Mixture Of Low-density Polyethylene Research Articles

Obtaining and Characterizing New Types of Materials Based on Low-Density Polyethylene and Thermoplastic Starch

Significant interest is devoted to the development of new polymer blends by using concepts of the circular economy. Such materials have predetermined properties, are easy to recycle, ecological, and have a low carbon footprint. This research presents obtaining and characterization of polymer blends based on low-density polyethylene (LDPE) and thermoplastic starch (TPS). In the first stage, TPS was obtained through the gelatinization process, and, in the second stage, mixtures of LDPE and TPS were obtained through a melt mixing process at 150 °C for 7 min. The physical–mechanical characteristics of the samples, like hardness, elongation at break, rebound resilience, and tensile strength, were determined. The sample containing maleic anhydride grafted low-density polyethylene (LDPE-g-MA) as a compatibilizer shows improvements in elongation at break and tensile strength (by 6.59% and 40.47%, respectively) compared to the test sample. The FTIR microscopy maps show that samples containing LDPE-g-MA are more homogeneous. The SEM micrographs indicate that TPS-s is homogeneously dispersed as droplets in the LDPE matrix. From the thermal analysis, it was observed that both the degree of crystallinity and the mass loss at high temperature are influenced by the composition of the samples. The melt flow index has adequate values, indicating good processability of the samples by specific methods (such as extrusion or injection).

Conversion of Low-Density Polyethylene (LDPE) and Mixed Low-Density Polyethylene with Polyethylene Terepthalate (LDPE and PET) into Hybrid Fuel

This research aims to provide the recycling techniques of low-density polyethylene (LDPE) and mixture of polyethylene terephthalate (PET) with low-density polyethylene (LDPE) waste. As a means of converting abundant waste to wealth, pyrolysis of LDPE and mixed LDPE - PET was carried out in a batch reactor made of stainless steel at temperatures between 450 – 460OC. The vapor produced from melting the waste was condensed to form the liquid hydrocarbon (fuel oil) product. The effect of reaction time and product yield were investigated. The physicochemical properties of the pyrolysis oil measured include density, specific gravity, flash point, color, fire point, flammability and viscosity. For the LDPE the flash point, fire point, density, specific gravity, and viscosity was found to be 39.5 oC, 48 oC, 8.1872, 0.793g/cm, 0.775g/cm3, and 1.566 cSt respectively while for the Mixture of LDPE with PET the flash point, fire point, density, specific gravity, viscosity and Sulphur content was found to be 44 oC, 48 oC, 8.1872, 0.7837g/cm, 0.7916 g/cm3, 1.1660 cSt and 8.1872 respectively. These values were found to be within the range of kerosene values. The fuel was tested in both kerosene lamp and petrol generator.

The Effect of Polypropylene and Low-Density Polyethylene Mixtures in the Pyrolysis Process on the Quantity and Quality of the Oil Products

The Effect of Polypropylene and Low-Density Polyethylene Mixtures in the Pyrolysis Process on the Quantity and Quality of the Oil Products

Co-pyrolysis of Azadirachta indica non-edible seed and waste LDPE: Analysis of kinetic models using thermogravimetric analyser and prediction modeling with Artificial Neural Network (ANN)

Energy production from waste biomass seeds and plastic wastes must be done immediately, keeping the future in mind, as waste plastic and seeds have become a major source of attractiveness for producing liquid fuel in a pollution-free environment and disposing of waste plastic, which causes serious environmental issues. In this study, theoretical modeling was used to assess the pyrolysis feedstock potential of Azadirachta indica, or Neem non-edible seeds, and waste LDPE (low-density polyethylene) in a set ratio. Thereafter, the TG-DTG data was applied into artificial neural network (ANN). The Azadirachta indica seed-waste LDPE mixture was TG-DTG examined at three heating rates of 10, 20 and 30 °C/min. The thermodynamic parameters were also obtained at the same heating rates. A blend sample requires less energy to pyrolyze than an individual sample. When ANN prediction modeling was used to predict TG-DTG data, R2 was always found unity in training, validation, and testing, and MSE was minimised for all heating rates. Levenberg-Marquardt trained the ANN model. According to the findings of this study, combining Azadirachta indica seed with waste LDPE could be a workable alternative that would result in an improvement to the process as a whole.

Hydrogenolysis of Polyethylene and Polypropylene into Propane over Cobalt-Based Catalysts.

The development of technologies to recycle polyethylene (PE) and polypropylene (PP), globally the two most produced polymers, is critical to increase plastic circularity. Here, we show that 5 wt % cobalt supported on ZSM-5 zeolite catalyzes the solvent-free hydrogenolysis of PE and PP into propane with weight-based selectivity in the gas phase over 80 wt % after 20 h at 523 K and 40 bar H2. This catalyst significantly reduces the formation of undesired CH4 (≤5 wt %), a product which is favored when using bulk cobalt oxide or cobalt nanoparticles supported on other carriers (selectivity ≤95 wt %). The superior performance of Co/ZSM-5 is attributed to the stabilization of dispersed oxidic cobalt nanoparticles by the zeolite support, preventing further reduction to metallic species that appear to catalyze CH4 generation. While ZSM-5 is also active for propane formation at 523 K, the presence of Co promotes stability and selectivity. After optimizing the metal loading, it was demonstrated that 10 wt % Co/ZSM-5 can selectively catalyze the hydrogenolysis of low-density PE (LDPE), mixtures of LDPE and PP, as well as postconsumer PE, showcasing the effectiveness of this technology to upcycle realistic plastic waste. Cobalt supported on zeolites FAU, MOR, and BEA were also effective catalysts for C2–C4 hydrocarbon formation and revealed that the framework topology provides a handle to tune gas-phase selectivity.

Effect of starch nanocrystals addition on the physicochemical, thermal, and optical properties of low‐density polyethylene (LDPE) films

AbstractThe aim of this study is to add rice and potato starch nanocrystals (SNCs) to a low‐density polyethylene (LDPE) matrix to reinforce its structure, improve its characteristics, and broaden its applicability. The SNCs were produced by acid hydrolysis and applied to the LDPE matrix by extrusion at a concentration of 0.5% and 1%. The films were characterized in terms of physical–chemical, thermal, and structural properties. The addition of 1% SNCs produced from rice starch reduced the oxygen permeability to 1.57 × 10−4 (ml mm/MPa/min/cm2) and increased the thermal stability of the films. The addition of potato starch SNCs in a 1% proportion increased the crystallinity of the films to 81.6%. Therefore, the incorporation of starch SNCs in the LDPE matrix showed adequate compatibility and the ability to improve the properties of the films. The mixture of LDPE with biodegradable polymers can be an alternative that can contribute to the increase in the rate of biodegradability.

Effect of Basalt Fibres on Thermal and Mechanical Properties of Recycled Multi-Material Packaging

The low-density polyethylene (LDPE)/aluminium mix obtained after the recovery of cellulose from multilayer aseptic packaging used in the food and beverage industry is generally destined for energy recovery. In this work we propose it as a matrix for value-added composite materials. A commercially available material (EcoAllene) obtained from multilayer packaging recycling was reinforced with short natural basalt fibres up to 30 wt.% by twin screw extrusion, aiming at improving the mechanical profile of such material and widening its applications. Thermal characterizations by thermogravimetric analysis and differential scanning calorimetry showed that the material is indeed a complex mixture of LDPE, HDPE, PP, and aluminium. Basalt fibres did not modify the melting and crystallization profile as well as the global degradation behaviour. Composites were then subjected to tensile, bending, Charpy impact tests and the fracture surfaces were investigated by scanning electron microscopy. Results highlighted a beneficial effect of basalt fibres to stiffness and strength in both loading conditions, with improvements by 107% and 162% for tensile and bending strength, respectively, which were linked also to a 45% enhancement of impact strength. This increased mechanical performance is promising for their use in automotive interiors and outdoor decking applications.

Lignin-Mediated Preparation of Hierarchical ZSM-5 Catalysts and Their Effects in the Catalytic Co-pyrolysis of Softwood Biomass and Low-Density Polyethylene Mixtures

Lignin-Mediated Preparation of Hierarchical ZSM-5 Catalysts and Their Effects in the Catalytic Co-pyrolysis of Softwood Biomass and Low-Density Polyethylene Mixtures

Exothermic Effects in Mixtures of Low-Density Polyethylene with 90 wt % of Low-Molecular-Weight Organic Compounds after Plastic Deformation under High Pressure

Exothermic Effects in Mixtures of Low-Density Polyethylene with 90 wt % of Low-Molecular-Weight Organic Compounds after Plastic Deformation under High Pressure

Biomass waste conversion into value-added products via microwave-assisted Co-Pyrolysis platform

The current work is focused to investigate the synergetic interactions between biomass (groundnut shell, bagasse, rice husk, Prosopis juliflora, mixed wood sawdust) and hydro-rich plastics (Low-density polyethylene (LDPE) and Polyisoprene (PIP)) in microwave co-pyrolysis. The heating value of co-pyrolysis oil (38–42 MJ kg−1) was enhanced dramatically compared to biomass pyrolysis oil (20–28 MJ kg−1). Among biomasses studied, the energy yield of bio-oil obtained from rice husk with LDPE mixture is higher (42%). Whereas bio-oil from polyisoprene and groundnut shell mixture has the highest energy yield (78%). Each gram of co-pyrolysis feedstock consumed 12–18 kJ of incident microwave energy. An increase in overall energy efficiency in co-pyrolysis (62–70%) is observed compared to that of biomass pyrolysis (46–57%). Actual mass yield (31–47 wt%) of co-pyrolysis bio-crude is lower than its predicted value (42–57 wt%) due to the formation of lighter gases. In the combinations of and hydrogen-rich plastics considered in this study, it was found that co-pyrolysis of LDPE: bagasse has produced bio-crude with the highest yield of aliphatic hydrocarbons (25.78%), and co-pyrolysis of LDPE: rice husk has produced bio-crude with high selectivity of aromatics (11.7%). The extent of de-oxygenation was promoted in the co-pyrolysis due to synergy.

Abiotic and biotic degradations of a LDPE blend in soil of South Brazil landfill

Polyethylene degrades slowly when discarded in the environment and exposed to natural weathering. A solution to this problem is the incorporation of additives to accelerate its biodegradation. In the present study, a biodegradable low-density polyethylene (LDPE) blend was obtained by the mixture of LDPE with a biodegrading additive (8% w/w) and the effect of accelerated weathering on biodegradation process was assessed. Chemical, mechanical, thermal, and morphological properties of non-aged and aged samples were studied. Results showed that aging process caused changes on structural characteristics (insertion of functional groups), morphological (appearance of micro-cracks and increased roughness), mechanical (greater stiffness and loss of plasticity) and thermal (lower degree of crystallinity and thermal stability) properties. The presence of biodegrading additive contributed to aging process, since polar functional groups were inserted into additive exposed to soil underwent greater degradation than their non-aged counterparts. CO2 production of aged LDPE blend demonstrated that accelerated weathering influences biodegradation process. In this work, due to availability of O2 gas, aerobic microorganisms can be the main responsible by the material deterioration, leading to production of microbial biomass, CO2 and H2O. Thus, the results of biodegradation (166 days) obtained in this work are promising, once it was reached a natural soil from South Brazil landfill.

4-Lump kinetic model of the co-pyrolysis of LDPE and a heavy petroleum fraction

Pyrolysis of post-consumer plastics is a promising strategy to recover valuable hydrocarbons from waste streams. In this study, the lumping approach is adopted to model the kinetics of a continuous co-pyrolysis process for low-density polyethylene (LDPE) and a heavy petroleum residue fraction (HPR). All evolving species are merged in four lumps based on their boiling range: residue (R, >410 °C), spindle oil (SO, 350–410 °C), light liquids (LL, IBP – 350 °C) and gas (G, noncondensable at 0 °C). The experimental results of a tubular laboratory cracker with a mixture of LDPE and HPR at different reactor lengths between 19.4 and 33 m provide data to estimate kinetic parameters for all six considered reactions and the overall reaction enthalpy. Based on the rate equations for irreversible, monomolecular, first-order reactions and the mass and heat balance of an incrementally modeled tubular reactor, a MATLAB algorithm solves the optimization problem including a bottom-up approach to find suitable initial values. The calculated frequency factors vary over a wide range from 102 to 108 s−1 and the obtained activation energies are between 147 and 313 kJ mol−1. The determined value for the overall reaction enthalpy is 4669 kJ mol−1. The results of the modeled system are in good agreement with experimental yields and can be implemented into a process model of the LDPE-HPR co-pyrolysis for simulation and optimization purposes.

Predicting gas solubility in semi-crystalline polymer solvent systems by consistent coupling of Sanchez-Lacombe EOS with a continuum mechanics approach

Solubility of gases in polymers plays a crucial role in several industrial sectors. This spans from chemical, pharmaceutical to polymer industry. While, in last years thermodynamic models have been successfully developed to predict the solubility of fluids in polymers, which are above the melting temperature or in a glassy state, thermodynamic models for predicting the fluid solubility in semi-crystalline polymer solvent mixtures are rare and even controversially discussed in literature. In this work a new theoretical framework based on a consistent coupling of SL-EOS with a continuum mechanics approach is developed to explain phenomena occurring due to gas solubility in semi-crystalline polymers on the one hand and predict gas solubility in semi-crystalline polymer solvent mixtures with a high accuracy on the other hand. Herein, the framework is applied to a n-butane/linear low density polyethylene mixture as well as to an i-butane/linear low density polyethylene mixture. The solubility of n-butane in the respective polymer is predicted for various temperature and pressure states, where the polymer is due to temperature variations in the molten as well as in the semi-crystalline state. A very good agreement between predicted and experimental solubility data could be achieved.

Estimation of protective ability, physical and mechanical properties of polymer inhibited films

Metal products are subjected to atmosphere corrosion during transporting and longtime storing. Utilization of packing materials eliminating the access of water vapor and aggressive gases to the metal products surface is an important ways of struggling against the corrosion. Among the methods of metal products protection against the corrosion, application of volatile inhibitors is one of most effective one. As a carrier of the volatile corrosion inhibitors, polyethylene films can be used. Study of strength and barrier properties of polyethylene films with a volatile corrosion inhibitor and without it accomplished. As an object of the study, the films, produced under laboratory conditions by extrusion with blowing of low-density polyethylene and mixture of low-density polyethylene and IFKhAN volatile inhibitor, developed by the Institute of Physical Chemistry (Academy of Sciences of RF). For accelerated corrosion tests, samples of 08пс cold rolled steel used. The prepared samples packed in the studied films, a part of the closed airtight, and another part – not compact. It was traced, that the samples packed in the polyethylene film without the volatile inhibitor, had a point corrosion. The airtight sealed polymer film casings protect the carbon steel much better, comparing with the not compact casings. The surface of samples corrosion worms, which were airtight packed, was 0.15%, not compact ones – 0.33%. When inhibited polymer film was used for not compact packing, the corrosion had a uniform character, no local corrosion worms (pitting) was observed. The corrosion products were spongy, weekly cohered with the basic metal, easily peeling off. During the test period, the samples airtight packed in polyethylene film, containing IFKhAN volatile inhibitors, had no areas of corrosion. It was found, that input of inhibitor into the polyethylene matrix results in decreasing the film strength properties due to formation structure defects at the sub-molecular level during the extrusion, and also as a result of inhibitor desorption.

Supercritical Fluid Media in Challenges of Substance and Material Dispersion

The paper deals with the problem of material dispersion using supercritical fluid media. At the same time, emphasis is made on modifications (SAS, GAS, SEDS and ASES) of the supercritical fluid anti-solvent method of dispersion. The results of SAS method implementation for dispersion of pure polycarbonate and polycarbonate doped with “CdSe/CdS - core/shell” quantum dots (carried out in the pressure range of 8.0-25.0 MPa at temperatures of 313.15 K and 358.15 K) are submitted. The range of the operating parameters has been established through the example of pure polycarbonate dispersion, which provides the production of nanoparticles with the size range of 10 100 nm. Encapsulation of CdSe/CdS quantum dots into polycarbonate using the SAS method has no effect on optical properties of the encapsulated quantum dots. The results of paracetamol dispersion using the SEDS method are presented. The effect of operating conditions of the paracetamol dispersion process on morphology of the obtained product is described. Co-dispersion of ethylene–vinyl acetate copolymers and low-density polyethylene mixtures by SEDS method has been carried out under pressures of 8.0-25.0 MPa at temperatures of 313 K, 323 K, and 333 K. The comparison of melting and crystallization between the resulting copolymer mixtures and mixtures with the same composition obtained by mixing in the liquid melt, has shown that implementation of SEDS results in an increase of crystallinity degree of the polymer mixtures.

The Effect of Mixing Conditions on the Mechanical Properties of Polymer Mixtures of Low-Density Polyethylene and Rubber Powder Based on Ternary Ethylene–Propylene–Diene Elastomer

The effect of mixing conditions on the properties of polymer mixtures of low-density polyethylene with vulcanizates and rubber powder based on ternary ethylene–propylene–diene elastomer was studied. Polymers were mixed by two techniques: using a rotor disperser by high-temperature shift deformations and in a Brabender mixer. The analysis of mechanical characteristics of rubber plastics manufactured using different types of equipment showed that deformation and strength properties of rubber plastics mixed in a rotor disperser are higher compared to those made in a Brabender mixer.

Crystallization of Polymer Mixtures in the Course of Their Solution-Enhanced Dispersion by Supercritical Fluids

The characteristics of phase equilibria for systems including toluene, supercritical CO2, and ethylene–vinyl acetate copolymers (EVACs) were studied experimentally. Solution enhanced co-dispersion of EVAC and low-density polyethylene mixtures by supercritical fluids (SEDS) was performed under pressures of 8.0–25.0 MPa at 313, 323, and 333 K. The comparison of melting and crystallization in the resulting copolymer mixtures with those in the same-composition mixtures obtained by melt mixing showed SEDS to result in an increase in the degree of crystallinity of the polymer mixtures.

Influence of Moringa oleifera derivates in blends of PBAT/PLA with LDPE

Abstract There are few studies about Moringa oleifera derivates in polymer developments where vegetable oil was used as a plasticizer and a biodegrading agent. The polymerization of moringa oil (MO) was carried out assisted by microwaves without catalysts presence. There aren’t studies about the polymerization of MO using microwaves technology. Moringa’s oil and its polymer (PMO) were used as a biodegrading agent for mixtures of low density polyethylene (LDPE) with poly(butylene adipate-co-terephthalate)/poly(lactic acid) (PBAT/PLA). The mixtures producted films that were characterized and submitted to biodegradation analysis in order to discuss the influence of moringa components. Results showed that both moringa components improved thermal properties and reduced the crystalline phase of the mixture. The addition of PMO had improved the biodegradation capacity up to five times while MO had improved it up to three times. The results showed the greatest influence of moringa components on biodegradation of mixtures with cited polymers.

Production of clean oil with low levels of chlorine and olefins in a continuous two-stage pyrolysis of a mixture of waste low-density polyethylene and polyvinyl chloride

In this study, a continuous two-stage pyrolyzer consisting of an auger reactor and a fluidized bed reactor was applied to produce an oil with a low level of chlorine from a mixture of low density polyethylene and polyvinyl chloride waste. In the experiment, the auger reactor operated at 300–400 °C, thus releasing HCl prior to the main pyrolysis in the fluidized bed reactor. The auger reactor also played a role in elevating vibrational modes of molecules to promote the production of ethene, propene, and 1,3-butadiene. The yields of those monomers totaled 29 wt.%. Pyrolysis oils obtained from the fluidized bed reactor were enriched with aromatics up to 95 wt.%. Together with the two-stage pyrolyzer and a lime hot filter, a pyrolysis oil having only 9.25 ppm chlorine could be obtained. This value is the lowest ever reported. This study showed that a two-stage pyrolyzer together with a lime hot filter could produce a pyrolysis oil with a very low chlorine content. Further, this work implies that the production of valuable monomers from the pyrolysis of polyolefins can be enhanced when a two-stage pyrolyzer is applied.

Effect of the Prodegradant-Additive Plastics Incorporated on the Polyethylene Recycling

The effect of degraded plastic with prodegradants on the polyethylene properties was studied. First, the mixture of low-density polyethylene (LDPE) with 5 wt.% prodegradant (oxo-degradable) additive was prepared by melt processing using a mixer chamber. Then, the degradation of the mixtures was evaluated by exposing the oxo-degradable LDPE in a Xenon arc chamber for 300 hours. The degraded material was characterized by infrared spectroscopy (FTIR) assessing the carbonyl index and the hydroperoxide band. Then, different percentages of degraded material (1, 5, 10, 20, and 50 wt.%) were incorporated into the neat LDPE. Mechanical and rheological tests were carried out to evaluate the recycling process of these blends. Also, the feasibility of the blends reprocessing was determined by analysing the melt flow index for each heating process and shear stress applied. It was evidenced that the increment of the content of the degraded material in the neat LDPE decreased the mechanical strength and the processability of blends due to the imminent thermal degradation. All the test results showed that the incorporation of degraded material causes a considerable reduction in the matrix properties during the reprocessing. Nevertheless, at low concentrations, the properties of the oxo-degradable LDPE–LDPE blends were found to be similar to the neat LDPE.