Macromolecular Symposia最新文献

In light of the ever-increasing demand for lightweight materials suitable for heat transport applications, many efforts are devoted to enhancing the thermal properties of polymer-based nanocomposites via nanofillers. In the present study, nanocomposites based on epoxy resin, including 3 wt% of multiwalled carbon nanotubes (MWCNTs), are prepared and then thermally characterized. More in detail, it is investigated the temperature increase over time, due to the Joule heating effect, when different voltage values (70, 80, and 90 V) are applied to the specimens. These experimental measures validate a simulation study performed with commercial software (COMSOL Multiphysics®), which allows the investigation of several thermal aspects of the Joule heating. A perfect agreement between experimental and modeling data is found. This means that, in support of experimental activities, modern computational methods can add knowledge in materials science to discover new advanced materials or investigate the existing ones in depth. The present case study examines the potential use of nano-reinforced polymeric materials for thermal applications involving the Joule effect.

The recycling of carbon fibers (CFs) from composites is becoming a necessity, with a gain both from economic and environmental point of views because carbon fibers are a high value-added material and the energy requirement for their production is pretty high. The use of such recycled fibers needs to find reliable applications to fully close the circular economic loop and here it is demonstrated that their applications as short fiber reinforcement in thermoplastics are not only convenient but as reliable as prostin fibers. This work wants to evaluate the effect of the recycling and reprocessing recycled carbon fibers versus pristine fibers, when inserted in polyprolylene (PP), in the presence of different amounts of compatibilizer to promote a better fiber/matrix interaction.

The current awareness of the environmental impact of the massive consumption of fossil fuel-based resources has prompted the development of biocomposites based on plastic and agro-industrial waste instead of virgin raw materials, promoting the new circular economy trend. This study uses a torque rheometer to analyze the effect of brewers’ spent grain (BSG) on processing a postconsumer high-density polyethylene (rHDPE)-based biocomposite. Processing parameters are measured to contrast the effect of BSG (20 and 40 wt%) and the addition of a coupling agent at low (10 rpm) and high speed (90 rpm). This work allows determining the viability of manufacturing recycled plastic biocomposite with agro-industrial waste at an industrial scale.

Rubber containing nanofiber is investigated as structural modifiers of carbon fiber reinforced polymers (CFRPs) to improve their delamination resistance. The ability to obtain long lasting nanofibrous shape from liquid nitrile butadiene rubber (NBR) has been demonstrated even without requiring instant cross-linking when a second component is used together with NBR in the process. The second component can be a thermoplastic which either melts, such as poly(e-caprolactone) (PCL), or holds steady, as poly(m-phenylene isophthalamide) (PMIA) or nylon 66, during CFRP curing process. Assuming that NBR is not crosslinked, during curing of low T_m thermoplastic-based rubber nanofibers, their morphology is lost, as for NBR/PCL, and both polymers blend with the surrounding epoxy resin thus leading to an outstanding toughening effect, but at the cost of the overall composite mechanical performance. When a second component is used which is preserved in nanofibrous fashion during curing (NBR/PMIA, NBR/nylon 66), instead, a good compromise is achieved, with still outstanding delamination hindering ability, together with almost fully preserved thermo-mechanical performances.

Plastic is a revolutionary material. However, pollution caused by plastic damages the environment, human health, and economy of different countries. It is important to find the new methods for recycling and reusing plastic materials. In this present study, plastic waste coming from high-density polyethylene (HDPE) cups (called HDPE_r in the following) are used together with virgin cork for production of composite materials. Different fractions of virgin cork with HDPE_r are tested and allow to obtain successfully composite materials. The properties of HDPE_r and composite are compared. The morphology of elaborated composite is studied by scanning electron microscope (SEM). The thermal properties are investigated by thermogravimetric analysis (TGA) analysis; the flammability study is performed using a cone calorimeter. Moreover, the mechanical properties of the samples stored under different conditions are studied by tensile strength experiments. The results show that the cork content has an effect on the mechanical and thermal properties. The feasibility of the composites based on cork and HDPE_r wastes opens the way of reusing of these wastes. The formulation of HDPE_r composites must be optimized by adding a flame retardant and a coupling agent.

Aimed by the increasing interest in the field of printed batteries, the study recently has demonstrated the possibility to successfully gravure print composites working as electrodes for Li-ion batteries. Gravure is one of the most appealing printing technique for the mass production of functional layers due to its unique ability to couple high speed and high resolution. The ink formulation is challenging because of the low viscosity ink requirement which makes difficult to obtain the proper functionality of the layer, especially in case of composite materials like electrodes, and a mass loading suitable for practical applications. Changing a material of the composite implies the study of a new gravure ink in terms of formulation and preparation process. Ruling the ink preparation can strongly decrease the process time promoting the industrial use of the gravure printing. For this reason, the study proposes a methodology, mainly based on the capillary number, able to suggest the best receipt for each specific ink. Here, a study case is reported, using lithium manganese oxide (LMO) as active material for the gravure printed cathode manufacturing. Such work gives the possibility to show the proposed methodology for ruling the ink preparation.

Cover:

This issue of Macromolecular Symposia contains selected papers presented at the 11th International Conference on “Times of Polymers (TOP) & Composites” organized by University of Campania “Luigi Vanvitelli”, Department of Engineering, Aversa, Italy, EU and Università Federico II and CRdC Tecnologie, Napoli, Italy, EU between 11 and 15 June, 2023.

The cover is provided by the Guest Editor, Luigi Grassia.

A graphene–polymer composite is used in the manufacture by 3D printing of bipolar plates for fuel cells. This composite is formed by a PVDF matrix with graphene. The thermal and dynamic mechanical characterization of this composite is studied, as well as the density of printed composite. The study finds that the material studied is a semicrystal polymer and is thermally stable. Density depends on filler in 3D printing, decreasing with fill percentage. The mechanical properties of these materials are good for fuel cell applications.

Wrist watches have accompanied people in the most important moments since the 1810s and have undergone an esthetic and mechanical transformation process to align with safety standards and regulations depending on the destination of each type of wrist watch. This article aims to determine the influence of the filling percentage and the most common filling geometry pattern on the mechanical tensile behavior of a watch bracelet model manufactured from flexible filament. The comparative study is carried out on samples with two different filling percentages, manufactured by using the FDM technology from a thermoplastic material polyether-polyurethane elastomer (TPU) with a hardness scale of 82A and thermoplastic elastomer (TPU) with a hardness scale of 93A, these being subsequently subjected to two-direction traction tests with the aim of determining the braking strap models resistance depending on the material hardness, thus, creating the prerequisites for finding a solution to increase the durability of the custom made watch straps from TPU through FDM technology.

The objective of the paper is to investigate the effect of organo-modified sepiolite (MSep) on morphology, mechanical, and viscoelastic properties of polyamide-11 (PA11) prepared by melt compounding at 5 wt.%. The study reveals that the addition of both unmodified sepiolite (USep) and organo-MSep to PA11 improves the reinforcement effect of the nanocomposite materials compared to neat PA11, being however more pronounced for the organo-modified one. Indeed, morphological analysis by transmission electron microscopy (TEM) shows a finer dispersion of organo-MSep in PA11 matrix than the unmodified one, which is characterized by a significant presence of fibers aggregates in number and size. Further, dynamic mechanical analysis (DMA) results are in a good agreement with both tensile properties and TEM observations.