Fast Moving Consumer Goods, including glue sticks, contribute greatly to global waste. This analysis analyses glue sticks environmental impact, addressing high disposal rates and PVA production concerns. The proposed solution takes a product-service system view, while utilizing sustainable materials like potato-based adhesives and CL-PHA bioplastics, alongside biodegradable Paperfoam packaging. It envisions a future with widespread adoption of refillable glue sticks, fostering both environmental and social benefits.

The Linear System Problem

A startling 35% of users report owning unused glue sticks, suggesting a disconnect between possession and utilization. This underuse is compounded by a troubling disposal rate; one-third of glue sticks are thrown away because they dry out, and a staggering 93% end up in general waste. The economic repercussions are clear, with sustainable options like those offered by UHU & Pritt costing three times more than their conventional counterparts.

The design of glue sticks, while user-friendly, harbours a linear business model that fails to consider the product’s end-of-life. The majority of the embodied energy and carbon footprint is attributed to the material and packaging, which also pose significant environmental threats. Despite the increasing use of natural ingredients and a decrease in PVA usage, the lack of visible labels on recyclability and the absence of infrastructure for sustainable materials like plant-based plastics create a barrier to eco-conscious choices.

There are some existing product service systems such as Terracycle that aim to recycle goods such as glue sticks. Terracycle provides two options. The first option is for the consumer to take the product to a Terracycle location and put it in a box, where the box is then sent to Terracycle where products such as glue sticks are separated by material composition, cleaned and melted into hard plastic that can be remoulded to make new recycled products. The second option aimed at establishments is to buy a zero-waste box, from 180 to 280 pounds, and fill it with empty glue sticks (or other glue containers) and then post it for free to Terracycle. However, this is inconvenient for users which reinforces the high amount of glue sticks that end up in general waste.

What Needs to Change?

Insights for what needs to change within this product sector can be divided into two distinct categories - Product Level and System Level.

At the product level, it is evident that disassembly poses a significant challenge, often due to concealed parts within the design. Addressing this issue by simplifying disassembly processes could greatly enhance the potential for end-of-life recycling and reuse. Moreover, personalization emerges as a crucial factor, as imbuing products with a sense of personal connection for users could foster greater care and attachment, thereby extending product lifespans. Additionally, there is a growing imperative to reassess the materials used in product manufacturing, particularly considering a transition towards more environmentally friendly alternatives labelled as 'Eco' materials. Furthermore, both packaging and product labelling should prioritize clear communication about sustainability attributes and recyclability to empower consumers with informed choices.

At the system level, enhancing consumer engagement stands out as a key objective. The system should prioritize providing engaging and informative experiences that seamlessly integrate sustainability principles into consumer lifestyles, thereby making sustainable choices more convenient and accessible. Furthermore, educational institutions should play a central role within the system, serving as hubs for disseminating knowledge and fostering sustainable practices among students, individuals, and businesses alike. Additionally, a fundamental shift towards a circular system model is recommended to minimize reliance on linear consumption patterns, thereby reducing landfill waste and promoting the adoption of sustainable practices throughout the entire product lifecycle.

System Level Concept

In the reimagined circular system of gluesticks, analysis can be conducted by examining the resource flow.

The journey begins with the cultivation of potatoes, which are subsequently processed into starch. This process involves cleaning, washing, crushing, dewatering, and drying to produce starch. This starch serves dual purposes in the product. Firstly, it can be utilized in manufacturing the packaging by combining starch, water, and paper fiber, which is then injection molded. This method has already been implemented by a company called 'Paperfoam'. Secondly, the starch is used in producing the glue itself, where starch and water are combined and heated to create the adhesive, a technique already demonstrated by Pritt. Less than one potato is required to produce a complete glue stick. For the casing of the glue stick, CL PHA, produced through the natural fermentation of farm waste by bacteria, can be employed. If both the farm waste and potatoes are sourced locally, they could originate from the same place. This PHA is then injection molded into the casings as a sustainable alternative to the thermoplastics currently utilized.

Once manufacturing is finished, the glue sticks can be stored until a customer places an order. With schools being the initial target customers, this specific process flow can be analyzed. The school purchases the service from ARC based on the number of students. These students then gain access to the website to personalize their item, selecting the color of the product and graphics to impart a sense of ownership. After all students have made their selections, the order is processed and dispatched to the school. Upon delivery of the glue sticks, students use them until the glue is depleted. However, by the school ordering refills and the students forming attachments to their glue stick casings, they can be reused multiple times. The casing should only become obsolete if it breaks due to misuse, the student completes school and no longer requires it, or for some other specific reason.

If the casing does become obsolete, the CL PHA can degrade in a matter of days on land, in rivers, and in seas. If the school has a compost, it can be disposed of there. The cycle can then recommence, even though the product may not degrade into the same soil where the potatoes are grown, the energy from the product is still returned to the earth, thus completing the circular loop.

Given that none of the interventions in the new system are unrealistic for this time period, it is reasonable to suggest that the time horizon for the new system could be within a year. However, for the manufacturing and economic feasibility of the CL PHA and other manufacturing methods to be scaled up, this may be closer to 5 years.

Product Level Design

Diving into the glue stick design and manufacturing process, as mentioned, they are made from potato starch and water, heated up. They are then cooled in a mold so that the glue solidifies. Next, they are quickly dipped in warm natural wax and cooled again. The sticks have a small hole through the middle to aid in refilling, slightly smaller than a bolt screw thread. The refill system is designed to be simple and tidy. Once the old glue stick has run out, a new one is taken out of the box and simply pushed into the bolt screw, then the bolt is turned at the bottom of the stick to pull the glue onto it. Due to the wax coating on the outside of the stick, users' hands will not get sticky during this refill process, resulting in no mess and no waste.

As for the packaging, like the casing, it is biodegradable and has very similar physical properties to existing packaging materials. For the glue sticks, the packaging will be a standard size box with square dividers to keep the sticks separate. They will not stick to the box due to the wax coating. The casings will be in a similar style but slightly larger box, again with dividers. They can come in multiple sizes depending on the order quantity.

Potential Impact of ARC

There are social and environmental benefits to this proposed product-service system.

Environmentally, natural disposal of the product means that no processes are used, thus saving energy. The refill method means no waste after a glue stick is used, and the speed of biodegradation of the casing means that there is essentially zero waste. The sustainability footprint is improved as many of the materials used to make the products are linked, resulting in a decrease in resource volume. Additionally, they are natural resources that return energy to the earth at the end of their life cycle. The way materials are sourced from the soil, and the disposal of the product in soil at the end of its life, demonstrate the improved circularity of the product.

An analysis of the product was carried out with the new materials, assuming that the new glue stick will last around a year, while an old one would last 3 months. Figure 3 shows that there is over a 3x reduction in energy usage and over a 7x reduction in CO2 emissions. These figures, along with the fact that the end-of-life of the product will be more sustainable, demonstrate the feasibility of the idea.

The product will teach children ownership, care, and sustainability if they are given an overview of the lifecycle of their product by their teachers. Previously, glue sticks were shared in the classroom, but this new system teaches them this important trait. If Covid-19 or similar diseases are present, this idea improves hygiene as items are not shared, therefore reducing the likelihood of spreading germs. All the elements in the system, such as materials and forms of transport, already exist in the world, making the intervention feasible as no drastic changes are needed to current infrastructure. The intervention is innovative in the way that students use stationary and the complete circularity of the model, and therefore will hopefully be recognized and adopted.

This type of circular product service system could be expanded to other stationary products, as well as targeting wider customers such as businesses and homes. Download the full report below for more details.