Study of print suitability of environment-friendly plastics using flexography printing

Within this work, we provide a comprehensive overview about research activities and current status with respect to rotary printed metallization for silicon solar cells. We will present the major results of the research project »Rock-Star« and previous activities which focused on the metallization of Si solar cells using flexographic printing and rotary screen printing. We demonstrate that the rear side metallization of passivated emitter and rear cells (PERC) can be realized with rotary screen printing on the same quality level as state-of-the-art flatbed screen printing. Furthermore, it is shown that both rotary screen printing and flexographic printing are able to realize the fine line front side metallization. Fine line front side contacts down to approx. 40 µm for rotary screen printing and around 30 µm for flexographic printing are demonstrated. However, further optimization is required to reduce finger width, increase finger height and thus decrease the mean lateral finger resistance. A major result of project »Rock-Star« is the development of an innovative demonstrator platform to enable rotary printed solar cell metallization with high printing speed and low cycle time per wafer. Newly developed transport, alignment and printing concept enables a cycle time of down to 0.45 s/wafer. The concept and features of the demonstrator machine are presented within this paper.

"Microplastics are plastic particles smaller than 5 mm in size that are now ubiquitous in the environment. It is a problem that is becoming a major concern for marine and terrestrial ecosystems as well as for human health. Microplastics can reach the final receiving environment from a variety of sources, but one of the major contributors is the breakdown of discarded large plastic products. Data shows that global plastic production has now reached 367 million tons. A significant proportion of plastic waste generated on land inevitably reaches water bodies. The fact that microplastic waste has become a serious problem, harming the environment and society, has led to the need for sustainable management approaches. A sustainable management approach to microplastic waste requires first identifying the root sources of the problem, reducing the generation of plastic waste and developing effective waste management strategies. An important way to reduce plastic waste generation is through recycling and the use of biodegradable alternatives. In addition, reducing the dependence on single-use plastics should be encouraged, and even going one step further, necessary regulations should be made in the legislation for such plastic products."

Plastics and climate change—Breaking carbon lock-ins through three mitigation pathways

Single-use plastic or paper products? A dilemma that requires societal change

The production of conventional plastics, which are essential to modern economies, primarily relies on fossil-based resources and is associated with significant environmental impacts. Global plastic production has increased markedly from 204 million tons in 2002 to 335 million tons in 2016 and is projected to rise further, leading to critical issues such as waste accumulation and increased greenhouse gas emissions. In response to these challenges, considerable research efforts have been directed toward the development of environmentally sustainable alternatives, particularly bioplastics. Among these, microbial derived polymers such as Polyhydroxyalkanoates and Polyhydroxybutyrate have attracted significant attention due to their biodegradable nature and the presence of hydrolysable ester bonds. These biopolymers are synthesized by microorganisms under specific stress conditions that are influenced by environmental and nutritional parameters, including pH, temperature, incubation period, and the availability of carbon and nitrogen sources, as well as the carbon to nitrogen ratio. In the present study, soil samples were collected from agricultural and coastal regions of South Gujarat and Goa for the isolation of potential Polyhydroxyalkanoate and Polyhydroxybutyrate producing bacteria. A total of isolates were screened and characterized based on their morphological and biochemical properties. Biopolymer production was further enhanced through the optimization of growth conditions under controlled laboratory settings. The developed bioplastic will be evaluated for safety prior to its potential application. This study demonstrates the potential of microbial bioplastics as sustainable alternatives to conventional plastics and underscores their relevance in promoting environmental protection and sustainable development.

In recent years, the consumption of plastic products intended for single use has increased. Directive (EU) 2019/904 aims to reduce the use and the resulting generated waste quantity of single-use plastic (SUP) products. Therefore, manufacturers of SUP products are required to contribute proportionately to the costs of disposing of their products in public collection systems, including litter waste. One possibility to develop a cost model is to determine SUP-product quantities in relevant municipal solid waste (MSW) streams. The partly low quantities and small size of specific SUP products and the focus on waste from public collection systems, including litter waste, impede special requirements for the sampling and analytical procedures. This article provides an approach for sampling and analysing MSW to determine SUP-product quantities. The developed sampling method examines the selection of a suitable sampling area, considering the possibility of extrapolation to a national scale. The adapted sampling procedure aims to achieve statistically representative results. The presented sample preparation is especially suitable for low quantities and small SUP-product sizes. The developed sampling and analytical method aims to achieve representative and reproducible results regarding SUP-product quantities in MSW. The results can contribute to the development of a cost model based on Directive (EU) 2019/904.

Petroleum-based plastics are lightweight and durable and exhibit excellent formability. However, the increase in global plastics production, coupled with the economic development of emerging countries, and the resulting marine pollution caused by plastic waste have become serious problems in recent years. Polysaccharides, such as starch and cellulose, are the most abundant biopolymers in nature and are particularly promising plastic alternatives owing to their renewability, sustainability, and biodegradability. However, owing to their lack of water resistance and adequate mechanical properties, large-scale application of polysaccharide films in single-use plastics is limited because water resistance is preferred in many daily scenarios. Further research is required to optimize bioplastics to make them economically and practically feasible. In this report, we focus on stimuli-responsive materials that form or dissociate cross-linked structures in response to slight changes in external stimuli or the environment. We developed starch-based films with different disintegration/dissolution rates in freshwater and seawater as environmentally friendly materials. Modified starch was mixed with oxidized cellulose or a water-soluble polymer to prepare a transparent, homogeneous film. After the introduction of hydrogen bonds, the starch complex film was stable in freshwater; however, in seawater, the hydrogen bond crosslinks dissociated, causing the film to dissolve rapidly. This technology balances degradability in marine environments with water resistance in everyday environments, providing an alternative means of reducing marine plastic pollution, and it is expected to be applied in a variety of industrial sectors.

This contribution focusses on three printing techniques: inkjet printing, flexographic printing and gravure printing for the manufacture of ITO structures based on nanoparticular ITO inks. The quality and stability of nanoparticular inks depends mainly on the dispersing step and is reflected by the achieved particle size distribution. The particle size distribution of the ITO inks has a distinct influence on the optical and electrical properties of the deposited ITO structures. The optimization of nanoparticular ITO inks concerning rheological behavior, wetting behavior and resulting material performance is presented. Inkjet printing was used as a low speed method to manufacture structures in the range of 30 μm. It is shown how coffee-staining, a frequently arising problem in inkjet printing, can be prevented by different strategies. Nanoparticular ITO structures with layer thicknesses clearly below 1 μm were printed. Gravure and flexography printing are well-established industrial printing processes with printing speeds above 100 m/min. These high-speed printing processes were used to print structures on PET film and glass substrates. Different solvents, e.g., water and ethanol, solvent compositions and binder types were varied to optimize the resulting ITO structures. The printed structures in the range of 10 to 2000 μm with thicknesses down to 1 μm were evaluated concerning surface topography and electrical conductivity. The high inter-grain porosity and the used organic additives limit the electrical conductivity of nanoparticulate ITO structures. To further improve their electrical conductivity laser post-treatment of printed ITO structures was performed.

Global production of plastics is clearly on the increase and plastic products have become an inextricable part of our everyday life. Over a short span of about 75 years plastics have penetrated diverse application areas replacing conventional materials quite successfully. Continued growth in production is expected in the medium term but questions on the sustainability of plastics are being raised. A key aspect of sustainability of plastics and rubber materials is their potential environmental toxicity and in particular human toxicity. Plastic resins, however, are nontoxic materials, composed of macromolecules that are neither digestible nor absorbable in the gut. Toxicity of plastics often observed is attributed to the numerous additives mixed in with the resin during processing and fabrication of products, the residual monomers, or catalysts trapped in the resin and the chemicals picked up by the plastics from the environment. Of these, the additives are present at the highest concentrations in plastic products. Knowing and evaluating the additives commonly used, their potential toxicity, and their intake routes to human users are essential for the sustainability of plastics.

Environmental impacts and mitigation potentials of CO2-based biodegradable plastic based on life cycle assessment – A case study of poly(propylene carbonate)

The issues related to setup downtime, raw material waste, and the quality defects are inevitable in the flexographic printing business. To enable sustainable continuous process improvements within the printing process, lean manufacturing methodologies, such as Value Stream Mapping, (VSM), can be a competitive management approach. Therefore, this study explores how the systematic application of VSM in a flexographic printing process can foster further the process improvement when combined with other lean activities, such as, 5S, single minute exchange of die (SMED), and kaizen etc. To assess the contribution of this lean approach, the Overall Equipment Effectiveness, (OEE), and manufacturing costs are taken as performance metrics. The results demonstrate that when integrated with 5-why root cause analysis and kaizen, VSM improved OEE by 24.31% and reduced manufacturing costs from US$0.762 million to US$0.6 million. Hence, the significance of the proposed combined lean approach for continuous improvement is reached.

Flexographic sleeves are made using various materials, including a sub-group with extremely durable polyurethane foam shock-absorbing layer. During exploitation, the sleeves are exposed to cyclic dynamic loading, and the flexographic printing process is highly sensitive to the changes in pressure. Deformation of printing elements occurs due to the almost two times higher residual strain of the exploited sleeves. Changes in the residual strain induce occurrence of the hysteresis losses, which lead to heat generation. The forces impacting the material are not strong enough to induce permanent deformation in the microstructure. Therefore, the leading cause of the change lies in the molecular structure of the parent polymer of the polyurethane foam cell walls, whose resilience is declining. The thickness of the exploited sleeves tends to be around 8 % lesser. In addition to high-frequency cyclic loads during printing, the adhesive layer of self-adhesive sleeves undergoes reduction in the share of acrylates, phthalates and rosin, thereby reducing the adhesive strength and the force needed to initiate the de-adhesion by half. The knowledge of mechanisms of change in certain characteristics of the sleeves enables predicting their service life and increasing the stability of the printing process through possible corrections of other process parameters.

Assessing threats, regulations, and strategies to abate plastic pollution in LAC beaches during COVID-19 pandemic

Microscopic particles of plastic, known as microplastics, have become a ubiquitous contaminant in the environment. Their presence in the marine environment has been correlated to the exponential increase in global plastic production over the past 70 years and the subsequent increased abundance of plastic litter in the oceans. Other sources of microplastics include synthetic microfibers associated with the washing of textiles and tire particles associated with the abrasion and wear of the tread on automobile tires. Microplastics are recognized as contaminants of emerging concern because they occupy the same size fraction as plankton and sediment, making them bioavailable to a wide range of organisms, and they have the potential to adversely impact environmental health. Ingestion of microplastics by humans is likely, but confounding any assessment of health impacts is the lack of estimates on the total human exposure to these particles. This article will review the magnitude of plastic production and waste, provide an overview of the major sources of microplastics in the aquatic environment and the hazards they pose to both environmental and human health, and present a case study of ongoing efforts to characterize the sources and fate of microplastic contamination in Charleston Harbor, SC, USA.

Global plastics production has grown rapidly in recent decades and is leading to an increased discharge of plastic waste into the environment, presenting a complex socio-ecological problem. The southern North Sea and its tributaries are affected by plastic pollution due to dense population, industrial use, as well as tourism and recreational activities. A paradigm shift is necessary to reduce the outflow of plastic waste from rivers and inland waters into the North Sea. In order to foster a socio-ecological transformation, one opportunity is to involve stakeholders from all sectors, who regulate, produce, trade, use, recycle and dispose plastic products, through a transdisciplinary process. Real-world laboratories as a science-practice interaction approach are conceptualised to produce robust knowledge to solve real-world environmental and societal challenges. The aim of this study is to determine how the design and early implementation phases of real-world laboratories should be executed to achieve socio-ecological transformation. We assessed the case study of an inaugural regional stakeholder meeting of the real-world laboratory ‘Plastic-FREE-sia’ in Northwest Germany by in-event observations and a subsequent participant survey. Our findings of this stakeholder workshop highlight the significance of involving diverse stakeholders from multiple sectors in the real-world laboratory process and emphasise the need for balanced representation. The interests, benefits and goals of individual stakeholders must be identified from the outset and aligned with the socio-ecological problem setting, in order to prevent conflicting objectives. Concluding recommendations for the design and early implementation phases of future real-world laboratories are formulated.