Density of Acrylic | The Complete Guide

Density of Acrylic

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).

The density of acrylic is typically around 1.18 g/cm3 or 1150-1190 kg/m3. However, this value can vary based on several factors, including the presence of additives or fillers and the specific techniques employed during manufacturing.

Compared to other materials, such as metals with a density of 7.8 to 22.6 g/cm³, the density range of acrylic plastic, which falls between 1.17 to 1.25 g/cm³, is relatively low.

Thanks to its low density, the lightweight of acrylic plastic is a significant contributor to its popularity, making it a prime choice for applications that demand a balance between lightness and high strength.

Before delving into the specifics of the density of acrylic material, I would like to explain the definition used to measure the density of any plastic material.

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 plastic material and influences its behavior in various conditions.

The density can be represented in gram per cubic centimeter (g/cm³) or kilograms per cubic meter (kg/m³).

How Acrylic Density Affects Its Other Properties 

Let’s dive into the interrelationship between acrylic density and its melting point, mechanical and thermal properties.

Melting point 

The melting point of acrylic is fundamentally governed by its density. This density is contingent on the material’s crystallinity, which refers to the extent of regular molecular arrangement within the polymer.

A higher density denotes increased crystallinity, which correspondingly elevates the melting point.

This is due to the more organized molecular structure, which requires additional energy (or heat) to disrupt the intermolecular forces, resulting in a higher melting point.

For instance, Poly(methyl methacrylate) (PMMA), a common type of acrylic, has a density of 1.18 g/cm³ and a melting point of approximately 160°C.

This can be ascribed to its semi-crystalline structure, where a certain level of molecular order exists.

Mechanical Properties

The density of acrylic plays a pivotal role in determining its mechanical attributes. Acrylic materials of higher density display increased tensile strength, firmness, and hardness, attributable to their closely-packed molecular arrangement.

This compact structure allows them to resist deformation better, thus leading to enhanced stability when subject to stress. In contrast, acrylics with lower density are associated with superior flexibility and shock absorption.

This advantage stems from their loosely-arranged molecular structure, providing more space for molecular movement and adjustment when the material is stressed.

Thermal Properties

ThemrAcrylic’s thermal properties – thermal conductivity, expansion, and heat resistance – are linked to its density. High-density acrylics typically show lower thermal conductivity due to their compact molecular arrangement, slowing heat transfer through the material.

Their more excellent crystallinity leads to higher heat resistance but a smaller coefficient of thermal expansion, which implies lower expansion or contraction with temperature changes.

Conversely, with their less ordered molecular arrangement, low-density acrylics display higher thermal conductivity and a more significant coefficient of thermal expansion.

Factors Affecting Plexiglass/Acrylic Density 

One of the critical advantages of Acrylic’s low density is its high strength-to-weight ratio. Which is a measure of how much strength a material has relative to its weight.

This property is fundamental in applications where weight is critical, such as aircraft and aerospace applications. Acrylic plastic has a high strength-to-weight ratio, which can withstand significant loads and impacts while remaining relatively lightweight.

Factors Affecting Acrylics’ density are as follows:

Type of Acrylic Plastic

Different types of acrylic plastic are available in the market, each with different mechanical properties and applications. Some types of acrylic plastic are denser than others due to differences in their chemical composition and manufacturing process. For example, cast acrylic plastic is denser than extruded acrylic plastic due to its higher molecular weight and more uniform structure.

Manufacturing Process

The manufacturing process used to produce acrylic plastic can also affect its density. For example, the cooling rate during the casting process can impact the density of the finished product. Any additives or fillers in the material can also influence its density.

Presence of Additives or Fillers

To improve its properties, acrylic plastic can be modified by adding various additives or fillers, such as pigments, stabilizers, and impact modifiers. These additives can increase or decrease the density of the finished product, depending on its composition and quantity.


The temperature at which acrylic plastic is processed and stored can also affect its density. In general, as the temperature of the material increases, its density decreases. This is due to the expansion of the polymer chains, which increases the volume of the material and reduces its density.

Interesting Read – Polypropylene Density | All You Need To Know

How Acrylic Density Affects Its Processing 

Acrylic plastic’s low density, high strength, and transparency make it an ideal material for processing. It’s low weight and easy-to-manipulate nature make it convenient to work with during processing. Additionally, the low density reduces the amount of material required to produce a product, which can lead to cost savings.

Acrylic plastic is also energy-efficient due to its low weight and ease of fabricating, making it suitable for various fabrication methods, including thermoforming, injection molding, and extrusion. The combination of low density and high strength makes acrylic plastic versatile and ideal for various applications.

Is Acrylic Heavier Than Glass?

Acrylic plastic is generally 50% lighter than glass, with a density ranging from 1.18 g/cm³, while glass has a 2.5 g/cm³ density. Despite its lower weight, acrylic plastic is known for its high strength and durability, making it a popular alternative to glass in many applications.


The density of acrylic plastic is an important attribute that can influence several factors, including the type of acrylic plastic, the manufacturing process, the presence of additives or fillers, temperature, humidity, and age.

Understanding these factors and their impact on the density of the transparent thermoplastic is essential for selecting the best material for a specific application and ensuring that it meets the desired performance requirements.

Leave a Comment