Plastics are materials made of high molecular polymers, which are light, durable and plastic. They are widely used in everyday life and in industrial areas, such as packaging, containers, electronics and construction materials. There is a wide variety of plastics, including polyethylene, polypropylene and polyvinyl chloride, each of which has unique properties and uses. While plastics facilitate human life, they also cause environmental problems because they are not easily degradable, hence the increasing emphasis on sustainable use and recycling of plastics。
Brief history of research
In 1869, john wesley hyatt invented the first synthetic plastic. This invention has had a profound impact on the production of a variety of consumer goods, such as photographic film, billiards, and has created a pioneer in the plastic age
In 1907, leo baekeland invented the first type of synthetic thermal plastic - electrical wood. This breakthrough in beckland led to the birth of a range of products, including electrical insulations, telephone casings and cooking tools. These two pioneering inventions paved the way for a series of breakthrough developments in the plastic history。
The invention of acrylic acid by the german chemist otto rohm in 1931 and its development in 1940 are important contributions to the plastic world. In 1971 pvc was invented to completely transform the plastic industry. High-intensity polystyrene, 1973, polyurethane, 1974 in 1984, linear low-density polyethylene (lhdpve) 1987; jpve (1988); and high-density polyethylene 1989. Two
Definitions and classification definitions
Plastics are materials that are mainly resins (or individual direct polymers during processing) and contain additives that can flow into formation during processing. Plastics do not contain fibres, coatings and glues. Plastic materials typically consist of two basic materials: a matrix material - resin - and an assistive material. The composition of materials and the ratio between components have some effect on the performance of plastics. Two
Classification
Purpose classification 2
Depending on the different uses of plastics, plastics are usually classified into generic, engineering and special plastics。
(1) generic plastics: generally referred to as high-yielding, wide-used, well-formulated and inexpensive plastics. There are five main types of generic plastics, namely polyethylene (pe), polypropylene (pp), polyvinyl chloride (pvc), polystyrene (ps) and acetylene-butadiene-styrene (abs). The five main types of plastics, which account for the vast majority of plastic feedstock use, can be classified as special plastic types, such as pps (polyserphides), ppo (polyethers), pa (nylon or polyamide), pc (polycarbonate), pom (polydealdehyde or polyoxins), etc., which are used only in small quantities in daily household products, mainly in high-end areas such as engineering, defence technology, and in such areas as automobiles, space, construction and communications。
(2) engineering plastics generally mean plastics that can withstand some external force, have good mechanical and durability, are low temperature, are more stable in size and can be used as engineering structures, such as polyamide, polysulfide, etc. In engineering plastics, they are divided into generic and special engineering plastics. Engineering plastics are widely used in electronics and electrical, automobiles, construction, office equipment, machinery, aerospace, etc., and plastic steel and wood have become an international trend。
Generic engineering plastics include polyamide, polyalphate, polycarbonate, modified polyphenyl ether, thermoplastic polyethylene, hypermolecular polyethylene, methylpentane polymers, ethylene co-polymer, etc。
Special engineering plastics are also divided into conjunctive non-intersectial forms. The interlocking types are: polyaminodimalamide, polythylene, polyamylamine, heat-resistant epoxy resin, etc. Non-intersectional types include polysing, polyethers, polysulphides, polyamide, polyether ketone, etc。
(3) special plastics generally refer to plastics with special functions that can be used in special applications such as aviation and space. For example, fluorinated plastics and organic silicon have prominent special functions such as high temperature resistance and self-molument, and enhance the special performance of plastics and foams with high intensity and buffers, all of which fall within the category of special plastics。
A. Enhanced plastics: enhanced plastic materials may be classified into particles (e. G., calcium plastics), fibre form (e. G., glass fibres or glass cloth enhanced plastics), sheet form (e. G., cloud mammogram plastics). The materials can be classified as bk plastics (e. G., shredded or asbestos-enriched plastics), inorganic minerals filled with plastics (e. G., stone or cloud-leaved plastics) and fibre enhanced plastics (e. G., carbon fibre enhanced plastics)。
B. Foams: foams can be divided into rigid, semi-hard and flexible foams. Hard foams are not flexible, compressed with a high hardness, are deformed only if they reach a certain stress value and do not recover once they are released; flexible foams are flexible, have a very small compression hardness, are easily deformed, are defunct and are less deformed; and semi-hard foams and other properties are between rigid and flexible foams。
Classification 2
Depending on the different physicochemical properties of plastics, plastics can be divided into thermal solid plastics and thermal plastics。
(1) thermal plastics (thermo plastics): refers to plastics that melt after heating, move to form after cooling and then melt after heating。
Thermal plastics are divided into hydrocarbons, ethylene-based with polar genes, engineering, cellulose, etc. Softer in heat, harder in cooling, softening and hardening over and over again and maintaining a certain shape. It is soluble in a solvent and has a melting soluble properties. Thermal plastics have excellent electrical insulation, in particular ptfe, ps, pe and pp, which have very low media constants and medium loss, suitable for high frequency and high voltage insulation materials。
Thermal plastics are easy to process in form, but are less heat resistant and susceptible to creeping, which varies with the load, ambient temperature, solvent, humidity. In order to overcome these weaknesses in thermoplastic plastics and to meet the needs for applications in areas such as space technology and new energy development, countries are developing melting-resistant resins such as peek, pes, pau and pps。
(2) thermal solid plastics: means plastics that are solid or have insoluble (melting) properties such as phenol, epoxy, etc. Under heat or other conditions。
Thermal solid plastics are also divided into two types of formaldehyde and other conjunctive types. Thermally processed forms into solids with insoluble insoluble solids with resin molecules that are interconnected by linear structures. More heat will decompose damage. Typical rigid plastics include materials such as phenol, epoxy, ammonia, unsaturated polyesters, furans, polysiliac ethers, and more recent polyphenyldipropanes. They have such advantages as high heat resistance and heat inflexibility. The disadvantage is that mechanical strength is generally low, but can be increased by adding fillings, making layer pressure material or model pressure material。
Process classification 2
Depending on the plastic formation method, it can be divided into different types of membrane pressure, laminate pressure, injection, crowding out, blowing plastics, casting plastics and reactive plastics。
(b) plastics with membrane-pressure plastics with much of a physical processing properties similar to those of general solid plastics
Scattered plastics are fibre fabrics impregnated with resins, which are combined with thermal pressure to form the whole material; and plastics that are similar to general thermoplastic plastics by injection, crowding out and blow-out
Embedding plastics means liquid resin blends, such as cast nylons, which can be dumped in the mould without pressure or with a slight pressure and which can be hardened to a certain shape
Reaction-injecting plastics are plastics, such as polyurethane, which are solidified by liquid raw materials, pressured into the membrane cavity, etc。
Various plastics
School name
Abbreviations
Chinese literary name
Commonly known as
Recovery
Identification
Purpose
Polyethylene
Pe
Polyethylene
Temperature items
Polypropylene
Pp
Polypropylene
100% gel, plastic
05
Microwave cooker box, available at about 100°c
High density polyethylene
Hdpe
High-density polyethylene
Hard soft glue
02
Cleaning, bathing products
Low density polyethylene
Ldpe
Low-density polyethylene
04
Preserve membrane, plastic membrane, etc
Linear low density polyethylene
Lldpe
Linear low-density polyethylene
Polyvinyl cloride
Pvc
Pvc
Sneaky
03
Very little for food packaging
General purpose polystyre
Gps
Universal polystyrene
Hard glue
Expansible polystyrene
Eps
Polystyrene foam
Hair bubble
High impact polystyre
Ips
Impact resistant polystyrene
Crush hard
Sterene-acryloI don't know
As, san
Styrene-propylene co-polymer
Transparent powerful rubber
Acrylonite-butadiene-styrene copolymers
Abs
Acrylonitrile-butadiene-styrene co-polymer
It's super-crap
Polymethyl methacrylate
Pmma
Polymethylacrylate
Jacques
Organic glass
Ethylene-vinyl acetatecopolimers
Eva
Ethylene-ethylene acetylene co-polymer
Rubber
Polythylene terephthalate
Pet
Polybiphenyl dimethylethylene ethyl ethyl ester
Polyester
01
Mineral water bottles, carbonated drinks
Polybutylene terephthalate
Pbt
Polybiphenyl dimethylate
Polyamide (nylon 6. 66)
Pa
Polyamide
Nylon
Polycarbonates
Pc
Polycarbonate
Bulletproof
07
Canteens, cups, bottles
Polyacestal
Pom
Polymethyl formaldehyde
Steel racing, steel grabbing
Polyphenyleneoxide
Ppo
Polyethers
Noryl
Polyphenylenesulfide
Pps
Polyphenyl sulphur ether
Polysulphur ether
Polyurethanes
Pu
Polyaminomethylate
Polyurethane
Polystyrene
Ps
Polystyrene
06
A bowl full of bubble noodles, a fast food box
Polytetra fluoroethylene
Ptfe
Polytetrafluoroethylene
Teflon, teflon
Component
Plastics are not a single ingredient and are made of many materials. High molecular polymers (or synthetic resins) are the main components of plastics. In addition, in order to improve the performance of plastics, support materials such as fillings, plasticizers, lubricants, stabilizers, colour agents, antistatic agents, etc., are added to high molecular compounds in order to be of good performance. Two
Plastic aids are also called plastic additives, which are compounds that polymers (synthetic resins) need to add to improve their processing performance or to improve the performance of the resin itself. For example, plasticizers are added to make the product soft in order to reduce the formation temperature of pvc resins; for example, blowing agents are added to make foams of light quality, insulation, insulation and sound insulation; some plastics have a temperature of thermal decomposition that is very close to the process temperature of formation and cannot be formed without the inclusion of thermal stabilizers. Plastic aids thus occupy a particularly important position in plastic form processing. Two
Synthetic resin
Synthetic resins are the most important component of plastics, which typically contain 40 to 100 per cent of plastics. Because of the high content and the nature of resins, which often determine the nature of plastics, resins are often seen as synonymous with plastics. For example, pvc resins are mixed with pvc plastics, phenol resins and phenol plastics. In fact, resin and plastic are two different concepts。
The resin is an unprocessed raw high molecular compound that is used not only in the manufacture of plastics but also as a feedstock for paints, glues and synthetic fibres. Apart from a very small proportion of plastics containing 100 per cent resin, the vast majority of plastics need to be added to the main component resins。
Fill
The filling, also called filling agents, increases the strength and heat resistance of plastics and reduces costs. For example, the inclusion of wood powder in phenol resin can significantly reduce costs, making phenol plastic one of the cheapest plastics, while also significantly increasing mechanical strength. The fillings can be divided into organic fillings, such as wood dust, shredding, paper and fabric fibres, and inorganic fillings, such as glass fibres, silicate soil, asbestos and carbon black. The content of fillings in plastics is generally controlled below 40%。
Plasticizer
Plasticizers, or plasticizers, increase the plasticity and softness of plastics, reduce their brittle and make plastics easier to process into form. Plasticizers (plasticizers) are generally mixed with resins, non-toxic, non-odour-free, high-boiling point organic compounds for light and heat stability, most commonly phenylenediate. For example, when pvc plastics are produced, flexible pvc plastics are available if more plasticizers are added, if not less. Stabilizer stabilizers are mainly reagents that maintain stability, such as high polymer plastics, rubber and synthetic fibres, to prevent their decomposition and ageing. In order to prevent photolysis and destruction of synthetic resins during processing and use, stabilization agents should be added to plastics to extend their useful life. Common is the use of hard-fat acids, epoxy resins, etc. The use of stabilizers is typically 0. 3 to 0. 5% of plastics。
Colours
Colours allow plastics to have a variety of colours. Organic dyes and inorganic pigments are commonly used as dyes. Synthetic resins are mostly white, semi-transparent or non-colored. Colours are often used in industrial production to increase the colour of plastics。
Lubricant
The role of lubricant is to prevent plastics from adhesive to metal moulds as they form, while at the same time making the surface of plastics smooth and beautiful. Common lubricants include, for example, hard-fat acids and their argon salts。
Antioxygen
To prevent thermal oxidation of plastics in heat-heated form or during high-temperature use, rendering them yellow, cracking, etc. In addition to the above-mentioned aids, flame retardants, blowing agents, anti-static agents, conductors, magnetic conductors, compatible agents, etc. May be added to plastics. To meet different usage requirements。
Antistatics
Plastics are a bad conductor for electricity, so they are easy to carry electrostatic, while antistatics give plastics light to medium electrical conductivity, thus preventing the accumulation of static charge on products。
Feature
The variety of plastics varies in terms of structure and composition. Some describe plastics as white as cotton, as transparent as glass, as soft as sponges; insulation as ceramics, as strong as steel; insulation as asbestos; rustproof as gold; and gearing in gear without lubrication. In general, plastic properties can be summarized as follows:2
1 light, higher than intensity. Plastics are light, and the general plastic density is in the range of 0. 9-2. 3 g/cm3, with only 1/4 of steel and about 1/2 of aluminium. Foams are less dense, ranging from 0. 01 to 0. 05 g/cm3. The strength by unit mass is referred to as the ratio strength, some of which is close to, or even greater than, steel. For example, the unit mass stretch strength of alloy steel is 1. 7 gpa, while fibreglass-enhanced plastics can reach 1. 7-2. 7 gpa。
2 excellent electrical insulation. Almost all plastics have excellent electrical insulation properties, such as very small inter-electric losses and excellent arc tolerance, which are comparable to ceramics。
3 good chemical stability. In general, plastics have good corrosive capacity for chemicals such as acid alkali, especially for polytetrafluoroethylene, which has a better chemical corrosive capacity than gold, and even for powerful corrosive electrolytics such as “king water”, known as “plastic king”。
4 good seismic, grinding. Most plastics have excellent seismic, grinding and lubrication properties. Many of the friction-resistant parts manufactured in engineering plastics use these properties of plastics to reduce their friction coefficients or further enhance their corrosion-resistant properties when certain solid lubricants and fillings are added to the corrosion-resistant plastics。
5 transparent and protective. Most plastics can be used as transparent or semi-transparent products, in which polystyrene and acrylic plastics are as transparent as glass. Organic glass is chemically named polymethylacrylate and can be used as aeroglass material. Plastic membranes such as polyvinyl chloride, polyethylene and polypropylene have good light and heating properties and are used extensively for agricultural membranes. Plastics have multiple protective properties and are often used as protective packagings such as plastic film, boxes, drums, bottles, etc。
6 seismic, soundproof. Some plastics are flexible and resilient, absorbing energy efficiently when subject to frequent mechanical shocks and vibrations from outside, and act as a loss of shock and sound。
Production process
The production of plastics consists of several processes. Some plastics often require plastic manufacture (or formulation) and pre-treatment (including pre-pressure, preheating or drying) before formation, which may be collectively referred to as material preparation. As a result, there are five complete processes for the production of plastics: 1 material preparation; 2 prototypes; 3 mechanical processing; 4 modifications; and 5 assembly. In the production of any product, the above order should normally be followed and should not be reversed, otherwise to some extent the quality of the product and the waste of labour and time will be affected. Where the production of certain products does not require complete passage through these five processes, the above order shall continue after the removal of certain processes. Three
Application area
The electrical industry is one of the first to use plastic materials, extending over time to electronics, home electricity and communications. Plastics are used mainly in the electrical and electronics industry as insulation, shielding, conductive power and heat. In the area of communications, plastic materials are used extensively not only for various end devices, but also for high-performance materials such as fibre-optics and cd-roms. China is a large producer of domestic appliances, and there is a high demand for plastic materials throughout the industry, close to 1/10 of total plastic consumption. Plastic materials are light, insulated, corrosive, high surface quality and easy to process, which are necessary for household appliances such as air conditioning, television, washing machines and refrigerators。
Agriculture is the basic industry in china, and new technologies such as membrane cover, greenhouses and water-saving irrigation have been implemented in recent years, increasing the demand for plastic materials in agriculture. The use of membrane cover increases crop yields by keeping warm, wet, fattening, corrosive, and by treating herbs, promoting plant growth and early harvesting. Vegetables and flowers are also growing four seasons thanks to the use of greenhouses and sunnets. Plastic tubings are light, corrosive, uncut, easy to transport, install and use, and are widely used in modern agricultural irrigation. In addition, plastic materials such as ropes, farm machinery, nets, sunnets, etc. Are also used and are easily cleaned over time。
The use of plastic materials in construction works has grown rapidly, mainly for drainage pipes, catheters, plastic doors and windows, furniture, decorative and waterproofing materials. Especially since the 1970s, the development of structural materials, such as low-breath plastics, has largely replaced wood, resulting in the rapid growth of plastics as structural components in construction materials. The use of plastic materials from abroad in the construction sector accounts for about 25 per cent of total production, while less than 10 per cent of the country has greater development potential。
In the packaging industry, plastic materials are the last show, with consumption accounting for about one quarter of total plastic production, the highest. Plastic film is used for packaging that has long been integrated into everyday life, and most light packagings such as food, knitting, clothing, medicine and miscellaneous items are used as plastic film. Heavy packagings, such as fertilizers, cement, food, salt and synthetic resin, were also replaced by plastic knitting bags for past sacks and oxen paper bags. Plastic packagings are both corrosive and less fragile than glass packagings and offer many eases of transport, making them widely used in the beverages, chemicals, etc。
Automobile industry is developing rapidly, using an average of over 100 kilograms of plastic materials per vehicle and showing an upward trend over the years. The application of plastics in the automobile industry has three main advantages: energy efficiency, enhancement of fittings, simplification of manufacturing processes and process. Energy saving is less than 0. 91 g/cm3 for plastics, such as polypropylene material. The enhancement of spare parts is derived from the variety and performance of plastic materials. Simplified manufacturing processes and processes are derived from the easy-to-formate properties inherent in plastic materials. As a result, “car plasticization” is not always the same。
In people's daily lives, plastics are used more widely, such as plastic sandals, slippers, raincoats, handbags, children's toys, toothbrushes, soapboxes, hot water bottles, etc., sold on the market. Extensive applications have also been made in various household appliances such as televisions, recorders, fans, washing machines, refrigerators, etc。
Plastic materials are also important in high-tech fields such as defence, aviation and space. For example, light quantification of weapons has made significant progress in terms of combat vehicles, guns, ammunition, etc.; fibre-enhanced plastics in lieu of aluminium alloy manufacturing aircraft can significantly reduce weight and save fuel; plastic materials account for half of their total accumulation in artificial satellites and spacecraft, and their status as light-quality, corrosive material is irreplaceable。
In the field of medical engineering, polymethyl acrylate became the primary material for tooth fares, dentures, tooth repair and artificial skulls in the 1930s. After the 1950s, plastics were used to make artificial organs in the human body, such as tubes, arthropods, oesophagus, artificial heart valves and artificial kidneys for in vitro use, etc. Due to long-term exposure to organisms, blood, body fluids, etc., such materials must be biologically adaptable and compatible. In addition, plastic materials are used in the manufacture of medical devices, such as syringes for one-time use, fluid bags, surgical devices, etc. In addition to the above applications, plastic materials have a wide range of uses in chemical, mechanical and daily life, and scientists believe that human beings have entered the age of high molecular synthetic materials. Two
Waste plastics affecting land pollution
Plastics and plastics can damage and contaminate the terrestrial environment and then be transferred to the aquatic environment, where most of the plastic waste in the oceans is land-related, but where there is a lack of data on the quantity of plastic waste on land compared to the large volume of plastic waste in the marine environment. The dumping of plastics on land or in landfills can lead to the abiotic and biological degradation of plastics, where plastic additives (e. G., stabilizers, partially harmful colourants, plasticizers and heavy metals) can penetrate underground and eventually into various aspects of the environment, resulting in soil and water pollution. Four
Marine pollution
An estimated 165 million tons of plastic waste were released into the world's oceans and seas in 2012, while an average of 8 million tons of plastic was released into the oceans each year, with approximately 5 trillion plastic debris floating in the oceans. From pollution to solutions: a global assessment of marine litter and plastic pollution has shown that all ecosystems, from the source of rivers to the oceans, face increasing threats. Plastics account for 85 per cent of marine litter, and by 2040 the amount of plastic pollution flowing into the sea will nearly triple, increasing by 23-37 million tons annually. This means about 50 kg of plastic per metre of coastline worldwide. In general, during degradation of plastics in the oceans, toxic chemicals such as polystyrene and bisphenol a are released into the water, causing water contamination. In addition, plastic debris floating in the oceans may be rapidly decolonized by marine organisms and may contribute to the movement of “external” or non-native species due to their long-term presence on the surface of the oceans. Four
Air pollution
Carbon dioxide and methane are released into the air when plastic waste from landfills is eventually dissolved. The estimated co2 equivalent emissions to the atmosphere were 20 million tonnes during the 2008 stacking of separated solid waste. Open burning of plastics and plastics releases pollutants such as heavy metals, dioxins, pcbs and furans, which, when inhaled, can lead to health risks, especially respiratory diseases. The pollution of the air by plastics poses a serious threat to the health of people and can also have a significant impact on future generations。
Effects on animals
Indeed, reports of threats to the survival of large marine mammals have been documented as a result of large quantities of plastic waste entering the world's oceans. Animals are exposed to plastic waste mainly through ingestion and entanglement, but ingestion is more frequent than entanglement, with most animals in the oceans eating them as food by mistake. And entanglements (e. G. Nets) can cause injury, damage or even death to marine animals. Many birds, sea turtles, fish, seals and other marine animals drown or asphyxiate as a result of their involvement in plastic debris. Four
Impact on public health
Most of the additives in plastics are potential carcinogens and endocrine disruptors. Ingestion, dermal contact and inhalation are the main routes for human absorption of these additives. Microplastics are a major contaminant that bioaccumulates in the food chain following ingestion of large quantities of fresh water and marine organisms, leading to public health risks. Biomonitoring studies of human tissues indicate that plastic components remain in the population and that human consumption of animals exposed to microplastics and plastic additives is harmful. Four
Economic impact
Marine litter and plastic pollution also have a significant impact on the global economy. In 2018, the impact of global marine plastic pollution on tourism, fisheries and aquaculture, as well as other costs (e. G. Clean-up costs), was estimated at at at least $60-19 billion. It is expected that, by 2040, enterprises may be exposed to financial risk of $100 billion per year if they are required by governments to pay for waste management in the expected amount and recoverability. Large quantities of plastic waste can also lead to an increase in illegal domestic and international waste disposal。
Environmental protection measures
Develop policies to reduce plastic waste objects
In order to combat and contain the persistent pollution of the environment by plastics, it is necessary to develop practical policies that must be followed and enforced。
Raising public awareness
Efforts must be made to make the public aware of the potential impact of plastic waste pollution on the environment and public health. This will significantly reduce pollution rates and protect the quality of the environment. People need to understand the chemical composition of plastics and their health effects. Four
Laws and regulations
China has developed and implemented a series of laws and regulations and policy measures in the area of plastic pollution management. The following are some of the main policies and regulations:
1. Technical norms for the control of waste plastic pollution: this is based on laws and regulations such as the law of the people's republic of china on the protection of the environment and the law of the people's republic of china on the prevention and control of solid waste pollution in the environment, which aim to prevent environmental pollution, improve the quality of the ecological environment and regulate and guide the management of waste plastics. This standard has been in force since 31 may 2022。
2. Measures for the management of plastics in the commercial sector: this regulation, issued by the ministry of commerce, became effective on 20 june 2023. It is intended to implement the provisions of the law of the people's republic of china on the prevention and control of solid waste pollution in the environment concerning the use and reporting of plastics in a single-use manner. This applies to the supervision and management of the use and reporting of disposable plastics in the business sector, including in the areas of retailing of goods, electronic commerce, catering, accommodation, exhibitions, etc。
3 “xivv” programme of action for the management of plastic pollution: published by the national development reform commission and the ministry of the environment, aimed at further strengthening the entire chain of plastic pollution and promoting greater effectiveness in white pollution management during the xivv period. The programme sets out the main objectives by 2025, including increased efficiency in plastic production, circulation, consumption, recycling, end-of-pipe treatment, and specific targets for source reduction, recycling and waste disposal。
Views on further strengthening plastic pollution management: this document sets out the overall requirements, basic principles and main objectives for enhancing plastic pollution management. It emphasizes the prohibition, restriction of the production, sale and use of some plastics, the promotion of alternative products, the regulation of plastic waste recycling and the establishment of a regulatory system for the production, circulation, use and disposal of sound plastics。
5. Report on plastic pollution management and recycling policies and practices in china: published by the joint working group on the green renewable plastic supply chain and the china environmental protection federation, which presents a baseline for plastic pollution management in china. The report outlines the evolution of china's plastic management policy and analyses its current plastic policy system from the perspective of top-level design, sectoral distribution of functions, and the full life cycle。
These policies and regulations reflect china's determination and action in the area of plastic pollution management, aimed at reducing plastic pollution and promoting sustainable development。
