Pretreatment of Plastic Waste: Removal of Colorants from HDPE Using Biosolvents

Plastics recycling remains a challenge due to the relatively low quality of the recycled material, since most of the developed recycling processes cannot deal with the additives present in the plastic matrix, so the recycled products end up in lower-grade applications. The application of volatile organic solvents for additives removal is the preferred choice. In this study, pretreatment of plastic packaging waste to remove additives using biosolvents was investigated. The plastic waste used was high-density polyethylene (HDPE) with blue and orange colorants (pigment and/or dye). The first step was to identify the type of colorants present in the HDPE, and we found that both plastics presented only one colorant that was actually a pigment. Then, limonene, a renewable solvent, was used to solubilize HDPE. After HDPE dissolution, a wide range of alcohols (mono-, di-, and tri-alcohols) was evaluated as antisolvents in order to selectively precipitate the polymer and maximize its purity. The use of limonene as solvent for plastic dissolution, in combination with poly-alcohols with an intermediate alkyl chain length and a large number of hydroxyl (OH) groups, was found to work best as an antisolvent (1,2,3-propanetriol and 1,2,4-butanetriol), leading to a removal of up to 94% and 100% of the blue and orange pigments, respectively. Finally, three cycles of extraction were carried out, proving the capability of the solvent and antisolvent to be recovered and reused, ensuring the economic viability and sustainability of the process. This pretreatment provides a secondary source of raw materials and revenue for the recycling process, which may lead to an increase in the quality of recycled polymers, contributing to the development of an economical and sustainable recycling process.

Fully Recyclable Bio-Based Epoxy Formulations Using Epoxidized Precursors from Waste Flour: Thermal and Mechanical Characterization

Organic wastes represent an increasing pollution problem due to the exponential growth of their presence in the waste stream. Among these, waste flour cannot be easily reused by transforming it into high-value-added products. Another major problem is represented by epoxy-based thermosets, which have wide use but also poor recyclability. The object of the present paper is, therefore, to analyze both of these problems and come up with innovative solutions. Indeed, we propose a completely new approach, aimed at reusing the organic waste flour, by converting it into high-value epoxy-based thermosets that could be fully recycled into a reusable plastic matrix when added to the waste epoxy-based thermosets. Throughout the research activity, the organic waste was transformed into an epoxidized prepolymer, which was then mixed with a bio-based monomer cured with a cleavable ammine. The latter reactant was based on Recyclamine™ by Connora Technologies, and in this paper, we demonstrate that this original approach could work with the synthetized epoxy prepolymers derived from the waste flour. The cured epoxies were fully characterized in terms of their thermal, rheological, and flexural properties. The results obtained showed optimal recyclability of the new resin developed.

POROUS PLASTIC MATRIX TABLETS OF LEVETIRACETAM FOR ZERO-ORDER CONTROLLED RELEASE: DEVELOPMENT AND FORMULATION OPTIMIZATION

Objective: The prior objective of the current research work was to develop once-daily levetiracetam extended/controlled-release tablets having zero-order release kinetics with the plastic matrix as the release retarding element. For a high water-soluble drug, the formulation of a dosage form so as to have an extended drug release has always been a difficult task. Methods: In the current work, levetiracetam which is a highly soluble drug was taken as the model drug for which extended-release matrix tablets were developed using varied plastic polymers like Polyvinyl acetate (PVAc), Polyvinyl chloride (PVC), Eudragit RSPO and Eudragit RLPO. PVP was considered as a pore-forming agent and PEG 6000 was taken as a water regulating agent. The porous plastic matrix tablets were prepared by embedding the drug in solvent-activated polymer dispersion followed by drying, sieving, mixing with other excipients and finally compressed. Including physical characterization studies and drug release studies, the tablets were subjected to SEM studies before and after the dissolution studies to analyze the effect of the pore former. Results: Pre-compression mixtures exhibited good packageability of 81-92% and hence the compressed tablets were strong enough with good tensile strength in the range of 0.78–0.90 N/mm2. Drug release study results showed that the drug release was controlled for a period of 12–24h. PVAc had shown better controlled-release among all the plastic polymers taken. PEG 6000 in combination with PVP produced the desired zero-order drug release. Conclusion: The levetiracetam porous plastic matrix tablets were developed with zero-order drug release that was effectively controlled for 24hr.

Creation of Basalt Plastics with Different Types of Hybrid Matrices

Basalt plastic, thanks to its complex of valuable operational properties, has a potential variety of applications. the article describes the technology of production of basalt plastics with various types of hybrid matrices, one of the components of which is cured in the molding process, and the second-like a binder in natural materials, retains its viscoelastic state. The viscoelastic component makes it possible to increase the deformation properties in the zones of their location, preventing cracking under increased loads. As a result of the conducted mechanical tensile tests, the average values of absolute breaking forces, tensile strength and elongation during fracture of basalt plastic samples with different types of hybrid matrices were obtained. The addition of viscoelastic components (such as technical wax, anaerobic, and organosilicon polymer materials) to the basalt plastic matrix allows to increase the elongation at fracture by 2...5%. Anaerobic polymer material in the basalt plastic matrix allows to increase the tensile strength of the composite material, as well as significantly reduce the dispersion of the measured values. This provides an effective prediction of the operational properties of the structural material in the design of products. On the basis of microanalysis of the structure of basalt plastics with different types of hybrid matrices, an explanation of the causes of changes in the mechanical properties of the resulting composite materials is given.

Influence of Elastic Modulus of Matrix on Conductivity of VGCF Dispersed in Plastic Matrix

Pressure-sensitive conductive material is used for various pressure sensors consists of a polymer nanocomposite with carbon nanotubes (VGCF). And the resistance in it were changed by adding applied load. Recently, carbon nanotubes (VGCF) has drawn attention as a function filler that imparts various functions to a resin, including electrical properties. In polycarbonate (PC) composite with VGCF, the resistance decreases with increase in applied load. And increase of the addition amount of VGCF was enhanced the mechanical properties and electronic properties. In addition, this conclusion suggested that strain of PC/VGCF caused reducing the resistance. Therefore, changing matrix is predictably effective on electrical properties in pressure-conductive materials. In the present study, we used various matrix had different elastic modulus. The addition amount of VGCF was 12.5% volume rate. We made silicone/VGCF and polyethylene (PE)/VGCF and polycarbonate (PC)/VGCF by twin screw extruder and injection moldings. To clarify the influence of elastic modulus of matrix on conductivity of VGCF dispersed plastic matrix composites. The experimental results showed that conductive property of pressure-sensitive conductive materials is related to elastic modulus of them.

Broadband asymmetric light transmission interfaces for luminescent solar concentrators

Luminescent solar concentrators (LSC) are actively researched to be incorporated in multi-functional building envelope systems. They consist of a plastic matrix with absorbing-emitting media that guides and concentrates light to...

Effect of wood particle size on the water absorption of wood-plastic composites

The main aim of this paper is to present the research findings which come out from the experimental determination of the influence of input raw material properties and composition on the water absorption of wood-plastic composites. During the WPCs production, important raw material parameters such as wood sawdust particle size, wood/plastic concentration ratio or type of plastic matrix can be recognized. In this research study, the aim was to produce WPCs of an acceptable and competitive level of quality which is determined from the final mechanical properties of WPCs. Particle size of wood sawdust used for production of WPC has significant influence on mechanical properties of composites and also on other important properties (water absorption, hardness, frost resistance, etc.). Using a variety combination of influencing variables the final quality of composites and also the operating parameters of the injection molding press can be improved. Their effect can be seen from the quality indicators and from the operating parameters of the injection press which has a direct impact on the production costs. The paper deals with the determination of the impact and the relationship between the input wood sawdust particles sizes, wood/plastic concentration ratio and water absorption of composites. By side intention of authors is to determine the possibilities of waste raw materials usage. The experimental research findings were obtained using a semi-operational injection molding press where the injection is provided by a working screw. As the input raw material, spruce sawdust, HDPE plastic matrix and recycled HDPE, represented by lids from PET bottles, was used. The effect of the input wood sawdust particle size on water absorption was determined according to a combination and default levels of wood/HDPE concentration ratio, using recycled HDPE instead of virgin HDPE and particle size of wood sawdust.