Properties Of Linear Low-density Polyethylene Research Articles

Tearing properties, crystallization behavior, microstructure, and morphology of LLDPE with different short branched chain distributions

Abstract The length and distribution of comonomers with short-chain branching (SCB) have a significant influence on the crystallization behavior and crystal structure of polymers, as well as the mechanical properties of the material. This study investigates the crystallization behavior and properties of linear low-density polyethylene (LLDPE) samples with similar density, molecular weight, and branching degree but varying SCB distributions. The results show that LLDPE with butene as the comonomer has a stronger ability to suppress crystallization compared to LLDPE with hexene as the comonomer due to its more uniform SCB distribution. Additionally, among LLDPEs with comonomers of octene, hexene, and butene, the LLDPE with the most uniform SCB distribution exhibits the weakest crystallization ability. Small-angle X-ray scattering (SAXS) and scanning electron microscopy (SEM) results indicate that LLDPE with more uniform distribution of SCB has smaller long-period and more regular lamellar structure. Therefore, LLDPE with more uniform SCB distribution exhibits weaker inhibition ability towards crystallization, leading to less agglomerated phases and weaker phase separation, resulting in higher tear strength.

Impact of Buriti Oil from Mauritia flexuosa Palm Tree on the Rheological, Thermal, and Mechanical Properties of Linear Low-Density Polyethylene for Improved Sustainability.

Recent advancements highlight the utilization of vegetable oils as additives in polymeric materials, particularly for replacing conventional plasticizers. Buriti oil (BO), extracted from the Amazon's Mauritia flexuosa palm tree fruit, boasts an impressive profile of vitamins, minerals, proteins, carotenoids, and tocopherol. This study investigates the impact of incorporating buriti oil as a plasticizer in linear low-density polyethylene (LLDPE) matrices. The aim of this research was to evaluate how buriti oil, a bioactive compound, influences the thermal and rheological properties of LLDPE. Buriti oil/LLDPE compositions were prepared via melt intercalation techniques, and the resulting materials were characterized through thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), Fourier-transform infrared (FTIR) spectroscopy, scanning electron microscopy (SEM), mechanical property testing, and contact angle measurement. The addition of buriti oil was found to act as a processing aid and plasticizer, enhancing the fluidity of LLDPE polymer chains. TGA revealed distinct thermal stabilities for buriti oil/LLDPE under different degradation conditions. Notably, buriti oil exhibited an initial weight loss temperature of 402 °C, whereas that of LLDPE was 466.4 °C. This indicated a minor reduction in the thermal stability of buriti oil/LLDPE compositions. The thermal stability, as observed through DSC, displayed a nuanced response to the oil's incorporation, suggesting a complex interaction between the oil and polymer matrix. Detailed mechanical testing indicated a marked increase in tensile strength and elongation at break, especially at optimal concentrations of buriti oil. SEM analysis showcased a more uniform and less brittle microstructure, correlating with the enhanced mechanical properties. Contact angle measurements revealed a notable shift in surface hydrophobicity, indicating a change in the surface chemistry. This study demonstrates that buriti oil can positively influence the processability and thermal properties of LLDPE, thus expanding its potential applications as an effective plasticizer.

Tannic acid-loaded halloysite clay grafted with silver nanoparticles improved the mechanical, antimicrobial, and degradation properties of linear low-density polyethylene films

Synthetic polymers used for food packaging contribute to plastic pollution due to poor degradability. While they prevent the entry of microorganisms, they may not protect against spoilage microorganisms in the packed food. Nanofillers have been used to improve such properties, but end-of-life degradation remains an issue, making plastic a persistent pollutant. Here, we tested a nanocomposite (Nc) of tannic acid-loaded halloysite nanotubes grafted with silver nanoparticles as a reinforcement to enhance the mechanical, antimicrobial, and degradation properties of Linear low-density polyethylene (LLDPE) films. LLDPE films incorporated with Nc significantly improved tensile strength (TS), elongation at break (EB), and oxygen permeability rate. Nc incorporated (at 5%-and 10%) LLDPE films exhibited a 1.89–2.85 log10 reduction in multi-drug resistant Staphylococcus aureus 1158c in chicken fillets. Both film types demonstrated silver migration below the European Food Safety Authority-mandated acceptable limit. Nc/LLDPE films disintegrated faster when exposed to incandescent light for 6 h, evidenced by significant reduction of weight, TS, and EB. Fourier-transform infrared spectroscopy, scanning electron microscopy, and X-ray photoelectron spectroscopy suggested oxidative degradation and breakdown of the polymer. Conclusively, Nc improved the functional properties and degradation rate of LLDPE films when exposed to light, showing potential for enhancing the sustainability of synthetic polymers.

Water Absorption Effect on Tensile Properties of Linear Low-Density Polyethylene (LLDPE) Blend with Recycle Acrylonitrile Butadiene Rubber Gloves (NBRr) in Saline Water

Nowadays, waste acrylonitrile butadiene rubber glove (NBRr) has been studied for use in building materials. The primary limitation of using rubber in construction was its low water absorption capacity. The goal of this research is to investigate the effect of Linear Low-Density Polyethylene (LLDPE) on water absorption and the temperature differential (20 and 30 oC) of NBRr blender composite in distilled water (DW) and saline water (SW). The rubber glove has been blended with heated two-rolled mills at 120 °C. The substance had been compressed using a hot press. Five samples had already been created. The sample was formed like a dumbbell. The five samples were immersed in DS and SW for 30 days at temperatures of 25°C and 35°C, respectively. The result shown the tensile strength, elongation at break Eb and Young’s modulus of LLDPE/NBRr blend decrease. The tensile properties of saline water lower compare to distilled water due to corrosion and degradation. Saline water contains dissolved salts, which can contribute to corrosion and degradation of the materials. The presence of salts can accelerate chemical reactions, leading to the degradation of the polymer matrix and the rubber phase. This degradation can weaken the material and reduce its tensile strength. Moreover, as the temperature increases, the thermal energy also increases, causing the polymer chains to gain more kinetic energy. This increased energy disrupts the intermolecular forces and reduces the overall molecular interactions within the material. Weaker intermolecular interactions lead to a decrease in tensile strength. As conclusion, hydrothermal effect tensile properties when temperature increase tensile properties decrease. distilled water has better diffusion than saltwater. LLDPE/NBRr blend was discovered that both distilled and salt-water absorption resulted in a decrease in tensile properties.

Enhancement of insulation properties of LLDPE by PPy-functionalized PS-NPs

The strategy of functionalized PS-NPs via PPy (PPy@PS-NPs) forming heterogeneous interface composition is highly efficient in increasing the insulation properties of linear low-density polyethylene (LLDPE). The morphology results show that PPy@PS-NPs are monodispersed in the LLDPE matrix after melting blend, which exhibits unparalleled engineering application value. The electrical insulation results show that PPy@PS-NPs introduced into the LLDPE matrix can reduce its DC electrical conductivity, enhance DC breakdown strength, and inhibit space charge accumulation. When the PPy@PS-NPs concentration is 0.5 wt%, the DC breakdown strength is 35.3 % higher than that of LLDPE. Mechanism research indicates that the depths of carrier traps are decreased due to high electron affinity caused by the introduction of PPy@PS-NPs, but the trap density is increased. The reported strategy of using functionalized polymer nanoparticles to improve the polymer insulation property provides new insights for developing future high-insulation materials and other functional materials based on functionalized polymer nanofillers.

Development and optimization of machine learning models for estimation of mechanical properties of linear low-density polyethylene

A hybrid methodology was developed and implemented for estimation of polymeric mechanical properties in rotational moulding process. The considered polymer in this study is linear low-density polyethylene, known as LLDPE, which has extensive application in plastic industry. The mechanical properties of the polymer were assessed and correlated to the oven residence time to build the predictive model of moulding process. A tiny dataset containing only 25 data rows via a number of machine learning models were assessed. Oven residence time is the only input, while the LLDPE's properties including tensile strength, impact strength, and flexure strength are the outputs considered in the machine learning models. We used tree-based ensemble methods for modeling in this work and they are tuned using FA (Firefly Algorithm) optimizer to find optimal hyper-parameters of them. Finally, the optimal models had shown a great performance to predict the output accurately. For tensile strength, the best model (FA-ET) has an R2 value of 0.9994, this score is 0.9995 for impact strength and 0.9968 for flexure strength. The tree-based models tuned in this study revealed to be robust in estimation of polymeric properties and can be used to obtain the products with the best quality.

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.