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थर्मोसेटिंग रेजिन का क्या विशेषता है?
एपॉक्सी रेजिन का प्रमुख उपयोग में कौन-कौन शामिल है?
पालीहाइड्रोक्सीएलकानोएट (PHA) कहाँ से प्राप्त होता है?
स्टार्च मिश्रण मुख्यत: किससे मिलकर बना होता है?
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लिग्निन-फेनोल समापात कहाँ से प्राप्त होता हज़?
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पॉलिमर गुणों का पारदर्शीकरण किसके माध्यम से किया जाता है?
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पॉलिमर कसरती सतह का मापन किस गुण से किया जाता है?
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क्या Tensile Strength मापता है?
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प्लास्टिक के संकुचन की प्रक्रिया में क्या होता है?
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पॉलिमर प्रॉपर्टी टेस्टिंग में Density के प्रमुख उपयोग क्या है?
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प्लास्टिक के लिए 'तापनीय घटना तापमान' क्या मापती है?
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किस परीक्षण से इंजीनियरों को प्रसंस्करण या सेवा के दौरान आयामिक परिवर्तनों का पूर्वानुमान करने में मदद मिलती है?
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किस परीक्षण से पॉलिमर सामग्री के चमकने, सुनने क्षमता, और काँच के संक्रमण तापमान के बारे में प्रकाश मिलता है?
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'UV Prakatikaran' किस उपकरण के माध्यम से होता है?
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'Moist Heat Ageing' क्या है?
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Study Notes
Plastic Materials: A Diverse Family of Polymers
Plastic materials have become ubiquitous across our modern world due to their versatility and durability. Let's delve into this diverse family of polymers by exploring some common types of plastic and their unique properties.
Thermoplastics
Thermoplastic materials represent a large portion of all plastic usage because they can be softened by heating them to above their melting point or below their glass transition temperature, allowing them to flow like liquids. This property allows thermoplastics to be easily molded, extruded, or shaped using various manufacturing processes. Some popular examples include:
- Polyethylene (PE): Found in products such as milk jugs, grocery bags, and toys, polyethylene comes in low density PE (LDPE) and high density PE (HDPE).
- Polypropylene (PP): Known for its resistance to chemicals and heat, PP is commonly used in food containers, automotive parts, and carpet fibers.
- Polyvinyl chloride (PVC): Often used in pipes, electrical insulation, and credit cards, PVC can be made flexible through the addition of plasticizers or rigid via stabilizing compounds.
- Acrylonitrile butadiene styrene (ABS): This blend offers impact strength, toughness, and rigidity often seen in applications like auto body panels, appliance housings, and consumer electronics casing.
- Polystyrene (PS): Characterized by its clarity and hardness, PS is widely used in packaging materials, disposable cutlery, and CD cases.
Thermosetting Resins
Unlike thermoplastics, when heated, thermosetting resins do not melt; instead, they cure or solidify irreversibly after reacting with catalysts, forming a three-dimensional network structure. Due to this crosslinked nature, thermosets cannot be remolded once set. Commonly encountered thermosets include:
- Epoxy resin: Used in composites, coatings, adhesives, and electronic encapsulants, epoxies offer excellent mechanical properties and chemical resistance.
- Melamine formaldehyde (MF): Employed primarily in laminates, MF provides fire retardancy and decorative surface finishes.
- Phenol formaldehyde (PF): Incorporated in adhesives, laminated boards, and electrical components, PF imparts high thermal stability and dimensional stability.
- Unsaturated polyester (UP) resin: Applied in fiberglass reinforced plastics (FRPs), UP resins exhibit good chemical resistance and toughness.
Biodegradable & Bio-based Plastics
In recent years, there has been increased interest in creating more environmentally friendly alternatives to traditional fossil fuel-derived plastics. These bio-based and biodegradable plastics help reduce reliance on non-renewable resources while mitigating waste accumulation. Examples include:
- Polyhydroxyalkanoate (PHA): Produced from organic wastes or renewable feedstocks, PHAs display impressive biocompatibility and biodegradability.
- Starch blends: Composed mainly of cornstarch mixed with other polymers, starch blends show promise in replacing conventional petroleum-based polymers.
- Lignin-phenolic composite: Derived from agricultural residue, these plastics present themselves as potential substitutes for phenolic resins.
While plastics carry numerous benefits, their environmental impacts must also be considered. By understanding the different categories and characteristics of plastics, we can make informed decisions towards reducing pollution and conserving natural resources.
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Description
Explore the world of plastic materials by learning about common types of plastics like thermoplastics, thermosetting resins, and biodegradable options. Understand their unique properties and applications in various industries while considering the environmental impact of plastic usage.
