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Introduction to Synthetic Polymers
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Today, weโll explore synthetic polymers, which are essential in our daily lives, from packaging materials to clothing. Can anyone name a common synthetic polymer?
How about polyethylene?
Exactly! Polyethylene is one of the most widely used synthetic polymers. What do you think itโs made from?
Isn't it made from ethene?
Yes, great answer! Ethene, or ethylene, serves as the monomer for polyethylene. Can anyone suggest where you might see polyethylene in use?
I see it in plastic bags and bottles!
That's right! Let's keep that in mind as we discuss more polymers today.
Different Types of Polyethylene
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Now let's dive deeper into polyethylene. There are different types: LDPE, HDPE, and LLDPE. Who can tell me one difference between them?
I think LDPE is more flexible than HDPE, right?
Absolutely correct! LDPE is highly branched and flexible, making it ideal for plastic bags. Does anyone know what makes HDPE different?
HDPE is denser and stronger, used in things like milk jugs.
Exactly! HDPE has a more linear structure, which gives it strength. Letโs remember LDPE is for flexibility and HDPE for strength.
What about LLDPE?
Good question! LLDPE combines properties of both LDPE and HDPE, making it useful in packaging films.
Polypropylene and Other Synthetic Polymers
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Now letโs discuss polypropylene, another important synthetic polymer made from propene. Can anyone tell me the key properties of polypropylene?
I think it has a higher melting point than polyethylene.
Thatโs correct! Polypropylene has a higher melting point and is quite versatile. What kind of products can you find polypropylene in?
I see it in food containers and some automotive parts.
Exactly! Itโs chemically resistant and strong. Now, who can share something about polystyrene?
Polystyrene is used in foam packaging and is pretty light!
Absolutely right! And that brings us to its expanded form, EPS, which is great for insulation. Remember, polystyrene can be general-purpose or high-impact.
Introduction & Overview
Read a summary of the section's main ideas. Choose from Basic, Medium, or Detailed.
Quick Overview
Standard
In this section, we dive into the world of synthetic polymers, detailing the major classes like polyethylene, polypropylene, and polystyrene. Each variety is explained with respect to its monomer, production process, physical properties, and common applications, illustrating their significance in various industries.
Detailed
Major Classes of Synthetic Polymers and Applications
This section provides an overview of the major classes of synthetic polymers, emphasizing their diverse applications. Synthetic polymers are critical in modern industry and daily life. We explore several polymers, detailing their structures, manufacturing processes, and applications.
1. Polyethylene (PE)
- Monomer: Ethene (CHโ=CHโ)
- Variants:
- Lowโdensity polyethylene (LDPE): Produced under high pressure/temperature, flexible, used in plastic bags and films.
- Highโdensity polyethylene (HDPE): Produced at lower pressures with Ziegler-Natta catalysts, stronger and used in containers and piping.
- Linear lowโdensity polyethylene (LLDPE): Combines properties of LDPE and HDPE, used in films and packaging.
2. Polypropylene (PP)
- Monomer: Propene (CHโ=CH-CHโ)
- Can be isotactic, syndiotactic, or atactic affecting its crystallinities and applications such as automotive parts and textiles.
3. Polyvinyl Chloride (PVC)
- Monomer: Vinyl chloride (CHโ=CH-Cl)
- Rigid and flexible forms depend on the presence of plasticizers, used in pipes and flooring.
4. Polystyrene (PS)
- Monomer: Styrene (CHโ=CH-CโHโ )
- Varieties include general-purpose, high-impact, and expanded polystyrene, used in packaging and insulation.
5. Polyethylene Terephthalate (PET)
- A condensation polymer used in beverage bottles and textiles, offering good gas barrier properties.
6. Polyamides (Nylons)
- Examples include nylon 6,6 and nylon 6, both used in fibers for textiles and engineering parts.
7. Polyurethane
- Versatile polymer used in foams, elastomers, and coatings.
8. Polyacrylonitrile (PAN)
- Forms carbon fibers and acrylic fibers through polymerization processes.
9. Polytetrafluoroethylene (PTFE/Teflon)
- Noted for its high chemical resistance and low friction, commonly used in non-stick cookware.
10. Polyvinyl Acetate (PVAc) and Polyvinyl Alcohol (PVA)
- Utilized in adhesives and water-soluble films.
11. Polyethylene Oxide (PEO) / Polyethylene Glycol (PEG)
- Used in pharmaceuticals and biocompatible materials.
12. Biodegradable Polymers
- Includes polylactic acid (PLA) and polyhydroxybutyrate (PHB); used in sustainable applications like packaging.
Audio Book
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Polyethylene (PE)
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1. Polyethylene (PE)
- Monomer: Ethene (CH2=CH2).
- Variants:
- Lowโdensity polyethylene (LDPE): Produced by free-radical polymerization under high pressure (1000โ3000 atm) and high temperature (~200โ300 ยฐC). Highly branched, less crystalline, low density (0.91โ0.93 g/cmยณ), flexible. Used in plastic bags, films, squeeze bottles.
- Highโdensity polyethylene (HDPE): Produced by ZieglerโNatta or metallocene catalysts at lower pressure. Largely linear, highly crystalline, higher density (0.94โ0.97 g/cmยณ), stronger and more rigid. Used in milk jugs, detergent bottles, piping, geomembranes.
- Linear lowโdensity polyethylene (LLDPE): Produced by copolymerizing ethene with a small amount of alpha-olefins (e.g., butene, hexene), yielding short, uniform branches. Combines properties of LDPE and HDPE. Used in films, packaging, stretch wrap.
Detailed Explanation
Polyethylene is a widely used plastic made from the monomer ethene. It has multiple forms based on its structure and production method:
- Low-density polyethylene (LDPE) is created under high pressure, resulting in a flexible and branched structure. It is commonly found in items like plastic bags and wrap.
- High-density polyethylene (HDPE) is produced at lower pressures and is more linear, giving it greater strength and rigidity, suitable for products like milk jugs and pipes.
- Linear low-density polyethylene (LLDPE) is a hybrid that combines features of both LDPE and HDPE, useful in various packaging applications.
Examples & Analogies
Think of polyethylene like different types of building materials for constructions:
- LDPE is like a soft, flexible material (like fabric) that allows for easy movement, similar to how plastic bags can bend and fold.
- HDPE, on the other hand, is like sturdy bricks that hold strong structures, similar to how a solid milk jug is less likely to collapse under weight compared to a plastic bag.
Polypropylene (PP)
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2. Polypropylene (PP)
- Monomer: Propene (CH2=CHโCH3).
- Produced by ZieglerโNatta or metallocene catalysts.
- Can be isotactic (all methyl groups on the same side โ crystallizable, high strength), syndiotactic (alternating methyl group orientation โ crystalline), or atactic (random methyl orientation โ amorphous, tacky).
- Properties: Similar to HDPE but higher melting point (~160 ยฐC vs. ~135 ยฐC), rigid, chemical resistant. Used in injection-molded parts, automotive parts, ropes, carpets, food containers.
Detailed Explanation
Polypropylene is a versatile plastic made from the monomer propene. Its properties vary based on how the polymer chains are arranged:
- Isotactic polypropylene has methyl groups aligned on the same side, making it strong and crystalline. This arrangement allows for a higher melting point and better structural integrity.
- Syndiotactic polypropylene alternates the orientation of the methyl groups, resulting in a material that is also crystalline but behaves differently.
- Atactic polypropylene has a random arrangement of methyl groups, making it softer and more tacky. Polypropylene is utilized in various applications due to its durability and chemical resistance.
Examples & Analogies
Think of polypropylene like different types of fabrics:
- Isotactic polypropylene is like a firm, sturdy canvas that holds its shape well, used for bags that donโt easily tear.
- Syndiotactic polypropylene resembles a stretchy fabric that is durable yet gives with motion, like elastic material in clothing.
- Atactic polypropylene is akin to a soft flannel that feels cozy but might not offer the structural strength needed for heavy-duty items.
Polyvinyl Chloride (PVC)
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3. Polyvinyl Chloride (PVC)
- Monomer: Vinyl chloride (CH2=CHโCl).
- Produced by radical polymerization. Properties depend on degree of plasticization:
- Rigid PVC (uPVC): No plasticizer. Hard, strong, weather resistant. Used in pipes, window frames, credit cards, signage.
- Flexible PVC: Contains phthalate or other plasticizers. Soft, pliable. Used in cables, flooring, upholstery, medical tubing.
- Thermal stability is an issue; often stabilized with Cu, Sn, or Ba/Zn compounds to prevent dehydrochlorination at high temperatures.
Detailed Explanation
Polyvinyl Chloride, commonly known as PVC, is made from the monomer vinyl chloride. Its properties can vary significantly based on the inclusion of additives:
- Rigid PVC, or unplasticized PVC (uPVC), does not contain plasticizers, making it hard and durable. It is commonly used in plumbing pipes and window frames due to its strength and weather resistance.
- Flexible PVC contains plasticizers, making it soft and pliable, suitable for applications like electrical cables and medical tubing. However, flexible PVC can have issues with thermal stability and requires additives to prevent degradation.
Examples & Analogies
Imagine PVC like the difference between a solid and a rubbery material:
- Rigid PVC is like a sturdy wooden board, perfect for making things that need to be strong and hold their shape, like window frames.
- Flexible PVC is like a soft rubber mat, which can bend and twist, making it ideal for applications that require flexibility, like electrical wiring insulation.
Polystyrene (PS)
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4. Polystyrene (PS)
- Monomer: Styrene (CH2=CHโC6H5).
- Produced by free-radical polymerization.
- Types:
- General purpose polystyrene (GPPS): Transparent, brittle.
- High impact polystyrene (HIPS): Have polybutadiene rubber dispersed in polystyrene, improving toughness.
- Expanded polystyrene (EPS): Bead foaming process yields closed-cell foam (Styrofoam), used for insulation and packaging.
- Properties: Low density, good rigidity, poor resistance to heat and UV, easily foamed. Used in disposable cutlery, CD cases, insulation, packaging peanuts.
Detailed Explanation
Polystyrene is produced from the monomer styrene and comes in several forms:
- General-purpose polystyrene (GPPS) is clear and brittle, making it suitable for items like CD cases that need to be transparent and cost-effective.
- High impact polystyrene (HIPS) incorporates rubber for added toughness, ideal for applications requiring durability without compromising on weight.
- Expanded polystyrene (EPS), often recognized as Styrofoam, is lightweight and has excellent insulation properties, used in packaging and building materials.
Examples & Analogies
Think of polystyrene as different types of glass:
- GPPS is like a regular glass window, clear but can break easily; used for display cases.
- HIPS is like tempered glass, stronger and less likely to shatter, used in children's toys.
- EPS is like bubble wrap, lightweight and protective, perfect for shipping fragile items.
Polyethylene Terephthalate (PET)
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5. Polyethylene Terephthalate (PET)
- Condensation polymer of terephthalic acid (HOOCโC6H4โCOOH) and ethylene glycol (HOโCH2โCH2โOH). Eliminates water during polymerization.
- Properties: Semi-crystalline, high tensile strength, good barrier properties for gases (CO2, O2), transparent.
- Applications: Beverage bottles, textile fibers (polyester), films for packaging and photography.
Detailed Explanation
Polyethylene Terephthalate (PET) is created through the condensation reaction between terephthalic acid and ethylene glycol, which results in the elimination of water. This polymer is known for its strength and durability:
- PET is semi-crystalline and exhibits high tensile strength, making it ideal for applications that require sturdy materials, such as beverage bottles and clothing fibers.
- Its ability to act as a barrier against gases like CO2 and O2 helps preserve products, ensuring longer shelf lives for beverages.
Examples & Analogies
Consider PET like a tough water bottle that can keep your drink fresh:
- Just as a sturdy water bottle prevents leaks and maintains temperature, PET's structure creates a high-quality barrier for nothing gets in or out.
- PET fibers in clothing act like a breathable layer, allowing your skin to feel comfortable while providing strength, similar to how a good backpack can withstand wear and tear.
Polyamides (Nylons)
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6. Polyamides (Nylons)
- Nylon 6,6: Condensation polymer of hexamethylenediamine (H2Nโ(CH2)6โNH2) and adipic acid (HOOCโ(CH2)4โCOOH).
- Nylon 6: Ring-opening polymerization of caprolactam (a cyclic amide).
- Properties: High strength, abrasion resistance, good thermal resistance, high melting point (around 260 ยฐC for nylon 6,6).
- Applications: Fibers for textiles, carpets; engineering plastics (gears, bearings); films.
Detailed Explanation
Polyamides, commonly known as nylons, are strong synthetic polymers made from the condensation reaction of specific diamines and dicarboxylic acids:
- Nylon 6,6 is formed from hexamethylenediamine and adipic acid, resulting in a material that is exceptionally strong and resistant to wear. Itโs widely used in textiles for clothing and industrial applications where durability is essential.
- Nylon 6 comes from the ring-opening of caprolactam and exhibits similar properties but may vary in specific application suitability due to differing chemical structures.
Examples & Analogies
Imagine nylon like a tough set of climbing ropes:
- Just as strong climbing ropes need to withstand friction and pressure during climbs, nylon's inherent strength provides durability in everyday materials like carpets and clothing.
- It's like a reliable tool that you trust; whether it's for guiding you up a hill or ensuring your clothes last longer.
Polyurethane
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7. Polyurethane
- Formed from diisocyanates (e.g., toluene diisocyanate, TDI; methylene diphenyl diisocyanate, MDI) reacting with polyols (polyesters or polyethers with multiple โOH groups). Reaction eliminates CO2 or no small molecule (depending on monomer).
- Can be flexible foam (bedding, upholstery), rigid foam (insulation panels), elastomers (wheels, rollers), coatings, adhesives, sealants.
Detailed Explanation
Polyurethane is a versatile polymer created through the reaction between diisocyanates and polyols. The reaction can result in various forms of polyurethane depending on the ingredients used:
- Flexible foams are common in furniture and bedding, providing comfort and cushioning.
- Rigid foams are used in insulation panels, offering excellent thermal resistance, while elastomers provide flexibility, making them suitable for wheels and various coatings.
Examples & Analogies
Think of polyurethane like different types of cushions:
- Flexible polyurethane foam is like a soft pillow that molds to the shape of your head, providing comfort.
- Rigid polyurethane acts like a sturdy pillow that doesnโt lose its shape, similar to how insulation panels keep your house warm without compromising on space.
Polyacrylonitrile (PAN)
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8. Polyacrylonitrile (PAN)
- Monomer: Acrylonitrile (CH2=CHโCโกN) polymerizes to give โ[โCH2โCH(CโกN)โ]nโ.
- Fibers spun and oxidized to form carbon fibers used in aerospace and sports equipment. PAN is also precursor for acrylic fibers (Orlon, Dacron) when copolymerized with vinyl acetate or other co-monomers.
Detailed Explanation
Polyacrylonitrile (PAN) is a polymer made from acrylonitrile and is significant in the creation of strong fibers. PAN can be processed into high-strength carbon fibers, which are crucial in industries like aerospace and sports equipment:
- Because of its lightweight and strength, carbon fibers made from PAN are used in highly demanding applications such as aircraft manufacturing.
- Additionally, when PAN is copolymerized with vinyl acetate, it forms acrylic fibers, which are widely used in textiles.
Examples & Analogies
Consider PAN like the threads in a climbing harness:
- Just as strong threads ensure safety in a climbing harness, carbon fibers derived from PAN provide the strength needed for aerospace applications.
- Similarly, acrylic fibers are like warm, breathable clothing that feels cozy yet protects you against the elements.
Polytetrafluoroethylene (PTFE, Teflon)
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9. Polytetrafluoroethylene (PTFE, Teflon)
- Monomer: Tetrafluoroethylene (CF2=CF2) polymerizes under free-radical conditions (initiator like ammonium persulfate) to give a โ[โCF2โCF2โ]nโ chain.
- Properties: Extremely chemically inert, high thermal stability (service up to 260 ยฐC), very low coefficient of friction.
- Applications: Nonstick coatings, chemical-resistant linings, gaskets, seals, insulating coatings for wires.
Detailed Explanation
Polytetrafluoroethylene (PTFE), commonly known as Teflon, is made from the polymerization of tetrafluoroethylene. Known for extraordinary properties, PTFE is highly resistant to chemicals and can withstand high temperatures:
- Its low coefficient of friction makes PTFE an excellent nonstick surface for cookware, preventing food from sticking while cooking.
- Additionally, itโs utilized for various industrial applications such as seals and gaskets, where chemical resistance is critical.
Examples & Analogies
Imagine Teflon like a smooth ice rink:
- Just as skaters glide smoothly over ice without friction, Teflon allows for easy cooking and cleaning without food sticking. PTFEโs properties ensure that it performs well in tough environments, similar to how a quality skating surface allows for optimal performance.
Polyvinyl Acetate (PVAc) and Polyvinyl Alcohol (PVA)
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10. Polyvinyl Acetate (PVAc) and Polyvinyl Alcohol (PVA)
- PVAc: Radical polymerization of vinyl acetate monomer (CH2=CHOโCOCH3) yields poly(vinyl acetate). Used in adhesives (white glue), paints.
- Partial or complete hydrolysis of PVAc yields PVA (โCH2โCHOHโ)n with extensive hydrogen bonding; used in films, textiles sizing, and as a water-soluble polymer.
Detailed Explanation
Polyvinyl Acetate (PVAc) is produced through the radical polymerization of vinyl acetate, making it a crucial component in adhesives and paints:
- PVAc is commonly found in household glues due to its strong bonding properties.
- When PVAc undergoes hydrolysis, it transforms into Polyvinyl Alcohol (PVA), which is useful in many applications because of its water solubility and ability to form hydrogen bonds, found in various films and textile applications.
Examples & Analogies
Think of PVAc and PVA like house paint and wallpaper:
- PVAc is like a paint that sticks impeccably to walls, providing a solid appearance and finish while also being easy to apply.
- PVA, when used in applications like textiles, acts like moisture-wicking fabric that keeps you comfortable by absorbing and releasing water.
Polyethylene Oxide (PEO) / Polyethylene Glycol (PEG)
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11. Polyethylene Oxide (PEO) / Polyethylene Glycol (PEG)
- Repeating unit โCH2โCH2โOโ. PEO generally refers to high molecular weight (โฅ20,000 g/mol), PEG to lower molecular weight. Water-soluble, biocompatible.
- Applications: Pharmaceuticals, cosmetics, lubricants, dispersants, polymer electrolytes (batteries), tissue engineering scaffolds.
Detailed Explanation
Polyethylene Oxide (PEO) and Polyethylene Glycol (PEG) are polymers characterized by a repeating unit of โCH2โCH2โOโ. PEO typically refers to higher molecular weights, while PEG refers to lower molecular weights. Their water-solubility and biocompatibility make them particularly versatile:
- Applications in pharmaceuticals and cosmetics include use as drug delivery carriers or skin moisturizers due to their gentle nature and ability to dissolve in water.
- In tissue engineering, they serve as scaffolds that support cell growth or as lubricants in various products.
Examples & Analogies
Imagine PEO and PEG as the perfect baking ingredients:
- PEO acts like a robust baking powder that creates an appealing cake structure, crucial for supporting cell growth in laboratories.
- PEG is like a light syrup that not only sweetens baked goods but also ensures they remain moist, similar to its ability to enhance the texture in cosmetic products.
Biodegradable Polymers (PLA, PHB, PCL)
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12. Biodegradable Polymers (PLA, PHB, PCL)
- Polylactic acid (PLA): Condensation polymer of lactic acid (2-hydroxypropanoic acid). Biodegradable, compostable, derived from renewable resources (corn starch). Used in disposable packaging, 3D printing filament, biomedical devices.
- Polyhydroxybutyrate (PHB): Bacterial polyester; has mechanical properties similar to polypropylene. Used in biodegradable packaging and medical implants.
- Polycaprolactone (PCL): Ring-opening polymer of caprolactone; biodegradable, low melting point (60 ยฐC), used in medical sutures, drug delivery.
Detailed Explanation
Biodegradable polymers such as Polylactic Acid (PLA), Polyhydroxybutyrate (PHB), and Polycaprolactone (PCL) are gaining attention due to their ability to break down naturally, making them more environmentally friendly:
- PLA is made from lactic acid derived from renewable resources like corn starch and is commonly used in disposable items and medical applications due to its biodegradability.
- PHB is produced by bacteria and has similar properties to traditional plastics, while PCL is known for a low melting point, making it suitable for applications needing easy handling, like sutures.
Examples & Analogies
Think of these biodegradable polymers like different kinds of food waste:
- PLA is akin to leftover vegetable scraps that naturally decompose and enrich the soil, embodying how compost can benefit the environment.
- PHB is like a natural yogurt container that won't linger in the environment forever; it safely breaks down instead of cluttering landfills,
- PCL is like biodegradable utensils that you can toss in a compost bin after a party, helping foster a healthier planet.
Definitions & Key Concepts
Learn essential terms and foundational ideas that form the basis of the topic.
Key Concepts
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Polyethylene: Made from ethene, used in various everyday products.
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Polypropylene: Derived from propene, known for strength and heat resistance.
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Polyvinyl Chloride: Commonly known as PVC, versatile in applications.
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Polystyrene: Essential for packaging and foam insulation.
Examples & Real-Life Applications
See how the concepts apply in real-world scenarios to understand their practical implications.
Examples
-
Polyethylene is found in plastic shopping bags and bottles.
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Polypropylene is used in food containers and automotive parts.
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Polystyrene is utilized in foam cups and packaging materials.
Memory Aids
Use mnemonics, acronyms, or visual cues to help remember key information more easily.
๐ต Rhymes Time
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Polyethylene bags are light and bright, making shopping a delight.
๐ Fascinating Stories
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Once, a brave little container made of polypropylene found home in a kitchen, loved for holding meals and staying strong even in the heat.
๐ง Other Memory Gems
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PE, PP, PVC, PS โ 'Plastic Entertainers for Peopleโs Versatile Choices.'
๐ฏ Super Acronyms
PES
- Polyethylene
- Polystyrene
- Polypropylene - The Major Synthetics.
Flash Cards
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Glossary of Terms
Review the Definitions for terms.
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Term: Polyethylene (PE)
Definition:
A synthetic polymer made from ethene, commonly used in plastic bags and bottles.
-
Term: Polypropylene (PP)
Definition:
A synthetic polymer derived from propene, known for its strength and heat resistance.
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Term: Polystyrene (PS)
Definition:
A synthetic polymer produced from styrene, used in various forms including foam and rigid plastics.
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Term: Polyvinyl Chloride (PVC)
Definition:
A versatile synthetic polymer often used in pipes and flexible products.
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Term: Condensation Polymerization
Definition:
A polymerization process that involves the reaction of monomers with the elimination of small molecules, such as water.