Polymeric Materials PDF

Polymeric Materials Dr/Ayat Nada  Course Contents Introduction to Material and Biomaterial. Non-metallic Materials. Ceramics Materials. Polymeric Materials. Piezoelectric Materials. Composites Materials. Mechanical Tests (Destructive and Non-Destructive). Characterization of Prope...

Polymeric Materials Dr/Ayat Nada  Course Contents Introduction to Material and Biomaterial. Non-metallic Materials. Ceramics Materials. Polymeric Materials. Piezoelectric Materials. Composites Materials. Mechanical Tests (Destructive and Non-Destructive). Characterization of Properties of Tissues. Polymers ✓ Polymers have assumed an important role in medical applications. Their unique properties are: 1- Flexibility 2- Resistance to biochemical attack 3- Good biocompatibility 4- Light weight 5- Available in a wide variety of compositions with adequate physical and mechanical properties 6- Can be easily manufactured into products with the desired shape Classification of Polymers ✓ There are 3 principal classes of polymers – thermoplastics, thermosets, and elastomers. ✓ Plastics can be a thermoplastic or thermoset. ✓ Elastomers, commonly known as rubber, differ from plastics in the fact they have a great capacity for large elastic deformation under an applied stress. In other words, they can be stretched over 100% of their Nylon PTFE original length with no PMMA PEEK permanent deformation.  Classification of Polymers Thermoplastics ✓ Thermoplastics , also known as plastomers, are plastics that can be moulded in a specific temperature range (thermoplastic). This process is reversible, i.e. it can be repeated as often as required by cooling and reheating to the molten state, unless what is known as thermal decomposition of the material begins due to overheating. This is what distinguishes thermoplastics from thermosetting plastics and elastomers. ✓ Another def: Thermoplastics are molten when heated and harden upon cooling. When frozen, however, a thermoplastic becomes glass-like and subject to fracture. You can heat and cool thermoplastics several times. ✓ Examples for Thermoplastics are Polythene, Polypropylene, Polystyrene, Polyvinyl chloride (PVC), Nylon and Teflon  Classification of Polymers Thermosetting plastics ✓ Thermosetting plastics are plastics that cannot be moulded any more after they have cured. Thermosetting plastics are hard, glassy polymer materials. ✓ Thermosets start out as small molecules called monomers and oligomers (several monomers long) and then due to chemical reactions form crosslinks between the growing chains. These crosslinks then ✓ Thermoset Materials examples: form a big network of tightly linked polymer Polyester. chains. Since the chains are formed via a chemical Silicone. reaction that links most of the long chains together, Melamine. when you heat a thermoset, the part retains is shape. Polyurethane. Epoxy. Classification of Polymers Elastomers ✓ Elastomers are dimensionally stable plastics that are, however, elastically mouldable. ✓ The plastics can change their shape elastically under tensile stress and pressure, but return to their original, unformed state afterwards. ✓ Elastomers are used as materials for tyres, rubber bands, sealing rings etc. The most well-known elastomers are vulcanised natural and silicone rubber. Application of Polymers in Biomedical Field 1- Tissue engineering 2- Implantation of medical devices and artificial organs due to its inert nature 3- Prostheses Task || Explain one application only 4- Dentistry 5- Bone repair 6- Drug delivery and targeting into sites of inflammation or tumors 7- Plastic tubing for intra-venous infusion 8- Bags for the transport of blood plasma 9- Catheter Polymeric Materials Epoxy resins ✓ Epoxy resins are classified as thermoset polymers. ✓ Epoxy resin is typically a two-part adhesive that can be used for repairs. It is often used to fix broken objects or to create a sealant. The adhesive will harden and form a strong bond once mixed together. ✓ This makes epoxy resin ideal for repairing items such as vases, figurines, ornaments, and more. ✓ This material is not compatible with body and may be toxic Polymeric BioMaterials PTFE ✓ (PTFE) Polytetrafluoroethylene is a fluorocarbon–based polymer. Commercially, the material is best known as Teflon. Teflon is a thermoplastic which is capable of repeatedly softening on heating and hardening on cooling ✓ PTFE has many medical uses, including: 1- Arterial grafts (artificial vascular graft) Can be woven into a porous fabric like mesh. When implanted in the body, this mesh allows tissue to grow into its pores, making it ideal for vascular grafts 2- Catheters, Tubes 3- Sutures 4- Uses in reconstructive and cosmetic facial surgery Polymeric Materials Poly methyl methacrylate, PMMA ✓ PMMA is classified as a “thermoplastic” (as opposed to “thermoset”) ✓ It is a hard brittle polymer that appears to be unsuitable for most clinical applications, but it does have several important characteristics. ✓ It can be prepared under ambient conditions so that it can be manipulated in the operating theater or dental clinic, explaining its use in dentures and bone cement. Polymeric Materials PEEK ,Poly ether ether ketone ✓ PEEK was developed in the late 1990s as a biomaterial that has superior physical, mechanical, and biological properties for biomedical applications. ✓ It is a thermoplastic, monochromatic, semi-crystalline polymer. ✓ PEEK is so biocompatible that it can be used in the spine, close to the heart, in the oral cavity and around damaged bone. ✓ PEEK also has a major role in most areas of restorative dentistry in the fabrication of implants, abutments, fixation screws, removable dentures, and fixed prostheses. This material is biocompatible in vivo and in vitro and radiolucent, with good mechanical, chemical, thermal, and electrical properties (e.g., resistance to high temperature, hydrolysis, and corrosion), and a good aesthetic appearance. Besides, it has neither toxic effects nor clinical issues. Porous Structure Porosity: ✓ Porosity refers to the amount of space within a material. Porosity can impact the ability of a biomaterial to integrate with the surrounding tissue and affect its mechanical properties. What is the meaning of porous structure? ✓ The porous structure at the cell level mainly refers to pits in the cell wall, including the cell wall of the vessel cell. Mass transfer between different cells is mainly through pits. There are both pit pairs and simple pits. Porous Material ✓ In materials science, a porous medium or a porous material is a material containing pores (voids). The skeletal portion of the material is often called the "matrix" or "frame". The pores are typically filled with a fluid (liquid or gas). ✓ If an object is porous, it has a great ability to hold fluid within itself. ✓ Sponges, wood, rubber, and some rocks are porous materials. ✓ In contrast, marble, glass, and some plastics are not porous and contain very few open pockets of air (or pores). ✓ Porous biomaterials can promote cell adhesion and growth and allow the diffusion of nutrients and waste products. Pore Size