Unit 2 PPT notes for BME - Acrylic polymers.pptx

Acrylic polymers are a class of synthetic resins made from derivatives of acrylic acid. These versatile materials are widely used in various industries due to their excellent properties, such as clarity, durability, and weather resistance.

1. 9 ACRYLIC POLYMERS Dr. D. Sudar vizhi , Assistant Professor ( Sl.G ), Department of Biomedical Engineering

2. ACRYLIC POLYMERS Simple acrylates have relatively high toughness and strength. These are obtained through addition polymerization of acrylic acid derivatives.

3. PMMA The most widely used poly acrylate is poly (methyl methacrylate , PMMA). Brittle in comparison with other polymers. It has an excellent light transparency (> 92% transmission) and a high index of refraction (1.49). This transparent material is sometimes referred as organic glass. It has excellent chemical resistivity and is highly biocompatible in the pure form. Therefore, this polymer is used extensively in medico-surgical applications as contact lenses, implantable ocular lenses, bone cement for joint fixation, dentures and maxillofacial prostheses.

4. ACRYLIC POLYMERS Acrylic resins can be cast molded or machined with conventional tools. They can be formed into the desired shape by thermoplastic means such as injection molding or in a chemoplastic way, i.e. curing a mixture of polymer and monomer in a mold at elevated temperatures.

5. ACRYLIC POLYMERS Most medical and dental acrylic resins are available as a two component system: a powder, which consists mainly of small PMMA spheres and beads a liquid, containing the monomer The powder and liquid are mixed in a ratio of approximately 2: 1 w/w and an easily moldable dough is obtained which cures in about 10 min or more quickly after heating in a gypsum mold.

6. ACRYLIC POLYMERS The monomer polymerizes and binds together the preexisting polymer particles. For dental purpose, pigments and fillers can be added to the powder. Surgical bone cements contain barium sulfate or zirconium oxide.

7. ACRYLIC POLYMERS

8. ACRYLIC POLYMERS When a monomer is converted to polymer the conversion may not be complete and the polymeric material may contain some residual monomer. The amount of unpolymerized material strongly depends on the conditions during polymerization. Therefore acrylic bone cements most certainly result in at least some contamination of the biological system with monomeric material. The effects of monomers on cardiovascular system include a transient drop of blood pressure, cardiovascular and pulmonary complications and embolism.

9. ACRYLIC POLYMERS The exothermic nature of polymerization reactions initiates a process of auto-acceleration in self-curing resins by which the temperature increases sharply. The in situ curing of this resin may, result in thermal damage to the surrounding tissues. Considerable vascular damage and osteocyte necrosis has been observed in this situation. Another aspect of the biocompatibility of acrylic resins is due to the fact that they are capable of causing allergic reactions. Some individuals who received acrylic dentures have complaints of sore mouth and a burning sensation accompanied by symptoms such as swollen oral mucosa.