“Only the best is good enough”, the motto whereby the LEGO Group built its foundation upon, was established in the year 1932 by a Danish family. The company’s name, having the meaning “play well” was created by combining the Danish words “leg godt” to produce what is now known worldwide as ‘LEGO’.
LEGO has become an essential part in a child’s play time and it contributes a significant role in child development and learning. However, have you considered what the LEGO bricks and blocks are made of and if they pose any harmful or detrimental threats to children or the environment, based on its source and processes by which they are made.
Polymers are found in numerous sources of nature. Some of these sources are fruits, wood, seeds and even animals and has been used for clothing, food and furniture for many years. In the 1860s, the first artificial thermoplastic polymer celluloid was discovered which was then followed by the making of numerous compounds that were produced from renewable resources. However, none of these new compounds were used in the making of LEGO blocks due to the application of synthetic polymers, made from crude oil and its by-products.
Raw Materials in LEGO
From the very beginning, Legos were made from plastics (polymers) which makes them very lightweight, cheap, durable, recyclable and odourless/odour resistant. These properties, make Legos the perfect childhood toy since it lasts a lifetime and is not easily destroyed. However, the kind of plastics being used to create these Legos varied over time. N.B. All plastics are polymers but not all polymers are plastics.
Composition of the LEGO Brick
Cellulose Acetate (CA) – C76H14O49, the initial bio-polymer used by the company, is a natural plastic made from natural cellulose. It is extracted mainly from wood and cotton seed fibres and synthesized by reacting the natural cellulose with acetic anhydride to produce CA (flake form) which is then finely ground to a powder and dissolved in a solvent. However, CA in the flake form, cannot be used as a thermo-polymer and must be compounded with esters to produce such transparent thermo-polymers/plastics (i.e. CA Granules).
ACRYLONITRILE BUTADIENE STYRENE (ABS)
The second the polymer used in the production of LEGOs is Acrylonitrile Butadiene Styrene (ABS). In this present day, the LEGO pieces being produced are mainly manufactured from the ABS thermoplastic. ABS is composed of three monomers, namely Styrene, Butadiene, and Acrylonitrile and has a chemical formula (C8H8)x·(C4H6)y·(C3H3N)z. While all three monomers are essential to the makeup of LEGO blocks, the butadiene element mostly contributes to the high impact strength and resistance of the plastic. It is a vastly resourceful raw material used to create a wide variety of synthetic rubbers It is the main rubber used in tires.
Polycarbonates (PC) are another set of thermoplastics used to produce specific LEGO components. They are utilised in the manufacturing of rods, flags, clips and transparent LEGO materials. However, they tend to display qualities that does not fit into the general makeup of LEGO blocks, such as low scratch resistance (i.e. it tends to easily be scratched.
Polyoxymethylene (POM) also known as Delrin (CH2O), is another thermoplastic used to create cloth and string-like LEGO pieces. It is a variant of nylon and is stable, corrosion resistant and would cause little to no harm if it is swallowed by a child.
Polyethylene (C2H4)n is one of the most commonly utilised thermoplastics worldwide due to its wide application. It can be found in materials such as plastic bags, bottles, containers, clear food wraps and even children’s toys.
Ethylene (the monomer of polyethylene), is a hydrocarbon that is gaseous at room temperature and under certain temperatures and pressures, can be made a liquid or solid. Generally, it is manufactured by the cracking of the natural gas ethane or the distillation of petroleum, generating ethylene as a by-product of these processes.
An alternative would be the utilisation of bio-plastics (plant-based plastics) by employing feedstocks or biomass that can be changed into another beneficial form of energy or fuel or can be used unadulterated. Currently, polyethylene is being produced by taking sugarcane and converting it into bio-polyethylene, which is considered a ‘green’ plastic. By doing so, scientists aim to reduce the chemical impact on human health and contamination to the environment. LEGO has announced that they will begin producing more ‘sustainable’ pieces by switching from ABS plastics to plant-based polyethylene, to minimise waste and environmental destruction. However, how would this change affect the integrity of LEGO toys/pieces and would this be beneficial when compared to ABS which the company has used for years?
THE COMPARISON OF BIO-BASED POLYETHYLENE (BIO-PE) TO ABS BASED ON SOURCE, STRENGTHM SUITABILITY AND RENEWABILITY/END-OF-LIFE CONCERNS
Acrylonitrile-C8H8, Butadiene-C4H6, Styrene-C3H3N (ABS) is a thermoplastic this is derived by the combination of three different monomer, as seen above. Each monomer component, however, contains different properties and sources and hence, contributes to the polymer in different ways.
Acrylonitrile is manufactured from propylene and ammonia. Butadiene is a by-product generated from the production ethylene via steam crackers and Styrene is made from the dehydrogenation of ethylbenzene. To create this terpolymer, it undergoes an emulsification process where the three monomer products are combined to form one product or a undergoes a patented process known as continuous mass polymerization.
The green plastic Bio-Polyethylene (bio-PE) is produced from plant-based feedstocks. It is derived from sugarcane which is converted into bio-ethanol, followed by bio-ethylene via the process of fermentation. Bio-ethylene is then polymerized to produce the different types of PE. The two common types are High-Density PE (HDPE) and Low-Density PE (LDPE) which displays different properties. The extent to which the PE is branched, determines what type of PE is produced.
LDPE vs HDPE
LDPE is softer and hence more flexible than HDPE which is harder. Because of this, HDPE can endure higher temperatures and doesn’t melts as easily as LDPE. It also has a greater resistance to chemicals.
Low-Density PE High-Density PE
Doesn’t operate well in colder temperatures Operates under higher temperatures
More branching, lower density Minimal branching, higher density and rigidity
Less tensile strength; greater ductility Greater tensile strength, low ductility
Used for grocery bags, plastic bottles, plastic cling-wrap, etc. Used for cutting boards, milk jugs, children’s toys, etc.
Both plastics generally have a great deal of strength, however, when it comes to comparing the strength of ABS plastics to PE, the latter is proven stronger. HDPE has a very high strength to density ratio.
The Gator company who is known for the manufacturing of hard cases for music and A/V gear, makes their cases out of Polyethylene plastics. A short experiment was conducted to compare the breakage threshold of their cases and the cases of their competitors (given the name (Brand X) which are made of ABS plastics. A hammer was used to test their strength and the results of such were the destruction of Brand X with just 3 hits. However, the Gator standard rack and pro-series lid sustained just dents after several blows with the hammer which proves the durability and strength of the polyethylene plastic over ABS plastic.
In ABS, the propylene and ammonia components from the acrylonitrile monomer, contributes to the chemical resistance and heat stability of ABS while butadiene and styrene contributes to toughness and impact strength and rigidity, processability and glossy finish, respectively. In its natural form, ABS is an opaque material that is beige or tan in colour. Because of its opaqueness, it can be easily coloured with pigments or dyes.
Some key features of ABS which makes this thermoplastic suitable for LEGOs are its hardness, toughness, rigidity, durability, strength and good chemical and impact resistance as well as being generally inexpensive. It is also has very good resistance to diluted acids and alkalis, moderate resistance to aliphatic hydrocarbons, however, it has a poor resistance to aromatic hydrocarbons, halogenated hydrocarbons and alcohols.
The comparison between LDPE and HDPE above suggests that HDPE would be used in the making of LEGO blocks due to its great resistance to breaking under tension and low ability to be deformed under compression, (for example, by hammering). Some other key features are toughness, flexibility, impact and chemical resistant as well as economical. HDPE is a bit less costly than ABS plastics.
Bio-PE is a transparent plastic that has a variety of uses. Its transparency allows Lego pieces to remain without colour as compared to those made using ABS plastics, where the majority are opaque, and colour is put to them. Furthermore, it generates approximately 2, 15 tons of CO2 for every ton of bio-PE manufactured.
RENEWABILITY / END-OF-LIFE CONCERNS
ABS plastics can be recycled like any other plastic, by taking its waste and converting it into various new objects. Recycling of ABS is essential, especially in the 3D printing business, where a lot of waste plastics are generated. One possibility is to reuse discarded 3D prints to create more 3D printing filaments, that is, making ABS plastic from other sources of ABS.
While recyclability of ABS plastics is a great advantage, it is not found to be very environmentally friendly as it cannot be degraded or renewed.
The production of ABS plastics is one thing, however, the destruction or end of life of these same plastics and its resulting effects is another. Even though, ABS plastics are known for their high heat resistance, on contact with extremely high temperatures, the probability of combustion is very likely. The occurrence of this, causes the organic materials in ABS to be broken down, producing toxic substances such as carbon monoxide and hydrogen cyanide. Therefore, the use of ABS in the food industry is recommended to be limited as it can cause these toxic components to be leached into foods. In addition, lengthy exposure to sunlight can cause damage to ABS materials.
Pyrolysis (decomposition by high temperatures) of plastics in little to no oxygen, allows for the breakdown of long polymer chains into smaller ones, producing a petroleum-like oil.
Even though bio-polyethylene is made from renewable biomass, it is not biodegradable, just like the ABS plastic. It is however, recyclable. HDPE products are usually recycled and are generally safe for storage of food or drinks because they are not known for the leaching chemicals. However, it is never recommended to reuse an HDPE container for food or drink that originally stored chemicals. LDPE products are occasionally recycled and are also classed as safe for food and drink storage.
The use of bio-PE has several advantages, one being it is made from renewable resources. Other advantages such as having a favourable carbon footprint and energy ratio as well as being 100% recyclable, allows for bio-PE to be preferred over oil-based ABS and it proves to conserve the environment. However, an issue in using sugarcane as its main source of biomass is that it is a food source and hence it would be more beneficial in remaining as such, instead of using it to produce bioplastics.