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:. ADHESIVES INTRODUCTION

Introduction
Adhesive advantages
Adhesive disadvantages
Adhesive applications
Definition of adhesive
Definition of polymer
Definition of adhesion
Adhesion theories
Contact angle
Surface energy
Thermoplastic
Elastomer
Thermoset
Glass transition temperature
Covalent chemical bond
Intermolecular forces
Mechanical properties adhesives
Polyaddition
Polycondensation
Polymerization
 
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Polymer - definition and classification of polymers.

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What are polymers?

The polymers are defined as macromolecules composed of one or more chemical units (monomers) that are repeated throughout a chain.

A polymer is like a thread joins many coins punched through the center, in the end we get a string of coins, the coins would be the monomers, and the chain with the coins would be the polymer.

The basic part of a polymer are the monomers, the monomers are the chemical units that are repeated throughout the chain of a polymer, eg polyethylene monomer is ethylene, which is repeated x times along throughout the chain.

Polyethylene = ethylene-ethylene-ethylene-ethylene-ethylene-...

polymer

Depending on the repetition or variety of monomers, polymers are classified as:

Homopolymer - It is called when the polymer formed by the same monomer throughout its chain.

Copolymer - It is called when the polymer formed by at least 2 different monomers along the entire chain.

The formation of the polymer chains are produced by different polyreactions that can occur between monomers. These reactions are classified as:

  • Polymerization
  • Polycondensation
  • Polyaddition

Depending on how they are linked or joined (chemical bonds or intermolecular forces) and on the arrangement of the different chains that forms the polymer, the resulting polymeric materials can be classified as:

Depending on the chemical composition, polymers can be inorganic such as glass, or they can be organic, such as adhesives of epoxy resin. Organic polymers can be also divided into natural polymers such as proteins and synthetic polymers as thermosets materials.

There are different parameters that measure the properties of polymers as the radius of gyration, the density of the polymer, the average distance between the polymer chains, the length of the quasi-static segment within the polymer chains, etc ...

Among the properties that define the properties of polymers, the most important are:

The glass transition temperature of the polymer.

The average molecular weight of the polymer molecular.

The glass transition temperature of polymers determines the temperature at which the polymer mechanical properties of polymers change dramatically, when the glass transition temperature is slightly below room temperature the polymer behaves like an elastic material (elastomer), when the temperature is higher than the glass transition temperature the polymer behaves as a rigid material (thermoset).

The average molecular weight directly determines both the size of the polymer and its chemical and mechanical properties of the polymer (viscosity, wet, creep resistance, abrasion resistance ...), for example polymers with high average molecular weight materials are very viscous.

There are a wide range of materials whose composition is based on polymers, all plastics, paint, coatings, adhesives, composites, etc ... these are examples of polymer-based materials we use in our daily life.

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