bio degradable polymer

8/7/2019 Bio Degradable Polymer

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Presented by

M.S.AASHIK MOHAMMED

I YEAR B.E,


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CONTENTSy DEFINITION

y CHARACTERISTICS

y TYPES OF BIODEGRADABLE POLYMER

y EXPLANATION OF POLYMERS ALONG WITH

THEIR APPLICATION

y POLYMER EROSION MECHANISM

yADVANTAGES &DISADVANTAGES

y REFERENCES


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DEFINITION:

The natural ability of chemical substance tobe broken down into less complex compoundshaving fewer carbon atoms by body fluids or

enzymes or microorganism. OR

It is defined as the breakdown of polymerinto its components monomers or oligomers uponcoming in contact with body fluids, enzymes andmicrobial flora.


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IDEAL CHARACTERISTICS OF BIODEGRADABLE

OF BIODEGRADABLE POLYMERS

y non-toxic,

y inert in nature

y

Should have relative stability.y capable of maintaining good mechanical integrity

until degraded

y capable of controlled rates of degradation.

y It is easily processable in the final product form

with an acceptable shelf life and easily sterilizedy It is metabolized in the body after fulfilling its

purpose.


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Types of biodegradable

polymers1. Natural biodegradable polymer

2. Synthetic biodegradable polymer


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NATURAL POLYMERS

y Natural polymers remains the primary choice of formulator because

- They are natural products of living organism- Readily available

- Relatively inexpensive

- Capable of chemical modification

y Moreover, it satisfies most of the ideal requirements of polymers.

y

But the only and major difficulty is the batch- to-batch reproducibility and purity of the sample.

Examples:

y Starch

y Cellulose

y Protein

y Natural rubber


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NATURAL POLYMERS

STARCH:

y Starch or amylum is a carbohydrate consisting of a large number of glucose units joined together by glycosidic bonds.

This polysaccharide is produced by all green plants as an energy store. It is the most important carbohydrate in the human diet

and is contained in such staple foods as potatoes,wheat, maize (corn), rice, and cassava.

y Pure starch is a white, tasteless and odorless powder that is insoluble in cold water or alcohol. It consists of two types of

molecules: the linear and helical amylose and the branchedamylopectin. Depending on the plant, starch generally contains 20

to 25% amylose and 75 to 80% amylopectin.Glycogen, the glucose store of animals, is a more branched version of

amylopectin.

y Starch is processed to produce many of the sugars in processed foods. When dissolved in warm water, it can be used as athickening, stiffening or gluing agent, giving wheatpaste.

y powder starch


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NATURAL POLYMERS

Cellulose:

y cellulose is an organic compound with the formula(C6H10O5n, a polysaccharide consisting of a linear chain of several hundred

to over ten thousand (14) linked D-glucose units.

y Cellulose is the structural component of the primary cell wall of green plants, many forms ofalgae and the oomycetes. Some

species of bacteria secrete it to form biofilms. Cellulose is the most common organic compound on Earth. About 33% of all

plant matter is cellulose (the cellulose content of cotton is 90% and that of wood is 4050%).

y For industrial use, cellulose is mainly obtained from wood pulp and cotton. It is mainly used to produce paperboardand paper;

to a smaller extent it is converted into a wide variety of derivative products such as cellophane and rayon. Converting cellulose

from energy crops into biofuels such as cellulosic ethanol is under investigation as an alternative fuel source.y Some animals, particularly ruminants and termites, can digest cellulose with the help ofsymbiotic micro-organisms that live in

their guts. Humans can digest cellulose to some extent, however it is often referred to as 'dietary fiber or 'roughage' (e.g. outer

shell ofmaize) and acts as a hydrophilic bulking agent for feces.

y Cellulose


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NATURAL POLYMERS

y Natural rubber, also called India rubber orcaoutchouc, is an elastomer(an elastichydrocarbon polymer)

that was originally derived from latex, a milky colloidproduced by some plants. The plants would be

tapped, that is, an incision made into the bark of the tree and the latex sap collected and refined into a

usable rubber. The purified form of natural rubber is the chemical polyisoprene, which can also be produced

synthetically. Natural rubber is used extensively in many applications and products, as is synthetic rubber.


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NATURAL POLYMERS

Proteins:

y Proteins are essential in everybody's diet. They are known as Building blocks of life. Proteins are complex

substances found in many foods and are made up of thousands of small units called amino acids. Proteins

from different foods in our diet contain different amino acids. There are 20 amino acids, divided into

essential and non-essential amino acids. Essential amino acids must appear in our diet because they cannot

be made by the body. The 9 essential amino acids we must eat in our diet include: Histidine, Isoleucine,

Leucine, Lysine, Methionine, Phenylalanine, Threonine, Tryptophan and Valine.


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POLYMERS BASED ON APPLICATION

Plastics:Plastics are typically polymers of high molecular mass, and may contain other substances to improve performance

and/or reduce costs. Monomers of plastic are either natural or synthetic organic compounds.

Plastic household items


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Fiber:y Fiber, also spelled fibre, is a class of materials that are continuous filaments or are in discrete elongated pieces,

similar to lengths of thread.

y They are very important in the biology of both plants and animals, for holding tissues together.

y Human uses for fibers are diverse. They can be spun into filaments, string or rope, used as a component of composite

materials, or matted into sheets to make products such as paper or felt. Fibers are often used in the manufacture of other

materials. The strongest engineering materials are generally made as fibers, for example carbon fiber and Ultra-high-

molecular-weight polyethylene.

ySynthetic fibers can often be produced very cheaply and in large amounts compared to natural fibers, but for clothing naturalfibers can give some benefits, such as comfort, over their man-made counterparts.


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Liquid Resins:

Water-based liquid resins are a key ingredient in specialty coatings, inks and paints.

These resins can be formulated into a durable coating that provides the characteristics and

performance attributes of the finished surface. Some benefits of coatings produced with liquid

resins include improved adhesion, chemical resistance and corrosion resistance.

Elastomer:

An elastomer is a polymer with the property of viscoelasticity (colloquially "elasticity"), generally having notably

low Young's modulus and high yield strain compared with other materials. The term, which is derived from elastic polymer, is

often used interchangeably with the termrubber, although the latter is preferred when referring to vulcanisates. Each of

the monomers which link to form the polymer is usually made of carbon, hydrogen, oxygen and/or silicon. Elastomers

are amorphouspolymers existing above their glass transition temperature, so that considerable segmental motion is possible.

At ambient temperatures rubbers are thus relatively soft (E~3MPa) and deformable. Their primary uses are

for seals, adhesives and molded flexible parts.


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SYNTHETIC POLYMERS

y Synthetic Polymers are defined as manmade polymers or plastics. First human made plastic was invented by Alexander Parks

in 1855. It was then called Parke sine (later on Celluloid).

y Polymers are made of small repeating structural units called monomers. Polyethylene is the simplest polymer, which consists

of ethene (ethylene) as monomer units and the corresponding linear polymer is called high density polyethylene (HDPE).

y Many polymeric materials having chain-like structures similar to polyethylene are known. Synthetic polymers are oftenreferred to as "plastics", well-known are polyethylene and nylon.

y Polymers formed by a straightforward linking together of monomer units, with no loss or gain of material, are called addition

polymers or chain-growth polymers. All of these are synthetic polymers.

Some General Synthetic Polymers :

y Polyethylene low density (LDPE)

y Polyethylene high density (HDPE)

y Poly(vinyl chloride) (PVC)

y Polystyrene (PS)


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SYNTHETIC POLYMERS

Polyethylene low density (LDPE):

Low-density polyethylene (LDPE) is a thermoplastic made from petroleum. It was the first grade of

polyethylene, produced in 1933 by Imperial Chemical Industries(ICI) using a high pressure process via free radical

polymerization . Its manufacture employs the same method today. LDPE is commonly recycledand has the number "4" as

its recycling symbol. Despite competition from more modern polymers, LDPE continues to be an important plastic grade. In

2009 the worldwide LDPE market reached a volume of 22.2 billion US-Dollars (15.9 billion Euro).

Polyethylene high density (HDPE):

High-density polyethylene (HDPE) or polyethylene high-density (PEHD) is a polyethylene thermoplastic made

from petroleum. It takes 1.75 kilograms of petroleum (in terms of energy and raw materials) to make one kilogram of HDPE.

HDPE is commonly recycled, and has the number "2" as its recycling symbol. In 2007, the global HDPE market reached avolume of more than 30 million tons.

Poly(vinyl chloride) (PVC):

y Polyvinyl chloride, (IUPAC Poly(chloroethanediyl)) commonly abbreviated PVC, is athermoplastic polymer. It

is a vinyl polymer constructed of repeating vinyl groups (ethenyls) having one of their hydrogens replaced with a chloride

group.

y Polyvinyl chloride is the third most widely produced plastic, after polyethylene and polypropylene .PVC is widely used

in construction because it is cheap, durable, and easy to assemble. PVC production is expected to exceed 40 million tons by

2016.

y It can be made softer and more flexible by the addition of plasticizers, the most widely used being phthalates. In this form, it is

used in clothing and upholstery, and to make flexible hoses and tubing, flooring, to roofing membranes, and electrical cable

insulation. It is also commonly used in figurines and in inflatable products such as waterbeds,pool toys, and inflatable

structures.


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SYNTHETIC POLYMERS

Polystyrene (PS)

y Polystyrene is one of the most widely used kinds of plastic.

y Polystyrene is a thermoplastic substance, which is in solid (glassy) state at room temperature, but flows if heated

above its glass transition temperature (for molding or extrusion), and becomes solid again when cooled. Pure solid

polystyrene is a colorless, hard plastic with limited flexibility. It can be cast into molds with fine detail. Polystyrene

can be transparent or can be made to take on various colors.

A polystyrene yogurt container


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ses syn e egr e

lymer

Currentlygreat advancements eingmade in lymer

technology.

yBiomedical applications

yEcological applications


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1. Biomedical applicationsy for the reconstruction of the peripheral nerves

y to culture retinal pigment epithelium alterations made to the retinalpigment epitheliums function and structures can cause variousocular ailments or diseases.

y biocompatible with bone proteins bone morphogenetic proteins(BMP) help in repairing bone defects and fractures

y as drug delivery systems. they are perfect for administering in-bodydrugs. Synthetic biodegradable polymers are used because theybecause they can release specific amounts or dosage of drugs intothe body at specified intervals.

yused in biodegradable sutures


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2.Ecological applications

y processing of plastic wastes is one of the major

applications. industries are using synthetic

biodegradable polymers to construct biodegradablepackaging, which are environment friendly


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POLYMER EROSION MECHANISM

y The term 'biodegradation' is limited to the description of chemical processes (chemical changes that alter either the molecular

weight or solubility of the polymer)

y Bioerosion' may be restricted to refer to physical processes that result in weight loss of a polymer device.

y The erosion of polymers basically takes place by two methods:-

1. Chemical erosion

2. Physical erosion


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CHEMICAL EROSION :

y There are three general chemical mechanisms that cause bioerosion

1. The degradation of water-soluble macromolecules that are crosslinked to form three-dimensional network.

As long as crosslinks remain intact, the network is intact and is insoluble.

Degradation in these systems can occur either at crosslinks to form soluble backbone polymeric chains (type IA) or at the mainchain to form water-soluble fragments (type IB). Generally, degradation of type IA polymers provide high molecular weight,water-soluble fragments, while degradation of type IB polymers provide low molecular weight, water soluble oligomers andmonomers

2. The dissolution of water-insoluble macromolecules with side groups that are converted to water-soluble polymers as a result ofionization, protonationor hydrolysis of the groups. With this mechanism the polymer does not degrade and its molecular weightremains essentially unchanged. E.g. cellulose acetate

3. The degradation of insoluble polymers with labile bonds. Hydrolysis of labile bonds causes scission of the polymer backbone,thereby forming low molecular weight, water-soluble molecules. E.g. poly (lactic acid), poly (glycolic acid)

The three mechanisms described are not mutually exclusive; combinations of them can occur.


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PHYSICAL EROSION:

y

The physical erosion mechanisms can be characterized as heterogeneous or homogeneous.

y In heterogeneous erosion, also called as surface erosion, the polymer erodes only at the surface, and maintains its physical integrity as

it degrades. As a result drug kinetics are predictable, and zero order release kinetics can be obtained by applying the appropriate

geometry. Crystalline regions exclude water. Therefore highly crystalline polymers tend to undergo heterogeneous erosion. E.g

polyanhydrides

y Homogeneous erosion, means the hydrolysis occurs at even rate throughout the polymeric matrix. Generally these polymers tend to be

more hydrophilic than those exhibiting surface erosion. As a result, water penetrates the polymeric matrix and increases the rate of

diffusion. In homogeneous erosion, there is loss of integrity of the polymer matrix. E.g poly lactic acid

BIO DEGRADABLE POLYMERS 23


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I DEGRADABLE LYMERS

y Useful for delivery of synthetic drugs as well as

proteins and biotechnological products .

yNo need subsequent retrival of the delivery

y Better drug utilization and improved patients

compliance.

y Targeted specific part of body hence reduce side

effect.y rovide controlled rate of drug release


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BI DEGRADABLE LYMERS

y Difficult to formulate a biodegradable system

y Carrier must be human friendly.

y Some polymers do not have detail information aboutits biodegradability, kinetic, stability profile


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bio degradable polymer

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