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polymars مساعدة

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  1. [1]
    Che_Hani
    Che_Hani غير متواجد حالياً

    جديد

    تاريخ التسجيل: Apr 2006
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    polymars مساعدة

    السلام عليكم ورحمة الله وبركاته

    اخواني المهندسين انا مهندس جديد في مصنع بوليمرات ولاني لااستطيع تحميل كتب البوليمرات لحجب الموقع في السعودية فارجو المساعدة في قسم البوليمرات اللاصقة التي تستخدم في الغراء بجميع انواعه واشكاله ولكم مني جزيل الشكر والتقدير

  2. [2]
    Peace_Friendship
    Peace_Friendship غير متواجد حالياً
    عضو


    تاريخ التسجيل: Jul 2005
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    brother Che_Hani,

    welcome to forum first,
    what is the english name of what you need?

    i suggest asking more specific question to make the answer easy.. it is difficult to answer general question sometimes.

    Salam Alaikom

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  3. [3]
    Che_Hani
    Che_Hani غير متواجد حالياً
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    Thumbs up شكرا

    شكرا اخ فرندشيب على اهتمامك والموضوع عن Emulsion Polymerization بالنسبة لاانواع الغراء الخاصة بالسجاد والموكيت فاارجو الافادة :confused:

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  4. [4]
    Peace_Friendship
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    تاريخ التسجيل: Jul 2005
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    brother Hani,,

    i have no idea about emulsion polymerization... what i know it is used to produce PVC (poly vinyl chloride)..

    My experience is in LLDPE (gas phase) & HDPE (slurry)...

    regards

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  5. [5]
    chopin
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    تاريخ التسجيل: Jan 2003
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    Thumbs up Emulsion polymerization

    Emulsion polymerization
    Emulsion polymerization is a type of polymerization that usually starts with an emulsion incorporating water, monomer, and surfactant. The most common type of emulsion polymerization is an oil-in-water emulsion, in which droplets of monomer (the oil) are emulsified (with surfactants) in a continuous phase of water. Water-soluble polymers, such as certain polyvinyl alcohols or hydroxyethyl celluloses, can also be used to act as emulsifiers/stabilizers. The name "emulsion polymerization" is a misnomer that arises from a historical misconception. Rather than occurring in emulsion droplets, polymerization takes place in the latex particles that form spontaneously in the first few minutes of the process. These latex particles are typically 100 nm in size, and comprise many individual polymer chains. The particles are stopped from coagulating with each other because each particle is surrounded by the surfactant ('soap'); the charge on the surfactant repels other particles electrostatically. When water-soluble polymers are used as stabilizers instead of soap, the repulsion between particles arises because these water-soluble polymers form a 'hairy layer' around a particle that repels other particles, because pushing particles together would involve compressing these chains.

    Emulsion polymerization is used to manufacture several commercially important polymers. Many of these polymers are used as solid materials and must be isolated from the aqueous dispersion after polymerization. In other cases the dispersion itself is the end product. A dispersion resulting from emulsion polymerization is often called a latex (especially if derived from a synthetic rubber) or an emulsion (even though "emulsion" strictly speaking refers to a dispersion of a liquid in water). These emulsions find applications in adhesives, paints, paper coating and textile coatings. They are finding increasing acceptance and are preferred over solvent-based products in these applications as a result of their eco-friendly characteristics due to the absence of VOCs (Volatile Organic Compounds) in them.

    Advantages of emulsion polymerization include[1]:

    High molecular weight polymers can be made at fast polymerization rates. By contrast, in bulk and solution free radical polymerization, there is a tradeoff between molecular weight and polymerization rate.
    The continuous water phase is an excellent conductor of heat and allows the heat to be removed from the system, allowing many reaction methods to increase their rate.
    Since polymer molecules are contained within the particles, viscosity remains close to that of water and is not dependent on molecular weight.
    The final product can be used as is and does not generally need to be altered or processed.
    Disadvantages of emulsion polymerization include:

    Surfactants and other polymerization adjuvants remain in the polymer or are difficult to remove
    For dry (isolated) polymers, water removal is an energy-intensive process
    Emulsion polymerizations are usually designed to operate at high conversion of monomer to polymer. This can result in significant chain transfer to polymer.

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    Don’t Stop

  6. [6]
    chopin
    chopin غير متواجد حالياً
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    Red face Process

    Process
    Emulsion polymerizations have been used in batch, semi-batch, and continuous processes. The choice depends on the properties desired in the final polymer or dispersion and on the economics of the product. Modern process control schemes have enabled the development of complex reaction processes, with ingedients such as initiator, monomer, and surfactant added at the beginning, during, or at the end of the reaction.

    Early SBR recipes are examples of true batch processes: all ingredients added at the same time to the reactor. Semi-batch recipes usually include a programmed feed of monomer to the reactor. This enables a starve-fed reaction to insure a good distribution of monomers into the polymer backbone chain. Continuous processes have been used to manufacture various grades of synthetic rubber.

    Some polymerizations are stopped before all the monomer has been reacted. This minimizes chain transfer to polymer. In such cases the monomer must be removed or stripped from the dispersion.

    Colloidal stability is a factor in design of an emulsion polymerization process. For dry or isolated products, the polymer dispersion must be isolated, or converted into solid form. This can be accomplished by simple heating of the dispersion until all water evaporates. More commonly, the dispersion is destabilized (sometimes called "broken") by addition of a multivalent cation. Alternatively, acidification will destabilize a dispersion with a carboxylic acid surfactant. These techniques may be employed in cominbation with application of shear to increase the rate of destabilization.

    After isolation of the polymer, it is usually washed, dried, and packaged.

    By contrast, products sold as a dispersion are designed with a high degree of colloidal stability.

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  7. [7]
    Che_Hani
    Che_Hani غير متواجد حالياً
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    Talking شكر خاص

    مشكور استاذ chopin على معلوماتك الي ساعدتني كثير خلال عملي ولك مني كل الشكر والتقدير

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  8. [8]
    رافد الدليمى
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    polymers:structure and properties
    محتاج هذا الكتاب

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