Understanding Plastics: Single-Use vs. Engineering Plastics

For decades, the global production of plastics has grown yearly by an average of 9% (1). Plastic production was reported as 1.7 million metric tons in 1950 (2), and this value reached 360 million metric tons worldwide in 2018 (3). The MacArthur Foundation estimated plastic production to double again over the upcoming two decades (4). Currently, plastics are categorized as single-use and engineering-use.

Single-use plastics are disposable solutions widely used daily for convenience at the cost of harming the environment by the resulting, long-term waste. On the other hand, engineering plastics provide high-performance capabilities to withstand various mechanical and environmental conditions. As a result, they can help create innovative solutions to evolve societies across all socioeconomic levels. Accordingly, this article intends to discuss the benefits and applications of engineering plastics and compare their properties against single-use variants.

Single-Use vs. Engineering Plastics

According to their use, plastics may be divided into single-use plastics and engineering plastics (5). Single-use plastics are disposable products thrown out after use, often in mere minutes, after which they are recycled or disposed of as solid wastes (6). Examples of single-use plastics include straws, bottles, bags, and wrappers.

In contrast, engineering plastics are a type of plastic with superior mechanical and thermal characteristics compared to single-use plastics (7). As a result, they produce goods with advanced technical or functional requirements in industrial applications to replace metals and ceramics (8). Typical applications of engineering plastics include areas where heat resistance, chemical resistance, impact, flame retardance, radiation resistance, or ease of processing is required (9).

The global production trends of single-use and engineering plastics are shown in Figure 1. Plastic production and its corresponding solid waste have grown dramatically, with single-use plastics representing a considerable portion of the total (1). Unlike engineering plastics, single-use plastics are a glaring illustration of the challenges associated with cultures that treat everything as disposable. Instead of investing in durable, high-quality items, people frequently prioritize convenience over long-term implications. Thus, single-use plastics have been responsible for most solid waste collection in the past decades compared to engineering plastics.

While single-use and engineering plastics can be made from the same materials, engineering plastics are made to a higher standard and are often designed to serve a long-term purpose (1, 8, 9). A comparison of the properties of single-use plastics and engineering plastics is shown in Table 1. Beyond their enhanced durability, engineering plastics provide better performance than single-use variants. However, the primary benefit of engineering plastics comes from how they are used. Thus, it is essential to distinguish the difference between the two types of plastics to justify decisions related to controlling, limiting, or prohibiting the production of these goods.

Engineering plastics and their applications

As mentioned previously, the uses of engineering plastics stem from their composition and manufacturing, enabling them to offer improved physical and chemical characteristics and sustain temperatures up to about 150°C. Engineering plastics replace conventional materials such as steel, glass, or ceramics across various applications. In addition to matching or exceeding them in weight-to-strength ratios, these plastics are significantly simpler to produce and fabricate—a benefit for complex designs. In 2020, about 22 million tonnes of engineering plastics were consumed across all product categories (10).

The application areas of these plastics include transportation, electrical and electronics, consumer goods, industrial, water/wastewater, construction, and civil. For instance, engineering plastics are considered game-changing products in various construction projects, such as geosynthetic liners in landfills and mines (11, 12) or high-density polyethylene (HDPE) pipes in water and wastewater systems (13). Other applications in the construction industry include concrete encasements (14), fibers inside concrete mixtures (15), and wall tiles and ceiling panels (16).

Benefits of engineering plastics to building societies

Engineering plastics offer effective, long-term solutions to problems faced by societies of all socioeconomic strata. For instance, geosynthetics, a type of engineering plastics, are widely utilized as economical and eco-friendly solutions compared to earth resources in infrastructure projects due to their capabilities in achieving the United Nations’ sustainable development goals (12, 17). Geosynthetics are often categorized into six types based on their functioning: moisture barrier, erosion, filtration, reinforcement, drainage, and separation. (18). Consequently, various geosynthetic families have emerged, including geomembranes, geotextiles, geocomposites, geonets, and geogrids.

Geosynthetics have become the material of choice for many embankment projects with soft soil layers due to providing cost-effective stabilization, excavation, reinforcement, and dewatering solutions (19). In addition, geosynthetics reduce the actual filling cost of the project by decreasing or preventing local failure (20). Besides the uses above, geosynthetics have perhaps made the most significant impact in the area of hydraulics owing to their critical role in providing a great degree of waterproofing to dam types, canals, liquid containments, reservoirs, and other applications where fluid control or containment is required (18, 21). Other applications of geosynthetics include mining projects and hazardous material containment (22).

Another important example of engineering plastics in the infrastructure industry is HDPE pipe and fittings, which are essential products in piping systems for their overall durability and economic benefits (23, 13). Generally, HDPE pipes offer outstanding properties such as good mechanical behavior, chemical resistance, self-lubricity, and cost-efficiency thanks to consistent flow capacity throughout their service life. The importance of HDPE piping systems against steel and concrete arises from their lighter weight, leak-proof joints, durability, low maintenance requirements, and overall longevity. Besides being utilized mainly in water and wastewater transport projects, HDPE pipes were successfully used as buried water cooling systems to prevent cracking due to thermal stress in the construction of big dams (24). HDPE pipes have enormous promise in agricultural applications, including above-ground pipelines and canal enclosures, where extreme weather and temperature changes are expected.

Conclusion

To summarize, there are significant differences between single-use and engineering plastics, with engineering plastics offering numerous benefits to building societies worldwide.

• While single-use plastics generate an enormous quantity of non-biodegradable waste yearly and should be curbed, policies should differentiate between single-use and engineering plastics.
• Engineering plastics are products that provide low-cost, long-term, and efficient solutions to building societies all around the world.
• Examples of engineering plastics used across various infrastructure projects include geosynthetics and HDPE.
• Geosynthetics offer critical improvements when used in landfills, mining, or hydraulic applications.
• HDPE plays a vital role in water and wastewater transporting systems by reducing construction costs and improving its durability.
• All communities stand to benefit from the strategic utilization of HDPE pipes, geosynthetics, and concrete liners.