Properties Of Linear Low-density Polyethylene Research Articles

Investigate the effect of short chain branching and lamellar thickness on mechanical and optical properties of linear low-density polyethylene by successive self-nucleation/annealing (SSA) technique

In this article, various polyethylenes based on Ziegler-Natta and metallocene catalysts with different comonomer contents were investigated by successive self-nucleation and annealing (SSA) technique. Lamellar thickness, short chain branches content (SCBC) and methyl sequence lengths (MSL) were calculated by the modified Thomson-Gibbs equation and suitable calibration curves available in the literature. Moreover, linear low-density polyethylene (LLDPE) samples with different physical, mechanical and optical properties were investigated according to heat of fusion, the lamellar thickness, SCBC and methyl sequence length (MSL) of the multiple peaks. The results showed that the mechanical and optical properties such as dart drop impact strength, Elmendorf tear resistance, softening point and haze are associated with the lamellar thickness and SCBC of the resins.

Dynamics of temperature dependence of the dielectric properties of a nanocomposite material based on linear polyethylene in the vicinity of the percolation transition

Within the frequency range of 30 to 105 Hz and temperatures of 18 to 80 °C, the dielectric properties of linear low-density polyethylene with impurities of flame retardant (20 wt.%) and multilayer carbon nanotubes (1.5 wt.%) were investigated using the oscilloscopic method. This concentration value of carbon nanotubes slightly exceeds the concentration of nanotubes (1%), at which the percolation transition begins for the dependence of the polymer electrical conductivity on the content of nanotubes. It has been shown that the frequency dependence of electrical conductivity can be approximated by two exponential dependences. It has been found that when the sample is cooled, changes in the values of dielectric permittivity and electrical conductivity do not occur in the same way as when heated. The temperature dependences of conductivity for low (102 Hz) and high (104 Hz) frequencies have been obtained.

Improvement of Mechanical Properties of Linear Low-Density Polyethylene (LLDPE) Films by Addition of Montmorillonite-Erucamide Nanocomposite (MMT-EU)

Improvement of Mechanical Properties of Linear Low-Density Polyethylene (LLDPE) Films by Addition of Montmorillonite-Erucamide Nanocomposite (MMT-EU)

The effect of boron nitride, carbon nanotubes, and their synergy on the properties of LLDPE and LLDPE/wax blend

AbstractThis study deals with the effect of two types of conductive fillers (viz., boron nitride and single walled carbon nanotubes) on the properties of the linear low‐density polyethylene (LLDPE) matrix and LLDPE/paraffin wax (PW) blend. Pure LLDPE and paraffin wax/LLDPE blend (30/70) were melt‐mixed with 2 wt% content of boron nitride (BN) and single walled carbon nanotube (SWCNT), as well as their synergy at 2 wt%. Because it is well‐known that both conductive fillers were able to improve the thermal conductivity of the paraffin wax/polymer blends, the aim of this study was to focus on the effect of both conductive fillers on the dispersion of paraffin wax into LLDPE matrix, mechanical properties, crystallization behavior, and thermal stability of the LLDPE/wax blend. Scanning electron microscopy (SEM) images of the LLDPE/paraffin wax blends depicted a phase separated system, which was further supported by two separate peaks from the differential scanning calorimetry (DSC). The morphology of the system showed that the addition of boron nitride (BN) into the LLDPE/paraffin wax blend had no affinity with the paraffin wax, while the addition of single walled carbon nanotubes (SWCNT) showed better dispersion into the LLDPE/paraffin wax/BN blend composites. The incorporation of the SWCNT and its synergy with BN enhanced the thermal stability of the LLDPE.

Effect of Ultrasound Treatment on Barrier Changes of Polymers before and after Exposure to Food Simulants.

In this study, we investigated the impact of ultrasound treatment on barrier properties of linear low-density polyethylene (LLDPE) and acrylic/poly(vinylidene chloride) polypropylene (PPAcPVDC)-coated pouches intended for food packaging before and after exposure to food simulants. Packaging pouches were filled with two food simulants, namely ethanol (10% (v/v)) and acetic acid (3% (w/v)), in order to simulate food–packaging interaction and possible compound migration from packaging materials. Samples were subjected to an ultrasound water bath treatment for 5 min, 15 min, and 30 min at 60 °C (±2 °C) and with an amplitude of 100% as an equivalent to the heat-treatment conditions combined with an ultrasound effect. Furthermore, the effect of temperature on the polymer barrier (water vapour and oxygen permeability) properties was tested at 20 °C, 40 °C, and 60 °C. Results showed that PPAcPVDC possessed better properties of water vapour permeability and oxygen permeability properties to LLDPE. Statistical analyses showed a significant (p < 0.001) impact of ultrasound treatment on the overall migration value, regardless of the food simulant used.

Improvement of Mechanical, Thermal, and Morphological Properties of Organo-Precipitated Calcium Carbonate Filled LLDPE/Cyclic Natural Rubber Composites

This study investigates the improvement of the mechanical, thermal, and morphological properties of linear low-density polyethylene (LLDPE)/cyclic natural rubber (CNR) after the addition of organo-precipitated calcium carbonate (O-PCC). The impact on the properties of the LLDPE/CNR/LLDPE-g-OA/O-PCC composites was investigated by a series of empirical experiments. First, the polymer composite was blended in the molten state using an internal mixer with a heating temperature of 160 °C and a rotation speed of 100 rpm. The LLDPE was placed in a chamber of internal mixer until melted, followed by CNR, LLDPE-g-OA, and O-PCC. The polymer composites with an O-PCC concentration of 5% obtained the optimal mechanical properties compared to other variations, with a tensile strength of 17.17 MPa and Young's modulus of 252.68 MPa. The presence of O-PCC resulted in better thermal stability and a change in the melting point temperature of 124 °C. The FTIR spectra of the polymer composite showed the specific characteristics of O-PCC at 872.1 cm–1. The morphology of the polymer composite indicates that the O-PCC is evenly dispersed in the polymer composite.

Nonlinear optical properties of LLDPE composites with titanium dioxide anatase phase

In this research work, the linear and nonlinear optical properties of linear low-density polyethylene (LLDPE) composites with anatase phase of titanium dioxide nanoparticles in different weight percentages are investigated. Solvent casting method have been used to synthesize the thin film of LLDPE/anatase nanocomposites. Thin films are characterized via XRD technique and field emission scanning electron microscope (FESEM). Wrinkles formed on the surface of thin films by adding the titanium dioxide. Linear optical and electrical parameters such as linear absorption coefficient, extinction coefficient, refractive indices, optical conductivity, and dielectric constants at various wavelengths from 190 nm to 2700 nm are determined for different weight percentages of nanoparticles in polymer nanocomposites. Z-scan technique has been employed to explore the nonlinear optical properties using CW laser at 532 nm wavelength. The nonlinearity is examined at various irradiance of laser to study the effect of irradiance on nonlinear optical properties. Pure LLDPE has saturable absorption (SA) at low laser irradiance. As the laser irradiance increases, the nonlinearity behavior turns from SA to reverse saturable absorption (RSA). The results show the suitability of the thin films for the applications in optical devices that involve the use of optical limiting properties of materials.

The Effect of Dialkyl Peroxide Crosslinking on the Properties of LLDPE and UHMWPE.

Peroxide has been considered a chemical agent that can be used to tune the properties of polymeric materials. This research evaluated the influence of different concentrations of dialkyl peroxides on the mechanical, thermal, and morphological properties of linear low-density polyethylene (LLDPE) and ultra-high molecular weight polyethylene (UHMWPE). The neat polymer, as well as those with the addition of 1% and 2% by mass of dialkyl peroxides, were subjected to compression molding and immersion in water for 1 h, under controlled temperatures of 90 °C. The values of the gel content found in the samples indicated that the addition of peroxide to the LLDPE and to the UHMWPE promoted the formation of a reticulated network. The structure obtained by the crosslinking led to less reorganization of the chains during the crystallization process, resulting in the formation of imperfect crystals and, consequently, in the reduction in melting temperatures, crystallization and enthalpy. The mechanical properties were altered with the presence of the crosslinker. The polymers presented had predominant characteristics of a ductile material, with the occurrence of crazing with an increased peroxide content.

Effect of Bi2O3 on the properties of linier low density polyethylene (LLDPE)/natural rubber compound (NRC) composites

The use of thermoplastic natural rubber (TPNR) has spread for many applications such as in footwear, hoses, seals, and automobiles. This increase is in line with the environmental awareness to produce materials that can be recycled. In this paper, the making of TPNR for car floor mat was studied. Bi2O3 filler was added to modify the performance of TPNR for car floor mat. In this study, the effects of Bi2O3 filler on the properties of linear low-density polyethylene (LLDPE)/natural rubber (NR) composites had been investigated. The weight ratio of LLDPE/NR was varied at 90/10; 80/20; 75/25; and 70/30. Bi2O3 filler loading was varied at 0; 20; 40; and 50 phr. The increase in NR and Bi2O3 filler reduced the tensile strength, elongation at break, and tear resistance, but increased the hardness and density of the composites. Compared to similar imported products, the samples prepared in this study showed higher values for all mechanical properties (tensile strength, elongation at break, tear resistance) but lower values in density. Scanning electron microscopy (SEM) micrograph of LLDPE/NR 75/25 composites either with or without the addition of 20 phr Bi2O3 filler displayed homogeneity of the mixture.

Swelling and electrical properties of LLDPE reinforced by SWCNTs nanocomposites for radiation and sensors applications

Linear low-density polyethylene (LLDPE) incorporated with single-walled carbon nanotubes (SWCNTs) by mistreatment casting technique. The result of various weight percentage loadings of SWCNTs on the swelling and electrical properties of LLDPE/SWCNTs nanocomposite also γ-irradiation effects had been investigated. It was found that, at low concentration, it uniformly disperses into an LLDPE matrix and provides LLDPE/SWCNTs nanocomposites with abundant improved electrical properties by nine orders of magnitude. Positive temperature coefficient of conductivity (PTCC)/negative temperature coefficient of conductivity (NTCC) was affected by the SWCNT contents. Transmission electron microscopy and scanning electron microscope techniques were used to investigate the dispersion of SWCNTs in the LLDPE matrix. Linear exceptional modification within direct current electrical conduction of percolative threshold-loaded LLDPE as a perform of γ-irradiation dose will be used as a nontoxic, easy, inexpensive, and sensitive method to evaluate the irradiation dose in range 10 Gy–1 kGy also can be used in fabrication of firing sensors with various ranges of temperatures.

Effect of iron poly(acrylic acid-co-acrylamide) and melamine polyphosphate on the flammability properties of linear low-density polyethylene

Iron poly(acrylic acid-co-acrylamide) (FeAA) and melamine polyphosphate (MPP) were synthesized, characterized by FTIR and blended with linear low-density polyethylene (LLDPE). The thermogravimetric analysis results exhibited that MPP, FeAA and MPP/FeAA increased the char residue of LLDPE at 750 °C. Cone calorimeter data demonstrated that MPP, FeAA and MPP/FeAA decreased the peak of heat release rate (pHRR) and total heat release of LLDPE. Digital photographs, SEM images, EDXS and FTIR analyses of char formed after cone test indicated that the presence of FeAA did not support formation of coherent char during combustion process of LLDPE. In contrast, LLDPE/MPP composite formed high-quality char layer on polymer surface. Moreover, addition of MPP to LLDPE/FeAA composites assisted in formation of char containing iron polyphosphate and polyaromatic structure. The mechanical properties, namely tensile strength, Young’s modulus, elongation at break and hardness of LLDPE composites, were measured.

Effect of graphene oxide as a filler material on the mechanical properties of LLDPE nanocomposites

Graphene oxide (GO) has high aspect ratios than many nanosize fillers such as carbon nanotubes and clay, besides its better mechanical properties than many polymers; so they are preferred as a filler material in polymer matrix composites. In this study, the effect of GO on the mechanical properties of linear low-density polyethylene (LLDPE) were experimentally investigated. LLDPE-GO nanocomposites were prepared by melt compounding method, and the extruded nanocomposite was shaped by injection molding machine for the mechanical tests. The mechanical properties investigated included tensile properties, fatigue properties, as well as hardness properties. Differential scanning calorimeter (DSC) was employed to study the thermal characterization of the composites. The results revealed that the addition of GO nanosheets indeed had a positive effect on the tensile, fatigue, and hardness properties. The tensile strength, Young's modulus, and Shore D hardness value were increased by 27.4%, 31.3%, and 9%, respectively, with a GO loading ranging from 0 wt.% to 2 wt.%. The addition of GO had a significant effect on the fatigue properties of the composites such as nearly exponential increment in the cyclic numbers. The samples with 2 wt.% of GO could endure up to 106 cycles during the tests, which is 100 times that of pure LLDPE. The morphological analysis via X-ray diffraction (XRD) and transmission electron microscopy (TEM) indicated that GO nanosheets were well exfoliated in the LLDPE matrix. However, there is no significant effect on the melting temperature, crystallization temperature and crystallinity of LLDPE based on DSC result.

Effect of reactive and nonreactive surface modifications and compatibilizer use on mechanical and flame-retardant properties of linear low-density polyethylene filled with huntite and hydromagnesite mineral

In the current study, huntite and hydromagnesite (HH) was used as flame-retardant additive in linear low-density polyethylene (LLDPE). The effect of HH amount on the flame-retardant and mechanical properties of the composites was investigated. The compatibilizer (ethylene butyl acrylate) use and the surface modifications with stearic acid and silane coupling agent were used in order to improve the mechanical properties of the composites. The mechanical properties of the composites were studied using tensile test and dynamic mechanical analysis. The fire-retardant properties of the composites were investigated using limiting oxygen index (LOI), mass loss calorimeter, vertical (UL 94 V) and horizontal (UL 94 HB) burning tests. According to the flammability test results, LOI value increased, horizontal burning rate reduced as the added amount of HH increased, whereas UL 94 V rating remained burn to clamp. According to the mechanical test results, the addition of HH reduced the tensile strength and elongation at break values and increased the elastic modulus and the β transition temperature of the LLDPE as the added amount increased. Only the compatibilizer use improved the flammability properties of the composites with improved tensile strength. Both stearic acid and silane modification merely increased the toughness of the composites.

Morphology and Mechanical Properties of Maple Reinforced LLDPE Produced by Rotational Moulding: Effect of Fibre Content and Surface Treatment

In this study, wood-plastic composites (WPC) were produced by rotomoulding, to study the effect of fibre content and surface treatment on their properties. Maple wood fibre, with or without surface treatment with maleated polyethylene (MAPE), was used to improve the mechanical properties of linear low-density polyethylene (LLDPE). From the composites produced, a complete morphological and mechanical characterisation was performed. The results showed that MAPE surface treatment improved the fibre-matrix interface quality and the mechanical properties (56% increase in tensile modulus and 60% increase in flexural modulus over the neat matrix with 19% in impact strength with respect to untreated fibres) at 30% wt.

Effect of corona treatment on adhesion enhancement of LLDPE

Polymers/metal laminates are often used to improve physical and mechanical properties, especially those required in building applications. A flat aluminum composite panel (ACP) consisted mainly of two thin metal sheets usually made of aluminum (Al) and a non-metal core, such as polyethylene (PE). The lack of adhesion associated with the low wettability of PE is a serious problem. An eco-friendly, dry, non-destructive corona treatment technique can be applied to solve this problem. In this work, the use of a corona treatment to enhance the adhesion properties of linear low-density polyethylene (LLDPE) was studied. The changes in surface and adhesion properties were thoroughly analyzed using various analytical techniques and methods to obtain the optimal parameters for corona discharge using contact angle measurements, Fourier transform infrared spectroscopy (FTIR), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and atomic force microscopy (AFM). AFM force adhesion measurements were used to analyze the effect of the corona treatment on the adhesion enhancement of LLDPE, and the peel tests confirmed a significant increase in peel resistance in the LLDPE/Al laminate. A synergy effect from using the corona treatment in combination with an ethylene acrylic acid dispersion primer was observed.

Thermoplastic elastomer based on LLDPE and EMA

The effect of organoclay as well as controlled dicumyl peroxide (DCP) curing on the morphology and physicomechanical properties of linear low-density polyethylene (LLDPE)/ethylene-co-methylacrylate (EMA) blends was explored in this article. The nancomposites were melt-compounded in an internal mixer, HAAKE RHEOMIX, at 140°C and a rotor speed of 60 r min−1. The nanocomposites were then cured in a compression mold at 170°C for 12 min, and their morphology and physicomechanical properties were evaluated. Exfoliated morphology was observed for DCP-treated nanocomposites. DCP initiated grafting between polymer and clay platelets resulted in high degree of reinforcement in all nanoclay-filled samples through exfoliation of clay platelets as well as interfacial cross-linking and controlled cross-linking in the two polymer phases. Reprocessability studies showed that LLDPE/EMA/Cloisite®20A nanocomposites cured with DCP up to 0.5 wt% can easily be reprocessed.

Preparation and Characterisation of Linear Low-Density Polyethylene / Thermoplastic Starch Blends Filled with Banana Fibre

In this study, the influence of banana fibre (BF) loading using sodium hydroxide (NaOH) pre-treated and succinic anhydride-treated (SA) BF on the mechanical properties of linear low-density polyethylene (LLDPE)/thermoplastic starch (TPS) matrix is investigated. LLDPE/TPS/BF composites were developed under different BF conditions, with and without chemical modifications with the BF content ranging from 5% to 30% based on the total composite. The tensile strength showed an increase with an increase of fibre content up to 10%, thereby decreasing gradually beyond this level. NaOH pre-treated and SA treated BF added with LLDPE/TPS composite displays a higher tensile strength as compared to untreated BF in LLDPE/TPS composites. Thermal behaviour of the BF incorporated in LLDPE/TPS composite was characterised using differential scanning calorimetry (DSC) and thermal gravimetric analysis (TGA). This showed that SA treated BF exhibits better thermal stability, compared to other composites. This is because of the improvement in interfacial adhesion existing between both the fibre and matrix. In addition, a morphology study confirmed that pre-treated and treated BF had excellent interfacial adhesion with LLDPE/TPS matrix, leading to better mechanical properties of resultant composites.

Evaluation of fire performance of linear low-density polyethylene containing novel intumescent flame retardant

A novel single-molecule intumescent flame retardant, melamine salt of montmorillonite phosphate (MMP), was synthesized and characterized by FTIR and XRD. The effect of MMP on the thermal stability and flammability properties of linear low-density polyethylene (LLDPE) was studied by thermogravimetric analysis, vertical burning test (UL-94V), and cone calorimeter. In addition, the synergistic effect between MMP and low concentrations from zinc borate (ZB) on LLDPE thermal stability and flammability properties was investigated. The results showed that addition of MMP and MMP/ZB to LLDPE improved the thermal stability at high temperatures and enhanced the char formation at 750 °C. UL-94V test results presented that LLDPE achieved V-0 rating at (30%MMP/5%ZB) loading level. The cone calorimeter data showed that MMP and MMP/ZB considerably reduced peak of heat release rate, mean heat release rate, total heat release, and mean mass loss rate of LLDPE. The data of fire performance index, fire growth rate index, and maximum average rate of heat emission indicated that MMP and MMP/ZB additives reduced the fire risks of LLDPE. The digital photographs, SEM images, and EDXS analysis for the char residue after cone calorimeter test showed the formation of coherent, compact, and thermally stable char layer on the polymer composites surfaces.

A Novel Intumescent Flame Retardant: Synthesis and Its Application for Linear Low-Density Polyethylene

A novel intumescent flame retardant, melamine salt of pentaerythritol phosphate montmorillonite (MPPM), was synthesized and characterized by \(^{1}\)H NMR, FTIR, and XRD. Its effect on the thermal stability and flammability properties of linear low-density polyethylene (LLDPE) was investigated. The thermogravimetric analysis data exhibited that MPPM enhanced the char formation and the thermal stability of LLDPE at high temperatures. The cone calorimeter results showed that addition of MPPM to LLDPE reduced greatly the peak of heat release rate, total heat release, mean mass loss rate, and fire growth rate index in all LLDPE composites. Moreover, MPPM increased the fire performance index of LLDPE and led to achieve V-0 rating in UL-94V test. The morphology, FTIR, and EDXS analysis for char residue after cone colorimeter test showed the formation of thermally stable char containing Al, Si, –\(\hbox {CH}_{2}\)–, P–O, P–O–C, C–N, and C=N. This meant that MPPM was efficient in reducing the fire hazardous of LLDPE.

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.