Foam plastic, its types, production
Each of you, when you hear the word polystyrene foam, imagine in your head a picture of small white round balls combined into a single weightless block. Let's look at what polystyrene foam is.
Polystyrene foam is not just one type of raw material. Polystyrene foam is plastic saturated with air particles. Depending on the type of foam used, its scope of application changes.
The foam manufacturing technology consists of three main stages:
- Connection of components.
- Saturation of the composition with oxygen
- Form formation.
An important point in the production of polystyrene foam is the saturation of the composition with oxygen, or, as it is also called foaming. How intensely the composition is saturated with oxygen affects the scope of application and type of foam.
Another important factor in the thermal conductivity of polystyrene foam is its ability to absorb moisture. The less the foam absorbs water, the higher its ability to retain heat.
According to production technology, there are two types of polystyrene foam:
- Foamed polystyrene foam;
- Extruded polystyrene foam.
Structure and composition of the finished material
Polystyrene foam is made from polystyrene foam balls that are filled with air.
Each thermal insulation material necessarily contains air located in the pores. The improved thermal conductivity index directly depends on the size of the atmospheric air masses contained in the material. The more there are, the smaller the thermal conductivity component will be. The foam manufacturing process comes from polystyrene foam beads that retain air.
In connection with the above, we can conclude that the concentration of polystyrene foam affects its thermal conductivity. If this value changes, then changes in thermal conductivity indicators occur within the boundaries of percentages. One hundred percent retention of air in the insulation is associated with its exceptional heat-saving ability, since air has the lowest thermal conductivity coefficient.
Due to the low thermal conductivity of the insulation, a high percentage of energy saving is ensured. If we compare brick with polystyrene foam, their ability to save energy will be noticeably different, because 12 cm of thermal insulation thickness is equivalent to 210 cm of thickness of a brick or 45 cm of log wall.
Expanded polystyrene foam
The most common type of foam used in everyday life. It is used for transporting furniture or various household items for safety. It is used as insulation.
The composition is saturated with gases by foaming.
- Expanded polystyrene is made according to the following principle.
- Initially, foam particles are mixed, and carbohydrate particles are added to them to foam the composition.
- Special additives are also added to improve the quality of the finished product.
- It is possible to add various dyes and form granules. The finished mixture is steamed and the final shape is formed.
What is the difference between rigid foam?
Foamed plastic masses, which, strictly speaking, is foam, have been one of the most popular insulation materials for many years. Essentially, this is gas-filled plastic, consisting of many cells, the main part of which do not communicate with each other, however, there are also communicating specimens, but their number is significantly lower than the first.
The main volume of this insulation is air, and, accordingly, it has a significantly lower density than raw materials. Keep in mind that the higher the density of the foam, the better this will affect the mechanical strength of the material. A similar material is obtained by pressing, which is based on the use of solid gas-forming agents together with powdered polymers.
Rigid foam plastic has found itself in the construction field as insulation and as packaging material. In addition, it is often used in industry, shipbuilding, aviation, etc. It is difficult to imagine fishing without it, and you can also find it in the field of electrical engineering. And all thanks to excellent characteristics. As mentioned above, it glues perfectly, so it is possible to obtain reinforced foam - you just need to connect it with a reinforcing element. You also have the opportunity to assemble a block of a given shape and size from this insulation. That is, as a structural element it will serve for quite a long time.
Extruded polystyrene foam
The manufacturing technology differs from foaming in that the finished mixture is not doused with steam. Individual granules are not formed from the finished composition. Carbon dioxide is used as a foaming element.
The appearance of the sheet has a continuous structure with closed porous cells.
If we look at the structure of the foam in more detail, we can understand that 2% is solids and 98% is air, enclosed in small chambers.
Main types of expanded polystyrene
Let's look at different types of polystyrene foam.
- Pressless. The foam granules are dried at a temperature of 80 degrees and foamed. This action is repeated several times. Then fill the form. More fragile look.
- Extruded.
- Extrusion. It is used in the food industry.
- Pressed. Quite durable looking.
- Autoclave.
Advantages of expanded polystyrene
- Retains heat well
- Long service life. At temperature readings from -40 to +40 it can last for 50 years.
- Resistant to moisture.
- Microorganisms, various bacteria, mold and mildew do not develop.
- Non-toxic. It can also be used in the food industry.
- Very light.
- Foam plastic with a thickness of 3 cm can be used as a good sound insulator.
- Some types have a fire-resistant coating.
Dimensions and thickness of polystyrene foam
Expanded polystyrene (foam) is produced in sheets of different lengths, widths and thicknesses. The last parameter is the main one in choosing this material.
The thickness of the product can be from 20 to 100 mm.
This material is very popular among builders. It is used to increase thermal insulation during bricklaying with solid bricks.
Pieces of foam plastic are placed under plywood, which is used to finish the floor under parquet or laminate. They can be used to insulate walls from the outside while finishing the walls with plasterboard. Most often it is used from the outside.
Foam plastic for insulation
In order to keep the house warm during the cold season, the house is additionally insulated with polystyrene foam. The best polystyrene foam for insulation is considered to be PSB-S-25.
This brand is chosen because of the following qualities:
- Dense material that can be installed on any surface.
- Retains heat quite well.
- Small mass.
- Tolerates transportation well.
- Acceptable price.
- Long service life.
Application of façade foam plastic
Facade foam is used in two cases. It is used as a base for plaster or as an independent coating that performs both insulating and decorative functions.
As a base for plaster, polystyrene foam is installed on the wall using cement glue. It is designed specifically for these purposes. It must be diluted in small portions with water. Within 30 minutes the glue sets. You need to work quickly.
- Glue is applied to the surface of the foam sheet and secured to the surface by pressing the sheet firmly. There is no need to apply glue to the side edges.
- After which the sheet is additionally secured using snipe umbrellas. IN
- Make a hole in the canvas and then install an umbrella. There must be at least five umbrellas per 1m2.
- After which the foam sheet is covered with a layer of cement glue. For better adhesion and improved strength of the structure, it is additionally reinforced with reinforced mesh.
- A mesh is installed on the not dried layer of glue, and with light movements it is embedded in the composition.
After the first layer of cement glue has dried, it is coated again, completely hiding the mesh. This coating must be coated with a primer and any plaster.
In its pure form, foam does not tolerate UV rays. For a longer service life, it must be coated with a protective layer. You can purchase already coated decorative sheets for the facade.
What do you need to know about sizes? What are they?
Foam sheets can be standard or custom sizes.
The length and width of the standard sheet are 1000, 2000 mm. The manufacturer can cut products into other non-standard sizes.
You can often find sheets of 1200x600 that meet the needs of the buyer and are in good demand. This can be a sheet with dimensions of 500x500, 1000x1000, 1000x500 mm.
On order, you can receive a batch of expanded polystyrene with sides of 900x500 or 1200x600 and other sizes, which does not contradict the standards.
Foam glue
Basically, foam plates are attached to the surface using glue. You need to choose glue for suitable conditions. If you attach it to the facade of a building, the glue must withstand temperature changes.
Adhesive for foam plastic should not contain gasoline or acetone, as they destroy the structure of the foam plastic. The glue is also selected for the surface on which the foam sheet will be attached.
Foam glue can be either dry or wet.
- To avoid making a mistake with your choice, you should not take the cheapest glue.
- It is better to spend a little more money, but get a product with detailed instructions and composition in accordance with GOST.
- When purchasing a dry mixture, pay attention to whether the packaging is damaged.
- Is the mixture really dry? Slight moisture may change the properties of the adhesive.
Chemical properties
The operational parameters of the material that determine durability under the influence of external factors include:
- chemical resistance - polystyrene foam is impervious to many substances, except solvents and oxidizing acids. Mixtures based on acetone, ethers and light hydrocarbons quickly dissolve foam, without leaving even visible traces of it. Foam plastic is moderately resistant to alkalis, however, it is still not worth specially exposing them to them;
- temperature resistance – foam plastic has a low temperature limit of destruction. Already at 60-70 °C, gases begin to be released from it, which are products of the destruction of the original polymer. At temperatures above 100 °C, the decomposition of polystyrene occurs especially intensively and is accompanied by an even greater amount of toxic emissions. Serious consequences on the body can occur even several days after inhalation.
The fire safety of polystyrene foam is interpreted in two ways by supporters and opponents of the material. The first claim about its high resistance to flame, arguing that the ignited foam practically does not support the fire without an external heat source. The latter complain about the release of large amounts of gases during a fire that are harmful to humans. When viewed objectively, polystyrene foam is a fairly flammable substance that requires proper handling when finishing buildings.
