Noise pollution is a nuisance either at work or home. By reducing the rate of this annoying factor, the concentration increases up to 48% and the rate of stress decreases by 27%, the error rate by 10% and the distraction rate in conversations by 51%. One way to prevent annoying noises and sounds entering from the street or side units is to use composite panels.
The word composite means a combination of two or more elements and a composite material that has different properties and attributes than its raw materials before it is combined. Composite panel or sandwich panels are composite or blended layers, in a way that a main layer is covered by two layers of coating. The thickness of the main central layer, which is made of polyethylene foam, varies depending on the application. The coating layers are metal and in most cases are made of steel or aluminum, which are determined based on the application in property. This coating keeps the insulation of the center layer connected and makes it easier to install on the wall of the building.
As mentioned above, the middle or central layers of these panels are normally made of polyethylene foam, which is considered as an oil and polymer product. Apart from polyethylene, other types of polymer foams are also used in the construction of types of composite panels. Main features for making these types of foams are thickness, tissue strength, adsorption rate and resistance to chemical and environmental destructive factors. This central layer is responsible for insulating against energy, and count as the main protection layer against noise and energy conduction. Due to the porosity in its texture, this foam traps air molecules and thus acts as an energy insulator. This energy can be acoustic or thermal. But additionally, flooring and partition walls also play a vital role in insulation.
Before we continue to go deeper how to insulate against sound, let’s first look at how sound is transmitted.
Sound transmission methods
Sound transmission is generally done in two ways: by air and by impact.
In the transmission of sound from the impact method, due to the collision of two objects with each other, the vibration resulting from the impact of the sound wave is directed around. In fact, sound is transmitted from one component to another.
In airborne transmission, air molecules also play the role of transmitting sound oscillations from one place to another. In this case, the sound is transmitted directly from the source to the surroundings.
Sound insulation means protecting the environment from both methods of sound transmission. As a result, the adsorption attributes of the materials are studied, and after all, the required material is determined according to the usage of the environment or place that intended for insulation.
Sound absorption by adsorbents
When sound hits an obstacle, part of it is reflected and the other part enters the sound barrier, and this process will repeat again and again. The barrier absorbs part of the incoming wave and passes the rest through to be released into space. In sound insulation materials, high absorption rate and low passage and reflection are considered as major factors. At porous surfaces, a large percentage of the energy is absorbed into the material and the amount of reflection decreases.
In double-layer sound insulation, such as aluminum composite panels or ACPs, two outer shells are used in addition to the interior space, which is vacuumed or insulated part. All materials have different amounts of sound absorption, which is related to the physical structure of the material. These materials cover different sound frequencies based on their characteristics. Porous materials have the ability to absorb sound with lower frequencies and in contrast absorb-able materials absorb more frequency with sound. By combining these two materials, more spectrum can be obtained. Polyurethane sponges are one such material.
The types of foams used in this work include: polyurethane sponges, rock wool, egg shoulder foams, rebound foam, pyramidal cloud, XP foam, flex panel.
Another way to make the middle layer of these panels is to use polyurethane foam spray. In this method, the insulating material, which is polyurethane, reacts as soon as it is sprayed with air and sits as a solid foam on the desired plate. Finally, the top layer, which is the outer covering, will be placed on it.
What kind of buildings or properties need insulation?
Hospitals, doctors’ clinics, libraries, theaters, conference halls, studios, and music schools are examples of places that need sound insulation indeed.
Quality required for proper insulation
Since these materials have a limit life time, the ease of replacement should be considered. As a result, they would be easier to install and dismantle. Also, these materials must be resistant to insect and microbial damage, that composite panels cover a variety of these demands perfectly.
However, in normal properties without any business purposes there is no need to jeopardize building design for sound insulation. This is considered as an added step to construction. Also, in addition to being suitable sound insulation, composite panels have a great application in the exterior of buildings and structures, and in addition to being insulated, they can perform facade design well without choosing designers and Restrict project implementer. These unique composite panel features makes it popular and efficient in various properties.