Ortho brackets that have suffer from deformation:
a- Ceramic brackets.
b- Metal brackets.
c- Self-ligating.
d- Plastic ***
CLASSIFICATION OF PLASTIC MATERIALS:
The term "plastics" includes a wide range of polymers, separated into several groups, and then divided into sub-families. Also, before approaching the chapter of the implementation, then the recycling of the plastics, let us establish a general classification of these thermosetting or thermoplastic materials (two large groups in which we will also incorporate the elastomers) by detailing their properties, their compositions, their aspects and final functions, while specifying which plastics are recyclable.
THERMOPLASTICS:
As a reminder, thermoplastics are compounds whose structure and viscosity can be modified by successive heating and cooling, reversibly. In this vast family of materials, favored by industrialists and often able to integrate the recycling cycle of plastic waste in France, we find the following polymers:
1- POLYOLEFINS:
This term refers to materials such as polyethylene (or PE, one of the most common thermoplastic resins in the world), and ethylene / vinyl acetate (EVA) copolymers, but also polypropylene (PP). processed in Paprec's plastic recycling plants, such as PE.
Obtained by polymerization of ethylene, polyethylene is a loosely waxy solid, completely colorless and odorless. It is soluble from 60-80 ° in some organic solvents, and is generally not plasticized.
There are two types of polyethylene: low density polyethylene (LDPE) and high density polyethylene (LDPE).
It is used in particular to make bags, films (future recyclable plastic waste), flasks, wine racks, toys, buckets, bowls, hoses or tanks. He enters the composition, for example, Tupperware trays. The recycling of waste in HDPE and the recycling of plastic waste in Pehd will make it possible to redo bags for industrial use, household waste, or bottles for cleaning products.
Copolymers of ethylene and vinyl acetate (EVA) are used pure or in admixture with other thermoplastics, to contribute to the production - among other things - of industrial glues.
Certain additives, such as calcium fillers, organic or inorganic pigments, antioxidants, surface modifiers (to smooth the resin and facilitate its electrical conductivity) or porogenic agents (to obtain cellular materials) are added to the polyethylenes before they are added. Implementation.
Polypropylene (PP) is a solid obtained by polymerization of propylene, which offers a good resistance to heat and melts at 160 or 170 °. Supplied in the form of powders, fibers or granules, it is used in particular to produce filters, pumps, bumpers, automobile tanks or films for various packaging. Moreover, after having integrated the plastic packaging recycling cycle, some of these products will make it possible to recreate envelopes for technical liquids. The adjuvants used during its manufacture are the same as those of polyethylene. The "injection" PP will produce easily recyclable plastic waste, but not the "film" PP. It should also be noted that thermoplastic elastomers can be obtained by grafting EPDM rubber (ethylene-propylene-diene monomer) to polypropylene.
2- POLYVINYLICS
The polyvinyl family comprises a very large number of thermoplastics, among which we find:
- Polyvinyl chloride (PVC), delivered in the form of powder, granules, paste, emulsion or dissolution. Flexible PVC makes it possible to manufacture coated fabrics for clothing and leather goods, insulation sheaths, adhesive tapes or tarpaulins (some of these products will be future recyclable plastic waste). Rigid, it is used to create sanitary pipes, windows, shutters, gutters, electrical cables, flooring and food or chemical packaging (future recyclable plastic waste as well). Stabilizers, lubricants, plasticizers, fillers and pigments can be added during the manufacture of the plastic. And while some PVC products are among non-recyclable plastics (such as plumbing pipes), a large number of products made from this material (often construction waste) incorporate the recycling cycle of plastic waste.
- Polyvinyl alcohol (PVAL), whose white resin is soluble in cold water and which is used in particular as a coating binder for paper-cardboard, for industrial glues or fabric primer.
- Polyvinyl acetate (PVAC) whose polymer is a transparent resin, delivered for commercial purposes in the form of granules, berlingots, pearls or various solutions. It is used in particular to produce paints, or quick-drying varnishes.
Polyvinylidene Chloride (PVDC), a powder characterized by good chemical resistance and high impermeability to water vapor, certain gases and certain oils, which manufacturers use to make complex paper-based materials (like aluminum foil) or various plastic films.
- Polybutyral, or polyformal, vinylic (PVB), delivered in the form of powders, emulsions or foils, which is used to make different varnishes for copper or aluminum cables, thanks to its high adhesion capacities to metal.
3- POLYSTYRENICS:
There are only two types of major polystyrene, polystyrene (PS) and styrene copolymers (SAN, ABS, MBS, SBS or SIS). However, it is necessary to distinguish different categories of PS: standard polystyrene, or crystal, because of its transparency (it is particularly rigid and fragile), polystyrene shock, more flexible, polystyrene heat, which is more resistant to very high temperatures and the expanded polystyrene (gas bubbles).
PS, solid up to 140 ° degrees, beyond which it becomes fluid, can be delivered commercially in the form of powders, granules, balls, pastes, solutions or semi-finished products (plates, tubes, sheets, etc.). Also made with chemical additives, various plasticizers or solvents, some fillers and a number of pigments, it is used in the composition of yoghurt pots, trays, cupboards, and counter doors. refrigerators or freezers.
Styrenic copolymers, on the other hand, are physical and chemical improvements of polystyrene. They are used to make a very large number of products, such as computer cases, coffee filters, jars, cosmetic packaging, vacuum hoods and even toothbrushes. Some plastic waste made of PS and ABS is part of the recycled plastics recycled by Paprec. Waste management in PS makes it possible to recreate films, packaging or insulation materials.
4- POLYACRYLIC AND POLYMETHACRYLIC:
This family splits into two categories of materials only, polymethyl methacrylate (PMMA) and polyacrylonitrile (PAN). The first (PMMA), obtained after polymerization of methyl methacrylate, is recognizable by its transparency, ease of use and resistance to aging. Delivered in the form of plates, castings, rushes, discs, sticks, powders, granules, or syrups, it can produce synthetic fibers, spectacle lenses, glazings, squares, rules, lenses and various hairstyling items. It is among recyclable plastics in plastic recycling plants.
The second (the PAN therefore) is used in particular as synthetic fiber by the textile industry, since its solubility in some given solvents allows it to be spun. But it is also used to create food films or various flasks.
If few additives are added to the polyacrylonitrile, the treatment of the PMMA plastic incorporates polymerization catalysts, dyes or pigments, plasticizers, silica fillers or solvents.
5- POLYAMIDES:
Only within their groups, polyamides (PA) are however distinguished by the number of carbon included in their monomers, that means the number that follows their different abbreviations (PA 6, PA 11, PA 12, etc.).
Obtained from amino acids or lactams, these very special materials do not see their structure soften gradually under the effect of heat, like other thermoplastics, but pass very quickly from the solid state to the liquid state.
Although polyamides are used primarily for the manufacture of textile fibers, they are also used to produce switches, sockets, gears, screws, household appliances, syringes or automotive equipment, and can incorporate recycling cycles of plastics.
6- POLYCARBONATES:
Compounds obtained from diphenylolpropane or bisphenol A, polycarbonates (PC) are materials for technical use, very rigid and low fuel. Delivered in the form of pellets, plates, sheets or films, they are used in compact discs, motorcycle helmets or safety glazing and can integrate a plastic recycling line.
7- CELLULOSICS:
With cellulose acetate (CA), manufacturers benefit from a transparent, flexible and stable material, which enables them to manufacture fibers, varnishes or photographic films. With cellulose nitrate (CN), formerly used to make celluloid (considered too unstable today), they produce various lacquers, paints, inks, glues or some artificial coatings.
8- LINEAR POLYESTERS:
Polyethylene terephthalate (PETP or PET), polybutylene terephthalate (PBTB) and polytetramethylene (PTMT) are three main linear polyesters, that is, products synthesized from ethylene glycol or butylene glycol. With little admixture, they were first used to make textile fibers or films (such as terphane), before their resistance to abrasion, oils, salt solutions and shocks led the plastic industry to include PET in the composition of ribbons, electronic components and bottles (recyclable PET), and PBTB in that of mechanical or insulating parts, subjected to high temperatures. The recycling of PET (or more specifically the recycling of plastic bottles) is one of Paprec's many activities in the field of plastic waste processing. Recycling plastic bottles also means making sleeping bags, automotive textiles, and of course new bottles.
9- POLYFLUORETHENES:
There are three types of polyfluoroethenes: polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE) and polyvinylidene fluoride (PVDF).
PTFE is in the form of a granular white powder. Its resistance to heat is very good even if it is not a real thermoplastic (beyond a certain temperature, it turns into irreversible gel), and it is illustrated in particular by a quasi water absorption. no, nonstick properties, high flexibility and good resistance to light as well as weathering. It is used to make non-stick coatings, hoses, bearings, bearings, seals and technical textile fibers.
PCTFE, on the other hand, is marketed in two distinct forms: plastic high-polymers (in the form of granules or powder) and liquid low polymers. The PVDF is a very recent subject, still in development. More thermally and chemically stable than PTFE, both are also used to make some types of artificial coatings.
10- POLYACETALS:
Polyoxymethylene (POM) and its associated copolymers are alone within the family of polyacetals. Rigid, extremely resistant, especially to organic solvents and heavy loads, and a good electrical conductor, the POM is delivered commercially in the form of molding powders, granules and semi-finished products (bars, sticks, tubes, etc.). It is used to make gears, screws, rods, friction parts, valves or portable tools.
11- POLYSULFONES:
Macromolecules containing sulfur dioxide, Polysulfones, such as Sulfover or Surfil (trade names), allow the manufacture of paints or varnishes. They offer good resistance to chemical bases, acids, oils and greases.
12- POLYSULFIDE OF PHENYLENE:
A particularly dark and rigid plastic, this polysulfide is resistant to heat or chemicals. It is used to manufacture anticorrosive parts, cooking utensils or coatings.
THERMOSETTING PRODUCTS:
Thermosetting plastics are compounds that, at the time of polycondensation (and / or implementation), under the action of the catalyst or the rise in temperature, their resins are transformed into infusible and insoluble finished objects. It will not be possible to change their structures, shapes or stiffness again after the plastics are made, and these materials only very rarely include the plastic recycling cycle.
In this family, we find the following compounds:
1- UNSATURATED POLYESTERS:
Unsaturated polyesters are crosslinked polymers made from unsaturated diacids (bodies capable of giving protons having two acid functions). Their resins are used in the manufacture of lacquers, varnishes, moldings, adhesives and various binders.
2- THE PHENOPLASTS:
From the polycondensation of phenols and aldehydes, the most common phenolic resins are called phenol-formaldehyde (PF). In the form of powders, syrups, granules, and liquid or solid resins, they enter into the composition, with some additives, certain printing inks, foams, abrasives, brake linings and clutch or various paintings.
3- AMINOPLASTES:
Aminoplasts, such as urea-formaldehyde (UF) or melamine-formaldehyde (MF) are derived from a polycondensation of urea and formaldehyde, or formaldehyde and melamine. The former is mainly used as an adhesive by the wood industry, when the latter is better known under the trade name of Formica.
4- POLYEPOXIDES:
After polycondensation of epichlorohydrin with a polyhydric alcohol or a phenol (such as bisphenol-A), poly-epoxides, or epoxy resins, are used in various forms (casting resins, powders, adhesives, etc.) to produce coatings. , adhesives and various paints, which benefit from the good quality of their adhesion to the metal.
5- POLYIMIDES:
Formed of aromatic dianhydrides and diamines, they are among the most recently synthesized plastics, offer very good resistance to high temperatures, radiation and chemicals, and serve in particular, in the form of films, to manufacture circuits. soft prints or cables used by aviation.
6- POLYURETHANNES:
Complex compounds made from polyols, chemical catalysts, polyisocyanates or expansion agents, polyurethanes (PURs) are at the heart of the manufacturing of a large number of products (foams, paints, preservatives, varnishes, adhesives and other various solutions). In an elastomeric thermoplastic form, they also allow the textile industry to create Lycra.
7- POLYORANOLSILOXANES:
Obtained by polycondensation of silanols and a certain number of chemical additives, they are also called silicones, are particularly thermostable (resistance to heat) and also allow the production of a vast family of products (Oils, fats, cosmetics, styling products, pipes, molded parts etc.).
CLASSIFICATION OF PLASTIC MATERIALS:
The term "plastics" includes a wide range of polymers, separated into several groups, and then divided into sub-families. Also, before approaching the chapter of the implementation, then the recycling of the plastics, let us establish a general classification of these thermosetting or thermoplastic materials (two large groups in which we will also incorporate the elastomers) by detailing their properties, their compositions, their aspects and final functions, while specifying which plastics are recyclable.
THERMOPLASTICS:
As a reminder, thermoplastics are compounds whose structure and viscosity can be modified by successive heating and cooling, reversibly. In this vast family of materials, favored by industrialists and often able to integrate the recycling cycle of plastic waste in France, we find the following polymers:
1- POLYOLEFINS:
This term refers to materials such as polyethylene (or PE, one of the most common thermoplastic resins in the world), and ethylene / vinyl acetate (EVA) copolymers, but also polypropylene (PP). processed in Paprec's plastic recycling plants, such as PE.
Obtained by polymerization of ethylene, polyethylene is a loosely waxy solid, completely colorless and odorless. It is soluble from 60-80 ° in some organic solvents, and is generally not plasticized.
There are two types of polyethylene: low density polyethylene (LDPE) and high density polyethylene (LDPE).
It is used in particular to make bags, films (future recyclable plastic waste), flasks, wine racks, toys, buckets, bowls, hoses or tanks. He enters the composition, for example, Tupperware trays. The recycling of waste in HDPE and the recycling of plastic waste in Pehd will make it possible to redo bags for industrial use, household waste, or bottles for cleaning products.
Copolymers of ethylene and vinyl acetate (EVA) are used pure or in admixture with other thermoplastics, to contribute to the production - among other things - of industrial glues.
Certain additives, such as calcium fillers, organic or inorganic pigments, antioxidants, surface modifiers (to smooth the resin and facilitate its electrical conductivity) or porogenic agents (to obtain cellular materials) are added to the polyethylenes before they are added. Implementation.
Polypropylene (PP) is a solid obtained by polymerization of propylene, which offers a good resistance to heat and melts at 160 or 170 °. Supplied in the form of powders, fibers or granules, it is used in particular to produce filters, pumps, bumpers, automobile tanks or films for various packaging. Moreover, after having integrated the plastic packaging recycling cycle, some of these products will make it possible to recreate envelopes for technical liquids. The adjuvants used during its manufacture are the same as those of polyethylene. The "injection" PP will produce easily recyclable plastic waste, but not the "film" PP. It should also be noted that thermoplastic elastomers can be obtained by grafting EPDM rubber (ethylene-propylene-diene monomer) to polypropylene.
2- POLYVINYLICS
The polyvinyl family comprises a very large number of thermoplastics, among which we find:
- Polyvinyl chloride (PVC), delivered in the form of powder, granules, paste, emulsion or dissolution. Flexible PVC makes it possible to manufacture coated fabrics for clothing and leather goods, insulation sheaths, adhesive tapes or tarpaulins (some of these products will be future recyclable plastic waste). Rigid, it is used to create sanitary pipes, windows, shutters, gutters, electrical cables, flooring and food or chemical packaging (future recyclable plastic waste as well). Stabilizers, lubricants, plasticizers, fillers and pigments can be added during the manufacture of the plastic. And while some PVC products are among non-recyclable plastics (such as plumbing pipes), a large number of products made from this material (often construction waste) incorporate the recycling cycle of plastic waste.
- Polyvinyl alcohol (PVAL), whose white resin is soluble in cold water and which is used in particular as a coating binder for paper-cardboard, for industrial glues or fabric primer.
- Polyvinyl acetate (PVAC) whose polymer is a transparent resin, delivered for commercial purposes in the form of granules, berlingots, pearls or various solutions. It is used in particular to produce paints, or quick-drying varnishes.
Polyvinylidene Chloride (PVDC), a powder characterized by good chemical resistance and high impermeability to water vapor, certain gases and certain oils, which manufacturers use to make complex paper-based materials (like aluminum foil) or various plastic films.
- Polybutyral, or polyformal, vinylic (PVB), delivered in the form of powders, emulsions or foils, which is used to make different varnishes for copper or aluminum cables, thanks to its high adhesion capacities to metal.
3- POLYSTYRENICS:
There are only two types of major polystyrene, polystyrene (PS) and styrene copolymers (SAN, ABS, MBS, SBS or SIS). However, it is necessary to distinguish different categories of PS: standard polystyrene, or crystal, because of its transparency (it is particularly rigid and fragile), polystyrene shock, more flexible, polystyrene heat, which is more resistant to very high temperatures and the expanded polystyrene (gas bubbles).
PS, solid up to 140 ° degrees, beyond which it becomes fluid, can be delivered commercially in the form of powders, granules, balls, pastes, solutions or semi-finished products (plates, tubes, sheets, etc.). Also made with chemical additives, various plasticizers or solvents, some fillers and a number of pigments, it is used in the composition of yoghurt pots, trays, cupboards, and counter doors. refrigerators or freezers.
Styrenic copolymers, on the other hand, are physical and chemical improvements of polystyrene. They are used to make a very large number of products, such as computer cases, coffee filters, jars, cosmetic packaging, vacuum hoods and even toothbrushes. Some plastic waste made of PS and ABS is part of the recycled plastics recycled by Paprec. Waste management in PS makes it possible to recreate films, packaging or insulation materials.
4- POLYACRYLIC AND POLYMETHACRYLIC:
This family splits into two categories of materials only, polymethyl methacrylate (PMMA) and polyacrylonitrile (PAN). The first (PMMA), obtained after polymerization of methyl methacrylate, is recognizable by its transparency, ease of use and resistance to aging. Delivered in the form of plates, castings, rushes, discs, sticks, powders, granules, or syrups, it can produce synthetic fibers, spectacle lenses, glazings, squares, rules, lenses and various hairstyling items. It is among recyclable plastics in plastic recycling plants.
The second (the PAN therefore) is used in particular as synthetic fiber by the textile industry, since its solubility in some given solvents allows it to be spun. But it is also used to create food films or various flasks.
If few additives are added to the polyacrylonitrile, the treatment of the PMMA plastic incorporates polymerization catalysts, dyes or pigments, plasticizers, silica fillers or solvents.
5- POLYAMIDES:
Only within their groups, polyamides (PA) are however distinguished by the number of carbon included in their monomers, that means the number that follows their different abbreviations (PA 6, PA 11, PA 12, etc.).
Obtained from amino acids or lactams, these very special materials do not see their structure soften gradually under the effect of heat, like other thermoplastics, but pass very quickly from the solid state to the liquid state.
Although polyamides are used primarily for the manufacture of textile fibers, they are also used to produce switches, sockets, gears, screws, household appliances, syringes or automotive equipment, and can incorporate recycling cycles of plastics.
6- POLYCARBONATES:
Compounds obtained from diphenylolpropane or bisphenol A, polycarbonates (PC) are materials for technical use, very rigid and low fuel. Delivered in the form of pellets, plates, sheets or films, they are used in compact discs, motorcycle helmets or safety glazing and can integrate a plastic recycling line.
7- CELLULOSICS:
With cellulose acetate (CA), manufacturers benefit from a transparent, flexible and stable material, which enables them to manufacture fibers, varnishes or photographic films. With cellulose nitrate (CN), formerly used to make celluloid (considered too unstable today), they produce various lacquers, paints, inks, glues or some artificial coatings.
8- LINEAR POLYESTERS:
Polyethylene terephthalate (PETP or PET), polybutylene terephthalate (PBTB) and polytetramethylene (PTMT) are three main linear polyesters, that is, products synthesized from ethylene glycol or butylene glycol. With little admixture, they were first used to make textile fibers or films (such as terphane), before their resistance to abrasion, oils, salt solutions and shocks led the plastic industry to include PET in the composition of ribbons, electronic components and bottles (recyclable PET), and PBTB in that of mechanical or insulating parts, subjected to high temperatures. The recycling of PET (or more specifically the recycling of plastic bottles) is one of Paprec's many activities in the field of plastic waste processing. Recycling plastic bottles also means making sleeping bags, automotive textiles, and of course new bottles.
9- POLYFLUORETHENES:
There are three types of polyfluoroethenes: polytetrafluoroethylene (PTFE), polychlorotrifluoroethylene (PCTFE) and polyvinylidene fluoride (PVDF).
PTFE is in the form of a granular white powder. Its resistance to heat is very good even if it is not a real thermoplastic (beyond a certain temperature, it turns into irreversible gel), and it is illustrated in particular by a quasi water absorption. no, nonstick properties, high flexibility and good resistance to light as well as weathering. It is used to make non-stick coatings, hoses, bearings, bearings, seals and technical textile fibers.
PCTFE, on the other hand, is marketed in two distinct forms: plastic high-polymers (in the form of granules or powder) and liquid low polymers. The PVDF is a very recent subject, still in development. More thermally and chemically stable than PTFE, both are also used to make some types of artificial coatings.
10- POLYACETALS:
Polyoxymethylene (POM) and its associated copolymers are alone within the family of polyacetals. Rigid, extremely resistant, especially to organic solvents and heavy loads, and a good electrical conductor, the POM is delivered commercially in the form of molding powders, granules and semi-finished products (bars, sticks, tubes, etc.). It is used to make gears, screws, rods, friction parts, valves or portable tools.
11- POLYSULFONES:
Macromolecules containing sulfur dioxide, Polysulfones, such as Sulfover or Surfil (trade names), allow the manufacture of paints or varnishes. They offer good resistance to chemical bases, acids, oils and greases.
12- POLYSULFIDE OF PHENYLENE:
A particularly dark and rigid plastic, this polysulfide is resistant to heat or chemicals. It is used to manufacture anticorrosive parts, cooking utensils or coatings.
THERMOSETTING PRODUCTS:
Thermosetting plastics are compounds that, at the time of polycondensation (and / or implementation), under the action of the catalyst or the rise in temperature, their resins are transformed into infusible and insoluble finished objects. It will not be possible to change their structures, shapes or stiffness again after the plastics are made, and these materials only very rarely include the plastic recycling cycle.
In this family, we find the following compounds:
1- UNSATURATED POLYESTERS:
Unsaturated polyesters are crosslinked polymers made from unsaturated diacids (bodies capable of giving protons having two acid functions). Their resins are used in the manufacture of lacquers, varnishes, moldings, adhesives and various binders.
2- THE PHENOPLASTS:
From the polycondensation of phenols and aldehydes, the most common phenolic resins are called phenol-formaldehyde (PF). In the form of powders, syrups, granules, and liquid or solid resins, they enter into the composition, with some additives, certain printing inks, foams, abrasives, brake linings and clutch or various paintings.
3- AMINOPLASTES:
Aminoplasts, such as urea-formaldehyde (UF) or melamine-formaldehyde (MF) are derived from a polycondensation of urea and formaldehyde, or formaldehyde and melamine. The former is mainly used as an adhesive by the wood industry, when the latter is better known under the trade name of Formica.
4- POLYEPOXIDES:
After polycondensation of epichlorohydrin with a polyhydric alcohol or a phenol (such as bisphenol-A), poly-epoxides, or epoxy resins, are used in various forms (casting resins, powders, adhesives, etc.) to produce coatings. , adhesives and various paints, which benefit from the good quality of their adhesion to the metal.
5- POLYIMIDES:
Formed of aromatic dianhydrides and diamines, they are among the most recently synthesized plastics, offer very good resistance to high temperatures, radiation and chemicals, and serve in particular, in the form of films, to manufacture circuits. soft prints or cables used by aviation.
6- POLYURETHANNES:
Complex compounds made from polyols, chemical catalysts, polyisocyanates or expansion agents, polyurethanes (PURs) are at the heart of the manufacturing of a large number of products (foams, paints, preservatives, varnishes, adhesives and other various solutions). In an elastomeric thermoplastic form, they also allow the textile industry to create Lycra.
7- POLYORANOLSILOXANES:
Obtained by polycondensation of silanols and a certain number of chemical additives, they are also called silicones, are particularly thermostable (resistance to heat) and also allow the production of a vast family of products (Oils, fats, cosmetics, styling products, pipes, molded parts etc.).
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