Low Density Polyethylene Blends Research Articles

Migration and storage study of food products packed in biodegradable films (LDPE and Modified Corn Starch)

This study focuses on the migration and storage properties of biodegradable films made from a blend of Low-Density Poly Ethylene (LDPE) and modified corn starch with food products. The overall migration (OM) from the biodegradable film in contact with food products such as potato chips and biscuits were investigated for six months using simulant ‘D’ as per IS 9845:1988. During the migration study, the highest OM was 3.94 mg/dm2 for potato chips and 3.47 mg/dm2 for biscuits, respectively within the permissible limit as per standards. The moisture content of the biodegradable films (T1 and T2) containing potato chips remained consistent with the product standard specification for up to four months. When biodegradable films containing biscuits T1 and T2 were compared to T0 up to four months, they showed 3.61% and 4.02% moisture content, respectively, indicating suitability as a packaging material. Results showed that the peroxide value (PV) of potato chips packed in films of all treatments increased from 1.91 to 6.87 meq kg-1 from 1 to 3 months which indicates the suitability of biodegradable film as a food packaging material. The findings revealed that the OM rate was affected by the type of food packed, duration of contact, and the type of packaging material, well within specifications of the Bureau of Indian Standards. Hence, this biodegradable film can be used for packing food products (Biscuits, Chips) safely.

Migration and storage study of food products packed in biodegradable films (LDPE and Modified Corn Starch)

This study focuses on the migration and storage properties of biodegradable films made from a blend of Low-Density Poly Ethylene (LDPE) and modified corn starch with food products. The overall migration (OM) from the biodegradable film in contact with food products such as potato chips and biscuits were investigated for six months using simulant ‘D’ as per IS 9845:1988. During the migration study, the highest OM was 3.94 mg/dm2 for potato chips and 3.47 mg/dm2 for biscuits, respectively within the permissible limit as per standards. The moisture content of the biodegradable films (T1 and T2) containing potato chips remained consistent with the product standard specification for up to four months. When biodegradable films containing biscuits T1 and T2 were compared to T0 up to four months, they showed 3.61% and 4.02% moisture content, respectively, indicating suitability as a packaging material. Results showed that the peroxide value (PV) of potato chips packed in films of all treatments increased from 1.91 to 6.87 meq kg-1 from 1 to 3 months which indicates the suitability of biodegradable film as a food packaging material. The findings revealed that the OM rate was affected by the type of food packed, duration of contact, and the type of packaging material, well within specifications of the Bureau of Indian Standards. Hence, this biodegradable film can be used for packing food products (Biscuits, Chips) safely

Quantifying nanoscale forces using machine learning in dynamic atomic force microscopy.

Dynamic atomic force microscopy (AFM) is a key platform that enables topological and nanomechanical characterization of novel materials. This is achieved by linking the nanoscale forces that exist between the AFM tip and the sample to specific mathematical functions through modeling. However, the main challenge in dynamic AFM is to quantify these nanoscale forces without the use of complex models that are routinely used to explain the physics of tip–sample interaction. Here, we make use of machine learning and data science to characterize tip–sample forces purely from experimental data with sub-microsecond resolution. Our machine learning approach is first trained on standard AFM models and then showcased experimentally on a polymer blend of polystyrene (PS) and low density polyethylene (LDPE) sample. Using this algorithm we probe the complex physics of tip–sample contact in polymers, estimate elasticity, and provide insight into energy dissipation during contact. Our study opens a new route in dynamic AFM characterization where machine learning can be combined with experimental methodologies to probe transient processes involved in phase transformation as well as complex chemical and biological phenomena in real-time.

Recycled polyethylene/polycarbonate blends compatibilized with oxidized polyethylene/CaCO3

AbstractPolyethylene (PE) and polycarbonate (PC) are not thermodynamically miscible, and they tend to be phase‐separated during melt‐processing, because of significant incompatibility in structures and properties. Interestingly, minerals such as CaCO3 are used in PE‐based supermarket bags for improving surface characteristics. In this study, recycled low‐density polyethylene (LDPE) and PC resins are melt‐blended at 50/50 wt%, without and with oxidized polyethylene (OPE) as a compatibilizer. A parallel experiment is conducted with 50/50 blends of virgin LDPE and PC resins. Various characteristics such as tensile, viscoelastic, melt‐flow, and phase morphology of the materials are analyzed. The 50/50 blend of recycled LDPE/PC blend shows an average tensile strength of 15 MPa, which increases to 24 MPa on the addition of 5 wt% OPE, where total recycled content is 95 wt% including 15 wt% CaCO3. Notably, the presence of CaCO3‐based filler in recycled LDPE has a profound effect in improving the mechanical performance of the materials.

A Study of Recycled Poly(butylene terephthalate) and Low-Density Polyethylene Blend

A Study of Recycled Poly(butylene terephthalate) and Low-Density Polyethylene Blend

Biodegradation of Blends of Low-Density Polyethylene with Natural Rubber in Soil

Biodegradation of Blends of Low-Density Polyethylene with Natural Rubber in Soil

Recycled LDPE/PETG blends and HDPE/PETG blends: mechanical, thermal, and rheological properties

The recycled low density polyethylene (LDPE), recycled high density polyethylene (HDPE) and recycled polyethylene terephthalate G copolyester (PETG) as post-processed plastic wastes from extrusion blow molding process were modified with blending process to improve the properties of those plastic wastes and decrease the amount of plastic wastes in the plastic processing plants. The recycled PETG was blended with recycled LDPE and recycled HDPE in various concentration from 0 wt% to 100 wt% in increments of 10 wt% as referred to LDPE/PETG blends and HDPE/PETG blends respectively prepared by co-twin screw extruder. The addition of PETG in the blending of LDPE and HDPE improved the mechanical properties and MFI of those polymer blends but decreased thermal stability, storage modulus, loss modulus and complex viscosity as compared to those of neat LDPE and neat HDPE. LDPE/PETG blends illustrated better impact properties and flexibility than those of HDPE/PETG blends.

Influence of High-Concentration LLDPE on the Manufacturing Process and Morphology of Pitch/LLDPE Fibres

A high modulus of elasticity is a distinctive feature of carbon fibres produced from mesophase pitch. In this work, we expand our previous study of pitch/linear low-density polyethylene blend fibres, increasing the concentration of the linear low-density polyethylene in the blend into the range of from 30 to 90 wt%. A scanning electron microscope study showed two distinct phases in the fibres: one linear low-density polyethylene, and the other pitch fibre. Unique morphologies of the blend were observed. They ranged from continuous microfibres of pitch embedded in linear low-density polyethylene (occurring at high concentrations of pitch) to a discontinuous region showing the presence of spherical pitch nodules (at high concentrations of linear low-density polyethylene). The corresponding mechanical properties—such as tensile strength, tensile modulus, and strain at failure—of different concentrations of linear low-density polyethylene in the pitch fibre were measured and are reported here. Thermogravimetric analysis was used to investigate how the increased linear low-density polyethylene content affected the thermal stability of linear low-density polyethylene/pitch fibres. It is shown that selecting appropriate linear low-density polyethylene concentrations is required, depending on the requirement of thermal stability and mechanical properties of the fibres. Our study offers new and useful guidance to the scientific community to help select the appropriate combinations of linear low-density polyethylene/pitch blend concentrations based on the required mechanical property and thermal stability of the fibres.

Influence of retarded injection timing on thermal performance and emission characteristics of a diesel engine fuelled with an optimized pyrolytic blend

The enormous rise in plastic waste leads to severe environmental issues and complete removal is a quiet challenge. The entire world focuses on finding new alternate for traditional conventional fuel. The waste low-density polyethylene is chosen as feedstock for the preparation of fuel from thermo-catalytic pyrolysis, considering the silica–alumina catalyst at a reaction temperature of 500 °C. From our previous study, the lower blends of waste low-density polyethylene exhibit a similar performance to diesel. However, brake thermal efficiency and oxides of nitrogen are not encouraging. Further improving combustion behaviour, the present research is carried out at different injection timings. The investigation is carried on standard injection timing of 23°bTDC and three retarded injection timings, namely, 21°bTDC, 19°bTDC and 17°bTDC. Retarded injection timing exhibits higher performance and lower unburned hydrocarbon, oxides of nitrogen and carbon monoxide emissions. However, smoke emission is increased due to the reduced heat release at all the considered test parameters. The result divulges that reduced performance and increased smoke at 17°bTDC due to the lack of burning rate. The combustion behaviour of 20% waste low-density polyethylene by volume at 19°bTDC is similar to that of diesel at 23°bTDC. Hence, the injection timing of 19°bTDC is preferred as an optimized condition for the test fuel 20% waste low-density polyethylene by volume.

Microstructure–sealing performance linkage of metallocene linear low density polyethylene and low density polyethylene blends

The microstructure–sealing performance linkages of linear low density polyethylene (LLDPE) and low density polyethylene (LDPE) blends using thermo-rheological tools are discussed. The effect of molecular architecture in metallocene catalyzed LLDPE (mLLDPE), Ziegler–Natta catalyzed LLDPE (ZN-LLDPE) on the miscibility, and rheological behavior of the blends with LDPE is shown. Even though the macro parameters like density, melt flow rate of the LLDPEs are comparable, subtle differences in the microstructure manifested by comonomer type and its distribution across molecular weight affects the sealing performance of the LLDPE/LDPE blends. For LLDPE matrix, tailor-made comonomer distribution affording thinner lamellas (viz., thickness <11.8 nm) is more critical to sealing process than having total higher comonomer content. For LLDPE/LDPE blends, the thicker lamellae of main chain polymer of LDPE co-crystallize with homo-polyethylene like fraction of LLDPE. The co-crystallization of LLDPE and LDPE helps to achieve hot tack sealing at lower percentage of molten polymer and it appears to be the dominating factor over diffusion of polymer chains across the melt interface to achieve sealing.

Microwave vacuum co-pyrolysis of waste plastic and seaweeds for enhanced crude bio-oil recovery: Experimental and feasibility study towards industrialization

Waste-to-energy is a promising approach to tackle the energy shortage and reduce the environmental pollution. The present study aimed to evaluate the technical and economic feasibility of microwave vacuum co-pyrolysis of seaweeds and low-density polyethylene (LDPE). Although the three studied seaweeds namely; Ulva intestinalis, Sargassum polycystum, and Hypnea valentiae showed similar thermal weight loss profile, U. intestinalis showed the highest biomass and bio-oil yields which resulted in superior bio-oil areal productivity of 30.1 g m−2. Therefore, it was selected for co-pyrolysis with LDPE at different blend ratios. Compared to individual pyrolysis of U. intestinalis, the increase inLDPE ratio enhanced the crude bio-oil production with simultaneous reduction in bio-char yield. The experimental bio-oil yields from co-pyrolysis showed higher values than the corresponding theoretical values, confirming a synergistic effect between the two feedstocks. The bio-oil produced from co-pyrolysis at 75% LDPE blend ratio showed better characteristics compared to the individual pyrolysis. Van Krevelen plot suggested that LDPE produces hydrogen radicals during co-pyrolysis reactions, which increased the H/C ratio and reduced the O/C ratio. GC/MS analysis confirmed that the increase in LDPE stimulates hydrocarbons proportion up to 51.2% at 75% blend ratio with significant reduction in N-containing compounds, carboxylic acids, furans, aldehydes/ketones, saccharides, and phenols. The economic feasibility analysis at a feedstock feeding rate of 11.4 ton h−1 using Aspen Plus showed estimated net profit of 23.17 million US$ for a 20-years life time plant. The present study provides a potential approach for sustainable energy recovery from waste plastic/seaweeds blend using microwave vacuum co-pyrolysis.

Manufacturing Pitch and Polyethylene Blends-Based Fibres as Potential Carbon Fibre Precursors.

The advantage of mesophase pitch-based carbon fibres is their high modulus, but pitch-based carbon fibres and precursors are very brittle. This paper reports the development of a unique manufacturing method using a blend of pitch and linear low-density polyethylene (LLDPE) from which it is possible to obtain precursors that are less brittle than neat pitch fibres. This study reports on the structure and properties of pitch and LLDPE blend precursors with LLDPE content ranging from 5 wt% to 20 wt%. Fibre microstructure was determined using scanning electron microscopy (SEM), which showed a two-phase region having distinct pitch fibre and LLDPE regions. Tensile testing of neat pitch fibres showed low strain to failure (brittle), but as the percentage of LLDPE was increased, the strain to failure and tensile strength both increased by a factor of more than 7. DSC characterisation of the melting/crystallization behaviour of LLDPE showed melting occurred around 120 °C to 124 °C, with crystallization between 99 °C and 103 °C. TGA measurements showed that for 5 wt%, 10 wt% LLDPE thermal stability was excellent to 800 °C. Blend pitch/LLDPE carbon fibres showed reduced brittleness combined with excellent thermal stability, and thus are a candidate as a potential precursor for pitch-based carbon fibre manufacturing.

Utilization of ABS from plastic waste through single-step reactive extrusion of LDPE/ABS blends of improved properties

Chemical mixture (C-M) of low density polyethylene (LDPE) and electronic waste made of acrylonitrile butadiene styrene (ABS) have been prepared via one step reactive extrusion. The morphology of prepared crosslinked blends has been investigated. Single phase morphology has been found in C-M as opposed to two phase morphology in physical blend. The extent of crosslinking has been observed by determining gel content through solvent extraction. The structural changes have been confirmed by FTIR and solid state 13C NMR spectroscopy. The C-M have been tested using DSC and TGA and have found to be thermally stable. The chemical mixture has showed excellent mechanical properties like increment in Young's modulus, ultimate tensile strength. The flexural properties have also been investigated and C-M has found to have enhanced flexural modulus and flexural stress. For C-M to be used in practical heat exposure conditions heat distortion temperature tests have been performed and C-M has shown better properties than pure LDPE and physical blend.

Utilization of LDPE plastic waste on the quality of pyrolysis oil as an asphalt solvent alternative

Natural asphalt cannot be used directly because of hardness and low penetration, so it needs to be softened with a solvent. A solvent that can be used is from oil plastic pyrolysis as an alternative additive. Plastics are now an inseparable item from daily necessities and are the largest pollutant on the environment. Plastic is a polymer that is difficult to be decomposed, and one way to decompose it is through pyrolysis or thermal cracking. This research studies the quality effect of low-density polyethylene (LDPE) plastics waste on the quantity and quality of oil yield produced through the pyrolysis process in the three reactor outlets. LDPE plastics waste used was distinguished: LDPE-White, LDPE Mixed-plastic, and LDPE Blend-plastic. The results showed that, in the process of plastic pyrolysis LDPE, in addition to affecting the yield of produced oil, the quality of plastic is also influenced by the length of time of pyrolysis. The better the quality of the plastic is, the higher the oil yield and the shorter the pyrolysis times are. LDPE plastic pyrolysis at 250 °C produces the maximum yield. Most oil yields, namely 99.78%, 75.60%, and 50.29% were produced by LDPE white plastics, mixed plastics, and blend plastics, respectively, when pyrolyzed for 110, 180, and 270 min. The economic yields of each plastic of 88.78%, 60.68%, and 40.35% were generated if each was hydrolyzed for 60, and 80 min.

Evaluation of Waste Blends with Sewage Sludge as a Potential Material Input for Pyrolysis

In line with the requirements of the circular economy, the European Union’s waste management legislative changes also concern the treatment of sewage sludge. Although sewage sludge production cannot be prevented, its quantities may be reduced by the synergetic effect of energy recovery via choosing a proper technology. Sewage sludge is difficult to apply as fuel alone, because of its high moisture and ash content. However, its energy use will be increased by adding suitable waste materials (different types of plastics, waste tires and paper rejects). Most recently, the thermal utilization of sewage sludge via incineration or pyrolysis has grown in importance. This article describes the fuel parameters of particular waste materials and of their blends with sewage sludge in connection with laboratory-scale thermal decomposition in an inert atmosphere, for their potential use in a semi-pilot plant pyrolysis unit. For pyrolytic application, the results of thermogravimetric analysis are needed in order to know the maximal temperature of thermal decomposition in an inert atmosphere, maximal mass losses, and weight loss rates. The samples of different thermoplastics mixed with sewage sludge, and low-density polyethylene blends with sewage sludge, had the lowest residual masses (70–74%) and the highest weight loss rates (11–19%/min). On the other hand, the blend of polyester rejects from tire processing, paper rejects and sewage sludge had the second highest residual mass (60%) and the lowest weight loss rate (3%/min).

Sustainable Biocomposites from Recycled Bale Wrap Plastic and Agave Fiber: Processing and Property Evaluation.

Plastic recycling to make sustainable materials is considered one of the biggest initiatives toward a greener environment and socioeconomic development. This research aims to investigate the properties of a blend of recycled bale wrap linear low-density polyethylene (rLLDPE) and polypropylene (PP) (rLLDPE/PP 50:50 wt % matrix), which was further reinforced with 25 wt % agave fiber prepared by injection-molding. Different ratios of a combined industrial compatibilizer (maleic anhydride-grafted PP/PE) were used (1–3 wt %), which were compared with a synthesized compatibilizer made from maleic anhydride–PP/rLLDPE in terms of mechanical and thermomechanical properties of the biocomposites. Incorporation of the compatibilizer in the composite improved the interfacial adhesion between the hydrophobic matrix and the hydrophilic agave fiber, which further increased the mechanical properties and heat deflection temperature of the composite. Scanning electron microscopy showed enhanced compatibility and adhesion between the fiber and the matrix by inclusion of 2 wt % compatibilizer. The synthesized compatibilizer-blended composite showed better mechanical properties than the industrial one, which indicates the potential application of this composite (around 62% recycled material) in the manufacture of packaging materials and commodity products.

Strategy for reducing molecular ensemble size for efficient rheological modeling of commercial polymers

We develop a method for efficient prediction of linear and nonlinear rheology of polydisperse polymers by judicious selection of a small number of representative polymer molecules from the large ensemble of chains comprising the molecular weight and branching distribution. Specifically, we use a numerical inversion of the double reptation model to select five or six representative molecular species to optimally fit the linear rheology of commercial polymers and then use the regressed parameters to compute the nonlinear rheology via the Rolie-double-poly (RDP) model. The method is tested for several model systems, namely, two polydisperse linear polystyrene (PS) samples described in Shivokhin et al. [Polym. Eng. Sci. 56, 1012–1020 (2016)] and Munstedt [J. Rheol. 24, 847–867 (1980)], a commercial linear low density polyethylene (LLDPE), and a low density polyethylene (LDPE) whose rheological properties are measured in the current study. For the linear polymers including the PS samples and the LLDPE, the predictions of the “representative” RDP model of the start-up extensional rheology are comparable to those of the “full” RDP model based on all the species drawn from the gas permeation chromatography characterization. The method then successfully predicts the linear rheology of blends of LLDPE and LDPE using the same representative molecules found by fitting each of the pure polymers. Further fitting the extensional rheology of the LDPE requires using the “priorities” q i and stretch relaxation times τ s , i of the representative molecules as adjustable parameters, whose values are then held fixed when predicting the extensional rheology of blends of the LDPE with the LLDPE roughly as successfully as does branch-on-branch model. The reduction in the number of representative polymer species offers new opportunities for faster simulations of flowing polymers, as well as for the prediction of segmental orientation to be used in the modeling of flow-induced crystallization.

Effects of nitrite incorporated active films on quality of pork

Nitrite (0.25–2%) incorporated thermoplastic starch (TPS) and linear low-density polyethylene (LLDPE) blend films were produced by the conventional blown-film extrusion process. Films were characterized and determined for efficacy as active packaging for pork steak. Scanning electron micrographs showed enhanced starch granule disruption due to melting. Increased nitrite contents enhanced the starch network and improved mechanical properties. Water vapor and barrier properties of blend films were improved by nitrite incorporation, with increased compatibility between TPS and LLDPE networks. Films containing 0.5% nitrite effectively improved redness and corresponded to 0.06 ppm residual nitrite and 75 ppm nitrosomyoglobin in packaged pork. Nitrite addition modified protein secondary conformation involving CO stretching bonds via H-bonding, while films with 1% and 2% nitrite significantly inhibited growth of lactic acid bacteria, yeast and mold, and retained softer texture during storage. Nitrite incorporated films were demonstrated as efficient active packaging to improve the quality of red meat products.

Effect of chitosan addition on the properties of low-density polyethylene blend as potential bioplastic

Plastics based on low-density polyethylene (LDPE) blends generally have limited miscibility, and it is difficult to obtain a homogeneous blend. Although they show excellent properties, their thermal degradation rate is a concern. This work aims to realize a homogeneous blend with higher chitosan concentration, thus expected to increase its degradation properties. An extrusion technique successfully synthesized LDPE and chitosan blends. The mixtures were prepared by adding maleic anhydride (MA) and tert-butyl peroxybenzoate (TBPB) as a compatibilizer and initiator, respectively. The addition of MA and TBPB resulted in homogeneous blends and using chitosan concentration of 40 %wt resulted in better tensile strength and elongation at break. The water uptake increased along with chitosan concentration in the blends. The thermal behavior analysis of the blends conducted by simultaneous TG/DTA revealed that the increase of chitosan concentration tends to improve the blend's thermal degradation slightly. Moreover, chitosan addition resulted in approximately a hundred times larger biodegradability compared to plastics based on LDPE alone.

Thermo-mechanical degradation of polypropylene (PP) and low-density polyethylene (LDPE) blends exposed to simulated recycling

Polypropylene (PP) and low-density polyethylene (LDPE) are among the most converted resins; as such, they also have the largest share in municipal waste fractions. Currently, there is a great societal and industrial need to recycle these polymers using thermo-mechanical processes. However, process-induced degradation during recycling operations may lead to irreversible changes. In this study, PP was blended with 0 to 10 wt.% of LDPE was subjected to consecutive twin-screw extrusion cycles (0 to 5 times) to mimic thermo-mechanical recycling. The effect of reprocessing on the rheological, thermal, and mechanical properties of PP/LDPE blends was investigated. An increase in MFR and decrease in viscosity was observed for PP and the blends. DSC results showed that the crystal structure of PP was seriously affected and generated more disorder with reprocessing. Although tensile properties were not substantially affected, all properties had a decreasing trend. While successive thermo-mechanical processing caused chain scission of the PP phase of the blend, the overall property of the studied blend composition maintained acceptable properties. Thus, recycling of PP with low PE blend additive is a feasible option not only to reduce plastic waste but also to generate value from an otherwise waste product.