Barrier Properties Of Nanocomposites Research Articles

Barrier properties of nanocomposites from high-density polyethylene reinforced with natural attapulgite

Attapulgite (ATT) has never been used as a barrier additive incorporated into polymers; instead, it has mostly been applied as a reinforcement or a nucleator. But ATT is very suitable as barrier additives in polymer materials because it can adsorb gas or water by virtue of its porous structure. In this study, ATT nanomaterials from natural minerals were purified and added to high-density polyethylene (HDPE) to prepare HDPE/ATT nanocomposites. The influence of a low content of ATT on the mechanical properties, crystallinity, morphology, water absorption, hydrophilicity, thermostability, and barrier properties of HDPE nanocomposites was analyzed. The results showed that adding a small amount of ATT could improve the mechanical properties, crystallinity, thermal stability, hydrophobicity, and barrier properties, but excessive amounts of it would reduce the mechanical and barrier properties. X-ray diffraction results showed that with increase in the ATT content, the peak did not significantly change and the nanocomposite material was mainly crystalline. According to the oxygen permeability test analysis, the oxygen barrier performance of the nanocomposite material was optimal when ATT was 0.4%. This great improvement in barrier performance might be ascribed to two reasons: (1) The presence of ATT extended the penetration path of molecules; (2) ATT itself had a porous structure, and molecules may be adsorbed and stored in it. Therefore, the addition of ATT led to good performance of HDPE nanocomposites, and this would lead to broad application prospects, which would be worthy of further study.

Mechanical and barrier properties of LLDPE/TPS/OMMT packaging film in the presence of POE-g-IA or POE-g-MA

This study investigates the influence of two functionalized polyethylene-1-octene elastomers (POEs), POE grafted itaconic acid (POE-g-IA) and POE grafted maleic anhydride (POE-g-MA), on mechanical and barrier properties of a novel nanocomposite. The composition was prepared from linear low-density polyethylene (LLDPE), thermoplastic starch (TPS), and organo-modified clay using the melt blending method. Characterization of the functionalized POEs and nanocomposites was performed using attenuated total reflection- Fourier transform infrared (ATR-FTIR) spectrophotometer, X-ray diffraction (XRD), transmission electron microscopy (TEM), field emission scanning electron microscopy (FE-SEM), mechanical, and barrier analysis. The ATR-FTIR spectrums confirmed the grafting of POE with itaconic acid and maleic anhydride. It was observed that the adding of compatibilizers have different effects on morphological, mechanical, and barrier properties of the nanocomposite. The d-spacing of the clay platelets was increased by 20 % and 15 % with POE-g-IA and POE-g-MA incorporation, respectively. The functionalized POEs improved the interfacial adhesion between starch and LLDPE. However, POE-g-IA showed better performance compared to POE-g-MA. Better dispersion of clay particles with POE-g-IA and profitable interaction of starch and LLDPE matrix improves mechanical properties. Besides, the oxygen gas permeability and diffusion coefficient from POE-g-IA contained nanocomposite decreased by 14 % and 22 %, respectively, compared with the other functionalized POE, due to the better dispersion of nanoclay.

Tailoring the mechanical and gas barrier properties of nanocomposites by incorporating a MWCNT/CuS hybrid nanofiller

Variation of MWCNT/CuS hybrid filler addition on the stress–strain curves of the nanocomposites.

Synthesis and Properties of a Novel Si-Ti Polymer/Montmorillonite Nanocomposites

Using methyl triethoxysilane, tetrabutyl titanate and ethyl acetoacetate as raw materials, the Si-Ti polymer was synthesized to prepare Si-Ti polymer/montmorillonite nanocomposites. The effects of OMMT content on the impact properties and barrier performance of nanocomposites were investigated. The results show that with the increasing of OMMT content, the impact properties of nanocomposites are improved significantly. The impact strength of nanocomposite with 10wt% OMMT is about twice times than that without OMMT. The gas barrier properties of nanocomposites are also improved significantly. Compared with pure Si-Ti polymer, the water absorption of nanocomposite with 6wt% OMMT is decreased by 60.3%.

Modification of Nanocrystalline Cellulose for Bioactive Loaded Films

Despite the use of petrochemical derived packaging, many problems such as browning and food spoilage still happen in food after harvesting. There is an increasing consumers concern for food shelf life to be extended as much as possible along with a big interest in green and bioactive materials, that could be used in direct contact with aliments. In order to reach public demand, biopolymers coming from natural sources such as plants or animals have been used to replace synthetic materials. Even though natural polymers are biodegradable, they do not reach regulations required with respect to mechanical properties in commercial applications. However, the mechanical properties can be improved when reinforced with nanoparticles. Several reinforcing nanoparticules such as clays, silica or silver have been used for industrial applications, but cellulose nanocrystals (CNCs) are a better choice for food industry due to their biodegradable and biocompatible nature as well as their outstanding potential in improving mechanical and barrier properties of nanocomposites. CNCs consist of anhydroglucopyranose units (AGU) linked together and several functional hydroxyl groups found on its surface. Modifications of the CNC surface chemistry can give to cellulose new functionalities that open the way to the development of new bioactive reinforcement in food packaging. The present review will be focused on covalent and non covalent modifications that can be achieved on surface CNC with the aim of adding functionalities to be applied for food industry.

Structure and properties of linear polyethylene-montmorillonite nanocomposites

Nanocomposites based on PE and three types of montmorillonite are prepared by melt blending on a Brabender plastograph. The structure of hybrid materials is studied with the use of X-ray diffraction analysis and transmission electron microscopy. The type of modifier and the polarity of the polyolefin matrix affect the character of the filler structure (intercalated and exfoliated) formed during blending with the polymer. A correlation is found between the parameters of structural organization and the mechanical and barrier properties of nanocomposites. The tensile modulus of the nanocomposites containing 3–5 wt % modified montmorillonite is 75% higher than that of the unfilled PE, whereas the time of combustion and the rate of flame propagation are 20 and 10% smaller, respectively.

Preparation and Performance of High-Barrier Low Density Polyethylene/Organic Montmorillonite Nanocomposite

Montmorillonite (MMT) was first modified with dodecyl dimethylbenzyl ammonium (DDA) salt and octadecyl trimethyl ammonium (OTA) salt. Then low density polyethylene (LDPE)/organic montmorillonite (OMMT) nanocomposites were prepared by twin-screw extruder and hot-press. Transmission electron microscopy (TEM) results showed that OMMT layers were homogeneously intercalated into the LDPE matrix. In terms of MMT, the modification effect of OTA is superior to that of DDA. CO2 and O2 barrier properties of nanocomposites were increased by 7 times and 4 times with 0.5 wt.% OTA-MMT loading, respectively. At 2 wt% OTA-MMT loading, water vapor permeability of LDPE has also decreased about 2.5 times. Compared with pure PE film, 49.5% and 178% improvement of tensile strength of nanocomposites films were obtained by addition of only 4 wt.% DDA-MMT and OTA-MMT, respectively. In addition, with only 0.5 wt.% OMMT loading, the onset degradation temperature of nanocomposites increases by 23°C and 26°C for LDPE/DDA-MMT and LDPE/OTA-MMT, respectively.