Summary. - Although Pakistan has an abundance of natural resources, it also faces a significant challenge with plastic

waste, producing 3.3 million tons annually. This environmental issue demands immediate action, especially due to the

Additionally, this study examined the effects of aramid short fibers and thermoplastic polyurethane (TPU) additives on

recycled polyamide-12 (PA-12). The inclusion of TPU decreased the modulus while increasing tensile strain and energy

at break, whereas aramid fibers increased the modulus. Deformation analysis revealed significant strain concentrations

in the central sections of these specimens, underscoring the impact of these additives on mechanical behavior. For

example, PA-12 with 20% TPU exhibited higher maximum deformation, reflecting its enhanced tensile properties.

Moreover, our deformation studies on Poly Butylene terephthalate with 0% HDPE and a blend containing 10% HDPE

demonstrated the influence of HDPE content on elastic strain distribution and total deformation. The findings showed

that the central region experiences substantial elastic deformation, which is critical for understanding stress distribution

in these materials.

Keywords: Environmental sustainability, Thermoplastics, Elastomers, Mechanical Behaviors, Resource Conservation,

Lecturer, NED University of Engineering and Technology (Pakistan),

ifrahasif@neduet.edu.pk, ORCID iD: https://orcid.org/0000-0001-7551-2199

Research Scholar, NED University of Engineering and Technology (Pakistan),

atifshahzad@cloud.neduet.edu.pk, ORCID iD: https://orcid.org/0000-0002-3277-7901

Student, NED University of Engineering and Technology (Pakistan),

arqamhashimi201@gmail.com, ORCID iD: https://orcid.org/0009-0004-5601-3262

economy, growing from a novel material to an indispensable component in countless applications [1]. A study

performed to evaluate blends of post-consumer recycled polypropylene (PPr) and virgin PP (PPv) at 25%, 50%, 75%,

and 100% PPr to assess processability, thermal stability, oxidative resistance, and mechanical performance. Increasing

PPr improved fluidity and inert-condition stability but reduced oxidation resistance and ductility. Extrusion

homogenization enhanced oxidative stability of recycled PP by 22%, supporting its use in circular economy

applications. [2]. Plastic encompasses a broad spectrum of materials with unmatched properties and extraordinary

diversity, finding applications across various sectors. Among these, engineering thermoplastics and advanced

engineering thermoplastics, also known as ultra-polymers, are particularly noteworthy for their unique characteristics

and exceptional performance [3]. Recent advancements in dynamic covalent chemistry have spurred interest in

polymer networks that mimic traditional cross-linked materials while retaining thermoplastic qualities [4].

with viscosity and degradation. Including melt flow rate, shear viscosity, and feedstock type greatly improved

prediction accuracy, with Generalized Additive Models reaching to 85.7% for tensile strength. Results highlight the

Microplastics, often linked to environmental pollutants, can attract materials such as metals, drugs, and polycyclic

aromatic hydrocarbons in aquatic environments [9]. The difficulty in combining PBT and PC for enhanced thermo-

chemical and mechanical resistance is compounded by phase boundary coalescence during melting, leading to

unwanted material segregation [10]. Developing applications for recycled plastics that are as functional as those made

from virgin polymers remains a significant challenge, particularly when integrating recycled HDPE into PE pipe-grade

resins used for pressure pipes [11]. Virgin polypropylene (Mosten TB 003) was mechanically reprocessed up to 18

times to simulate recycling cycles, with mechanical, thermal, and molecular properties evaluated. Reprocessing caused

chain shortening, ~30% molecular weight loss, reduced thermal stability, and yellowing. HS-SPME/GC–MS detected

fewer volatiles in highly reprocessed PP, with key compounds identified at 120 °C. [12].

This innovative method enables the incorporation of various reinforcements and polymeric materials into thermoset

Within the realm of polyurethane, thermoplastic polyurethane (TPU), a segmented block copolymer classified as a

thermoplastic elastomer (TPE), is widely used across numerous industrial domains [18,19]. The pervasive use of plastic

polyolefins, polyesters, and polystyrene, which constitute 80% of the global plastic market, has turned waste disposal

into a significant environmental issue. Consequently, environmental protection organizations and plastics

manufacturers are continually researching innovative methods to recycle and upcycle waste plastics into sustainable

new products [20]. The advent of thermoplastic composites has leveraged the remelting and remolding capabilities of

thermoplastic matrices while preserving the thermomechanical properties of embedded fibers [21].

favored over conventional materials like metals or aluminum [22-24]. In composite materials, plastics often serve as

matrices reinforced with fibers for enhanced strength in specific directions [25,26]. These materials, which exhibit

greater strength compared to simple plastics, are commonly used in constructing industrial pressure tanks, offering high

stress-bearing capability while reducing weight [27,28].

Mechanical properties between virgin high impact polypropylene, injected, and recycled one was compared by

Fernandes and Shazad [29,30]. Two mixtures, one composed of 30% recycled PP and 70% virgin PP, and other one of

50% recycled PP and 50% virgin PP were assessed to investigate the impact of recycling on mechanical properties.

They observed that the tensile properties (ultimate tensile strength, yield strength and strain) did not vary, however, the

impact resistance only for samples with up to 30% recycled PP was acceptable for automotive use. Samples above this

though their strength is rarely evaluated against that of virgin materials. Consequently, it is important to investigate

how recycling affects the mechanical properties of these materials. A simulation-based approach can help analyze their

mechanical properties comparable to virgin polymers, thereby assessing their suitability for similar applications.

2. Methodology. - The major focus of this study was mechanical properties evaluation of recycled plastics commonly

used at domestic and industrial level. Four polymers were selected for recycling purpose due to their extensive use.

These selected polymers are listed below:

extensive examination of their viability for eco-friendly and sustainable applications, providing insightful information

on the industrial utilization of these recycled materials.

Using ASTM D638 for tensile testing and ASTM D256 for impact testing of recycled materials, mechanical properties

were assessed, providing an understanding of the way extrusion parameters affect material qualities for industrial

applications. Tensile tests were performed at room temperature, 20°C, and 60°C in accordance with ISO 527 standards.

When the stress reached 5 MPa, the testing speed was increased to 50 mm/min from 1 mm/min. The data was sampled

side effect of also reducing the yield strength and young’s modulus as illustrated by Fernandes [25]. This drawback

was countered by addition of inorganic fillers such as Calcium carbonate, CaCO3 which provides increased impact

material and pelletized through a 3mm screen. Qualitative analyses revealed a higher CaCO3 level (about 5%) and trace

amounts of rubber. Table III comprised of different mixing compositions, Virgin with recycled bottle material (VRB)

and Virgin with recycled pipe material (VRP).

greatly increases density, from 908 kg/m³ for stabilized recycled polypropylene to 1029 kg/m³ for a 20% calcium

carbonate blend.

The melt flow index also rises with elastomer content, from 14.6 g/10 min for a 5% EOR blend to 19.6 g/10 min. Melt

flow rate measures how easily a polymer flows when melted, which affects its processability during manufacturing.

Density measures mass per unit volume and influences a polymer’s mechanical properties. Both values are important

for optimizing polymer performance in different applications.

The density values of various PVCr composites which are represented in Table III. 5x samples were tested for

evaluation of density fluctuations and mentioned in Table VI. S0 illustrate the minimum amount of recycling and S5

indicate the maximum amount as shown in Table III.

3.2 Melt Viscosity. - The renograms of PVCr composites are characterized in Figure II indicate that recycled polymer

matrix results in the reduction of melt viscosity.

impact on the yield stress and Young's modulus at room temperature. However, the recycling procedure reduced the

impact strength of PP which is the result of additional hardness. The tensile properties of polypropylene were tested at

-20°C, 23°C, and 60°C with various calcium carbonate and elastomer compositions are presented in Table VII.

Maximum deformation (13 mm) was observed from loading end towards center. Significant stress concentration was

noted towards center which indicate the failure point due to potential necking. The deformation decreases towards the

other end of the specimen. The maximum deformation value of 13 mm is higher than that of the recycled PA-12

specimen, suggesting that the addition of TPU affects the mechanical properties and deformation behavior of the

material under the applied load.

ANSYS Simulation of PBTr: Structural dynamics of PBT after adding high-density polyethylene (HDPE) were

performed and the results provided information on the distribution of stress during deformation as shown in Figure

XIV and Figure XV. The behavior of PBT without HDPE is illustrated in Figure XIII in which 3.48mm maximum

deformation achieved. This might direct future optimizations for its use in a variety of engineering settings. This method

stress bearing area.

high-density polyethylene under a specified loading condition. The strain is measured in mm/mm and displayed with a

color gradient, where blue represents the minimum strain (0.000036008 mm/mm) and red signifies the maximum strain

(0.024592 mm/mm). The highest strain is concentrated in the central region of the specimen, while the strain values

decrease towards the ends. This pattern indicates that the central section experiences the greatest elastic deformation,

reflecting the material's response to the applied load and highlighting areas of potential stress concentration and failure.

higher maximum deformation, reflecting its improved tensile properties.

deformation, which is crucial for understanding stress distribution in these materials.

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