Mechanical Properties Of Recycled Material Research Articles

Super-resolution Fluorescence Imaging of Recycled Polymer Blends via Hydrogen Bond-Assisted Adsorption of a Nile Red Derivative.

A key challenge in the recycling of multilayer plastic films of polyethylene and polyamide, as typically used for food packaging, is to assess and control the phase separation of the two types of polymers in the recycled material, the specifics of which determine the mechanical strength of the recycled material. However, visualizing the polyamide-in-polyethylene domains with conventional fluorescence methods or electron microscopy is challenging. We present a new approach that combines the point accumulation in nanoscale topography (PAINT) super-resolution method with a newly synthesized Nile Red probe (diOHNR) as the fluorescent label. The molecule was modified to undergo a hydrogen bond-assisted interaction with the polyamide phase in the blend due to its two additional hydroxyl groups but preserves the spectral properties of Nile Red. As a result, the localization density of the probe in the PAINT image is 13 times larger at the polyamide phase than at the polyethylene phase, enabling quantitative evaluation of the spatial polyamide/polyethylene distribution down to the nanoscale. The method achieved a spatial resolution of 18.8 nm, and we found that over half of the polyamide particles in a recycled sample were smaller than the optical diffraction limit. Being able to image the blends with nanoscopic resolution can help to optimize the composition and mechanical properties of recycled materials and thus contribute to an increased reuse of plastics.

Advancing Plastic Recycling: Challenges and Opportunities in the Integration of 3D Printing and Distributed Recycling for a Circular Economy.

The concept of the circular economy has emerged as a promising solution to address the mounting concerns surrounding plastic waste and the urgent need for sustainable resource management. While conventional centralized recycling remains a common practice for plastic waste, centralized facilities may prove inadequate in handling the ever-increasing volumes of plastic waste generated globally. Consequently, exploring alternative recycling methods, such as distributed recycling by additive manufacturing, becomes paramount. This innovative approach encompasses actively involving communities in recycling practices and promotes a circular economy. This comprehensive review paper aims to explore the critical aspects necessary to realize the potential of distributed recycling by additive manufacturing. In this paper, our focus lies on proposing schemes that leverage existing literature to harness the potential of distributed recycling by additive manufacturing as an effective approach to plastic waste management. We explore the intricacies of the recycling process, optimize 3D printing parameters, address potential challenges, and evaluate the mechanical properties of recycled materials. Our investigation draws heavily from the literature of the last five years, as we conduct a thorough critical assessment of DRAM implementation and its influence on the properties of 3D printing structures. Through comprehensive analysis, we reveal the potential of recycled materials in delivering functional components, with insights into their performance, strengths, and weaknesses. This review serves as a comprehensive guide for those interested in embracing distributed recycling by additive manufacturing as a transformative approach to plastic recycling. By fostering community engagement, optimizing 3D printing processes, and incorporating suitable additives, it is possible to collectively contribute to a more sustainable future while combatting the plastic waste crisis. As progress is made, it becomes essential to further delve into the complexities of material behavior, recycling techniques, and the long-term durability of recycled 3D printed components. By addressing these challenges head-on, it is feasible to refine and advance distributed recycling by additive manufacturing as a viable pathway to minimize plastic waste, fostering a circular economy and cultivating a cleaner planet for generations to come.

Improving the mechanical properties of 3D printed recycled polypropylene‐based composites through adjusting printing temperature

AbstractThis work aimed at investigating the effects of recycling on the mechanical properties of recycled polypropylene (PP)‐based composites and improving the mechanical properties of recycled materials by adjusting the remanufacturing temperature. In this study, 3D printing was selected as the remanufacturing approach and the composites were ground and reextruded up to nine times to simulate mechanical recycling. The gel permeation chromatography results indicated that the recycling led to a reduction in molecular weight, increasing the melt fluidity of the materials. Excessive melt flow of material during printing caused the poor quality of printed parts with macro and micro defects, deteriorating the mechanical properties of the printed specimens. To improve the final quality and mechanical properties of the printed specimens, melt flow during the printing of recycled materials was adjusted by tuning the printing temperature. The results found that the mechanical properties of the recycled PP‐based composites were well enhanced by using tuned printing temperature.

Mechanical Properties of Recycled Polymer Materials in Additive Manufacturing

The publication focuses on the testing of the tensile strength of samples produced by Fused Filament Fabrication additive manufacturing technology. Three materials rPLA, rPETG and rPET were tested. These materials are recycled PLA (Polylactic Acid), PETG (Polyethylene Terephthalate Glucol) and PET (Polyethylene Terephthalate). These materials were used to create samples for tensile testing according to ASTM D638. In addition to testing the materials, the methodology was also tested using sets of specimens printed with no outer perimeters, one outer perimeter and two outer perimeters. Tensile diagrams were created from the measured data. Statistical processing and comparison of the measured data is performed in the publication. In the discussion, a comparison of the mechanical properties of recycled materials for 3D printing versus virgin materials for 3D printing by Fused Filament Fabrication technology is made.

Evaluation of cement treated reclaimed asphalt pavement and recycled concrete pavement bases

Cement stabilization is the most frequently used technique to enhance the mechanical properties of recycled materials. Reclaimed Asphalt Pavement (RAP) and Recycled Concrete Aggregate (RCA) are abundantly available recycled materials and utilization of these materials in road construction is a sustainable and eco-friendly process. However, the advantage of cement stabilization of RCA over RAP and blending with Conventional aggregates (VA) as a base and subbase course material at different stabilization levels is unknown. In the current study the same is investigated by stabilizing mixes with cement contents varying from 2 to 6% and blending with VA compared in terms of physical properties, compaction characteristics, and the performance tests like Unconfined Compressive Strength (UCS), Indirect Tensile Strength (ITS), and Modulus of Elasticity (E) at 7 days of curing period. From the results, it is observed that recycled aggregate blends need higher cement contents to satisfy the specifications as base layer for high volume roads and the stabilization of RCA is more pronounced compared with RAP. Significant improvement in strength is observed when blended with VA at all cement contents. However, RCA mixes achieved maximum strength at equal proportions of RCA and VA. No particular trend is observed in Optimum Moisture Content (OMC) and Maximum Dry Density (MDD) for RCA blends due to the non-homogeneous distribution of mortar. The Elastic modulus of the RCA mixes declines with RCA content at higher cement content due to brittle nature. Summarily, 25% RAP, 25% RCA and 50% RCA blends at 6% cement performed well.

The Potential of Reusing Technical Plastics

The paper will focus for technical plastics, which are comprised of high performing segment of synthetic plastics with excellent thermal and mechanical properties in comparison to commodity plastics. Although commodity plastics contribute to 80% of the total plastic consumed worldwide, technical plastics had seen immense development in past decades mainly due to their superior performance and their market value is predicted to reach above $90 billion by 2020. While technical plastics are generally expensive than commodity plastics, they exhibit superior mechanical strength, high heat resistance, toughness, rigidity and ease to process. Due to these exceptional characteristics, they are extensively used in electrical and electronics, consumer goods and transportation applications. This high growth and extensive usage of technical plastics had led to huge amount of waste generation especially from end-of-life waste electrical and electronic equipment (WEEE) which mainly composed of acrylonitrile butadiene styrene (ABS) and polycarbonate (PC) plastics. Generally, these materials from the plastic waste show good properties and can be recycled. The recycling of WEEE possess certain challenges such as fraction of WEEE are composed of over 10 different types of polymers, presence of different types of fillers, colorants, fire retardants and finally oxidative degradation of butadiene rubber phase in electronics products during service time which deteriorate mechanical performance. However, using methods such as melt blending had shown to improve the mechanical properties of recycled material and enabling the possibility of recycled technical plastic to make their way back into more consumer and industrial products.

Low temperature solid‐state extrusion of recycled poly(ethylene terephthalate) bottle scraps

AbstractThe processing of poly(ethylene terephthalate) (PET) involves thermal and hydrolytic degradation of the polymer chain, which reduces not only the intrinsic viscosity and molecular weight, but also the mechanical properties of recycled materials. A novel PET/bisphenol A polycarbonate/styrene–ethylene–butylene–styrene alloy based on recycled PET scraps is prepared by low temperature solid‐state extrusion. Hydrolysis and thermal degradation of PET can be greatly reduced by low temperature solid‐state extrusion because the extrusion temperature is between the glass‐transition temperature and cold‐crystallization temperature of PET. Modification of recycled PET by low temperature solid‐state extrusion is an interesting method; it not only provides an easy method to recycle PET scraps by blend processing, but it can also form novel structures such as orientation, crystallization, and networks in the alloy. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 102: 2692–2699, 2006

Chemical modification of virgin and recycled poly(ethylene terephthalate) by adding of chain extenders during processing

The processing of recycled poly(ethylene terephthalate) (PET) involves thermal and hydrolitic degradation of a polymer, which reduces the molecular weight, the intrinsic viscosity, and the mechanical properties of recycled materials. Degradative effects can be limited by using chain extenders. Preliminary tests show that the diisocyanates are more reactive toward the end groups of virgin PET than are bis-oxazolines or diepoxides under the experimental conditions used. So, samples of modified virgin PET with diisocyanates possess molecular weight and intrinsic viscosity (Mw > 60,000 g/mol and [η] > 1 dL/g) superior to those of virgin PET (Mw > 40,000 g/mol and [η] > 0.70 dL/g). Chemical modification of recycled PET by diisocyanates leads to an increase in the molecular weight from 30,000 to 51,000 g/mol, the intrinsic viscosity from 0.60 to 0.84 dL/g, and the mechanical properties, particularly the elongation at break, from 5 to 300%. Chemical modification of recycled PET by injection molding is an interesting method from an industrial point of view because it provides a recycled material possessing properties close to virgin PET in one-step processing. © 2001 John Wiley & Sons, Inc. J Appl Polym Sci 79: 1816–1824, 2001