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What is High Impact polystyrene forming? HIPS can be produced by all conventional plastic forming methods. This product usually does not require pre-drying and can be dried for 2 hours at 80 degrees. The most common method of forming this copolymer is the injection molding process. The plastic injection process is one of the most widely used methods of making and shaping polymer products such as food packaging, some containers, some TV parts, syringes, telephones.

In general, injection is a simple process in which a thermoplastic, in the form of a granule or powder, passes through a funnel and enters a barrel. In the barrel, the materials soften under heat. These materials are then forced through the extractor into an injection mold and cooled. After the required time for the plastic to reach the solid-state, the mold is opened and the manufactured part is removed. Among the most important advantages of the plastic injection process, we can mention the very high variety in the type of molds and final products, as well as the possibility of making the product with high speed and accuracy.

HIPS

In this article, we will explain plastic injection molding machines and types of injection molding processes for High Impact Polystyrene Forming (HIPS).

Plastic injection machine in High Impact Polystyrene Forming

In early plastic injection machines, the material first moves inside the soft machine and then into the extractor and the mold holes. Due to the distribution of material inside the barrel to improve heat transfer, a torpedo is placed in the barrel.

This type of device consists of two barrels. First, the raw materials are poured into the first barrel. In this barrel, there is a spiral that softens the material and transmits it to the second barrel through a one-way valve. A piston in the secondary barrel pushes the material into the extractor and then into the plastic injection mold.

These types of devices are rarely used today; Because they have a higher price due to their more complex system. Today, the screw injection machine is mostly used.

In today’s screw injection molding machines or injection molding machines, an extruder screw in a hot-rolled barrel has two roles. The screw can rotate normally to melt the material and transfer it to the barrel. It is also able to move forward like a piston and inject material into the mold.

High Impact Polystyrene Forming and Injection Processes

High Impact Polystyrene Forming Technology

The processes used for High Impact Polystyrene Forming (HIPS) typically include the injection molding process, the injection blow molding process, and the tensile injection molding process.

The injection molding process generally consists of four steps. First, after the mold is closed, the screw pushes the material forward into the mold without injection. The air inside the mold is expelled through small vents or vents.

Then, when the cavities are filled and the mold is filled, the helix continues to push the material forward to maintain pressure (holding time). This allows excess molten material to enter the cavities to prevent material from accumulating during cooling.

Once the valves are closed, the melt can no longer enter the mold and the pressure inside the mold will still be high. In this case, the screw starts to turn and spin, and new plastic comes out of the funnel and pushes them forward.

As the plastics move forward, the heat begins to melt through the electric barrel heaters as well as the shear forces applied to the material.

In other words, when the fully molten material is discharged at the end of the screw, the molten material collected at the end of the screw pushes it back so that the screw rotates and rotates and at the same time moves backward.

After a predetermined period, the screw stops rotating to complete the process of solidification and stabilization of the mold. When enough molten material collects in front of the screw, the screw stops rotating. The mold is cooled during screw recovery. The screw must remain constant for a period after the recovery time to complete the cooling of the mold.

When the mold and molten material have cooled sufficiently, the mold is opened and the product is discarded. Then the mold is closed again and this cycle will be repeated.

Injection blow molding process in a nutshell: First, the initial product is made by the conventional injection molding method, and then it is placed in another mold, blown into it, and finally removed. Most thermoplastics can be made by injection molding.

Tensile injection blow molding is the same as the Injection blow molding process, except that before blowing air and the final formation of the part, the initial product is slightly warmed and stretched in the longitudinal and transverse directions.

In fact, by doing so, the amorphous chains of the polymer material are stretched and oriented, which leads to the formation of a different type of crystallinity. The chains orient in the direction of applying stress and apply a linearly arranged structure throughout the area under stress. This orientation in the structure of the material can cause the mechanical strength of the product.

What is the difference between thermoplastic and thermosetting polymer? The main difference between thermoplastic and the thermosetting polymer is related to the melting of these materials. Thermoplastics can melt in any way and be reused. Regarding thermosetting polymers, we must say that these materials have a permanent shape and also cannot recycle new forms of plastic. Another major difference is the non-fragility of thermosetting polymers, which is in contrast to the fragility of thermoplastics.

In comparison, thermosetting polymers have more strength and durability than thermoplastics. In some cases, we see that thermosetting polymers are up to 10 times stronger than thermoplastics.

Investigation of structure and difference between thermoplastic and thermosetting polymer

Structural differences of these widely used materials

To better understand the difference between thermoplastic and thermosetting polymers, we intend to study the structure of these materials.

Thermoplastic:

Thermoplastics are a type of widely used polymer. Thermoplastic melts at very high temperatures and after the cooling process can take any shape and become solid. Thermoplastics are materials that typically have a high molecular weight.

The polymer chains in these materials are joined together by forces between molecules. If there is enough energy, it will be possible to break down the intermolecular force. One of the main features of thermoplastics is their high moldability.

Regarding the reversible thermoplastic process, which is considered as the most important difference with thermostats, it should be said that by eliminating the intermolecular energies that cause this polymer to have a solid shape, we will see the melting of this material.

After cooling, the intermolecular forces return and the thermoplastic returns to the solid-state. In this way, it is possible to make different devices with it. Thermoplastics have many physical properties between the melting point and the formation temperature of solid crystals, which help to produce different products.

Thermosetting polymer

The most important difference between thermoplastic and thermosetting polymers is that thermostats are highly resistant to high temperatures and melting. By creating cross-links between the polymer chains in this material, it can be turned into a soft and viscous polymer or a harder and stronger material than before.

To define and identify the bonds in the structure of a thermosetting polymer, it is placed in a chemically active medium and introduced by a chemical reaction. Normally, this process is interpreted as cooking.

To start this process, the thermosetting polymer is placed at a temperature above 200 ° C and is done with the help of high-energy electron beams and ultraviolet rays and the use of additives. The crosslinks present in this material are stable chemical bonds that have a very strong 3D structure when the polymer is crosslinked.

This structure shows high resistance to heating. This process is known as the irreversible process. In this process, the raw material is transformed into a polymer network that has a stable heat capability.

During cross-linking in the thermosetting polymer, the molecular weight of the polymer increases. Thus the melting point increases. Given this, we find that when the melting point is higher than ambient temperature, the material retains its solid-state; If the temperature rises uncontrollably.

These products decompose instead of melting. Some of the most popular examples of thermosetting polymer include vulcanized rubber, polyester fiberglass, bakelite, vulcanized rubber, and melamine.

Comparison of thermoplastics and thermosetting polymers

The difference between thermosetting polymer and thermoplastic

• Thermoplastics are more widely used than thermosetting polymers.
• Thermosetting polymers have higher processing costs compared to thermoplastics.
• Other features of thermoplastics in manufacturing and processing compared to thermosetting polymer have higher properties, energy, and efficiency.
• There are many materials in thermoplastics; In particular, composites that are highly prone to failure, while thermosetting polymers have a high resistance to failure.
• Thermoplastics melt very quickly, while thermosetting polymers are highly resistant to melting.
• Another case that exists in thermoplastics and is referred to as a defect of this material. That is, thermoplastics have a creeping problem while thermosetting polymers have high strength.

Natural and synthetic polymers are found in human life. Polymers are synthetic or natural. These two polymers are different from each other.

Introduction of natural polymer

Natural polymer is created by natural processes. These polymers are present in the human body, plants, and animals. Proteins, amino acids, DNA, RNA are all-natural polymers that exist in nature and the bodies of living things. Wool, silk, honey are examples of natural polymers.

Synthetic polymer

Synthetic polymer

Synthetic polymers are made as a result of chemical processes. This type of polymer is produced by humans in laboratories and factories. Scientists and engineers design and manufacture these materials and products. Polyethylene, Teflon, polyacrylic, PVC are examples of synthetic polymers.

Differences between Natural and synthetic polymers

Natural polymer is found in nature and is constantly being produced. Carbohydrates, starches, and proteins are all-natural polymers. Synthetic polymers are produced by chemical processes in laboratories and factories. Rubber, nylon, bakelite, PVC, UPVC are all prominent examples of this type of polymer.

Examples of natural polymers

Natural polymer is produced by natural processes. This type of polymer is not harmful; It is often used as a raw material in many food and pharmaceutical industries. Recently, in developed countries, this type of polymer has been considered and synthetic polymers are removed from human life in a slow process.

Undeveloped and developing countries have not yet reached the stage of conscious abandonment of synthetic polymer products and are causing dangerous and harmful damage to their nature and society.

Types of natural polymers

Polysaccharides are made from polysaccharide particles. Galactose, glucose, and fructose are the most important natural polymers used in the food industry and are found in plants and animals. There are plant carbohydrates in the form of starch and animal carbohydrates in the form of glycogen.

Amino acids, polyamides, polypeptides, are natural polymers and are found in the bodies of living organisms. DNA and RNA are prominent examples of polynucleotides. Pectin is an example of a natural polymer.

The natural polymer was the inspiration for synthetic polymers. By studying the cellular, molecular, and chemical structure of these materials, scientists were able to design and produce synthetic polymers that in some ways resembled natural polymers.

Types of synthetic polymers

Types of synthetic polymers

Oil has been the source of many synthetic polymers. Some synthetic polymers are made from petroleum, which is used in the production of many chemicals and polymers. Some synthetic polymers are obtained by condensation called condensation polymers and others by polymerization, known as additive polymers.

Pay attention to natural polymers and discard synthetic polymers

Some synthetic polymers are classified as organic and inorganic polymers. Organic polymers are made of hydrocarbon particles, and the mineral particles of the raw material are mineral polymers. Polystyrene, Teflon, polyethylene, polypropylene are examples of this classification.

Comparison of natural and synthetic rubber

Rubber can be found in nature, which is the sap of the tree. This type of rubber is a type of polymer made from crude isoprene particles. Rubber is made by processing some raw materials such as isoprene.

Natural rubber is sticky and wears out very quickly. It is destroyed when the raw materials are spilled. With sulfur, it can be made elastic. By combining different raw materials, synthetic rubber is prepared.

Natural polymer

Natural polymer

The physical, chemical, and mechanical properties of this type of rubber are very different from natural rubber and that is why it is difficult to decompose even after the disappearance of these properties. The decomposition of synthetic rubber is harmful to humans and nature.

How to produce synthetic rubber

Single polyisoprene chains are attached to other polyisoprene chains during a chemical process (vulcanization). With this process, in the rubber industry, this artificial product can be produced many times. Sulfur is also used. The method used in the production of rubber is irreversible.

In this process, soft and elastic materials are joined together in chemical processes, resulting in harder and stronger materials. In this way, the adhesives become smooth and soft materials, and as a result, the rubber never sticks to metal and plastic surfaces.

synthetic rubber

Conclusion

Natural and synthetic polymers are found in human life. Proteins, amino acids, DNA, RNA are examples of natural polymers and these materials are used in many food, pharmaceutical, and medical industries. Today, with the turn of man to nature, these substances have been considered.

Synthetic polymers are derived from petroleum and are sometimes classified as organic and inorganic polymers. This type of polymer is prepared and designed by combining several raw materials. It is harmful to human life and is gradually being phased out of human life in developed countries. It is hoped that one day, in all countries of the world, these substances will be completely removed from human life.

What are thermoplastic types? Thermoplastic refers to materials that melt when the temperature rises without undergoing chemical changes. Another feature of thermoplastics is that we can melt them several times and solidify them again. This material, like most liquids, flows when it is melted; This is different from materials that have cross-linking capabilities.

Familiarity with the sign of thermoplastic types

• TPE elastomer has a fixed position in various industries.
• EPDM
• EPM
• NBR
• PBR
• SBS
• SEBS
• TPS
• TPO
• PBR
• TPV
• TPR
• TPS
• TPO

What are the physical and mechanical properties of thermoplastic types?

properties of thermoplastic types

Thermoplastics often have a solid-state in the crystalline and amorphous parts when they are below the melting point. This material receives its elasticity from the amorphous parts and its strength from the crystalline part. It is noteworthy that if the temperature rises more than the melting point of the crystalline parts, they lose their state.

Thermoplastics have a unique feature of recyclability; This has made this polymer model very popular. Another feature of thermoplastics is the ability to be in the freezing and thawing cycle continuously. One of the best, cheapest, and most widely used thermoplastics is polyethylene.

The structure of thermoplastics is composed of a combination of plastic and rubber, which has the capabilities of rubber and plastic; That is why it has extraordinary mechanical and physical properties.

Features of different types of thermoplastics

As mentioned, thermoplastics can change shape at different times. In this way, the molten material is placed in the molds and after cooling, the molds take on a new form.

Another feature of thermoplastics is their weldability. Of course, it should be noted that both plastics should be selected from the same material during welding operations. The welding wire you choose must also be made of the same plastic, otherwise, welding is not possible. Therefore, you can’t connect two different types of plastic by welding.

Some thermoplastics can be bonded by chemicals, adhesives, such as solvents, etc. Thermoplastics have a plastic-like function when placed at temperatures below melting before they take on a paste. This function is also present at temperatures higher than paste. Another advantage of thermoplastic is its very high flexibility at very low temperatures.

Applications of thermoplastics

Applications of thermoplastics

Thermoplastic TPU:

It is a type of thermoplastic that has the ability to self-repair. It is used in coated and breathable fabrics and medical products such as gloves and gowns.

Other applications of this material include its use as a cable cover, film and thin sheet, hydraulic hoses, electric wire jackets, sealing of automatic hub connection and small wheels, etc.

EPDM / PP TPV thermoplastic:

This type of thermoplastic is used in very sensitive cases such as aerial sealing of the car and the inside of its hood. Another function is to use it for sealing medical and foam products. It is also used as insulation for wire jackets and small wheels.

AEM TPV Thermoplastic

Used as electrical connections, undercarriage, train shaft sealing drive, air duct, hose cover.

As mentioned earlier, thermoplastics are made from a combination of rubber and plastic. This alloy has the mechanical and physical properties of plastic and rubber.

Thermoplastic material is amorphous or macromolecular in shape and structure. Part of this material has the ability to crystallite.

These materials are produced and marketed in various forms in the form of cubes, cylinders, grains, and the form of lenses, and in some cases in powder form. These grains are often seen with a diameter of 3 mm. These materials are used to make different types of thermoplastics such as polystyrene, polyethylene, polypropylene.