Поліуретан, commonly abbreviated as PU or PUR, is a versatile class of polymers formed through the reaction of compounds containing isocyanate groups with polyols or other molecules containing active hydrogen groups.
Unlike many conventional plastics that are associated with a relatively narrow range of properties, polyurethane can be engineered across an exceptionally broad spectrum—from soft, flexible foams and elastomers to rigid structural foams, покриття, клеї, герметики, and hard engineering components.
This versatility comes primarily from polyurethane’s segmented molecular structure and the ability to modify its chemistry, crosslink density, cell structure, та умови обробки.
By selecting different polyols, isocyanates, chain extenders, catalysts, blowing agents, і добавки, manufacturers can tailor polyurethane for requirements such as cushioning, стійкість до стирання, Теплоізоляція, хімічна стійкість, гнучкість, Поглинання удару, і розмірна стабільність.
This article examines what polyurethane is from both a materials-science and manufacturing perspective, including its chemical structure, major types, властивості, Методи виробництва, переваги, обмеження, and engineering applications.
1. What Is Polyurethane?
Polyurethane is a polymer containing a significant number of urethane linkages, typically represented by the chemical structure:
–NH–CO–O–
These urethane groups are commonly generated through a reaction between an isocyanate group (–NCO) and a hydroxyl group (–OH):
R–NCO + R′–OH → R–NH–CO–O–R′
This reaction is the fundamental chemistry behind polyurethane production.
Однак, commercial polyurethane materials rarely consist only of simple repeating urethane units.
Their molecular structures may also contain ether, ester, сечовина, carbonate, aromatic, aliphatic, or other functional groups, depending on the raw materials selected.
This is why two products both described as “polyurethane” can have dramatically different properties.
Наприклад, a flexible polyurethane foam used in furniture may be soft and highly resilient, whereas a polyurethane elastomer used for industrial rollers may have high hardness, Сила на розрив, і стійкість до стирання.
A rigid polyurethane foam used in refrigeration equipment, тим часом, is primarily engineered for low thermal conductivity and dimensional stability.
Thermosetting and Thermoplastic Polyurethanes
Polyurethane materials can broadly be divided according to their molecular architecture and processing behavior.
Thermosetting polyurethane develops a permanently crosslinked network during curing.
Once sufficiently cured, it cannot simply be melted and reshaped without causing chemical degradation.
Many cast elastomers, покриття, клеї, and rigid polyurethane systems fall into this category.
Thermoplastic polyurethane (ТПУ) contains predominantly linear or physically associated polymer structures and can be softened by heating and processed repeatedly within its thermal-processing window.
TPU combines many characteristics of elastomers with thermoplastic processing methods such as injection molding and extrusion.
The distinction is important because it directly affects manufacturing, Переробка, repairability, and end-use performance.
Major Characteristics of Polyurethane
Although polyurethane formulations vary considerably, many polyurethane materials exhibit a useful combination of mechanical and chemical properties.
Типові характеристики включають:
- High abrasion and wear resistance
- Good elasticity and resilience
- Adjustable hardness
- Хороша ударостійкість
- Good resistance to oils and many chemicals
- Excellent adhesion to many substrates
- Хороша втома
- Wide processing flexibility
- Good thermal insulation in cellular forms
- Ability to produce both flexible and rigid structures
The exact performance depends strongly on the formulation.
Наприклад, polyurethane is often highly resistant to abrasion, but resistance to hydrolysis, UV radiation, спека, or specific chemicals varies significantly between different polyurethane chemistries.
Отже, material selection should always be based on the specific polyurethane formulation and operating environment, rather than on the generic term “PU.”
2. Chemical Composition and Molecular Structure of Polyurethane
Поліуретан (Пу) is not a single chemical compound but a broad family of polymers whose properties can be tailored through the selection and proportion of different chemical building blocks.
The fundamental polyurethane reaction occurs between isocyanate groups (–NCO) і hydroxyl groups (–OH), producing urethane linkages.
By changing the molecular structure, функціональність, molecular weight, and ratio of the reactants, manufacturers can produce materials ranging from flexible foams and elastomers to rigid foams, покриття, клеї, and high-strength engineering components.
Core Chemical Building Blocks
The two principal reactant families are isocyanates and polyols.
Other components, including chain extenders, crosslinkers, catalysts, blowing agents, ПАР, and performance additives, are introduced when specific mechanical, термічний, обробка, or environmental characteristics are required.
| Component Category | Первинна функція | Common Examples |
| Isocyanates | Provide reactive –NCO groups and contribute to hard segments, міцність, жорсткість, та хімічна стійкість | MDI, TDI, HDI, IPDI |
| Polyols | Form soft segments and strongly influence flexibility, еластичність, hydrolysis resistance, and low-temperature behavior | Polyether polyols, polyester polyols, polycarbonate polyols |
| Chain Extenders | Increase hard-segment content and regulate molecular weight, твердість, Сила на розрив, and phase structure | 1,4-Butanediol (BDO), ethylene glycol, diamines |
| Crosslinkers | Introduce three-dimensional network structures and increase rigidity, розмірна стабільність, і теплову стійкість | Trimethylolpropane (TMP), multifunctional polyols |
Catalysts |
Control reaction rate and influence the balance between competing polyurethane reactions | Tertiary amines, organometallic catalysts |
| Blowing Agents | Generate gas and create the cellular structure of polyurethane foams | Вода, pentane, Co₂, selected physical blowing agents |
| ПАР | Stabilize the developing foam and control cell size, рівномірність, і морфологія | Silicone-based surfactants |
| Добавки | Modify specific performance characteristics such as flame resistance, УФ-стійкість, забарвлення, Окислювальна стійкість, or processing behavior | Антипірени, UV stabilizers, антиоксиданти, пігменти |
3. Major Types of Polyurethane
Polyurethane is a versatile polymer family rather than a single material with fixed properties.
By changing the isocyanate, polyol, chain extender, crosslink density, blowing system, та умови обробки, manufacturers can produce polyurethane materials ranging from soft and highly flexible foams to rigid structural polymers and high-performance elastomers.
Flexible Polyurethane Foam
Flexible polyurethane foam is characterized by an open-cell structure, відносно низька щільність, and high resilience.
It is produced by combining polyols and isocyanates with blowing agents and other additives under controlled foaming conditions.
Its interconnected cellular structure allows the material to compress and recover repeatedly.
Foam density, cell size, твердість, стійкість, and compression set can be adjusted through formulation and processing.
Типові програми включають:
- Furniture and mattress cushioning
- Automotive seats and interior components
- Acoustic and vibration-control products
- Packaging and protective materials
- Flexible seals and cushioning elements
For cushioning applications, щільність, indentation hardness, стійкість, and compression set are often more important than tensile strength alone.
Rigid Polyurethane Foam
Rigid polyurethane foam has a predominantly closed-cell structure and is designed for high stiffness, розмірна стабільність, and thermal insulation.
Its low thermal conductivity results primarily from the cellular structure and the gas contained within the cells.
Depending on formulation and manufacturing process, rigid PU and PIR-based systems can provide excellent insulation performance at relatively low density.
Common applications include building insulation, refrigerated equipment, cold-storage panels, insulated pipes, and appliance insulation.
A typical rigid foam formulation must balance several properties simultaneously:
| Власність | Важливість |
| Щільність | Influences strength, розмірна стабільність, і теплові показники |
| Closed-cell content | Important for insulation and moisture resistance |
| Міцність на стиск | Determines load-bearing capability |
| Теплопровідність | Critical for energy-efficiency applications |
| Стабільність розмірів | Controls long-term performance under temperature changes |
| Flammability performance | Important for building and transportation applications |
Polyurethane Elastomers
Polyurethane elastomers occupy an important position between conventional rubber and rigid engineering plastics.
They can combine relatively high tensile strength and abrasion resistance with substantial elastic deformation.
They are available as thermoplastic polyurethane (ТПУ), cast polyurethane elastomers, and thermoset systems.
Polyurethane elastomers are particularly valued for applications involving repeated mechanical loading, вплив, тертя, або стирання.
Колеса, ролики, ущільнювачі, прокладки, втулки, компоненти конвеєра, and industrial wear parts are common examples.
Their performance depends strongly on the hard-segment content and molecular architecture.
Increasing hard-segment concentration generally increases hardness and modulus, while appropriate soft-segment chemistry maintains elasticity and elongation.
Thermoplastic Polyurethane (ТПУ)
TPU is a thermoplastic form of polyurethane that can be repeatedly softened by heating and processed using conventional thermoplastic manufacturing technologies.
Unlike highly crosslinked thermoset polyurethane, TPU primarily relies on physical interactions and segmented polymer morphology to achieve its mechanical properties.
This makes it suitable for injection molding, екструзія, Молодування, and other continuous manufacturing processes.
TPU can be formulated across a broad hardness range, typically from very soft elastomeric grades to relatively rigid engineering grades.
Типові програми включають:
- Cable jackets and protective coverings
- Автомобільні компоненти
- Industrial hoses and tubing
- Seals and flexible connectors
- Footwear components
- Consumer-product housings and protective parts
Cast Polyurethane
Cast polyurethane is produced by mixing reactive components and pouring the formulation into a mold, where polymerization and curing take place.
This process is particularly useful for manufacturing large or customized elastomeric components that would be difficult or uneconomical to produce through conventional thermoplastic processing.
Cast polyurethane can be formulated for different combinations of hardness, еластичність, tear resistance, стійкість до стирання, та хімічна стійкість.
Industrial rollers, scraper blades, носити вкладиші, ущільнювачі, втулки, and impact-resistant components are typical applications.
Polyurethane Coatings, Adhesives, and Sealants
Polyurethane is also widely used as a functional surface or bonding material rather than as a bulk structural component.
Поліуретанові покриття can provide abrasion resistance, хімічна стійкість, weatherability, гнучкість, and attractive surface finishes. They are used on metals, пластмаси, деревина, concrete, and other substrates.
Polyurethane adhesives can form strong bonds between dissimilar materials and are used in automotive, будівництво, footwear, меблі, and industrial assembly.
Polyurethane sealants combine adhesion with elastic deformation, allowing joints to accommodate movement caused by thermal expansion, вібрація, or mechanical displacement.
4. Key Properties of Polyurethane
Поліуретан (Пу) is distinguished by its unusually broad range of mechanical, термічний, хімічний, and physical properties.
Unlike metals or many conventional thermoplastics, polyurethane is a material family whose performance can be extensively modified through the selection of isocyanate type, polyol chemistry, hard-segment content, crosslink density, добавки, щільність, and cellular structure.
Отже, there is no single set of mechanical properties that represents all polyurethane products.
A flexible polyether elastomer, a rigid insulation foam, and a high-hardness cast polyurethane may all be chemically classified as polyurethane while exhibiting completely different performance characteristics.
The following values should therefore be treated as representative engineering ranges or examples rather than universal specifications.
Final material selection should always be based on the manufacturer’s tested datasheet under the relevant ASTM, ISO, or EN standard.
Механічні властивості
| Власність | Typical Engineering Range / Приклад | Main Controlling Factors |
| Density – solid elastomer | ~1.1–1.3 g/cm³ | Polymer chemistry, наповнювачі |
| Density – rigid PU foam | ~30–45 kg/m³ for many insulation products | Blowing system, формулювання, cell structure |
| Сила на розрив | ~15–50+ MPa for many elastomers | Твердість, molecular structure, crosslinking |
| Подовження | ~300–700% for many flexible elastomers | Soft-segment chemistry and crosslink density |
Твердість |
~45 Shore A to 70 Shore D+ | Hard-segment content, crosslinking |
| Thermal conductivity – elastomer | ~0.15–0.25 W/(м · k), залежний від класу | Density and formulation |
| Thermal conductivity – rigid foam | ~0.020–0.030 W/(м · k) | Cell structure, газовий, щільність, старіння |
| Питомий об'ємний опір | Can reach ~10¹³ Ω·cm in suitable grades | Формулювання, волога, температура |
| Long-term service temperature | Common grades roughly −30 to +80°C; specialized grades higher | Polymer chemistry and formulation |
Стирання та зношування
Polyurethane is particularly well known for its resistance to abrasive wear.
Properly formulated polyurethane can outperform many conventional elastomers in applications involving sliding, прокатка, вплив, or repeated contact.
This characteristic makes polyurethane attractive for industrial rollers, компоненти конвеєра, носити вкладиші, ущільнювачі, колеса, втулки, and mining equipment components.
Однак, abrasion resistance is not a universal property of all polyurethane grades. Polyol chemistry, твердість, crosslink density, температура, counterface material, змащування, and wear mechanism can all influence actual service life.
Elasticity and Resilience
The flexible soft segments of polyurethane allow significant reversible deformation. This gives many polyurethane elastomers excellent resilience and energy-return characteristics.
Resilience is particularly important in components subjected to repeated compression or impact.
Наприклад, polyurethane wheels and rollers need to deform under load while recovering their shape rapidly enough to limit permanent deformation and heat generation.
The balance between elasticity and hysteresis is therefore an important consideration in dynamic applications.
Хімічна стійкість
Polyurethane generally provides good resistance to oils, мастило, паливо, and many industrial chemicals, although performance varies substantially between formulations.
Polyether-based polyurethane often provides better hydrolysis resistance, while polyester-based systems may offer advantages in certain mechanical and chemical environments.
Chemical compatibility should therefore be evaluated against the specific chemical, концентрація, температура, час контакту, and mechanical loading condition rather than relying on a generic statement that polyurethane is chemically resistant.
Теплові властивості
Polyurethane’s usable temperature range depends strongly on its chemistry and physical structure.
Many conventional polyurethane elastomers operate effectively over a broad moderate-temperature range, while specialized formulations are designed for elevated or low-temperature service.
At sufficiently high temperatures, polymer chain mobility increases and mechanical properties decline. При низьких температурах, some formulations become significantly stiffer and less flexible.
Rigid polyurethane foam is also valued for its low thermal conductivity and is therefore widely used for thermal insulation.
Water and Hydrolysis Resistance
Hydrolysis resistance is particularly important in outdoor, морський, гідравлічний, and humid environments.
Polyether-based polyurethane generally offers better resistance to hydrolytic degradation than conventional polyester-based polyurethane.
Однак, polyester polyurethane can provide excellent mechanical and wear properties in suitable environments.
For long-term water exposure, material selection should consider not only water itself but also temperature, рН, мікроорганізми, механічне напруження, and exposure duration.
Електричні властивості
Many polyurethane formulations provide useful electrical insulation characteristics, including relatively high electrical resistivity and dielectric strength.
These properties support applications such as cable jackets, electrical encapsulation, Захисні покриття, та електронні компоненти.
Все -таки, electrical performance can change with temperature, вологість, частота, формулювання, and filler content.
5. Polyurethane Hardness
Hardness is one of the most commonly specified properties of polyurethane, particularly for elastomers, ролики, колеса, ущільнювачі, прокладки, Захисні покриття, і стійкі до зносу компоненти.
Однак, polyurethane hardness should not be interpreted simply as a measure of overall material strength.
In polyurethane engineering, hardness primarily describes the material’s resistance to localized deformation under a specified indentation test condition.
What Does Polyurethane Hardness Mean?
When a force is applied to a polyurethane surface, the material deforms around the indenter.
A harder polyurethane exhibits less indentation under the specified test conditions, whereas a softer grade undergoes greater localized deformation.
Because polyurethane can range from very soft elastomers to rigid engineering materials, different hardness scales are used for different hardness ranges.
For flexible and elastomeric polyurethane, hardness is commonly measured using the Shore hardness scale.
Shore A is generally used for softer to moderately hard polyurethane, в той час Шор Д is used for harder formulations.
The selected scale should always be reported together with the hardness value because, наприклад, 80 Shore A and 80 Shore D represent very different material conditions.
Common Polyurethane Hardness Ranges
| Hardness Range | Типові характеристики | Typical Performance | Представницькі заявки |
| 20–40 Shore A | Very soft and highly flexible | High compliance, низький модуль, excellent cushioning and vibration absorption | Soft seals, прокладки, cushions, acoustic damping components |
| 40–60 Shore A | Soft to medium hardness | Good elasticity, стійкість, and flexibility with moderate load capacity | Flexible wheels, втулки, vibration isolators, footwear components |
| 60–80 Shore A | Medium-hard elastomer | Good balance of flexibility, навантажувальна ємність, і стійкість до стирання | Ролики, колеса, втулки, компоненти конвеєра |
80–95 Shore A |
Hard elastomer | Higher stiffness, вантажопідйомність, and wear resistance with reduced flexibility | Industrial rollers, heavy-duty wheels, Носіть прокладки, високонавантажені компоненти |
| 50–80 Shore D | Very hard polyurethane | High rigidity and dimensional stability with strong resistance to impact and wear | Шестерні, кулачок, guide components, структурні частини, зносостійкі компоненти |
These ranges are representative rather than universal specifications.
Commercial polyurethane formulations can extend beyond these ranges, and the relationship between hardness and mechanical performance depends on the polymer chemistry, crosslink density, filler content, температура, and testing method.
6. Polyurethane Manufacturing Processes
Polyurethane can be manufactured through several processing technologies, and the appropriate method depends on the polyurethane chemistry, product geometry, required hardness, щільність, обсяг виробництва, розмірна толерантність, and end-use performance.
Reaction Injection Molding (RIM)
Reaction Injection Molding is a high-productivity process in which two or more liquid polyurethane components—typically an isocyanate and a polyol formulation—are accurately metered, mixed, and injected into a closed mold.
The chemical reaction takes place rapidly inside the mold, where the material fills the cavity and subsequently cures into the required shape.
RIM is particularly suitable for large components because the relatively low viscosity of the reacting system allows complex molds to be filled with comparatively low injection pressures.
Reinforcing materials or fillers can also be incorporated into specialized formulations to improve stiffness, розмірна стабільність, або ударний опір.
Продукти:
Typical RIM products include automotive body panels, бампери, spoilers, корпуси обладнання, structural covers, промислові корпуси, and large lightweight molded components.
Cast Polyurethane
Cast polyurethane is produced by mixing reactive polyurethane components and pouring the liquid mixture into a prepared mold.
The material then cures at room temperature or under controlled heating, depending on the formulation.
This process provides considerable flexibility in material formulation.
Manufacturers can adjust hardness, еластичність, tear resistance, стійкість до стирання, damping characteristics, and chemical resistance by selecting appropriate polyols, isocyanates, chain extenders, catalysts, і добавки.
Cast polyurethane is especially valuable for products that require висока зносостійкість, Поглинання удару, еластичність, or customized hardness.
Degassing may be performed before casting to minimize entrapped air and internal voids, particularly for precision components.
Продукти:
Звичайні продукти включають industrial rollers, колеса, втулки, ущільнювачі, прокладки, Носіть прокладки, scraper blades, vibration isolators, shock absorbers, mining components, and custom polyurethane liners.
Стиснення ліплення
Compression molding uses a measured amount of polyurethane material placed into a heated mold cavity.
The mold is then closed and pressure is applied, allowing the material to flow, conform to the cavity, and cure under controlled temperature and pressure.
The process is commonly used for thermosetting polyurethane systems and elastomeric compounds.
Proper control of mold temperature, тиск, curing time, and material charge is essential because insufficient curing can reduce mechanical performance, while excessive temperature or curing time can affect the material’s final properties.
Compression molding is particularly effective for relatively simple or moderately complex geometries and can provide good dimensional consistency in medium- до великого обсягу виробництва.
Продукти:
Типові продукти включають герметичні кільця, прокладки, pads, бампери, vibration-damping components, носити тарілки, protective covers, and molded polyurethane elastomer parts.
Injection Molding of Thermoplastic Polyurethane (ТПУ)
Thermoplastic polyurethane can be processed using conventional thermoplastic лиття під тиском обладнання.
Unlike thermosetting polyurethane, TPU can be repeatedly softened by heating and solidified by cooling, allowing it to be melted and injected into a mold without a permanent chemical crosslinking reaction.
During processing, precise control of Температура розплаву, тиск впорскування, температура форми, drying conditions, і швидкість охолодження є важливим.
TPU is hygroscopic to varying degrees, and excessive moisture in the pellets can cause hydrolytic degradation, поверхневі дефекти, бульбашки, or reduced mechanical properties. Proper pre-drying is therefore an important part of TPU injection molding.
Продукти:
TPU injection molding is widely used for protective cases, flexible connectors, ущільнювачі, cable components, колеса, рукоятка, consumer-product components, автомобільні запчастини, медичні компоненти, and wear-resistant industrial parts.
Екструзія
Polyurethane extrusion is primarily used for producing continuous profiles, трубки, фільми, простирадла, and other products with a constant cross-sectional geometry.
Thermoplastic polyurethane pellets are heated and plasticized in an extruder before being forced continuously through a specially designed die.
The extrusion process requires careful control of barrel temperature, screw speed, температура матриці, extrusion rate, умови охолодження, and material moisture.
Die design is particularly important because polyurethane’s viscoelastic behavior can influence dimensional stability and die swell.
Продукти:
Typical extruded products include TPU tubing, hoses, ущільнювачі, прокладки, смуги, фільми, профілі, кабельні оболонки, protective sleeves, and flexible membranes.
Reaction Casting and Centrifugal Casting
For certain large or rotationally symmetric polyurethane components, reaction casting and centrifugal casting can be used.
In reaction casting, reactive polyurethane components are introduced into a mold and allowed to polymerize and cure in situ.
Відцентрове кастинг uses rotational force to distribute the reactive material against the mold wall, producing a relatively uniform tubular or ring-shaped component.
These processes are particularly useful when conventional molding would require expensive tooling or when the component has a large diameter and relatively simple rotational geometry.
Продукти:
Заявки включають large polyurethane rollers, рукава, трубки, кільця, лайнери, pipe coatings, and specialized wear-resistant cylindrical components.
Foaming and Foam Molding
Polyurethane foams are manufactured by combining reactive polyurethane components with a blowing system that generates a cellular structure during polymerization.
Залежно від рецептури, the blowing mechanism may involve chemical blowing agents, such as water reacting with isocyanate to generate carbon dioxide, or physical blowing agents.
The formulation determines whether the resulting foam is гнучкий, semi-rigid, or rigid.
Cell size, щільність, ВІДЧИНЕНО- or closed-cell structure, and dimensional stability are controlled through the balance of polyols, isocyanates, catalysts, ПАР, blowing agents, та умови обробки.
Продукти:
Flexible polyurethane foam is commonly used for seating cushions, mattresses, acoustic materials, і автомобільні салони,
while rigid PU and PIR foams are widely used for building insulation panels, refrigeration insulation, thermal insulation systems, and energy-efficient equipment.
CNC Machining of Polyurethane
Обробка з ЧПУ is not a primary polymerization process, but it is an important secondary manufacturing method for polyurethane components.
A polyurethane block, аркуш, стрижень, or pre-cast blank can be machined using CNC turning, фрезер, свердління, and other operations to achieve precise dimensions and complex geometries.
Because polyurethane is flexible and can deform under cutting forces, machining parameters must be selected according to the material’s hardness and elasticity.
Excessive cutting force, Генерування тепла, or tool deflection can result in dimensional inaccuracies or poor surface quality. Sharp cutting tools and appropriate workholding are particularly important for soft grades.
Продукти:
CNC machining is commonly used for precision polyurethane seals, custom bushings, зношуються компоненти, ролики, прототипи, інженерні частини, replacement components, and low-volume customized products.
7. Applications of Polyurethane
The exceptional versatility of polyurethane allows it to serve as a structural material, elastomer, покриття, adhesive, sealant, піна, and insulation material.
Its applications therefore extend from consumer products to demanding industrial equipment.
Автомобільна промисловість
Typical applications include seat cushions, headrests, suspension bushings, кріплення двигуна, ущільнювачі, steering components, внутрішня обробка, instrument-panel components, Захисні покриття, and acoustic insulation.
Industrial Rollers and Wheels
Polyurethane rollers are widely used in:
- Конвеєрні системи
- Material-handling equipment
- Printing machinery
- Пакувальне обладнання
- Textile machinery
- Forklift wheels
- Guide rollers
- Drive wheels
Ущільнювачі, Прокладки, and Bushings
Polyurethane’s combination of elasticity, tear resistance, and abrasion resistance makes it suitable for dynamic sealing applications.
PU seals and hydraulic components are commonly used where the material experiences repeated sliding, тиск, and mechanical deformation.
Bushings and damping elements also benefit from polyurethane’s ability to absorb vibration while maintaining structural integrity.
Mining and Heavy Equipment
Mining and construction equipment expose polymer components to severe abrasion, вплив, пил, волога, і механічне навантаження.
Polyurethane is therefore used for носити вкладиші, screen panels, chute liners, scraper blades, ролики, hydraulic seals, and protective components.
In abrasive environments, a properly formulated polyurethane component can significantly reduce maintenance frequency compared with less wear-resistant elastomers.
Будівельні та будівельні матеріали
Polyurethane plays an important role in modern building systems.
Rigid polyurethane and polyisocyanurate foams provide low thermal conductivity and are widely used in insulated panels, refrigeration systems, building envelopes, roofs, стіни, and pipe insulation.
Polyurethane sealants and coatings are also used for joint sealing, waterproofing, підлога, Захисні покриття, and concrete protection.
Electrical and Electronic Products
PU materials can provide electrical insulation together with flexibility and environmental protection.
They are used for кабельні оболонки, potting compounds, encapsulation materials, з'єднувачі, Захисні покриття, and vibration-damping components.
Formulations can be designed to provide specific combinations of dielectric properties, вологостійкість, гнучкість, and flame resistance.
Footwear and Consumer Products
Flexible polyurethane and TPU are widely used in consumer products because they offer a favorable combination of comfort, стійкість, довговічність, та гнучкість дизайну.
Заявки включають shoe soles, sports footwear components, protective cases, рукоятка, колеса, Спортивні товари, luggage components, and flexible consumer-product parts.
8. Advantages of Polyurethane
- Unmatched performance tunability — hardness, density and mechanical properties can be precisely engineered across an extraordinarily wide range from a single chemical base.
- Exceptional abrasion and wear resistance — polyurethane elastomers routinely deliver 3–10× the service life of rubber alternatives in heavy-wear applications.
- Superior thermal insulation — rigid PU foam is the most thermally efficient commercially available organic insulation material, reducing building energy consumption by 30–50%.
- Broad processing adaptability — can be manufactured via foaming, кастинг, розпилення, лиття під тиском, extrusion and in-situ application methods.
- Universal substrate adhesion — coatings and adhesives bond strongly to metal, деревина, concrete, glass and most plastics.
- Відмінне вібраційне демпфірування — flexible foams and elastomers absorb shock and noise effectively, making them indispensable for automotive and industrial NVH control.
- Свобода дизайну — liquid processing enables production of large, складні, integrated parts that would be impossible with rubber or rigid plastic.
9. Limitations of Polyurethane
- Moderate temperature resistance — standard grades have continuous service limits of 80–120°C. Long-term exposure above this range causes thermal degradation and permanent property loss.
- Hydrolysis sensitivity — polyester-based polyurethanes degrade gradually in prolonged hot, humid environments. Polyether grades perform better but still have limits.
- UV degradation of aromatic grades — standard aromatic polyurethanes yellow and chalk under prolonged UV exposure. Aliphatic grades solve this but at significantly higher cost.
- Raw material handling hazards — unreacted isocyanate monomers are respiratory irritants and require proper ventilation and PPE during processing. Fully cured products are safe for normal end use.
- Горючість — unmodified polyurethane is combustible and can release toxic fumes during combustion. Flame-retardant formulations are required for building and transportation applications.
- Recycling challenges — crosslinked thermoset polyurethane cannot be remelted, making mechanical recycling difficult. Chemical recycling technologies are emerging but not yet universally available.
10. Екологічні та стійкі міркування
| Аспект | Оцінка |
| Renewable resources | Bio-based polyols are increasingly available, derived from vegetable oils or plant sources. |
| Переробка | Thermoplastic polyurethanes (ТПУ) are recyclable; thermosets (rigid foams, many elastomers) are not. |
| Споживання енергії | Production of polyurethane from petrochemicals is energy-intensive. |
| Lifecycle assessment | Depends on the formulation and application; утеплення (rigid foam) can provide significant energy savings. |
| Кінець життя | Foam waste is difficult to recycle; incineration is a common disposal route. |
| Health and safety | Isocyanates are toxic; proper ventilation and PPE are essential during handling. |
| Biodegradability | Conventional polyurethane is not biodegradable. |
11. Polyurethane vs. Rubber and Conventional Plastics
Polyurethane occupies a distinctive position between elastomers and engineering plastics.
The following comparison highlights the major differences between polyurethane and several commonly used materials.
| Власність | Поліуретан | Natural Rubber | Поліетилен (ПЕ) | Нейлон |
| Тип матеріалу | Versatile polymer; available as elastomer, термопластичні, thermoset, і піна | Natural elastomer | Thermoplastic | Інженерний термопласт |
| Типова твердість | Приблизно 20 Shore A to 70+ Шор Д, depending on formulation | Approximately 20–90 Shore A | Typically Shore D range for rigid grades | Typically Rockwell or Shore D; generally rigid |
| Сила на розрив | Common elastomer grades approximately 20–60 MPa; formulation-dependent | Approximately 15–30 MPa for many commercial grades | Approximately 10–40 MPa, залежний від класу | Approximately 50–100 MPa for many engineering grades |
| Подовження на перерві | Commonly 200–700% for elastomeric grades | Commonly 400–800% | Typically 100–1,000% depending on grade | Generally much lower than elastomeric polyurethane |
| Стійкість до стирання | Відмінний; one of the major advantages of polyurethane | Добре до відмінного | Помірний до добра | Добрий |
| Сліз | Від дуже добре до відмінно | Відмінний | Помірний | Добрий |
| Elastic Recovery | Excellent in properly formulated elastomers | Відмінний | Generally lower than elastomers | Відносно обмежений |
Ударний опір |
Дуже добре; remains highly effective in many demanding applications | Відмінний | Добрий, particularly in PE grades designed for impact resistance | Добре до відмінного |
| Oil and Grease Resistance | Generally very good, particularly with suitable polyester- or polyether-based formulations | Relatively poor; oils can cause swelling and deterioration | Generally good against many chemicals, but solvent resistance varies | Добрий, although certain chemicals and moisture can affect performance |
| Хімічна стійкість | Good to excellent depending on chemistry; polyester and polyether PU behave differently | Limited against oils, паливо, ozone, and some chemicals | Excellent resistance to many acids, луг, and aqueous chemicals | Good resistance to many hydrocarbons and oils, but sensitive to certain acids and moisture |
| Moisture Resistance | Formulation-dependent; polyether PU generally performs better in humid environments | Good in many applications but sensitive to environmental aging | Дуже добре | Moisture absorption can be significant and can affect dimensions and mechanical properties |
Weathering / UV Resistance |
Good to excellent with appropriate stabilization; aliphatic PU offers particularly strong UV resistance | Обмежений; ozone and UV can accelerate degradation | Загалом добре, especially with UV stabilizers | Помірний; UV stabilizers may be required for outdoor service |
| Температурна стійкість | Broad range, but highly formulation-dependent; many grades operate from sub-zero temperatures to approximately 80–120°C continuously | Commonly effective over approximately −50 to 80°C, depending on compound | Broad range; залежний від класу | Generally higher continuous-use temperature capability than elastomeric PU |
| Flexibility at Low Temperature | Good to excellent for properly formulated grades | Відмінний | Good for suitable low-temperature grades | Generally lower than flexible polyurethane and rubber |
| Water Absorption | Загалом низький, but varies significantly with chemistry and cellular structure | Низький до помірного | Дуже низький | Relatively high compared with PU and PE |
| Load-Bearing Capability | Excellent for elastomers; high-performance grades can withstand substantial compressive and dynamic loads | Добрий, but long-term deformation can be significant | Good for structural thermoplastic applications | Відмінний for rigid engineering components |
Втома |
Excellent in many dynamic applications | Excellent under suitable cyclic loading | Добрий | Добрий |
| Методи обробки | Кастинг, reaction injection molding, лиття під тиском, екструзія, стиснення ліплення, foaming, обробка | Latex processing, ліплення, екструзія, vulcanization | Підприємство для ін'єкцій, екструзія, Молодування, rotational molding | Підприємство для ін'єкцій, екструзія, обробка |
| Типові програми | Колеса, ролики, ущільнювачі, втулки, прокладки, vibration isolators, покриття, ремені, foams, шестерні | Tires, ущільнювачі, рукавички, vibration mounts, hoses, elastic components | Упаковка, труби, контейнери, лайнери, фільми, structural plastic parts | Шестерні, підшипники, втулки, Структурні компоненти, electrical parts |
| Main Advantage | Exceptional combination of стійкість до стирання, еластичність, міцність, вантажопідйомність, та гнучкість дизайну | Excellent elasticity, втома, and resilience | Низька вартість, хімічна стійкість, low moisture absorption | Висока сила, жорсткість, розмірна стабільність, і температурна здатність |
| Main Limitation | Properties vary considerably with formulation; some grades are sensitive to hydrolysis, спека, або ультрафіолетове опромінення | Poor resistance to oils, ozone, and some chemicals | Lower temperature and mechanical performance than many engineering polymers | Moisture absorption and sensitivity to certain chemicals can affect performance |
12. Висновок
Polyurethane occupies a unique position in the materials world as the most design-flexible polymer platform available today.
Its microphase-separated molecular structure enables performance tuning across the full spectrum from soft foam to rigid engineering plastic, supporting critical functions across nearly every industrial sector.
No other single material family can simultaneously serve as cushioning, утеплення, structural component and protective coating with equal effectiveness.
As global demand for energy efficiency, lightweighting and advanced materials grows, polyurethane will remain a foundational industrial material — evolving from its petroleum-based origins toward a more sustainable, circular economy future while retaining the extraordinary versatility that has made it indispensable to modern manufacturing and construction.
Поширені запитання
Is polyurethane plastic or rubber?
Polyurethane falls into a category between rubber and plastic. Soft polyurethane elastomers behave much like rubber, while hard polyurethane grades approach engineering plastic performance.
Unlike true rubber, it is not crosslinked via vulcanization; unlike true plastic, it is highly elastic across most of its hardness range. It is most accurately classified as an elastomeric polymer.
Is polyurethane flammable?
Some formulations are flammable. Flame retardants are typically added for applications requiring fire resistance.
Rigid polyurethane foam, used in building insulation, must meet strict fire safety standards.
What is the difference between polyether and polyester polyurethane?
Polyether polyurethane has better hydrolysis resistance, microbial resistance, and low-temperature flexibility.
Polyester polyurethane has higher tensile, розірвати, and abrasion resistance but is susceptible to hydrolysis and microbial attack.
What is TPU?
TPU stands for Thermoplastic Polyurethane. It is a type of polyurethane that can be processed like conventional plastics (лиття під тиском, екструзія) and is recyclable.
It is used in hoses, трубки, фільми, footwear, and many industrial applications.
How is polyurethane foam made?
Polyurethane foam is produced by reacting an isocyanate with a polyol in the presence of a blowing agent (typically water), catalysts, and surfactants.
The reaction produces CO₂ gas, which expands the polymer into a foam.
