Plastics are part of petrochemical industries and plastic products are considered among industrial goods. Plastics have been widely mixed with today’s life and entered the production process of many products. From the point of view of the experts of this industry, the plastic industry has a suitable position from the point of view of profitability, competitiveness, added value and employment, and in the case of correct policy making and determination of appropriate strategies, a competitive advantage can be imagined for this industry. It increases competitiveness in this industry and creates a double added value. Less attention has been paid to research and development (R&D) and product design based on Iranian culture and ergonomic realities in the industry. This industry is used in various industries as follows: aerospace industry, construction industry, electronic industries, packaging industry, transportation industry, component manufacturing and automobile industry, household and office appliances and furniture, industrial equipment and equipment, industries Related to the fields of medicine, agriculture, gardening and textile industries.
Introduction of plastics
Plastics are part of petrochemical industries and plastic products are considered among industrial goods. Plastics have been widely mixed with today’s life and entered the production process of many products. From the point of view of the experts of this industry, the plastic industry has a suitable position from the point of view of profitability, competitiveness, added value and employment, and in the case of correct policy making and determination of appropriate strategies, a competitive advantage can be imagined for this industry. It increases competitiveness in this industry and creates a double added value. Less attention has been paid to research and development (R&D) and product design based on Iranian culture and ergonomic realities in the industry. This industry is used in various industries as follows: aerospace industry, construction industry, electronic industries, packaging industry, transportation industry, component manufacturing and automobile industry, household and office appliances and furniture, industrial equipment and equipment, industries Related to the fields of medicine, agriculture, gardening and textile industries.
What is plastic?
The American Society for Testing and Materials defines plastic materials as follows:
Plastic is a material that has an organic substance with high molecular weight as a main component, it is solid in the manufactured state, and in some stages of its production or processing, it can be transformed into the desired shape by flowing or liquefying. In other words, plastics are organic materials with high molecular weight that can be useful and in different forms. Some of them are found naturally, but they are produced artificially, and in general, plastics are compared to metals and alloys. It is much weaker, softer, more resistant and less resistant to hydrochloric acid ions in concentrated sulfuric acid, nitric acid, solvents and lower thermal limit. Plastics are synthetic polymers that can be melted and molded under pressure and temperature, but the interesting thing about plastics is the wide range of features that have created a special place for this polymer. So that some of them are inflexible, that is, they can be turned, and some others are soft and flexible, which can be used in very delicate applications. metals, glass, wood, fibers, etc.
Plastic is a product that is used for various purposes. Plastic may be hard or soft, transparent or opaque. It can look like wood or leather or silk. It can be used in making toys or heart valves. There are more than 10,000 different types of plastic. The primary raw materials for making plastic are oil and gas. These fossil fuels are sometimes combined with oxygen and chlorine to make different types of plastic.
Some types of plastics can be recycled and some cannot be recycled. Many people think that plastics are wastes that are ultimately irreplaceable, or because they consume fossil fuels, they are called energy-hungry. This is not the case, and plastics are very efficient in terms of energy and consumption. It means that much less energy is used to make a plastic bottle than to make a glass bottle. Also, since plastics are light in weight, less energy is used to transport them. Although plastics are generally light, but disposing of them in landfills is not a good option, but there are two other ways, recycling and incineration. The use of these methods leads to the recovery of some plastic values, which can be used in re-construction. Plastic items are used.
Incineration of waste causes the recovery of chemical energy that can be used to generate steam and electricity. In the case that ground burial of plastics does not have any of these advantages, and in addition, sanitary burial of plastic means permanent burial because this type of waste does not decompose. to be
The plastics industry is very important due to its strong connection with the oil industry.
In fact, it can be said that if there is no oil, we will not be able to produce plastics. Until the mid-1950s, the main source of raw material for the plastic industry in Europe was coal, in this regard, coal tar, coke, coal gas, and ammonia. Coal tar is a source for aromatic chemicals such as benzene, toluene, phenol, naphthalene, and related products. which eventually led to the production of important plastics such as polyethylene resins and nylons.
The development of the petrochemical industry is probably the biggest unique factor in the growth of plastics, for this reason, the petrochemical industry is noticeably visible in our daily life through the production of plastics.
Historically, the plastic industry has experienced very rapid growth. Although artificial plastics have widely penetrated the market since the end of the 19th century. But in fact, this industry grew with the end of World War II and the entry of relatively cheap petrochemical raw materials into the market, and our current era can be called the era of plastics; The direction of construction and the speed of growth of this industry is more than other industries. This is due to the advantages of new technologies and the intervention of economic parameters in replacing plastics instead of materials such as metal, glass, wood, ceramics, etc. For example, we can mention the replacement of a plastic pipe due to its price and ease of installation and connection in comparison with its metal sample. At present, due to the new developments in the automotive industry or household appliances, plastic parts have become a very suitable substitute for metal parts in this category of products due to weight reduction and increased fuel efficiency. He pointed out that today, about 70% of the types of polymeric plastics in the market belong to four groups: polystyrene (PS), polyethylene (PE), polypropylene (PP), and polyvinyl chloride (PVC).
For the production of these four product fields, there is a lot of competition between chemical companies: “Dow-BF Goodrich-Phillips-Union Karabide-V Pont-Monsanto-Exxon” is of particular importance, considering the price of plastic goods offered to the market. There is intense competition between manufacturers. In some cases, certain plastics are only produced by one or two producers, and the competitive aspect is lost.
Since 1869 when the first plastic named cellulose nitrate was obtained until now, there has been a huge change in this industry. The growth of the production of all kinds of plastic and its presence in daily life is such that it is almost impossible to continue living without it. This assumption is realized when we know that from pens, cabinets, televisions, writing desks, chairs, lamp stands and telephones to even Glasses frames are made of this type of polymer. The matter will become more interesting when we know that only in the United States of America, at the beginning of the 80s, a figure equivalent to 14 million dollars of plastic resin was produced for the preparation of various products.
Plastic forming process:
The history of plastic formation begins with the development of phenic acid in the 20th century. In the beginning, there was no production of plastic materials, it was derived from natural materials, hence the progress on limiting the product is one of the conventional processes.
Several years after the industrial production of phenolic acid gum, chloride gum was produced and then a fatty liquid used in the production of synthetic rubber was produced. Almost all the main ingredients are developed from artificial gum. The history of the molding method, which was the first injection molding machine in Germany in 1921. These machines are an extension of the diecast machines (pressure casting) and are the basis of all pressure machining methods, rolling machines and extrusions (with pressure). expulsion) which is still available today.
The development and popularization of plastic molding is due to the properties of the materials and the price and execution efficiency that comes from the uniformity of synthetic materials, and also the mass of extraordinary production ability to reduce the finished price of the product has made this product more popular.
An industry will not develop until there are supplies and requirements for the demands. The plastic industry is an example of modeling that meets the demand. One of the problems in the plastic industry is the loss of energy and another problem is caused by excessive energy consumption.
Important features of plastic materials:
An important feature of plastic materials in the industry is its processability. If a substance can be melted or dissolved, it can be used in industry, otherwise it cannot be used industrially because it cannot be used to prepare materials.
The role of plastics in the industry:
About 23.5% of plastics are used in packaging industries.
About 20% of plastics are used in construction industries.
It is important to use sponge insulation in order to reduce the heat loss of buildings and preserve valuable energy sources.
About 8% of plastics are used for home appliances such as electrical appliances, sofas and furniture.
Explaining that in automobile manufacturing, the industry trend is moving towards the production of chassis and all the subassemblies related to the floor of the car during an injection-reaction process.
Now cloth sails and wooden cabins have given their place to nylon sails and polyester body.
Artificial skin, artificial heart and plastic medicine are among the uses of plastics in medicine.
The nose of the airplane, the joints under the wing, the joints of the wing to the body are considered plastic components of the airplane.
produce :
For the production of plastics in the world, due to their variety and number and the lack of working information, it will be difficult to make approximations. However, this study can be done more accurately about the most important of them. In 1982, a capacity of 55.8 million tons for the production of consumer plastics (light and heavy polyethylene-polypropylene-polyvinyl chloride and polystyrene) in the world and it is expected that this capacity will increase to 68.3 million tons in 1990.
Most of the plastics are produced in the United States of America, Western Europe and Japan.
The future of plastics:
Basically, the reason for the remarkable growth lies in the mutual effect of three factors on each other:
1- Increasing knowledge of the characteristics and capabilities of plastic materials
2- The ability to improve plastics due to the emergence of new materials, better qualities of current equipment and better process equipment
3- The continuous reduction of the cost of raw materials of plastics compared to the cost of common materials such as leather, paper, metals and ceramics
Properties:
Currently, various plastics with completely different properties are manufactured and marketed by various manufacturers in the world. These properties are described below in terms of their importance in the use of plastics:
1-Being light
On average, the weight of a piece of plastic is approximately 1.2 the weight of an aluminum piece and 1.6 of the weight of an iron piece. Land, sea, and air transportation industries prefer metals.
2- Heat insulation
Plastics generally don’t transfer heat well, and for this reason, they are widely used as heat insulators in industries and in the construction of objects that are close to heat but should not be heated (such as the steering wheel of vehicles, handles of dishes, tables and chairs, etc.). And in this sense, it is superior to materials.
3- Being electrically insulated
Plastics generally do not transmit electricity well, so they are widely used as electrical insulators in electrical and electronic industries, such as covering all kinds of wires, cables, electrical devices and tools, making various types of keys, screws, sockets, and the like.
4- Being transparent
Some plastics are transparent and are used instead of glass.
5- Coloring
Plastics can be produced in different colors so that the manufactured piece does not need to be painted like metals and wood.
6- Resistance to atmospheric conditions
Most plastics are extremely resistant and stable in different weather conditions and are free from the problems that arise for wood and metals in this regard.
7- Resistance to solvents and chemicals
Most plastics are resistant to solvents and chemicals and do not corrode like metals, and in this sense, their use in food and health industries is very abundant.
8- Being hygienic
Microbes-bacteria-parasites-mushrooms and algae cannot grow on plastics. This feature has caused the use of plastics in medical and surgical, dental, pharmaceutical, food and agriculture industries and in health matters. to be
9- Ease of construction
Plastic parts and products can be easily made in the desired shape from one mold, millions of plastic parts can be produced quickly, which is never possible to make the same parts from metals or glass.
10- Inexpensive
Due to the abundance of raw materials and the ease of making them, the production of plastic parts and products is much cheaper than making the same part from natural materials.
11-Compatibility
Many of the mentioned properties can be present in one type of plastic, for example, it is possible to make plastic that is very light but also very strong and hard, so plastic parts can be important and different conditions, or in other words, compatible with these conditions. if this compatibility is not seen in natural materials.
Desirable properties of plastic such as lightness, transparency and transmittance, stability against chemical reactions, weathering and abrasion, formability, adhesiveness, impactability, low water absorption, color stability, size stability, among others, have caused the increasing use of plastic in buildings. Many plastics are lighter than traditional materials and some of them can be made porous to have a very low specific weight.
Some structural or semi-structural parts are made with plastic, plastic is used as an auxiliary material in construction, and sometimes plastic forms a part of building composite materials (composites). They strengthen plastics for structural purposes. In (90%) cases, this reinforcement is done with glass wire, and in other cases with other fibers such as cotton, hemp, mountain cotton, synthetic fibers and metal fibers. About (85%) of reinforced plastics are polyester resins and the rest are acrylic, melamine, phenolic, silicone, nylon, polystyrene and PVC resins.
Plastic is also used for making waterproofing materials, steam sealing, sealants, sealing, production of water supply and sewage pipes, passing electric wire and covering electric wire and cable. The waterproofing and vapor barrier sheets are made of polyethylene and PVC. The joints are made of PVC in standard thicknesses of 0.5, 1 and 1.5 mm. Seals (waterstop) are also made of PVC.
Plastics in making sanitary appliances, pump parts, faucets and showers, door and window fittings, plumbing connections, lining of water supply pipes and water storage sources, making glues and paints, work tools, tool handles, drawing and surveying tools, mold oil, additives Concrete, pre-made sandwich concrete connecting parts and used in making switches, sockets, lamp caps and chandelier parts are also used. Light plastic aggregates are used in making light concrete. Doors, windows and kitchen shelves are often made of PVC. Polyethylene sheets are used to cover construction materials and protect new works from cold, freezing, snow, rain, heat, wind, evaporation of concrete water and the like.
Special properties for choosing plastic parts and ordering from manufacturers:
1-melt viscosity:
This feature determines the polymer process. TFF has a very high melt viscosity and nylon has a low melt viscosity.
2- Molding temperature:
which is the minimum process temperature for melt viscosity (hardening to the desired level of molding). In this field, engineering plastics need high temperature, and at the same time, PE polymer needs a low temperature to reach the desired level of molding.
3-Hardness and flexibility:
Unsoftened PVC (homopolymer) and thermosetting polyesters are very hard and tough. And softened EVA and LDPE plastics are very flexible.
4-Strength:
Engineering plastics need high strength, while olefinic polymers (PE and PP) do not need much strength.
5-Difficulty:
Soft heat often has a very hard surface.
6- Scratch resistance:
Thermosetting polyester and UF have good scratch resistance and polystyrenes have poor scratch resistance despite their high hardness.
7- Being shiny:
Cellulose acetate-polysulfones have a shiny and transparent surface.
8-Transparency:
The transparency of plastic is determined by the percentage of light reflection. Few plastics have good transparency, such as MMA-PS and polycarbonates.
9- Resistant to yellowing:
Polystyrenes turn yellow when exposed to light, but polymethyl methacrylates are resistant to yellowing.
10- Impact strength:
Polystyrenes have weak strength, and at the same time, plastic like ABS has good impact strength, even though it is very hard.
Among the special properties that can be imagined for plastics, the following can be mentioned:
11- Wire flexibility
12- Chemical resistance (against acids-bases, etc.)
13- Resistance to oil and fat
14- Resistance to pollution
15- Creep resistance
16- Flame resistance
17- Thermal resistance
18- Atmospheric resistance
19- Resistance to rays and ultraviolet
20- Tensile fracture resistance
21- Dielectric constant
22- Dielectric strength
23- Specific electrical resistance
24- Attractive water
25- Permeability
26- Mold shrinkage
27- Ability to weld (join)
28- Price
Additives of plastics:
The physical division of these additives is done into four groups:
solids, rubbers, liquids and gases, the latter of which is used in the manufacture of cellular resins. In terms of performance, we are facing more groups, the following are the most important:
1- Fillers
2- Emollients and emollients.
3- Lubricants and lubricants
4- Anti-aging additives
5- Late burners
6- Colors
7- Puffing agents
8- Networking factors
9- Degradable additives against ultraviolet waves
In general, additives should have the following specifications, unless such requirements are excluded due to their performance:
1- They should have effective performance
2- They must be stable under process conditions
3- They must be under stable operating conditions
Conversations
5- They should be non-toxic and not taste or smell to the substance.
6- It should be cheap.
7- They should not affect the properties of basar in the opposite way.
The materials that are added to improve the properties of plastics are:
v Polymers
v Lubricants (they increase the flexibility of plastics)
v Colorants (to improve appearance properties)
v Flame retardants (decrease the rate of employment)
v Fillers (weight change to reduce cost)
v Reinforcers (increasing mechanical properties such as compressive or tensile strength such as concrete)
v Bubblers (increasing hardness by creating a spongy structure)
Stabilizers (to increase their life)
v Catalysts (to increase the speed of setting or solidification)
