Resins
Resins and polymers are also known as film formers or binders. There are natural resins, synthetic resins, natural polymers and synthetic polymers, Resins are those materials which hold the resinous state. Neither all the polymers are resin nor all the resins are polymers.
- Resins are judged by their properties e.g. appearance, saponification value, acid value, colour, odour, hardness, specific gravity, refractive index melting and softening point.
- Resins are vicious, liquid polymers derived from organic or synthetic sources. Their benefit centers on their ability to transition from a liquid into a customizable solid, homogeneous structure.
- In polymer chemistry and materials science, resin is a solid or highly viscous substance of plant or synthetic origin that is typically convertible into polymers.
- Plants secrete resins for their protective benefits in response to injury. The resin protects the plant from insects and pathogens. A clear example of the longevity and durability of resin is the encapsulation of insects in amber.
- Many of these naturally occurring resins have practical uses today and equivalents have been manufactured from petrochemicals.
- Resin usage as a single, homogeneous form is commonly used in the form of moulds as well as protective linings and coatings.
- Polymers themselves are substances comprised of a built-up structure of a large number of similar units bonded together. Classic examples of synthetic polymers include resins and plastics.
Resins & polymers introduction-
Resins and polymers are also known as film formers or binders. There are natural resins, synthetic resins, natural polymers, and synthetic polymers.
Following content has been discussed in this video-
- Polymers & its classification.
- synthesis of polymers.
- process of polymerization
- addition reaction
- step and chain growth polymerization
- Bulk polymerization
- Suspension polymerization
- Solution polymerization and
- Emulsion polymerization.
Classification of Resins
Testing & evaluation (RESINS)
Acid Value
Acid value of a resin is expressed as the number of milligrams of potassium hydroxide required to neutralize the free acidity of 1 g of nonvolatile material under the conditions of the test It is the Indication of reactivity with basic materials –pigments etc it is determined by titrating a solution of sample against standard solution of KOH or NaOH in presence of phenolphthalein indicatior.
The test method discussed in this video- play from start to 13:25 min.
Non-volatile matter
Non volatile mater in a resin solution is the percent mass of dried resin in resin solution. It helps us to know the density of the material or the solid part by weight. For example primer is having high non volatile content than enamel. It is determined with the help of petri disc, weighing balance and desiccator.
The test method discussed in this video- play from 13:25min to 17:25min.
Softening point
Softening point is the temperature at which a hard solid resin start melting or softening. It helps us to know the melting point of the resin. The high melting point resin or polymers are generally preferred over low melting point. It is determined with the help of ring and ball method whose description is given in the video.
The test method discussed in this video- play from 17:25min to 23:00min.
Solubility
Solubility of a resin or polymer is very important as regard to selection of true solvent for the material. Normally like dissolves like i.e. polar solvent dissolve polar resin or polymer and non polar solvent dissolve non polar resin or polymers. It is tested by taking solvents of varying polarity and then one part of resin and 2 part of solvent are taken in a test tube and the clarity of solution is checked. A transparent solution will represent the high solubility of the resin in solvent.
The test method discussed in this video- play from 23:00min to end.