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PLAegg—Green Composite from Eggshells and Polylactic Acid

Abstract

Based on the principles of circular design, this paper aims to present the development process of PLAegg, a biodegradable, compostable, and recyclable composite produced from eggshells and polylactic acid. The material was developed within the scope of the We Won’t Waste You project, a partnership between Design Studio of the Faculty of Engineering of the University of Porto and Matosinhos City Council, which through Oficina Design intends to reuse waste to develop new materials and products. Several experiments were performed varying the formulations and material processability. The Material Driven Design method was used as the validation procedure. The material developed was applied to a new product, a lamp named LEXI lamp. There was a concern about creating simple, functional, easy to produce, and maintain standard electrical components. Packaging, manual, and an estimate of the production costs of the final product were also developed.

Introduction

Since the most primitive times, man produces waste in different forms, resulting from appropriating nature to satisfy his needs (Berríos 2006), including food waste. If diversity is not enough, the waste generated changes over time, in both quantity and quality, following human societies’ technological, cultural, and behavioral changes. The more the population increases and the more the economy grows, the greater the amounts of waste generated and the more diverse (Calijuri and Cunha 2019). The food industry, one of the largest industries in the world estimated by the World Bank to comprise 10% of all economic output, is of paramount importance to the economy. However, the dramatic increase in the requirements of the world population and the food supply chain will lead to a sharp increase in food production over the next 50 years. In these circumstances, high volumes of waste from the food industry attract increasing social, political, and scientific attention at the national and international levels (Otles et al. 2015). According to the results of the Food and Agriculture Organization report (FAO 2011), approximately one-third of the food produced for human consumption is lost or wasted globally. Large amounts of the resources used in food production are spent in vain, and their production causes the emission of greenhouse gases.

Eighty percent of the environmental impact of a product, service, or system is determined at the design stage (Thackara 2005). Therefore, by the nature of the activity, designers can help to reverse this trend, and several strategies can be adopted for a more conscious design. According to Papanek (1995), designers can create something new or redo something to make it better. However, they must be careful with what they create due to the environmental changes that result from human actions. He adds that designers must give their contribution in the search for solutions. They can positively influence the design of environmentally friendly solutions to contribute significantly throughout the product cycle, from the extraction of raw materials, passing through production where it can produce in a “cleaner” way using recycled materials and generating less waste.

Manzini (2008) argues that society must move towards reducing material consumption in search of sustainable development. By definition, sustainable development meets society’s present needs without compromising the needs of the next generations. This concept does not focus only on environmental issues, as actions for more sustainable development must be broad and encompassing, in addition to the environment, society, and the economy (Arruda et al. 2018). In the scope of design, with the increasing innovation of technologies, products appear increasingly desirable and quickly replaceable and disposable, generating vast volumes of waste. Thus, it is essential to practice a circular economy, in which the entire product life cycle is analyzed, putting all aspects related to sustainability under analysis (Marques 2012).

The Problematic of Solid Waste

According to the UN report (2020), the world population, currently around 7.79 billion people, is expected to reach 8.5 billion in 2030, 9.7 billion in 2050, and 10.8 billion in 2100. With the population increase, the need to use natural resources to produce consumer goods grows equivalently. Consequently, there will be a significant increase in waste products that will be mostly discarded, thus triggering one of the major problems faced by today’s society: the unrestrained production of waste. The global impact of solid waste generation on the planet has increased rapidly every year (Fernandes et al. 2018). According to the World Bank Group (Kaza et al. 2018), the global waste generation in 2016 was estimated at 2.01 billion tons. The forecast is that by 2030, the world should generate 2.59 billion tons of waste annually, and by 2050, this number is expected to reach 3.4 billion tons (Fig. 1).

Fig. 1
figure1

World population/global waste generation (source: prepared by the author based on Kaza et al. 2018 and UN 2020)

Europe and Central Asia generated 392 million tons of waste in 2016, or 1.18 kg per person per day. The total represents 20% of the world’s waste. The largest generators of waste per capita are found in some countries with high levels of tourism and the economic centers of Western Europe. Portugal is above average, with 1.26 kg per person per day. Regarding the composition of waste, the category with the highest percentage in Europe and Central Asia is food and green waste, which accounts for 36% of the total waste produced (Kaza et al. 2018).

According to the Portuguese Environment Agency, in 2018, 52 million tons of urban waste was produced in Portugal, 4% more than in 2017. In mainland Portugal, 494 million tons was produced, of which 36.4% was in the category of bio-waste. This increase may be related to an economic improvement, which shows the tendency to move away from the objective of decoupling waste production from economic growth. Fifty-eight percent of the waste generated was landfilled, and only 13% was sent to recycling (Agência Portuguesa do Ambiente 2019) (Fig. 2). A significant part of urban waste can be reused and materially recovered, and be returned to the economy as a secondary resource. Waste management to recovery and (re)incorporation into the economy is one focus of the circular economy to European public policy. Since the percentage of waste recovered in Portugal is lower than the European average, it is a priority that waste starts to be considered a resource (BCSD 2019).

Fig. 2
figure2

Waste production in Portugal (source: prepared by the author based on Agência Portuguesa do Ambiente 2019)

Circular Economy

For the past 150 years, the industrial economy has been dominated by a linear model of production (Wautelet 2018b), where manufactured capital, human capital, and natural capital contribute to human well-being, supporting the production of goods and services in the economic process (Brears 2018). The Industrial Revolution increased the economy’s productivity with innovative technological advances and brought unprecedented prosperity to society. This economic system provided incentives to increase sales and simulate economies of scale, which led to increased consumption of goods and services (Wautelet 2018a).

The linear model is built on three assumptions: there are no limits to natural resources, the easy availability of resources (energy and raw materials), and the Earth’s unlimited regenerative capacity. This system led to the depletion of natural resources. The more the economy grows, the more significant amount of raw material is needed to produce goods and consequently a more significant generation of waste and environmental degradation (Brears 2018).

This model is based on the “extracting resources—producing goods—consuming—depositing waste” chain. Along this chain, the levels of waste are significant, with a loss of economic and environmental value (Michelini et al. 2017). The linear system made sense when it emerged at the dawn of the industrial revolution because resources were abundant and the population was small (Pike et al. 2010). Today, it is ineffective to face the main challenges of modern society, such as the reduction of poverty and social inequalities, climate change, water scarcity, loss of biodiversity, and depletion of natural resources.

The need for an alternative to the traditional model has led to the emerging debate on the circular economy (CE) that aims to replace the linear economic model by decoupling global economic development from the consumption of finite resources and eliminating waste from the system. For this purpose, it is intended to maximize the efficiency of resources and minimize waste production. It is an approach that transforms the function and role of resources: industrial waste can become raw material for other processes (Wautelet 2018b).

The Ellen MacArthur Foundation (EMF) defines CE as “Restorative and regenerative by design and aims to keep products, components, and materials at their highest utility and value at all times, distinguishing between technical and biological cycles” (Ellen MacArthur Foundation 2015). Thus, the principles that guide the CE prioritize adopting new production tools and methodologies, reducing waste generation, and encouraging the adoption of renewable energies (Ellen MacArthur Foundation 2019a).

Design at CE is complex and requires a transformation of thinking to shift “from the current product-centric focus to a system-based approach.” Circular design (CD) seeks to deliver a functional product or service composed of excellent materials that offer the best performance, minimizing the negative impact throughout the product’s life cycle (Fifield and Medkova 2016). The durability of a product and the ability to repair, recycle, and reuse its components and materials depend mainly on the product’s design (European Commission 2019). The designer plays a crucial role in CE, in the decisions taken in the early stages of the product development process, and in the possibility of relationships between products and consumers, providing them with possible alternatives after disposal (Bovea and Pérez-Belis 2018).

According to Bovea and Pérez-Belis (2018), the characteristics of a product directly influence how the value chain will be built and managed. Therefore, designers must have guidelines to guide them through developing product designs towards CE principles. CD challenges the creation of products and materials to minimize the use of primary raw materials, reducing the loss of value of products and materials and keeping them circulating in closed cycles. At the end of a product’s life, its components or materials must be transformed into resources for a new process (Fifield and Medkova 2016).

Following these principles, in the CD methodology, products must be designed considering all phases of their life, from the extraction of the resources necessary for production to the last treatment and destination after use. This analysis makes it possible to determine which material is most viable throughout the process and how its production affects the environment (Manzini and Vezzoli 2002). In addition to a new way of designing, CD considers actions to extend the useful life, durability of products, and design for the disassembly, reuse, and recycling of materials and components (European Commission 2019). Therefore, the role of design is to link the “technically possible” with the “ecologically necessary,” driving new proposals that reflect the current culture of respect for the environment (Manzini and Vezzoli 2002).

Egg Shells

The presence of eggs in Portuguese gastronomy is massive. Popular stories tell that the tradition of Portuguese sweets originates in the convents. The solid religious component present in Portuguese culture is the consequence of numerous convents and monasteries. It was common practice to use egg whites to iron habits and filter liquids in convents, as in wine production. The high consumption of egg whites generated many unused egg yolks destined for the garbage or distributed to pigs. Thus, out of the need to reuse these egg yolks, countless recipes for sweets were born, which were even sold by the nuns to reinforce the convents’ budget and ensure the religious’s daily needs.

Currently, egg production worldwide is 65.5 million tons per year, with Asia as significant contributors to global production growth. In Portugal, 14,671 tons of eggshells is discarded as waste (Fig. 3). Therefore, its use is an excellent opportunity to reduce the environmental impact and obtain greater profits (Ikhmayies et al. 2019).

Fig. 3
figure3

Worldwide egg production (source: prepared by the author based on Ikhmayies et al. 2019)

The egg products and derivatives industry currently produces many eggshells considered animal by-products not intended for human consumption. Due to the lack of definition of adequate strategies for managing this by-product, the landfill has traditionally been used as a final destination, resulting in a solution with a high management cost (Magalhães et al. 2011; Arabhosseini and Faridi 2018; Guedes 2014).

According to the report Cities and Circular Food Economy released at the 2019 World Economic Forum by EMF, cities can play an essential role in the transition from a system that, in addition to reducing food waste, seeks to eliminate the concept of “waste.” They can ensure that they are used at their highest value, turning them into new products ranging from organic fertilizers to biomaterials, medicines, and bioenergy. Instead of a final destination for food, cities can become centers of transformation into a range of valuable materials, driving new sources of revenue (Ellen MacArthur Foundation 2019b).

Eggs are composed of three main components: eggshells, including membranes; albumen; and yolk. The yolk is surrounded by the albumen, surrounded by the membranes, and, finally, by a hard eggshell (Mine 2008). It consists of approximately 3.5% of the organic matrix, comprising the membranes of the bark and some constituents, and 95% of calcium carbonate in the form of calcite (Huopalahti et al. 2007).

Eggshell residues can be reused as a raw material for other industries (Figueira 2014). Possible applications range from low investment processes such as fertilizers and animal feed to high investment for processing for human consumption, heavy metal absorption, paper treatment, catalysts for biodiesel production, production of hydrolyzed or concentrated protein, bone, and dental implants. The latest applications need significant investments but can provide more valuable products (Arabhosseini and Faridi 2018; Oliveira et al. 2009). In Portugal, more specifically at the University of Aveiro, a team of researchers discovered a process already patented that allows eggshells to manufacture ceramic materials (Falcão 2015).

One of the problems in eggshell processing is completely separating the carbonate from the membrane in an economical and environmentally correct manner (Oliveira et al. 2009). Recently, some technologies have emerged that allow an industrial and efficient separation of the shell and the respective membranes (Ruff et al. 2012). A patented method was made to break the connection between the membranes and the shell through a tank with turbulent water. The membranes are retained in the liquid while the shells are deposited on the bottom of the tank (Falcão 2015).

Given the above, it is concluded that the reuse of eggshells represents an excellent opportunity to develop new materials and products. It is a raw material with potential found in large quantities in the context of this investigation.

We Won’t Waste You

We Won’t Waste You (WWWyou) is a research project developed at the Design Studio of the Faculty of Engineering of the University of Porto (DSFEUP) that aims to propose the reuse of waste in developing new materials and products. The WWWyou theme is a challenge launched to students of the master’s program in Industrial and Product Design (MDIP) at the University of Porto (UPorto) through the proposal of developing products that use materials derived from various residues. Within the scope of the WWWyou project, Oficina Design emerged, a social design workshop implemented through a partnership between the Association for the Integrated Development of Matosinhos, the Municipality of Matosinhos, and the DSFEUP. In this workshop, the program proposes the technical training of people in situations of economic vulnerability through the manufacture of products developed by students in the master’s degree.

The students, organized in teams, were then challenged to create products to promote tourism in Matosinhos made from the local waste production. The primary constraint was that the proposals should be made with low technology and simple manufacturing systems; they should be small and easy to transport.

The Project-Based Learning (PBL) method was applied to the learning process, where each team of students was free to define the organization and management of their process, setting goals, and setting schedules. The PBL is a student-centered method, where the student is primarily responsible for their learning in small groups and under the guidance of a teacher. The problems are presented to the student as a learning tool to achieve the knowledge necessary for their resolution and develop collaborative work skills (Kokotsaki et al. 2016). All phases of the design process were experienced, research, development, and final prototyping. In the initial investigation on the types of waste produced in large quantities and with a significant impact on the city, the following were identified: eggshells, lids and plastic bottles, cans, cardboard, algae, sugar, fishing nets, coffee grounds, inner tire tubes, and shells. The process presented below details the development process of PLAegg developed from eggshells.

Material Development

Initially, the eggshells were crushed, and several tests were carried out in search of an ideal binder for the composition of sustainable material (Fig. 4). Some of the binders used are the following: white glue, gelatin, clay, silicone, potato starch, nets, crystal resin, pine resin, high-density polyethylene (HDPE), and polylactic acid (PLA). The samples with HDPE and PLA were the experiments that aroused the most significant interest, considering the structural and aesthetic aspects. The PLA was selected because it is a biodegradable, recyclable, and compostable polymer.

Fig. 4
figure4

Tests with different binders: a. white glue; b. gelatin; c. clay; d. silicone; e. potato starch; f. nets; g. crystal resin; h. pine resin; i. white glue; j. colored HDPE; k. HDPE; l. PLA

PLA is a semicrystalline or amorphous thermoplastic. It is a polymer synthesized from renewable sources such as corn, potatoes, and sugar cane (Santana et al. 2018; Davim 2017; Lefteri 2017). It is a biocompatible, biodegradable, and biologically absorbing material, besides good mechanical properties and processability, thermal stability, and low environmental impact (Santana et al. 2018; Teixeira 2017). The material is commonly used in many industries, especially in biodegradable medical implants and food packaging (Santana et al. 2018). The PLA used in this investigation was the Ingeo™ 3260HP, from the American company NatureWorks®. According to the datasheet, Ingeo™ 3260HP is a low viscosity product designed for high flow injection molding applications (NatureWorks 2019a). The end-of-life options indicated by NatureWorks® for its products are composting, recycling, anaerobic digestion, chemical recycling, incineration, and the landfill (NatureWorks 2019b).

Production Process

PLAegg’s production process is divided into five stages (Fig. 5). The first step is the manual removal of the eggshell’s organic part. The eggshells were washed with water and dried in a kiln at 200ºC for 60 min. Afterward, they were manually grounded using a pestle and separated by grain size using a vibratory sieve shaker (45 μm, 75 μm, 106 μm, 250 μm, 425 μm, 600 μm, 850 μm). The particles were manually mixed with PLA (Ingeo™ 3260HP) binder previously heated to a temperature of approximately 200 °C for 10 min. The mixing process between the eggshell and the PLA was initially carried out experimentally, using accessible instruments (portable induction hob, thermometer, frying pan, and a rubber spatula) to ensure the agility of the process with a low initial investment. In the future, this process can be carried out with automatic mixers, such as the injection process.

Fig. 5
figure5

PLAegg’s production process

Material experiments (Fig. 6) were carried out to find the ideal ratio between PLA and eggshells and its behavior in molds with different shapes and materials, and check the influence of particle size on moldability and the aesthetic properties of the material.

Fig. 6
figure6

Material’s experiments with different ratios between eggshell and PLA: a. 18wt% of eggshell; b. 16wt% of eggshell; c. 15wt% of eggshell; d. 12.5wt% of eggshell; e. 4wt% of eggshell; f. 20wt% of eggshell; g. 15wt% of eggshell; h. 10wt% of eggshell; i. 10wt% of eggshell; j. 4wt% of eggshell; k. 9.4wt% of eggshell; l. 9.1wt% of eggshell; m. 9.1wt% of eggshell; n. 5.9wt% of eggshell; o. 4wt% of eggshell; p. 15wt% of eggshell; and q. 15wt% of eggshell

The experiments observed that the addition of eggshells to the binder gives a yellowish tone to PLA. When the percentage of eggshells is reduced, the material becomes lighter and more translucent. It was noticed that the composite is suitable for molding in various shapes using metallic and silicone molds, and it is also suitable for injection molding. The only constraint found was the speed with which the material cools, which makes handling it laborious.

The next step in the investigation was applying the Material Driven Design (MDD) method to assess the perception of the material under development with the general public.

Material Driven Design

The MDD consists of a method developed by the Industrial Design department of the Technological University of Delft, Holland, and by the Design department of the Polytechnic of Milan, Italy (Moreira 2018), intending to provide support to designers in the definition of a project where the starting point is a particular material. The method has four main action steps:

  1. 1.

    Understand the material: technical and experiential characterization;

  2. 2.

    Creating a vision of experience in materials;

  3. 3.

    Manifesting standards of experience in materials;

  4. 4.

    Developing concepts in products/materials.

For the MDD application, 14 samples were produced with defined proportions and particle sizes (Fig. 7 and Fig. 8). The 850μm, 600μm, and 425μm samples incorporated 12.5wt% eggshell. Those of 250 μm and 106 μm incorporated 6.7wt% of eggshell. Finally, the 75 μm and 45 μm received 3.4wt% and 1.4wt% eggshell respectively.

Fig. 7
figure7

Samples with a brown eggshell

Fig. 8
figure8

Samples with white eggshell

  • Step 1: Understand the material

In this stage, we intend to understand the material and characterize it technically and experimentally (Karana et al. 2015). One of the significant difficulties encountered in the molding process was that it was necessary to soften the PLA and mix it with the eggshell before it was placed in the mold to guarantee a homogeneous material as a final result. With injection molding, it was found that it is possible to mix the two materials at the time of injection and still obtain a uniform material. Tests were carried out to check the material’s behavior when subjected to a cutting tool (hand saw, band saw, and mini tool). In both tests, the material melts with the cutting blade friction’s heat, and the result had a surface irregular and challenging to finish.

Water and fire resistance tests were carried out. The contact with water took place by immersing the material in a container with water. For 60 days, the material was observed and handled daily to identify possible changes in its structure. As a result, it was found that the material did not change. The fire resistance test was carried out with the flame of a lighter in constant contact with the sample. After about 10 s, the material started to burn, only ceasing after being extinguished by the researcher. Figure 9 presents images referring to the experiments carried out to characterize the material.

Fig. 9
figure9

Experiments for material characterization: a. cutting with a manual saw; b. fire resistance; c. cutting with a mini tool; d. mold for vertical injection; e. water resistance; f. electric polisher; g. silicone mold; h. cut with a band saw

  • Step 2: Experimental characterization of the material

This step helps to understand how other people interact with the material. The Meaning Driven Materials Selection (Karana et al. 2010) and the Materials-to-Experiences at four levels Toolkit (Karana and Rognoli 2019) developed by the same author were used as a support method. The study was conducted with 32 students. One of the main objectives was to verify people’s perception of the material in its different variants, specifically the use of different sizes and colors (white or brown) for the eggshell.

The samples were placed in front of the participants, and they were instructed to handle the samples freely so that they could choose the sample they found most interesting. It was observed that a large part of people would run their fingers over the surface of the samples when they started to handle the samples. Other perceived interactions were raising, turning, placing it against the light, smelling, feeling the weight, and tapping with the nails to hear the sound produced. Running the finger over the surface was the most perceived interaction. It was observed that the samples analyzed initially were generally those with the largest shell size.

It can be assumed that the larger eggshell granulometry gives the perception that the samples have a rough surface because when the interviewees found that the surface was smooth, they expressed surprise. The presence of larger particle size is the most pleasant since the four most chosen samples were those of 850 µm (7 people), 600 µm (6 people), and 425 µm (10 people). Two of the four most selected samples were produced with white eggshells and the other with brown eggshells (Fig. 10).

Fig. 10
figure10

Samples that the participants most chose

The study participants elected curiosity, attraction, and comfort as the emotions most transmitted by the material. The words that most represent the material are natural, calm, and welcoming at an interpretive level. Forty-four percent of the participants think that this is a material with unique characteristics; the most cited were transparency, smoothness, aesthetic texture, and color. The most pointed unpleasant characteristics were the irregularities (of the samples), fragility (transmitted by sample thickness 5 mm), the sound it produces when scratched, and the ignorance of not knowing the raw material. When asked about a material’s unique quality, the most cited were the three-dimensionality (transmitted by the transparency and presence of eggshell particles), color, translucency, and texture.

Finally, they were asked to indicate an option for applying the material: 18 people chose lamps. Furniture pieces (tables, chairs, and benches) were selected by 11 people; small decorative (vases, jars, bowls, trays, and clocks) objects also appeared among the most suitable products.

  • Step 3: Create material/product concepts

This last step serves to integrate and gather all the findings and conclusions from the previous steps to form a set of concepts for applying the material under study.

The material’s translucency and three-dimensionality were the most attractive aspects; therefore, they were strongly considered in creating concepts. The three-dimensionality is obtained through the visibility of the eggshell particles, which occurs more significantly with the use of larger size particles. Therefore, the final material mainly used large particles (850 µm, 600 µm, and 425 µm), keeping the proportion of 12.5wt% of eggshell so that the three-dimensional aspect could be maintained. Concerning the color of the eggshells, the ones that aroused the most interest were those of brown color, besides being the shells that are in greater quantity in the Portuguese market.

The next phase was to study the material’s application in a lighting fixture design, as translucency was one of the outstanding characteristics and was one of the most mentioned applicability suggestions by the study participants. To overcome the fragility perception (transmitted by sample thickness), it was recommended to apply it to pieces with a greater thickness.

LEXI Lamp

Among the main findings, the valorization of the material’s aesthetic and translucent aspects was highlighted, which led to its application to a lighting fixture. The LEXI lamp (Fig. 11) was designed after many sketches, experiments, and tests (Leite 2020). LEXI is a compact decorative table lamp that represents the principles of circular design (European Commission 2019). It is a simple and functional device and is easy to produce and maintain.

Fig. 11
figure11

LEXI lamp

The manufacturing process of the LEXI lamp involved several phases: the preparation of the PLAegg composite, molding process, manual press, and, finally, the installation of the electrical components (Fig. 12).

Fig. 12
figure12

LEXI lamp production process

For a product to be considered a CD, it must follow some guidelines (European Commission 2019). For this reason, a piece with a timeless, modular design, few components that facilitated its maintenance and cleaning was proposed. Combining more than one lampshade makes it possible to obtain new lamps, thus providing more product applications. In order to encourage the extension of the lamp’s life, all electrical components are standard and easily accessible on the market, which facilitates their replacement if necessary. Another premise is that all components of the product were easily disassembled and easily accessible. The necessary tools (screwdriver and pliers) for the disassembly and maintenance of the product were minimized, in addition to being commonly found tools. As shown in Fig. 13, the LEXI lamp is composed only of the lampshade (10 mm thickness) and the electrical components. Because it is a lamp produced with only one material (biodegradable) and the electrical components are easy to disassemble, they can be easily separated and sent correctly for recycling. According to EC, the developed material fits into the biological cycle, it is a material that adds value to the biosphere, and its valorization can occur through industrial composting. The remaining materials of the lamp are the so-called waste electrical and electronic equipment (WEEE) and are included in the technical cycle. After being recovered through recycling, WEEE becomes raw material for industries where they originate new products and, in this way, the cycle is closed.

Fig. 13
figure13

LEXI lamp components: a. PLAEgg lampshade, b. cord, c. LED bulb E14 4 W 2700 K, d. E14 socket, e. hollow threaded in galvanized steel M8, f. cable clamp, g. switch and h. plug 10a

Three prototypes of the LEXI lamp were produced, executed with the three most chosen particle sizes (850 µm, 600 µm, and 425 µm) during the application of the MDD method, with the proportion of 12.5wt% of eggshell kept constant. In Fig. 14, it can be seen that the difference in granulometry among each of the pieces is noticeable.

Fig. 14
figure14

LEXI lamp

The concept of sustainability is a solid theme to bring together students from different backgrounds with the common goal of developing integrated academic knowledge (Neto et al. 2019). During this investigation, an exercise was carried out with students of the Integrated Master in Environmental Engineering (MIEA) and those of the MDIP to promote environmental awareness among students and better understand the environmental impacts of products (Facca 2020). In this project, the students of MIEA assessed the environmental impacts of the lamp proposed by the students of MDIP. This cooperation was promoted and supervised by the teachers involved (Fernandes et al. 2020). The life cycle assessment methodology was used to deeply understand the product’s environmental impact, which allowed a complete approach to the product’s life cycle under study. The environmental impacts were assessed from the production of the raw materials to the end of the product’s life. The main environmental problems were identified. Below are some points to bet on outlining a strategy to optimize the environmental performance of the product:

  • Increase energy efficiency when drying the eggshells: put more eggshells in each batch;

  • Increase energy efficiency during the production of the diffuser: a two-part mold was proposed, and the step of placing it in the oven was not necessary;

  • Use more resistant silicone mold: the silicone used in the production of the mold was replaced by one with the durability of approximately 50 pieces, in contrast to the one used previously, which had a durability of only 20 pieces.

Packaging is essential for products for tourism promotion, considering that they are often purchased as gifts and need to be transported safely by the tourist during the trip. Since this, the dimensions and weight are relevant factors to be taken into account. A compact packaging made from discarded cardboard from the city of Matosinhos was proposed. The visual communication was developed in three labels with information about the product and the WWWyou project. Along with the packaging, an instruction manual was developed with information regarding the assembly and cleaning of the product. In the product development process, it is crucial to ensure that the production of the concepts fits within an economically viable and market-competitive budget. The estimated cost associated with the LEXI lamp was €34.67 per piece. The estimative was made considering the production of a single piece, and it is predicted that when produced in greater quantity, the cost will decrease.

Results

As the first result of this research, an innovative composite material was developed, called PLAEgg, produced from a mixture of food waste (eggshells) and polylactic acid. The development methodology was experimental and based on the principles of circular design. It included an initial survey of food waste in the region, laboratory experiments for the correct processing of eggshells, tests with different binders to create a sustainable composite material, tests of different transformation processes, and types of molds. For material validation, the Material Driven Design method helped understand the users’ perception and possible applications, indicating the possibility of developing a lamp to test the material’s application.

The second result is the LEXI lamp product, a sustainable decorative table lamp produced with PLAEgg. It is a timeless and modular piece, consisting of a PLAEgg diffuser and universal electrical components, easily found for repair and replacement, ensuring a long service life and easy maintenance and cleaning. The simplicity of its shape allows for a large number of combinations and applications.

As future studies, there are laboratory tests to define the technical characteristics of the material, which will allow a precise definition of a detailed technical file, and thus open up new application possibilities, which unfortunately was not possible within the time determined for this investigation.

Conclusion

The project developed a material from waste, aiming to highlight sustainability issues that need urgent attention from society, not just focusing on the technical properties. In this experience, it was possible to prove that the eggshells and PLA mix give rise to a material that improves the material’s aesthetic qualities, maintaining its characteristics of sustainability, biodegradability, and moldability. The resulting material paves the way for new product designs that carry an important message about sustainable issues and promote small and local environmental impacts, reducing the number of eggshells going to landfills.

It was also possible to prove that the approximation between the community and the university can constitute a partnership with social and environmental benefits. The application of the PBL methodology allows students to face real problems, thus addressing the dilemmas and responsibilities they will face in their future professional performance. The application of PBL methodology results in a more effective and fulfilling learning process.

Through design and the principles of circular economy, it has also been proven that it is possible to develop products capable of reducing the negative environmental impact caused by the high volume of waste disposed of incorrectly in landfills. Furthermore, food waste can provide a diverse basis for developing innovative materials, capable of presenting technical and aesthetic qualities to develop new products and act as a message, making society aware of the need to rethink its consumption habits.

Data Availability

All data generated or analyzed during this study are included in this published article.

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Acknowledgements

The authors wish to thank INEGI—Instituto de Ciência e Inovação em Engenharia Mecânica e Engenharia Industrial for the technical support, equipment, and materials.

Funding

This research was supported by the Master program in product and industrial design of the University of Porto.

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RL: term; conceptualization; methodology; investigation; writing, original draft preparation; reviewing and editing. AF: reviewing and editing, conceptualization, supervision. BR: reviewing and editing, supervision. JA: resources, reviewing and editing, supervision.

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Correspondence to Rita Leite.

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Leite, R., Fernandes, A., Rangel, B. et al. PLAegg—Green Composite from Eggshells and Polylactic Acid. Mater Circ Econ 3, 22 (2021). https://doi.org/10.1007/s42824-021-00032-4

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Keywords

  • Food waste
  • Eggshell
  • Circular design
  • Eco-design
  • Innovation
  • Circular economy