, Ltd.     

Dyeing with Hydrotalcite Hybrid Nanoclays and Disperse,Basic and Direct Dyes

Textile effluents are among the most polluting industrial effluents in the world. Textile finishing processes, especially dyeing, discharge large quantities of waste that is difficult to treat, such as dyes. By recovering this material from the water, in addition to cleaning and the possibility of reusing the water, there is the opportunity to reuse this waste as a raw material for dyeing different textile substrates. One of the lines of reuse is the use of hybrid nanoclays obtained from the adsorption of dyes, which allow dye baths to be made for textile substrates. This study analyses how, through the use of the nanoadsorbent hydrotalcite, dyes classified by their charge as anionic, cationic and non-ionic can be adsorbed and recovered for successful reuse in new dye baths. The obtained hybrids were characterised by X-ray diffraction and infrared spectroscopy. In addition, the colour was analysed by spectrophotometer in the UV-VIS range. The dyes made on cotton, polyester and acrylic fabrics are subjected to different colour degradation tests to assess their viability as final products, using reflection spectroscopy to measure the colour attribute before and after the tests, showing results consistent with those of a conventional dye.     

Effect of ultrasonic extrusion on properties of colloids and bio-based nanocomposites containing epoxidized soybean oil and nanoclay

Colloid prepared with epoxidized soybean oil (ESO) and a nanoclay, organically modified montmorillonite (OMMT), has been processed using an ultrasonic twin-screw extruder under various ultrasonic amplitudes and screw rotation speeds. Ultrasonic treatment has significantly increased OMMT dispersion in ESO, according to wide angle X-ray diffraction and rheological data. Yield stress, storage and loss modulus, and complex viscosity and relaxation time of the colloid have been increased with increase of ultrasonic amplitude. Under certain high ultrasonic amplitudes, the increase of one to two orders of magnitude in the above-mentioned properties of colloids has been observed. Creep and recoverable compliance have been decreased with the increase of ultrasonic amplitude. The tremendous changes in rheological properties of the colloid are a result of significantly improved OMMT dispersion with the aid of ultrasonic treatment. With no or low ultrasonic treatment, a higher screw rotation speed has improved OMMT dispersion since it brings more mixing effect. However, at high ultrasonic amplitudes, a higher rotation disrupts jet flow and has led to less dispersion improvement compared with the same colloid extruded at a lower rotation speed. Colloids extruded at 400 rpm were cured using triethylenetetramine to prepare bio-based nanocomposites. The nanocomposite prepared using colloid treated at 13 μm shows improved tensile strength and modulus compared with the nanocomposite prepared using untreated colloid.     

Effect of nanoclay on performance of neat and SBS-modified bitumen and HMA

The aim of this research was to investigate impact of nanoclay on rutting and moisture damages resistance of neat and SBS-modified asphalt binder and mixture. 4% SBS was blended with 2% nanoclay and 6% nanoclay was used and compared with neat and 4% SBS-modified asphalt binder and mixes. Results of performing rotational viscosity, dynamic shear rheometer, repeated creep recovery, indirect tensile strength, and dynamic creep tests indicated nanoclay has positive impact on rutting and moisture damages resistance of neat and modified asphalt binder.     

An Experimental Study of Surfactant Polymer for Enhanced Heavy Oil Recovery Using a Glass Micromodel by Adding Nanoclay

The nanotechnology has been widely used in several other industries, and the interest in the oil industry is increasing. Nanotechnology has the potential to profoundly change enhanced oil recovery (EOR) and to improve mechanism of recovery, and it chosen as an alternative method to unlock the remaining oil resources and applied as a new EOR method in last decade. Conventional production procedures give access to on average only one-third of the original oil in place, the use of surfactants and polymers allows for recovery of up to another third of this oil. Chemical flooding is of increasing interest and significance due to high oil prices and the need to increase oil production. Objective of this research is Identification of potential of nanoclay as an appropriate agent for improving the efficiency of surfactant polymer flooding in five-spot glass micromodels. In this work a series of solvent injection experiments was conducted on horizontal glass micromodels at same conditions. Observations showed that in the case of nanoclay concentration, the nanoparticles concentration increased the slope of recovery curve and consequently improved the final oil recovery. Also, the results of experiments illustrated that improvement of heavy oil recovery in micromodel test with nanoclay (60.6%).     

Comparison of nanoclay and carbon nanofiber particles on rheology of molten polystyrene nanocomposites under supercritical carbon dioxide

The effects of nanoparticles and high‐pressure carbon dioxide (CO₂) on shear viscosity of polystyrene (PS) were studied. Master curves of PS, PS + 5 wt % carbon nanofibers (CNFs), and PS + 5 wt % nanoclay (Southern Clay 20A) without CO₂ were created based on parallel‐plate measurements. The results showed that addition of nanoparticles increased the viscosity of the neat polymer. Steady‐state shear viscosity of PS in the presence of CO₂ and nanoparticles was measured by a modified Couette rheometer. The effect of supercritical CO₂ on these systems was characterized by shift factors. It was found that under the same temperature and CO₂ pressure, CO₂ reduced the viscosity less for both PS‐20A and PS‐CNFs than neat PS. Between the two types of nanoparticles, CNFs showed a larger viscosity reduction than 20A, indicating a higher CO₂ affinity for CNFs than 20A. However, the advantage of CNFs over 20A for larger viscosity reduction decreased with higher temperature. A gravimetric method (magnetic suspension balance) was used to measure the excess adsorption of CO₂ onto CNFs and nanoclay, thus, CO₂ showed a higher affinity for CNFs. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2010     

Nanoclay/Polypropylene Composite Monofilament Processing and Properties Using Twin and Single Screw Extruders

The structure and properties of nanoclay/polypropylene composite monofilaments were characterized using scanning electron microscopy, thermal gravimetric analyzer, differential scanning calorimeter, and Instron universal testing machine. Twin and single screw extruders were used to produce composite monofilaments with different weight percentage and types of nanoclays and compatabilizers. Final properties of composite monofilaments were affected by the amount of nanoclay. The tensile strength values decreased compared to the pure polypropylene monofilaments for all composite samples. There was not a significant change at melting point; however, decomposition temperature of composite polypropylene monofilaments increased about 10–18% compared to pure polypropylene monofilaments.     

Crystal and morphology development in immiscible nonpolar polymer blend nanocomposite based on low-density polyethylene and linear low-density polyethylene in presence of clay and compatibilizer

In this work, polyolefin-blend/clay nanocomposites based on low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and organically modified clay (OC) were prepared by melt extrusion. Various grades of maleic anhydride (MA) grafted polyethylene (PE-g-MA) were used and examined as compatibilizers in these nanocomposites. Differential scanning calorimetry analysis showed that OC and compatibilizer affect the crystallization behavior of LDPE/LLDPE with different mechanisms. Thermodynamic calculations of wetting coefficient based on interfacial energy between OC, LD, and LL, Morphological characterization based on field emission scanning electron microscopy, X-ray diffraction, small angles X-ray scattering, and dynamic rheology measurements revealed that the compatibilizer and OC were localized at the interface of LDPE and LLDPE phases with a preferred tendency toward one phase. Results demonstrated that at a specific amount of OC, there is an optimum compatibilizer concentration to achieve nanodispersed OC and beyond that the compatibilizer causes a structural change in the polymer crystalline morphology. It was also found that the tensile property enhancement of LDPE/LLDPE/OC nanocomposites is closely related to the crystalline structure development made by incorporation of both OC and compatibilizer.     

Effect of nanoclay on mechanical and thermal properties of triblock SBS (styrene–butadiene–styrene) and its binary blend nanocomposites: comparison between polyethylene and polystyrene

ABSTRACT

In this study, the effect of organo-modified nanoclay (OMMT) on the mechanical and thermal properties of SBS and its blend with low-density polyethylene (LDPE) and polystyrene was investigated. The effect of nanoclay content in the presence of LDPE or PS on the final properties of SBS was studied by tensile tester, dynamic mechanical thermal analysis (DMTA), thermal gravimetric analysis (TGA), X-ray diffraction (XRD) analysis and scanning electron microscopy (SEM). Addition of nanoclay affected the mechanical and rheological properties. From X-ray and DMTA results, it was found that due to more affinity between the nanoparticles and the SBS/PE blend, the 2 theta characteristic peak of nanoclay shifted to lower angles. SEM studies showed better dispersion and lower inter-particle distance of nanoparticles in SBS/PE composites in comparison with SBS/PS and SBS composites, confirming the XRD and DMTA results. It can be concluded that nanoclay acts as a compatibilizer in the SBS/LLDPE blend. TGA studies showed higher stability of SBS/PS composites compared to SBS and SBS/PE ones.     

聚合物/黏土纳米复合材料技术及相关中国专利分析

基于聚合物/黏土纳米复合材料专利数据,对中国专利中的专利申请的相关领域的申请时间分布、申请人情况和技术构成等角度进行分析表明,该领域的专利申请基本上从3个方面进行保护,即聚合物/黏土纳米复合材料、聚合物/黏土纳米复合材料的制备方法、黏土组合物(包括黏土和改性剂);专利申请的发明重点在于聚合物基体种类、黏土改性剂的组分,以及复合材料制备方法。在中国申请的专利中,外国申请人一般企业居多,中国申请人主要是高校和科研院所。