Linear Low Density Polyethylene Blends Research Articles

Effect of PANI on Thermal, Mechanical and Electromagnetic Properties of HDPE/LLDPE/PANI Composites

In this work, polyaniline (PANI) in emeraldine-base form, synthesized by chemical oxidation polymerization, was protonated with hydrochloric acid (HCl). Composites based on high-density polyethylene (HDPE) and linear-low density polyethylene (LLDPE) blends with PANI were prepared in molten condition using a torque rheometer. The effect of compatibilizer agent (maleic anhydride-grafted high density polyethylene, HDPE-g-MA) and different contents of PANI on the blends-based composites was also investigated. Thermal, mechanical, and electromagnetic (electric permittivity) measurements and morphological aspects of the composites were evaluated. The addition of PANI content in the composites decreases the degree of crystallinity of HDPE and LLDPE blends, which implies that PANI particles make it difficult for co-crystallization to occur in the HDPE and LLDPE, respectively. On the other hand, the addition of compatibilizer agent in the HDPE and LLDPE blends increased the degree of crystallinity. The complex parameters of permittivity in the frequency range of 8.2 to 12.4 GHz varied as a function of the PANI content in the blend. It was also observed that the compatibilizer agent increased the composite stiffness and decreased the electric permittivity values. This result shows that the increasing rigidity of the molecular structure of the polyethylene matrix hindered the dissipation of the electromagnetic energy in the sample.

Improved Morphology and Properties of Nanocomposites, Linear Low Density Polyethylene, Ethylene-Co-Vinyl Acetate and Nano Clay Particles by Electron Beam

Surface modification of linear low-density-polyethylene (LLDPE), ethylene-co-vinyl acetate (EVA), and clay nanoparticles composite films was promoted by potassium permanganate solutions in HCl acidic medium using eight conditions by variation times and temperature, also concentrated oxidation solution of LLDPE and EVA blend films shows a very good clarity and tensile properties, this property can be improved by adding the clay nanoparticles as a filler in the composite. The influence of electron beams (EB) irradiation and amount of clay nanoparticles loading on the overall properties of linear low-density polyethylene (LLDPE) /ethylene-co-vinyl acetate blends was investigated. Samples were subjected to the EB irradiation with the dose values of 75 and 150kGy, afterwards mechanical and thermal properties of the LLDPE/EVA blends with and without clay nanoparticles at different irradiation dosages were utilized in order to analyze the characteristics of the final composite. These enhanced properties are due to the homogenize dispersion of Clay nanoparticles in LLDPE matrix. Moreover, in order to verify these characteristics and compare composite samples with and without Clay nanoparticles (Cloisites 30B), some tests such as DSC, TGA, PSA, SEM and Optical Micrographs (OM) were taken from the samples.

Novel ternary blends of natural rubber/linear low-density polyethylene/thermoplastic starch: influence of epoxide level of epoxidized natural rubber on blend properties

Novel degradable materials based on ternary blends of natural rubber (NR)/linear low-density polyethylene (LLDPE)/thermoplastic starch (TPS) were prepared via simple blending technique using three different types of natural rubber (i.e., unmodified natural rubber (RSS#3) and ENR with 25 and 50 mol% epoxide). The evolution of co-continuous phase morphology was first clarified for 50/50: NR/LLDPE blend. Then, 10 wt% of TPS was added to form 50/40/10: NR/LLDPE/TPS ternary blend, where TPS was the particulate dispersed phase in the NR/LLDPE matrix. The smallest TPS particles were observed in the ENR-50/LLDPE blend. This might be attributed to the chemical interactions of polar functional groups in ENR and TPS that enhanced their interfacial adhesion. We found that ternary blend of ENR-50/LLDPE/TPS exhibited higher 100 % modulus, tensile strength, hardness, storage modulus, complex viscosity and thermal properties compared with those of ENR-25/LLDPE/TPS and RSS#3/LLDPE/TPS ternary blends. Furthermore, lower melting temperature (T m) and heat of crystallization of LLDPE (∆H) were observed in ternary blend of ENR-50/LLDPE/TPS compared to the other ternary blends. Also, neat TPS exhibited the fastest biodegradation by weight loss during burial in soil for 2 or 6 months, while the ternary blends of NR/LLDPE/TPS exhibited higher weight loss compared to the neat NR and LLDPE. The lower weight loss of the ternary blends with ENR was likely due to the stronger chemical interfacial interactions. This proved that the blend with ENR had lower biodegradability than the blend with unmodified NR.

Mechanical and Barrier Properties of LLDPE/Chitosan Blown Films for Packaging

The blends of linear low-density polyethylene and chitosan were prepared by using a two-step melt-compounding process and then were made into blown films for packaging. LLDPE-g-MAH was used as compatilizer to enhance the dispersing effect of chitosan in the matrix. Fourier transform infrared spectra and scanning electron microscope images of the blown films confirmed that there were new amide bonds formed between chitosan and LLDPE-g-MAH. The mechanical and barrier properties of the LLDPE/chitosan blown films were investigated. The result indicated that the breaking strength and elongation decreased as the chitosan content increased. In addition, the water vapour permeability of the blend films could be improved up to 200% with the increment of chitosan content, and the oxygen permeability decreased about 20% compared with the films without chitosan. It was found that LLDPE-g-MAH had obvious effects on the mechanical properties and oxygen permeability apart from the water vapour resistance. Copyright © 2015 John Wiley & Sons, Ltd.

Investigating the effect of accelerated weathering on the mechanical and physical properties of high content plastic solid waste (PSW) blends with virgin linear low density polyethylene (LLDPE)

In developing countries, plastic solid waste (PSW) poses a serious threat due to the increase in the dependency on landfilling as well as other environmental issues. Hence, valorising the accumulated waste is essential to promoting more environmentally friendly practices. In this work, the mechanical and physical properties of virgin linear low density (LLDPE) and LLDPE blends with PSW are reported. The formulations studied contained the following virgin to waste ratios (wt.%/wt.%): 100/0, 75/25, 50/50, 25/75 and 10/90. The effect of photo-degradation on the studied specimens was investigated using accelerated weathering tests in a UV chamber. Young's modulus showed an increase with exposure duration due to change in the samples' crystallinity. The loss of mechanical integrity (i.e. stress and strain at rupture) of the samples studied was related to the photo-degradation mechanisms, namely cross-linking and photo-oxidation. Haze and light transmission measured indicated that there was a loss of the amorphous regions in the samples studied after about 200 h of continuous exposure. The total change in colour (ΔE) was estimated but did not show a clear trend, indicating a clear dependency on wash mechanism and continuous loss of polymer colour and degradation.

Fabrication of Cellulose Based Reinforced Linear Low Density Polyethylene with Polyethylene Terephthalate Composite: Effect of <i> Acacia catechu </i> as Coupling Agent

Biodegradable reinforced composites are playing a vital role in the variety of application for their outstanding performance. Linear Low Density Polyethylene (LLDPE) and Polyethylene Tere-phthalate (PET) blends were prepared by twin screw extruder in different composition. The mechanical properties in 10% PET with LLDPE blend showed the best results where as tensile strength (TS) 9 MPa and percentage elongation at break (%Eb) 33. Cellulose based reinforced PET + LLDPE composite were prepared by compression molding with the optimized jute content 62% that revealed the highest mechanical properties. Cellulose based composites treated with Acacia catechu (AC) solutions (0.1% - 5% w/v) at different soaking time (2 - 20 min.) where observed significant improvement of the mechanical properties. Cellulose treated with 0.1% AC for 2 minutes soaking time depicted the highest mechanical properties and TS is 115% higher than untreated. Composite prepared with 0.1% AC treated showed the best mechanical properties as tensile strength (TS), bending strength (BS), tensile modulus (TM) and bending modulus (BM) were to be 47 MPa, 39 MPa, 1220 MPa and 1784 MPa respectively. The properties of TS, BS, TM and BM were improved as 9%, 30%, 14% and 34% respectively, which were better to untreated composite. Electrical properties such as dielectric constant and loss of the treated and untreated composites were found to be higher dielectric constant of treated jute composite than that of untreated samples. Water uptake and soil degradation of untreated and treated composites performed in significant study. The effect of AC with cellulose composites has found in remarkable changes in the mechanical properties.

LDPE Filled with LLDPE/Starch Masterbatch: Rheology, Morphology and Thermal Analysis

This paper reported the effect of starch-based additive (PSN), on the rheology, morphology and thermal behavior of low-density polyethylene (LDPE). PSN was a commercial masterbatch of corn starch and linear low-density polyethylene (LLDPE) in the ratio of 45/55. Compositions of LDPE/PSN blend ratios at 100/0, 80/20, 70/30 and 60/40 were prepared by melt blending. It was found that addition of PSN to LDPE decreased its storage modulus (G′), loss modulus (G′′) and dynamic viscosity (η′) especially at low frequency. Results of the loss tangent (tan δ) measurements indicated a tendency of forming a maximum in the low-frequency region for the samples with high PSN content. Effect of temperature on the viscosity indicated that Arrhenius-type relation with a single slope was followed by neat LDPE, while the LDPE filled with PSN followed a non-Arrhenius-type relation with multiple slopes. Differential scanning calorimeter results indicated that the blend was partially compatible. Thermogravimetric measurement results confirmed that no degradation could happen at the temperature of rheology tests. Scanning electron microscopy studies revealed that starch was uniformly distributed in the blend of LDPE and LLDPE.

Controlled migration of antifog additives from LLDPE compatibilized with LLDPE grafted maleic anhydride

This paper summarizes a study of controlled migration of an antifog (AF) additive; sorbitan monooleate (SMO), from linear low density polyethylene (LLDPE) films containing a compatibilizer, LLDPE grafted maleic anhydride (LLDPE-g-MA). LLDPE/LLDPE-g-MA/SMO blends were prepared by melt compounding. Bulk and surface properties of compression molded LLDPE films containing SMO and LLDPE-g-MA were characterized using Fourier transform infrared spectroscopy and contact angle measurements. Thermal properties were investigated using a thermal gravimetric analyzer. Diffusion coefficient (D) was calculated, and AF properties were characterized using a “hot fog” test. Compression molded films were characterized for their morphology using high-resolution scanning electron microscopy, and rheological properties were measured using a parallel-plate rotational rheometer. It was found that the LLDPE/LLDPE-g-MA/SMO systems are characterized by a slower SMO migration rate, a lower diffusion coefficient, and lower contact angle values compared with LLDPE/SMO blends. These results are well correlated with results of a hot fog test. Morphological studies revealed a very fine dispersion of SMO in the LLDPE films, when 3 phr LLDPE-g-MA was combined with 1 phr SMO. Thermal analysis results show that the incorporation of 3 phr LLDPE-g-MA and 1 phr SMO significantly increases the decomposition temperature of the blend at T > 400°C. At high shear rates, the LLDPE blends show that the AF and the compatibilizer have a lubrication effect on LLDPE. Copyright © 2014 John Wiley & Sons, Ltd.

Effect of electron beam irradiation on dynamic mechanical, thermal and morphological properties of LLDPE and PDMS rubber blends

The effect of electron beam irradiation on the blends of linear low-density polyethylene (LLDPE) and poly dimethyl siloxane rubber (PDMS) prepared over a wide range of compositions starting from 70:30 to 30:70 (LLDPE: PDMS) by varying the radiation doses from 50 to 300kGy has been studied. The dynamic modulii and dielectric strength of the blends increase on irradiation at 100kGy as compared to that for the unirradiated blends. Degree of crystallinity and melting behaviour remain unchanged upon irradiation upto a dose of 100kGy, beyond which it decreases. Thermal stability increases with increase in the proportion of PDMS rubber in the blend as well as on irradiation at 100kGy. The phase morphology of the blends examined under the SEM exhibit two phase morphology before electron beam irradiation, whereas single phase morphology is observed after electron beam irradiation due to intra- as well as inter-molecular crosslinking leading to a miscible system.

Tapping-mode force spectroscopy using cantilevers with interferometric high-bandwidth force sensors

We quantitatively map the surface forces and elastic modulus in tapping-mode atomic force microscopy (AFM). To achieve this, we use custom-built cantilevers with interferometric high-bandwidth force sensors that can resolve nonlinear tip-sample interaction forces, combined with a set of algorithms to process the force sensor signals in real-time. Our technique achieves quantitative mechanical measurements, while retaining nanoscale spatial resolution and minimal loading forces in tapping-mode AFM. Moreover, conventional tapping-mode AFM images are not affected and can simultaneously be acquired. As a practical demonstration, we use our technique to quantify the mechanical properties of a polystyrene and linear low-density polyethylene blend.

Thermal Analyses of Blends of Hyperbranched Linear Low-density Polyethylene (LLDPE) with High-density Polyethylene and LLDPE Prepared by Dissolving Method

Blends of high-density polyethylene (HDPE), moderate and hyper-branched LLDPEs (LLDPE and HbPE, respectively) have attained widespread commercial applications, though the understanding of the mechanical and melt-flow properties of such blends has been handicapped by the absence of a consensus concerning the degrees of mixing of the components. Moreover, usually the blends are obtained by melt blending, which may not ensure the initial homogeneity of the components. In our work the mixtures were prepared by dissolving the conventional LLDPE having branching content 7.2 wt% with HbPE with comonomer content 17.8 wt% in xylene at 130 °C and stirring for 2 hours. The same procedure was applied for the blending of HDPE with HbPE. After dissolving the mixtures were cooled in liquid nitrogen and after that freeze dried in vacuum line. The ratio of components in the blends was varied. Differential scanning calorimetry has been used to investigate the miscibility and thermal behavior of the blends. For this purpose isothermal and non-isothermal treatment of prepared blends were conducted. By preliminary study the double melting peaks in non-isothermal endotherms have been observed in all the studied blends. The presence of two peaks in DSC scan can be attributed to the formation of separated crystals from both the high density/linear low density and highly branched components. However, certain limited degree of co-crystallization is detected in all the LLDPE/HbPE blends and HDPE/HbPE blend rich in HbPE component.http://dx.doi.org/10.5755/j01.ms.17.3.589

Effect of Elastomer on Flame Retardancy, Thermal Degradation, and Mechanical Properties of Intumescent Flame-Retardant Polyethylene

Ethylene—acrylic ester—maleic anhydride (EAEM), as a compatibilizer, has been used to modify a new halogen-free flame retardant linear low-density polyethylene (LLDPE) in this article. Intumescent flame retardants (IFRs) consist of a charring—foaming agent (CFA), ammonium polyphosphate (APP), organic montmorillonite (OMMT) and an antidripping agent. Based on limiting oxygen index values and UL-94 ratings, the IFRs show the effective flame retardancy in the blend of LLDPE and EAEM. Comparative study on the thermal degradation of the composites demonstrates that the IFRs can reduce initial temperature ( Tinitial) of thermal degradation of the composites, and make the main thermal degradation peak move to the high temperature. CONE results reveal that the IFRs can form a char layer on the surface of the composites and clearly change the decomposition behavior of the IFR-LLDPE/ EAEM composites. Whether OMMT is contained or not in the IFRs, the IFRs show a little effect on reducing tensile strength of the composites. This result is proved by well dispersion of IFRs in the blend observed from scanning electron microscopic images. EAEM is also beneficial for improving the flame retardancy and mechanical properties of the composites.

Dynamic rheological, morphology and mechanical properties of compatibilized LLDPE/EMA blends

Blends of linear low density polyethylene (LLDPE) and ethylene-co-methyl acrylate (EMA) having 60/40 composition was studied with and without compatibilizing agent. The compatibilizing agent used was maleic anhydride grafted linear low density polyethylene (LLDPE-g-MA). The LLDPE backbones of the compatibilizer are compatible with LLDPE blend component, whereas the maleic anhydride is affinated with carbonyl groups of EMA. The effectiveness of the compatibilizing agent was evaluated using different techniques like mechanical, thermal, scanning electron microscopy and rheological studies. Best compatibilization effect was found in the blend at a loading of 3 wt% of compatibilizer since at this level of compatibilizer complex viscosity, tensile strength, modulus, elongation at break, impact strength was found to be higher. The increase in the melt viscosity, storage modulus and thermal stability of the compatibilized blends indicated enhanced interactions between the discrete LLDPE and EMA phases induced by the functional compatibilizer.

Degradation and Moisture Absorption Study of Potato-starch Linear Low Density Polyethylene Blend

Composite of linear low density polyethylene (LLDPE) and potato-starch was produced and subjected to degradation studies with the agencies of enzymes, exposure to weather and immersion in water. Enzymatic hydrolysis degraded the matrix to an extent greater than 40% loss in strength and about 20% loss in elongation–at-break within just 10 days. These deteriorations correlated with the decrease in weight. Immersion in water indicated increased uptakes with starch content which also corresponded with decrease in tensile strength and elongation-at-break with time of immersion. Exposure to weather completely reduced the composites to easily crushable masses the extent of which was also related to starch content. Micrographs of the tested samples showed that the weak points are the starch sections which after being eaten up by microorganisms or swollen up by moisture lend the matrix more amenable to further degradation.

Comparative study of the morphology and properties of PP/LLDPE/wood powder and MAPP/LLDPE/wood powder polymer blend composites

In this study, polypropylene (PP)/linear low-density polyethylene (LLDPE) and maleic anhydride grafted polypropylene (MAPP)/LLDPE blend systems were comparatively investigated. The blends and composites contained equal amounts of the two polymers, and the compatibility and miscibility between the two polymers were investigated. Composites with 10, 20 and 30 wt% wood powder (WP), but still with equal amounts of the two polymers, were prepared and investigated. The morphologies, as well as mechanical and thermal properties, of the blends and the blend composites were investigated. The MAPP/LLDPE blend and composites showed better properties than the PP/LLDPE blend and com- posites as a result of the stronger interfacial interaction between MAPP, LLDPE and WP. The SEM and DSC results of the PP/LLDPE/WP blend composites showed that WP located itself more in the LLDPE phase. In the MAPP/LLDPE/WP composites the WP was in contact with both polymers, although it had a greater affinity for MAPP. The TGA results show that the MAPP/LLDPE blend and composites are more thermally stable than the PP/LLDPE blend and composites.

Structure and Properties of PA66/Irradiated LLDPE Blends

The oxygen-containing groups such as C—O, C=O, and C(=O)O were introduced onto linear low density polyethylene (LLDPE) chains by ultraviolet irradiation in air. The irradiated LLDPE was used for modifying polyamide 66 (PA66), and PA66/irradiated LLDPE (90/10) blends were prepared. The structure and properties of the PA66/irradiated LLDPE (90/10) blends were investigated by X-ray diffraction, differential scanning calorimetry, scanning electron microscopy, thermogravimetry, the Molau test, and mechanical measurements. Compared with that in PA66/LLDPE (90/10) blends, the irradiated LLDPE in PA66/irradiated LLDPE (90/10) blends remained in an orthorhombic structure, and the face space did not change. But the melting temperature and the crystallinity of irradiated LLDPE and PA66 in PA66/irradiated LLDPE (90/10) blends decreased due to the strong interface interaction between irradiated LLDPE- and PA66-restrained crystallization. The dispersion of irradiated LLDPE and interfacial adhesion between irradiated LLDPE and PA66 in PA66/irradiated LLDPE (90/10) blends were improved. With increasing irradiation time, the tensile and the impact strength of PA66/irradiated LLDPE (90/10) blends first increased and reached a maximum when the irradiation time was 36 h. Compared with that of PA66/LLDPE (90/10) blends, the tensile and the impact strength of PA66/LLDPE irradiated for 36 h (90/10) blends was enhanced by 31% and 160%, respectively.

Phase Structure of Compatibilized Poly(Lactic Acid)/Linear Low-Density Polyethylene Blends

Blends of PLA and linear low-density polyethylene (LLDPE) were compatibilized with glycidyl methacrylate (GMA)–grafted poly(ethylene-octene) copolymer (mPOE). Effects of compatilizer on phase structure of compatibilized PLA/LLDPE were studied by spreading coefficient calculation prediction, scanning electron microscopy (SEM), differential scanning calorimetry (DSC), and wide-angle X-ray diffraction (WAXD) analysis. The spreading coefficient calculations, based on experimental and calculated surface tension data, show that mPOE spreads on LLDPE extensively to encapsulate LLDPE completely, which is in good agreement with the results of DSC, SEM, and WAXD analysis. The chemical reaction between the end carboxyl groups or end hydroxyl groups of PLA and epoxy groups of mPOE, which is suggested as the driving force leading to an ideal interfacial adhesion between PLA and the dispersed phase, was confirmed by Fourier transform infrared ray (FT-IR) spectroscopy analysis.

Predicting physico-mechanical properties of LLDPE and PDMS rubber blends using ANFIS-based model

Blends of linear low density polyethylene (LLDPE) and poly dimethyl siloxane (PDMS) rubber have been identified as a promising material for cable insulation. The influence of processing parameters on the physico-mechanical properties of these blends has been investigated and the same has been optimised for preparing these blends. In practice, it is not possible to carry out several experiments to identify the relationship between the intermediate processing parameters and physical properties. To address this issue, the relationship between the processing parameters and the mechanical properties of the optimised LLDPE and PDMS rubber blends have been mapped using a non-linear system identification technique namely, adaptive-network-based fuzzy inference system (ANFIS) without carrying further experiments, but with the available experimental data. In this model, the effect of the number of fuzzy rules on the model performance has been investigated to predict the properties and to correlate the above relationship. This paper reports the development of ANFIS-based model for predicting the LLDPE/PDMS rubber blends in reducing the experimental trials and its success over the ANN model.

Processability and mechanical properties for binary blends of PP and LLDPE produced by metallocene catalyst

AbstractProcessability at extrusion coating and mechanical properties of the films obtained are investigated by means of linear and nonlinear rheological measurements and tensile tests for blends of polypropylene (PP) and linear low‐density polyethylene (LLDPE). Both materials are produced by metallocene catalyst. The processability of PP is found to be improved by the addition of LLDPE; the blend shows low level of motor torque and head pressure in an extruder and small level of neck‐in as compared with pure PP. Further, the anisotropy of ultimate tensile strength, which is prominent for PP, is reduced by blending with LLDPE. As a result, the blend having 20 wt % of LLDPE shows appropriate properties in the molten state for extrusion coating and in the solid state as a film. © 2009 Wiley Periodicals, Inc. J Appl Polym Sci, 2009

A novel fiber-reinforced polyethylene composite with added silicon nitride particles for enhanced thermal conductivity

A novel thermally conductive plastic composite was prepared from a mixture of silicon nitride (Si 3N 4) filler particles and an ultrahigh molecular weight polyethylene–linear low density polyethylene blend. The effects of Si 3N 4 particle sizes, concentration, and dispersion on the thermal conductivity and relevant dielectric properties were investigated. With proper fabrication the Si 3N 4 particles could form a continuously connected dispersion that acted as the dominant thermally conductive pathway through the plastic matrix. By adding 0–20% Si 3N 4 filler particles, the composite thermal conductivity was increased from 0.2 to ∼1.0 W m −1 K −1. Also, the composite thermal conductivity was further enhanced to 1.8 W m −1 K −1 by decreasing the Si 3N 4 particle sizes from 35, 3 and 0.2 μm, and using coupling agent, for the composites with higher filler content. Alumina short fibers were then added to improve the overall composite toughness and strength. Optimum thermal, dielectric and mechanical properties were obtained for a fiber-reinforced polyethylene composite with 20% total alumina–Si 3N 4 (0.2 μm size) filler particles.