Low-density Polyethylene Waste Research Articles

Thermochemical Valorization of Plastic Waste Containing Low Density Polyethylene, Polyvinyl Chloride and Polyvinyl Butyral into Thermal and Fuel Energy

Pyrolysis is a promising technology for transforming waste plastics (WPs) into high-value products. In the near future it will play a key role in the circular economy, as a sustainable and environmentally friendly method of managing this waste. Although the literature reports on the pyrolysis of plastics, it is focused on pure polymers. On the other hand, the state-of-the-art knowledge about the pyrolysis of mixed and contaminated WPs is still scarce. Industrial waste processing usually uses polymer mixtures containing various impurities that influence the pyrolysis process during chemical WPs recycling. In the paper the pyrolysis of three types of WPs: low density polyethylene (LDPE), polyvinyl chloride (PVC) and polyvinyl butyral (PVB) from repeated mechanical recycling of plastics, as well as their binary and ternary mixtures, is considered. The influence of particular components on the pyrolysis process is analyzed. The aim is to determine synergistic behavior of the mixtures during the pyrolysis process, which is important for increasing the efficiency and quality of the obtained bioproducts. Methods such as thermogravimetric (TG/DTG) analysis coupled with Fourier transform infrared spectroscopy (FTIR) and mass spectroscopy (MS) are used. The variations in the initial and final temperature of pyrolysis, mass loss and mass loss rate are determined. The content of PVC significantly lowers the initial temperature and mass loss and increases the final temperature. The pyrolysis of the considered mixtures shows a noticeable synergism—in the initial stage of pyrolysis up to a temperature around 450 °C, the mass loss is accelerated compared to what is predicted by simple superposition. The inhomogeneity of the mixtures as well as the waste origin causes a significant variation in the activation energy. Three main conclusions are obtained: (i) if the waste does not contain PVC, the pyrolysis is nearly complete at a temperature around 500 °C at a heating rate of 10 °C/min, whereas PVC is not fully processed even at 995 °C; (ii) the synergistic effects affect significantly the pyrolysis process by accelerating some steps and lowering the activation energy; and (iii) the presence of PVC noticeably lowers the temperature of the first stage of PVB pyrolysis. The investigation results prove that chemical recycling of mixed LDPE, PVC and PVB waste can be an effective method of plastic waste management.

Investigation of waste LDPE with Pongamia pinnata seed for sustainable resource recovery: Thermodynamics, Kinetics and artificial neural network modeling for co-pyrolysis potential

Pyrolysis conversion offers the advantages of significant waste reduction and potential energy recovery. This work examined the potential of combining plastic and agricultural wastes as pyrolysis feedstocks. The mixture of waste low-density polyethylene and Pongamia pinnata seeds was analysed using differential and thermogravimetric methods. In addition to the Coats-Redfern (CR) method, Kissinger-Akahira-Sunose (KAS), Flynn-Wall-Ozawa (FWO), Friedman (FRM), and Kissinger (KN) model-free methods were also applied to calculate the kinetic parameters. The apparent activation energy (Ea) calculation demonstrated that the co-pyrolysis conversion required Ea values of 125–154 kJ mol−1. The artificial neural network (ANN) model was considered to validate thermogravimetric data. The R2 values were near unity in training, validation, and testing conditions, with the minimum possible value for mean square error obtained for the considered heating rates. The Pongamia pinnata seeds and waste plastic mixture could surely be utilized to lessen environmental degradation, add value to leftover seeds and waste low-density polyethylene by extracting fuel for transportation and other commercial activities, and produce industrial chemicals, as found through the kinetic modelling, thermodynamic parameters, and ANN modelling.

Utilization of recycled concrete aggregates in LDPE-bonded cementless paver blocks

This study investigates the utilization of recycled concrete aggregates (RCA) in waste low-density polyethylene (LDPE)-bonded, non-traffic cementless paver blocks. RCA is incorporated at varying percentages (0%, 25%, 50%, 75%, and 100%) to replace virgin coarse aggregates. Differential scanning calorimetry (DSC), thermal gravimetric analysis (TGA), and melt flow index (MFI) were performed to characterize the thermal and physical properties of LDPE. RCA was treated using a 2-phase treatment technique to incorporate its efficient utilization. Four types of LDPE-to-aggregate mixes, namely, A (1:2.5), B (1:3), C (1:3.5), and D (1:4), were prepared to determine the optimal ratio and the quality control parameters through trial mixes. Paver blocks were evaluated based on their compressive strength, density, water absorption, and thermal strength stability. The results indicate that performing a double-treatment on RCA, optimized mix ratios, and identifying quality control parameters enhances the overall performance of paver blocks. A 35 MPa strength is achieved with 75% replacement, 1:3.5 LDPE-to-aggregate ratio, 30:70 coarse to fine aggregate ratio, and 50 mm depth, with a melt mixing temperature of 180–210°C. Microstructure analysis reveals a strong inter-transition zone (ITZ) for 75% replacement. The ANOVA, followed by a post-hoc analysis, was performed to validate the significance of these results.

Comparative Analysis of Kerosene Grade Fuel from Pyrolysis of HDPE and LDPE Waste Plastics

To curb the menace of plastic waste and energy crisis, this study investigated the conversion of high-density polyethylene (HDPE) and low-density polyethylene (LDPE) grades of plastics to kerosene. Plastics sourced from dumpsites within Port Harcourt metropolis in Rivers State, Nigeria were shredded and pyrolyzed (thermally degraded under inert condition at a temperature range of 350-400oC). The obtained hydrocarbon liquid was distilled using distillation column at a temperature range of 150-270oC and characterised to evaluate the physico-chemical parameters such as flash point, density, copper corrosion, and calorific value and compared against the acceptable standard. The result showed that these properties were within the permissible limit. However, the sulphur content and smoke point of HDPE and LDPE were above and below the limits, respectively. The GC-MS and GC-FID results of kerosene samples obtained from both grades of plastics indicates that the product comprised C9 to C17 grades.

Laboratory investigation on the properties of warm mixing-recycled asphalt containing waste oil and plastics

ABSTRACT The integration of warm-mix and regeneration technologies is gaining momentum due to its dual advantages: enhancing the utilization of recycled asphalt and promoting environmental sustainability. In this study, these technologies by leveraging waste materials were synergized. Specifically, kitchen waste oil underwent chemical treatment to serve as a rejuvenator, while waste low-density polyethylene was transformed into pyrolysis wax, a beneficial additive for the asphalt mix. Utilizing these waste components, a sustainable warm mixing-recycled asphalt blend was formulated. This blend’s efficacy was meticulously evaluated through viscosity tests, rheological assessments, four-component analyses, and FT-IR evaluations. Optimal results emerged when incorporating 5% waste pyrolysis wax and 3.3% waste oil into warm recycled asphalt, notably improving viscosity reduction, high-temperature performance, rutting resistance, and fatigue life at 25 °C. Moreover, the four-component test shows the component of aged asphalt after adding the optimal combination is basically consistent with that of the neat asphalt. Importantly, FT-IR tests affirmed that pyrolysis wax bolstered the blend’s oxidation resistance. Through gray correlation analysis, we deduced that asphalt’s component changes are intricately linked with rheological property variations. Notably, the carbonyl index exhibited a pronounced negative correlation with rutting and fatigue life.

3D Oleophilic Sorbent Films Based on Recycled Low-Density Polyethylene.

Recycling low-end, one-time-use plastics-such as low-density polyethylene (LDPE)-is of paramount importance to combat plastic pollution and promote sustainability in the modern green economy. This study valorizes LDPE waste by transforming it into 3D oleophilic swellable thin films through a process involving dissolution, phase separation, and extraction. These films are subsequently layered using a customized polypropylene (PP) based nonwoven fabric separator and securely sealed in a zigzag pattern. The zigzag-shaped seal enhances the adhesion of pollutants to the sorbent by providing wire curvatures that increase retention time and uptake capacity. As a result, the sorbent exhibits impressive oil uptake capacities, with immediate and equilibrium values of 120 g/g and 85 g/g, respectively. Notably, the as-prepared sorbent demonstrates low water retention and high selectivity for oil, outperforming commercially available oil sorbents. The unique design involving a 3D-film structure, superposed films, and a zigzag-shaped seal offers a sustainable and value-added solution to the issues of LDPE waste and oil spills on water surfaces.

Pengaruh Penggunaan Limbah Plastik LDPE sebagai Modifikator Campuran AC-WC

In recent years, the increasing amount of plastic waste in many cities in developing countries, including Kupang City, has become a serious environmental problem. The use of plastic waste as a pavement material is one solution to deal with the problem of plastic waste. One type of plastic that can be used as an asphalt mixture modification material is Low Density Polyethylene (LDPE). This research aims to determine the use of LDPE plastic waste modified with AC-WC (Asphalt Concrete-Wearing Course). Five variations of AC-WC mixture were made based on LDPE plastic waste content of 6, 7, 8, 9, 10% based on optimum bitumen content (OBC). Marshall test method was used to determine the OBC and to evaluate the marshall characteristics of LDPE modified AC-WC. The OBC of conventional AC-WC was found to be 5.23% by weight of total aggregate while the ptimum plastic modified bitumen content (OPMBC) of LDPE modified AC-WC was 7.45% by weight of OBC. AC-WC modified with 7.45% LDPE waste had 47.98% higher OPMBC compared to conventional AC-WC

Eco-synthesis, characterization and application of waste plastics pyrolysis char in arsenic removal from contaminated water: An integrated circular framework with parametric response surface methodology optimization-cum-artificial neural network model

Eco-synthesis of a novel, cost-effective activated adsorbent from waste low-density polyethylene plastic pyrolysis char at 550 °C and its arsenic adsorption potential in simulated aqueous media has been investigated. Characterization reveals good surface chemistry and evolved morphology of activated char adsorbent with carbon structures at high pyrolysis temperature, thereby facilitating high arsenic adsorption uptake. A unique integrated framework of kinetic equilibrium investigation, parametric optimization applying response surface methodology (RSM) with responsive arsenic adsorption efficiency and artificial neural network (ANN) model for response validation has been presented. There is reasonably good fitting of experimental equilibrium figures into the Langmuir isotherm model (R2 = 0.9920). The effects of adsorbent pyrochar dose, arsenic concentration, contact time and pH on the arsenic removal capacity have been depicted via conjugate RSM graphs. The ANN regression curves showed R2 value of 0.99436, validating the model with ANN architecture as 4–8-1. Iron oxide complexation with arsenic on adsorbent surface is reported to play a dominant role in the proposed adsorption mechanism. The proposed hybridized model can be applied to examine the adsorptive removal of various contaminants in water. Techno-economic analysis of scaled-up community arsenic filter showed high removal efficiency (> 90%) of arsenic by activated plastic pyro-char adsorbent from contaminated water at an affordable cost of 0.67 $/m3 of treated water. The activated plastic waste pyro-char with an adsorption capacity of 7.21 mg/g is, therefore, environmentally sustainable in plastic waste management in the post-pandemic era for a ‘waste to wealth’ circular economy with perspective arsenic removal from contaminated water.

Catalytic pyrolysis of waste high-density (HDPE) and low-density polyethylene (LDPE) to produce liquid hydrocarbon using silica-alumina catalyst

Catalytic pyrolysis of waste HDPE and LDPE polyethylene was successfully carried out using a silica-alumina catalyst at 450 °C under N2 atmosphere. The synthesized silica-alumina is mesoporous and shows type IV isotherm. Thermal pyrolysis (without any catalyst) provided 47% wax-like hydrocarbons at 485 °C. On the other hand, more than 80% liquid yield was achieved using silica-alumina catalysts from waste HDPE and LDPE. The highest liquid yield was obtained from LDPE (87.69%) than HDPE (83.25%) at a catalyst-to-plastic ratio of 1:25. The 1H NMR shows that the liquid product does not contain any aromatic compound. The GC-MS, 1H NMR, and FTIR confirmed that the liquid contains linear and branched alkanes and alkenes. J. Bangladesh Acad. Sci. 47(2); 195-203: December 2023

Utilization of fuel energy from single-use Low-density polyethylene plastic waste on CI engine with hydrogen enrichment – An experimental study

An effective strategy to reduce global waste is to convert the waste into Energy effectively. Single-use Low-density polyethylene (LDPE) plastic waste poses an environmental challenge by slower decomposition. Pyrolysis is one of the best techniques for converting waste plastics into Waste Low-density polyethylene pyrolysis oil (WLPO), a useful energy source similar to diesel. Operating an engine directly with neat WLPO lowers the performance and increases carbon monoxide, unburnt hydrocarbons, and smoke emissions than diesel. Hence, to enhance the performance and emission characteristics of the engine operating with WLPO dual fuel mode, different flow rates of hydrogen induction from 3 to 12 lpm were studied. The results were compared with diesel and neat WLPO. 12 lpm of hydrogen induction shares 15.19 % of hydrogen energy in combustion for WLPO. Compared to neat WLPO, 12 lpm hydrogen induction has a percentage increase of 22.89 in brake thermal efficiency, 15.88 in peak pressure, 60.85 in heat release rate, and 61.46 in Nitrogen oxides, as well as a percentage decrease of 53.42 in smoke, 48.94 in carbon dioxide, 53.99 in unburnt hydrocarbons, and 86.86 in carbon monoxide. Also, these are all similar to and better than the neat diesel operation except for the NOx emission. The hydrogen induction with WLPO increases the engine performance and reduces the smoke and carbon emissions. This fuel usage with hydrogen in IC engines indirectly supports LDPE plastic waste reduction by utilization and reduces objectionable emissions.

Plastic Waste Sheets Effects on Reclaimed Asphalt Pavement Performances

Abstract This paper aims to examine physical and mechanical performances of a Reclaimed asphalt pavement (RAP) material reinforced with 5 to 15 mm size sheets of plastic waste. The three types of plastic used in the study are: low density polyethylene (LDPE), high density polyethylene (HDPE) and polyethylene terephthalate (PET) with 1%, 1.5%, and 2% dosage by weight of aggregates. Obtained Duriez test results testify to a 9% to 30% improvement in moisture resistance for all types of plastic compared to virgin mixture while for LDPE waste plastic type workability test attests an acceptable compaction condition for RAP material with less than 1.5% of waste plastic. Nevertheless, it has been noticed an increase in void index and compaction difficulties starting from 1.5% dosage, resistance to rutting has also improved with the addition of waste plastic, an improvement in fatigue strength was also observed particularly at 2% dosage.

Characterisation of new sustainable gypsum composites with low-density polyethylene waste from single-use bags

The main objective of this research is to determine the feasibility of using Low-Density Polyethylene (LDPE) waste as secondary raw material in the production of new eco-friendly gypsum composites. For this purpose, LDPE waste in crumb form has been incorporated as a partial replacement by weight of the plaster material powder at percentages of 1%, 2% and 3%. Additionally, the gypsum binder in traditional gypsum composites has been replaced for LDPE waste in granulated form, at percentages of 2.5%, 5.0% and 7.5%. The experimental campaign has involved a detailed physical and mechanical characterisation of the gypsum compounds produced to study their potential applications in the construction sector. The results show that more efficient materials are obtained with the addition of these plastic wastes, significantly reducing bulk density and thermal conductivity coefficient compared to traditional gypsum-based materials. Additionally, a considerable reduction in capillary water absorption coefficient and open porosity has been observed. Moreover, the mechanical strengths in flexion and compression surpassed the limits established by current regulations for all the prepared mixtures. In this way, these innovative gypsum composite materials can be useful for application in the production of prefabricated elements, promoting the reincorporation of these plastic wastes, which currently present a challenge from the perspective of sustainability and circular economy.

Performance, emission and combustion characteristics of liquid fuel produced through catalytic co-pyrolysis of waste LDPE and Pongamia pinnata seeds: An experimental investigation in CI engine

As there is an urgent need to address the global problem of increasing plastic waste and decreasing petroleum-based fuels, it is possible to convert waste plastic and unused biomass seeds into fuels that can be utilized in transportation sector. The current study deals with blending pure diesel (D100) with the liquid fuel (PB2) obtained from the co-pyrolysis of Pongamia pinnata seeds and waste low-density polyethylene (LDPE) with Calcium oxide (CaO) as the catalyst. Three blends of D100, namely, PB2@10 (with 10 % blend), PB2@20 (with 20 % blend) and PB2@30 (with 30 % blend) were tested for performance, emission and combustion in an unmodified CI engine for an analytical comparative analysis using standard methods. The results showed that the BSFC was almost same (0.3 kg/kWh) at higher loads for all three blends, while the BTE was found to be equal or increased compared to D100 in the range of 27–30 % at higher loads for higher blends. NOx formation was found to decrease by 19.4 % and 13 % at the highest load for PB2@30 andPB2@30. The smoke formation also decreased for all blends (maximum 22.5 %) while the maximum difference of lambda was determined to have decreased in comparison to D100, close to 1 at higher loads. The maximum cylinder pressure and temperature were also found to have increased during combustion by approximately 1 % for PB2@10 while that of PB2@20 and PB2@30 remained quite close to D100. The obtained renewable liquid fuel could certainly be utilized in blends with pure diesel for use in vehicles.

Study on optimal preparation and rheological characteristics of waste low density polyethylene (LDPE)/styrene butadiene styrene (SBS) composite modified asphalt binder

The sustainable utilization of waste low density polyethylene (LDPE) in asphalt pavements has enormous environmental and economic benefits. To enhance and benefit more from LDPE, this study deals with use of LDPE and styrene butadiene styrene (SBS) collectively for composite modification of asphalt binder. The study intends to identify the optimal blending parameters of LDPE/SBS composite modified asphalt binder by using the orthogonal experiment. The paper deals with the investigation of conventional properties and rheological properties such as Penetration, softening point, ductility, Superpave rutting parameter (G*/sinδ), failing temperature, rotational viscosity and multiple stress creep and recovery (MSCR) test parameters of the binder. Moreover, the dispersion of modifiers in asphalt binder is studied by optical microscopy. The test results point out that the optimal blending parameter for preparing LDPE/SBS composite modified asphalt is 90 min of blending at 180 °C maintaining a rate of 2500 rpm. The blending time parameter has the highest influence on the properties, with the blending temperature and blending rate having a relatively lower impact. Although, both the LDPE and SBS individually have a good impact on high temperature characteristics of asphalt binder but together as a composite, in addition to showing improved high temperature properties, they also reveal high resistance towards permanent deformation and better elastic behaviour. It is concluded that the LDPE/SBS composite modified asphalt binder performs well and is recommended better for high temperature climates. Furthermore, it is good way to enhance the application of LDPE in pavement industry and promote environmental sustainability.

Laboratory evaluation of properties of modified asphalt binder with different types of additives

This research aims to assess the properties of Polymer Modified Bitumen (PMB) binder prepared with different types of additives such as (Waste low density polyethylene (W-LDPE) and crumb rubbers (CR)and Styrene Butadiene Styrene (SBS)). Most of these additives are sustainable materials since it is derived from old scrap materials. All the above-mentioned materials (W-LDPE, CR and SBS) were added with percentages of (2, 4, and 6 percentage) of the weight of pure asphalt binder. Several tests were conducted to evaluated the properties of improved asphalt binder such as penetration test, Ductility test, Softening point test, Rotational viscosity test as well as thin-film oven test. The results of investigation revealed that, the using of different types of PMB significantly improved the physical properties and performance of asphalt. The using of sustainable waste materials such as W-LDPE and CR significantly improve the properties of PMB and contribute in recycling great amount of waste materials. Also, the results showed that the using of high percentage of SBS (6%) significantly increase the viscosity of asphalt binder and that can affect workability of Hot Mix Asphalt (HMA) compared with same percentages of W-LDPE and CR).

Biodegradation of low-density polyethylene (IDPE) by bacteria isolated from dump sites in some metropolitan cities in north central Nigeria

In this study, biodegradation of Low-Density Polyethylene (LDPE) by bacteria isolated from dump sites was evaluated in a liquid Basal Salts Medium. The bacteria, including Psuedomonas aeruginosa, Bacillus megaterium, Providencia stuarti, Alcaligenes faecalis, Enterobacter hormaechei, Klebsiella pneumonia and Proteus vulgaris were isolated from soil samples taken from municipal dump sites in some metropolitan cities in North Central Nigeria, namely, Abuja, Makurdi and Jos and screened for their ability to utilize LDPE using the clear zone method. 0.500 gram waste LPDE strips (1 cm x 5 cm) were placed into a 500 milliliter flask containing sterilized liquid medium at 30 °C and incubated in a rotary shaker for eight (8) weeks. Each bacterium was added to a separate flask. Biodegradation was measured by pH changes of the media and gravimetrically by weight loss of the waste LDPE strips two weekly during the incubation period. The results obtained showed a gradual decrease in the pH of the media originally set at 7.05 with incubation time for all isolated bacteria. Psuedomonas aeruginosa and Providencia stuarti recorded the highest weight loss of the LDPE strips after eight (8) weeks at 19.80±0.04 %, with a final pH of 3.75±0.01 and 19.20±0.42 %, and final pH 4.85±0.01 respectively followed by Bacillus megaterium at 13.40±0.10% and final pH of 3.95±0.01. Klebsiella pnuemonia and Proteus vulgaris recorded the least gravimetric weight loss at 1.40±0.02 %, with a final pH of 4.75±0.01 and 0.80±0.01 %, pH 4.85±0.01 respectively. This work reveals that bacteria play a vital role in the degradation of low-density polyethylene waste in the natural environment. This can be applied to the development of commercial bioreactors in the future for the degradation of polyethylene wastes.

Optimum conditions for the biodegradation of waste low-density polyethylene strips by bacteria isolated from parts of north central Nigeria

Optimum conditions (Temperature, pH and incubation time) were studied for selected bacterial isolates Pseudomonas aeruginosa1(PA1), Pseudomonas aeruginosa2 (PA2), Bacillus megaterium, Providencia stuarti, Alcaligenes faecalis, Enterobacter hormaechei, Klebsiella pneumonia and Proteus vulgaris to biodegrade low-density polyethylene (LDPE) waste by using Basal Salts Medium (BSM) containing 0.500g LDPE strips (1 cm by 5 cm each) using changes in mechanical properties and weight loss of the strips as indicators for ability of these microorganisms to degrade LDPE. The results revealed that four of the eight bacterial isolates, Pseudomonas aeruginosa1, Pseudomonas aeruginosa2, Bacillus megaterium, and Providencia stuarti showed high ability to degrade the LDPE strips after 8 weeks of incubation in liquid Basal Salts Medium at pH 6.5 -7.5 and 32oC. The tensile strength of the LDPE strips was reduced by 0.047±0.41 MN/M2 (47%) for P. aeruginosa1, 0.040±0.30 MN/M2 (40%) for P. aeruginosa2, Bacillus megaterium, 0.033±0.61 MN/M2 (33%), and Providencia stuarti, 0.027±0.41 MN/M2 (27%). The weight loss of the LDPE recorded for Pseudomonas aeruginosa1 was 19.80±0.04 %, for Pseudomonas aeruginosa2 19.40±0.08 %, 13.40±0.10 %, for Bacillus megaterium and 19.20±0.42 % for Providencia stuarti respectively. There was significant difference in the weight loss of the LDPE strips at pH 6.5 for Bacillus megaterium, Providencia stuarti, Alcaligenes faecalis and Enterobacter hormaechei and at 30-32 oC for Pseudomonas spp., Bacillus megaterium, Klebsiella pneumonia and Proteus vulgaris(P>0.05 %).

Catalytic Pyrolysis of Waste Low-Density Polyethylene (LDPE) Carry Bags to Fuels: Experimental and Exergy Analyses

The present investigation reports the results of experiments related to the conversion of low-density polyethylene (LDPE) waste carry bags to fuel through an economic catalytic pyrolysis method in a batch reactor using zinc oxide (ZnO) as the catalyst. Plastics are highly beneficial for the day-to-day activities of human beings; however, their decomposition is limited due to their strong covalent bonding. Degradation of these big molecules into smaller ones or monomers has been attempted by several researchers in recent decades, with limited success. Pyrolysis is one of the ideas used to convert plastics, with the crowded structure of polymers, into fuel rather than small molecules. Among these plastics, LDPE is widely used as carry bags throughout the world, and, herein, the results of catalytic pyrolysis of the conversion of LDPE into fuel are reported. A compact laboratory-scale batch reactor, specially designed at our laboratory, was used to carry out the pyrolysis process. Different dosages of ZnO were used as a catalyst to carry out the pyrolysis at a specific temperature. The optimal dosage of ZnO for a 50 g waste LDPE batch was found to be 0.6 g to get the maximum oil yield. The yielded oil was analyzed chemically through Fourier transform infrared spectroscopy (FTIR) and a Reformulyzer M4 Hydrocarbon Group Type Analyzer. Evaluation of physical and chemical exergy along with exergetic efficiency of the process was carried out. The described experiments and the results represent a small but significant step toward curbing the menace of plastic solid wastes, which are degrading the environment and human life worryingly, and allowing them to be utilized for generating low-cost fuel for transportation and other applications.

Accelerated aging of polymer composite from Pennisetum purpureum fibers with recycled low-density polyethylene

The use of natural fibers (NF) as reinforcement in polymer composites have been an interesting option to improve their mechanical properties and to decrease production costs since several crops can produce large amounts of NF with low cost. This is particularly attractive for polymer waste recycling that depends of the production of cheap materials to be economically viable. Elephant grass ( Pennisetum purpureum schum) is a tropical climate plant of fast growth with high potential for production of NF. However, studies on the use of P. purpureum fibers as reinforcement in polymers, mainly for recycled polymers, have been restricted. The aims of this study was to evaluate the action of the P. purpureum fibers on the properties of composites using matrix of low-density polyethylene waste (LDPE-w) as well as to verify the behavior of recycled polymer when submitted to the accelerated photochemical aging using UVA radiation. LDPE-w and LDPE-w composite with P. purpureum fibers (LDPE-composite) were analyzed at different aging times by tensile and impact tests, melt flow rate, scanning electron microscopy and Fourier transform infrared. It was verified that P. purpureum fibers induce defects in matrix of LDPE-w, decreasing the performance of mechanical properties. Similar effect also occurs when LDPE-w is submitted to the first hours of accelerated aging. On the other hand, effects of stabilization of the degradation on the polymer matrix can be attributed to the P. purpureum fibers at high aging times. Thus, P. purpureum presents high potential for use as reinforcement in recycled thermoplastic waste.

Investigating the Use of Post-Consumer LDPE Waste and Stone Dust in Sustainable Concrete Composites

The construction industry is one of the largest producers of greenhouse gases and waste materials. One potential solution to reduce the environmental impact of construction is to use sustainable materials in the production of concrete. The effects of adding low-density polyethylene (LDPE) waste and stone dust on the mechanical properties of the 7-days cured composite materials adopting two independent categorical variables with five levels each, creating 25 groups were investigated. The dependent variables are compressive strength, tensile strength, flexural strength, and water absorption. The results show that increasing LDPE waste content and stone dust content improves the mechanical strength of the composite material but increases water absorption. The optimal combination of LDPE waste content and stone dust content is 30% LDPE waste and 40% stone dust, based on the highest values of compressive, tensile, and flexural strength and the lowest value of water absorption in the group. It also provides linear regression models and correlation analysis to determine the relationships between LDPE waste content and each dependent variable. On this basis, it suggests that LDPE waste can improve the mechanical properties of the composite material and its water resistance, but the optimal amount of LDPE waste depends on the type of material and application. The study concludes that incorporating LDPE waste and stone dust into composite materials can be a sustainable solution for waste management and the production of low-cost, high-performance materials.