Density OF PLA Plastic | The Definitive Guide

Density of PLA

Plastic material density is defined as the mass per unit volume of the material, typically measured in either gram per cubic centimeter (g/cm³) or kilograms per cubic meter (kg/m³).

PLA density is 1.25 g/cm3 g/cm3 and 1240 kg/m3.

The density of the popular biodegradable plastic is slightly higher than water (1 g/cm³). This is notably less dense compared to many frequently used petroleum-based plastics such as polyethylene (with a density range of 0.92 to 0.96 g/cm³) and polypropylene (with a density range of 0.9 to 0.92 g/cm³)

Before diving into the PLA plastic density shebang, I would like to clarify how plastic material density is measured.

What is Density?

Plastic density is the measurement of a substance’s mass about its volume. It is a key physical property that characterizes a material and influences its behavior in various conditions. The density can be represented in units of either gram per cubic centimeter (g/cm³) or kilograms per cubic meter (kg/m³).

Factors That Affect the PLA Density

Several factors can influence the density of PLA, including the kind of starch or sugar utilized as the raw material, the method of production, and the addition of fillers or additives.

The type of starch or sugar used as the raw material can significantly impact the density of the final product. For example, corn starch typically has a higher density than sugarcane or potato starch, which can result in a denser final product.

How PLA is produced can also influence its density. This is because factors such as the alignment of the polymer chains during production can impact the density of the resulting product.

Additives and fillers can alter the PLA’s density. Fillers can increase density, while certain additives can lower it by creating voids within the material. The type and amount of additives used determine the final density of the plastic.

How Temperature Impacts the Density of PLA?

The temperature at which PLA is processed can also impact its density. The polymer chains can become more flexible at higher temperatures, leading to a lower density. Conversely, the polymer chains become more rigid at lower temperatures, leading to a higher density.

It is essential to note that the temperature at which PLA is processed can also affect its other properties, such as its strength, stiffness, and flexibility. As a result, it is important to choose the appropriate processing temperature based on the specific needs of the final product.

How Does PLA Density Affect Its Processing?

Melt Viscosity

The viscosity of the melted PLA is directly related to its density. A higher density usually results in higher viscosity, making the material more difficult to process. This can lead to poor flow, increased melt temperatures, and longer processing times, all of which can impact the product’s final quality.

To mitigate these issues, manufacturers may need to use specialized processing equipment or adjust processing conditions, such as temperature and pressure.

Mechanical Properties

The density of PLA can also impact its mechanical properties, such as strength, stiffness, and toughness. A higher density will generally result in a stronger and stiffer material, but it may also be more brittle. On the other hand, a lower density may result in a more flexible and impact-resistant material, but it may also be weaker.

The specific mechanical properties of PLA will depend on the density and the specific formulation and processing conditions used.

Thermal Properties

The density of PLA impacts its thermal properties, including thermal stability, heat conduction, and thermal expansion. A higher-density PLA enhances its thermal stability and heat conduction due to the increased bonding between its polymer chains. Conversely, a lower-density PLA reduces thermal stability and heat conduction due to a decrease in bonding and the presence of gaps and faults within the material.

Applications of Low Density and High-Density PLA

Talking first about low-density PLA is typically used for applications that require flexibility, such as packaging, toys, and textiles. In these applications, the material’s low density makes it more flexible and easier to form into the desired shape.

Conversely, high-density PLA is favored for applications that demand rigidity and strength, such as medical devices like implants and prosthetics. The increased density in this type of PLA offers increased rigidity and strength, making it a suitable option for these crucial applications.

How Density of PLA Affects 3D Printing 


PLA plastic is most popular for its variety of applications in 3D printing. Some of the most common applications of PLA with 3D printing are Food packaging and containers, Toys and figurines, Replacement parts and functional objects, home décor items such as vases and lamps, Phone cases, and other electronic accessories, etc.

The method of 3D printing is all bout layer adhesion water FDM, SLA, or SLS. The material’s quality determines the flow behavior during the printing process.

A higher density PLA leads to a higher viscosity of the melt and a slower cooling rate, which can result in incomplete layer fusion and poor layer adhesion. On the other hand, a lower-density PLA results in a lower viscosity of the melt and a faster cooling rate, which can lead to improved layer adhesion and reduced warping.

However, this also reduces the mechanical properties of the final product, such as strength and toughness.

The Conclusion

The density of PLA plastic can vary depending on the manufacturer and production process. However, on average, PLA plastic has a density of 1.25 g/cm3, making it a lightweight and sustainable alternative to traditional petroleum-based plastics.

Its biodegradability and low environmental impact make it a popular choice for consumer products, packaging, and medical applications. Despite some limitations, the increasing demand for eco-friendly solutions makes PLA a promising material for the future.

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