Abstract
Brands and products counterfeiting, and falsification are global problems for the development and distribution of high‐tech industrial and food products, which affect world economies. One ...way to solve these problems is to develop original packaging with protection elements and labeling against counterfeiting, which excludes the possibility of replication and forgery by printing or other methods. The most reliable way to protect packaging from counterfeiting is the use of new materials with unique optical properties and constantly updated technologies for packaging manufacturing and labeling. This paper proposes a new multi‐level technology for the design, manufacture and hidden labeling of polymer packaging made from several layers of transparent polymer films. The design and marking of the multilayer films are combined with perforation, thermal treatment and heat sealing of the package. The reliability of the proposed markings is based on the characterization of optical pleochroism effects in transparent multilayer polymer materials with shape memory. The thermomechanical and optical properties of films made of bulk thermoplastics (polypropylene, polystyrene, polyvinyl chloride and polyethylene) were characterized in polarized light. The modification and combination of these films provide a high color difference and sufficient contrast of hidden markings, allowing to identify genuine products by bar codes formed from shape memory films in sealing seams of flexible polymer packaging.
Due to the increasing discussion about sustainable and CO2-reduced materials, the demand for cellulose-based fibres as a reinforcing component in thermoplastic composites has increased considerably. ...Knowledge about the possibilities of modifying fibres for improved adhesion
to the plastic matrix is essential in this context. The fibre/matrix adhesion in cellulose fibre-reinforced polymers is of considerable importance for the design of composite materials. Unfortunately, there are no standards for many essential methods to determine fibre/matrix adhesion. In
this review article, various methods for measuring the interfacial shear strength between fibres and matrix, as an indirect characterisation of adhesion, are presented. Additionally, a brief overview of different methods for surface modification of cellulose fibres to improve the adhesion
to a thermoplastic matrix is given. This review focuses on the fact that the parameters for the production of test specimens as well as the test method itself can vary considerably from study to study. Because of this, the comparison of data from different publications is not always possible.
Therefore, in this article, the main influencing factors and differences in the methods are presented and discussed. Based on a systematic review and a clear description and discussion of the methods, the reader is given a broad basis for a better understanding of characteristic values for
fibre/matrix adhesion.
In this contribution, we present a partitioned‐domain method coupling a particle domain and a continuum domain for multiscale simulations of inelastic amorphous polymers under isothermal conditions. ...In the continuum domain, a viscoelastic–viscoplastic constitutive model calibrated from previous molecular dynamics (MD) simulations is employed to capture the inelastic properties of the polymer. Due to the material's rate‐dependence, a temporal coupling scheme is introduced. The influence of the time‐related parameters on the computational cost and accuracy is discussed. With appropriate parameters, multiscale simulations of glassy polystyrene under various loading conditions are implemented to showcase the method's capabilities to capture the mechanical behavior of polymers with different strain rates and with non‐affine deformations of the MD domain.
This review introduces groundbreaking insights in polymer science, specifically spotlighting a novel review of the solid-state modification (SSM) approach of thermoplastic polymers, a method not ...extensively explored. Unlike traditional melt polymer modification, SSM stands out by incorporating monomers or oligomers into the amorphous phase of polymers through innovative exchange reactions. The background of the study places thermoplastics within the context of their increased use over the past century, highlighting their versatility in various applications and the associated environmental and health concerns due to certain additives. The results section outlines the unique aspects of SSM and its increasing recognition for its potential to enhance material performance in areas such as catalysts and composites. It also discusses the application of SSM in modifying different thermoplastic polymers, highlighting various studies demonstrating the method's effectiveness in altering polymer properties. Finally, this work emphasizes SSM's importance in environmental sustainability and its potential in the recycling and upcycling of plastic materials. It acknowledges the challenges and future perspectives in the field, particularly regarding the scalability of SSM techniques for industrial applications and their role in advancing a circular economy in the polymer industry.
Abstract
The determination of the laser intensity profile necessary to weld two thermoplastic parts is crucial for understanding and optimizing the laser welding process in polymers and composite ...materials. Traditional methods of measuring the laser beam intensity profile, such as laser beam profiling techniques, can be difficult to implement and expensive. In this paper, we present the development of a technique that combines a numerical inverse method with experimental temperature measurements to determinate the laser intensity distribution at the weld interface. This technique does not require specialized or expensive equipment and accounts for variations in laser beam intensity caused by different components and interfaces. The technique uses thermocouple sensors to measure interface temperatures during welding, and an analytical gaussian model to estimate the laser intensity distribution at the weld interface. The model is then used as input data in a numerical heat transfer model. The technique is validated through experimental investigations on transparent and absorbent Polylactic acid polymers.
Polymer modified bitumens were prepared by blending bitumens with different thermoplastic polymers (SBS, SEBS, EVA and EBA). The fundamental properties (e.g. morphology, rheology and ageing) of the ...modified binders were studied using fluorescence microscopy, dynamic mechanical analysis, creep test (bending beam rheometer), and gel permeation chromatography. The results indicated that the morphology and rheological properties of the modified binders were influenced by characteristics and content of the polymer and nature of the bitumen. When a continuous polymer phase was formed at a sufficiently high polymer content (about 6%), the rheological properties of the binders were improved significantly. At a given polymer content, the modified binders containing SBS and SEBS differ widely from those containing EVA and EBA in their rheological behavior. The ageing properties of the binders were also strongly dependent on types of polymer. In most cases, the rheological changes during ageing were related to oxidation of bitumen and/or degradation of polymer. In addition, the effect of ageing was testing condition (e.g. temperature) dependent.
Fiber-reinforced polymers (FRPs) are low-density, high-performance composite materials, which find important applications in the automotive, aerospace, and energy industry, to only cite a few. With ...the increasing concerns about sustainability and environment risks, the problem of the recycling of such complex composite systems has been emerging in politics, industry, and academia. The issue is exacerbated by the increased use of FRPs in the automotive industry and by the expected decommissioning of airplanes and wind turbines amounting to thousands of metric tons of composite materials. Currently, the recycling of FRPs downcycles the entire composite to some form of reinforcement material (typically for cements) or degrades the polymer matrix to recover the fibers. Following the principles of sustainability, the reuse and recycling of the whole composite—fiber and polymer—should be promoted. In this review paper, we report on recent research works that achieve the recycling of both the fiber and matrix phase of FRP composites, with the polymer being either directly recovered or converted to value-added monomers and oligomers.
The joining of materials is essential to many industrial applications used today. However, it still lacks a reliable and true single step method to join different types of materials including ...polymers. Laser welding was primarily employed for metals until some decades ago, but with the rise of high power solid state lasers, applications have emerged in the polymer field. With the recent addition of fiber lasers, true clear to clear welding, joining two of the same transparent polymer layers, has become feasible at a different wavelength range, which benefits the sealing of microfluidic devices. A number of research efforts were made at performing welds of thermoplastics at this wavelength range, however without attempts at offering elaborate explanation of the observations. In our work, a laser welding system using a Thulium fiber laser at 1940 nm was used to join a variety of thermoplasts, without the use of additives or prior processing. By optically and chemically characterizing the materials, a basis was established that links intrinsic material properties to observed welding performance, as determined by mechanical shear tests on the welded materials. We found that four of the ten considered thermoplastic polymers lend themselves to sufficiently strong bonding to allow the creation of leak-proof microfluidic devices by use of laser welding at this wavelength.
This article reviews the recent development in performance and fabrication of carbon nanotubes (CNTs)‐based polymer nanocomposites synthesized by melt‐mixed process. CNTs have attracted enormous ...attention, since its presence (even in low concentration) causes drastic improvements in the mechanical and electrical properties of several polymer composites. It is suggested that the dispersion state of CNTs within polymer matrices is dictated by the cohesive strength of the CNTs “agglomerates.” Based on this suggestion, this review involves an in‐depth investigation on the origin of this CNTs “agglomerates” when present within polymer matrices. Attempts have also been done to investigate and correlate the varying extent of CNTs “agglomerates” in different polymer matrices. It is considered that the extent of dispersion of CNTs “agglomerates” depends on the interfacial interaction between the two phases, difference in their melt viscosities, and types of CNTs, compatibilizer and modifier used. A comprehensive study has been done on the effect of processing parameters used during melt‐mixing process; functionalization of CNTs, and the effect of compatibilizers and modifier on the final properties and morphology. Herein, an attempt has been done to study the correlation between the synthetic procedure, developed structure, and observed properties of nanocomposites of polymers and CNTs.
► ABS/graphite composites are developed. Tensile tests and wear experiments are conducted. ► Significant decrease takes place in the mechanical properties as the filler content increases. ► Severe ...adhesive wear mechanism is activated for the neat ABS. ► Improvement in the friction behavior and the anti-wear abilities by addition of graphite.
Thermoplastic-based polymer composites containing solid lubricant filler have been developed using a hot compression molding technique. The thermoplastic polymer is Acrylonitrile Butadiene Styrene (ABS) which is of great importance in applications such as bearing and slider material. The solid lubricant employed is graphite powder. Four mass ratios of the graphite particles in the ABS matrix were considered in the range of 0–7.5%. The mechanical properties of ABS composites were investigated using tensile test. The results show that the mechanical properties decrease significantly with the increase of graphite particles amount. Friction experiments were also conducted using a reciprocating tribometer recently developed in our laboratory. For each of the considered mass ratio, evolutions of the friction coefficient, the weight losses and the wear scar micrograph with respect to the number of sliding cycles were analyzed. Severe adhesive wear mechanism is activated for the ABS without graphite particles. Addition of graphite in ABS matrix exhibits lower friction coefficient and weight losses, whose values decrease as the weight fraction of graphite increases in the polymer matrix. Based on scanning electron microscopy (SEM) observations, the worn surface of the filled ABS composites reveals the development of a specific third body which reduces friction and wear. The best friction coefficient and weight loss were obtained with 7.5% in weight (7.5
wt%) of graphite.
PDF
