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Preparation and Characterization of Reinforced Egg Shell Polymer Composites
1Senthil J, 2Madan Raj.P
1Asso. Professor, Mechanical Engineering, Aarupadai Veedu Institute of Technology, Vinayaka Missions University
2PG Scholar, Manufacturing Engineering, Aarupadai Veedu Institute of Technology, Vinayaka Missions University Email: 1[email protected], 2[email protected]
Abstract: - It presented by this article of, the mechanical properties and water absorption of egg shell polymer composites as a function of egg shell powder to be tested.
Polymer composite was fabricated by mixing Calcium Carbonate with (15, 20) wt. %of egg shell powder to obtain desirable properties. The parameters such as tensile strength, tensile modulus, elongation at break and flexural test were carried out on the prepared samples. Animal fiber of egg shell composites are considered to have potential use as reinforcing agents in polymer composite materials because of their principle benefits such as good strength and stiffness, low cost, and be an environmental friendly, degradable, and renewable material. It was found that the addition of egg shell powder to the polymer leads to decrease the tensile strength, modulus of elasticity, hardness on other hand it increases the % elongation at break and flexural strength . Water absorption of the composites behaviors as function of days has also been investigated, and it increases by increasing exposure time for the same filler content, while the absorbed amount of water increases, by increasing the wt.% of egg shell constant exposure time.
I. INTRODUCTION
1.1 INTRODUCTION TO COMPOSITE
MATERIALS
Generally Composite materials can be defined that are formed by the combination more materials to achieve properties that are superior to those of their constituents.
Polymer composites consist of a polyester resin as the matrix, with fibers as the reinforcement medium.
Considerable interest has been generated in the manufacture of thermoplastic composites due to their unique properties, including their good mechanical properties, their thermal stability, and a reduced product cost. Due to the combination of more than one material, the properties of composites are influenced by many factors such as filler characteristics, filler content, and interfacial adhesion. This can cause the behavior of filled polymers to be more complex than their unfilled counterpart.
This study was based on the modification of egg shell powder, an inorganic material, in the calcium carbonate egg shell powder composites. Inorganic materials
usually require chemical modifications to increase filler/polymer interactions. Polyethylene is a hydropholic polymer, while egg shell powder is hydrophilic filler. The chemical modification acts as a ''bridge'' between the inorganic filler and the organic polymer matrix. The ''bridge'' must bond to the filler and in turn must strongly interact with the polymer. In this report tested on the mechanical properties of calcium carbonate with egg shell powder composite.
1.2 DEFINITION OF EGG SHELL COMPOSITE MATERIALS
Egg shell-reinforced composite materials consist of high strength and Modulus embedded in or bonded to a matrix with distinct interfaces (boundaries) between them. In this form, egg shell powder, calcium carbonate and matrix retain their physical and chemical identities;
they will produce a combination of properties that cannot be achieved with either of the constituents acting alone. In general, egg shell with calcium carbonate polymer are the load-carrying members, while the surrounding matrix keeps them in the desired location and orientation, acts as a load transfer medium between them, and protects them from environmental damages due to elevated temperatures and humidity, for example.
Thus, even though the fibers provide reinforcement for the matrix, the latter also serves a number of useful functions in a egg shell reinforced polymer composite material.
1.3 GENERAL CHARACTERISTICS
Many fiber-reinforced polymers offer a combination of strength and modulus that are either comparable to or better than many traditional metallic materials. Because of their low density, the strength–weight ratios and modulus–weight ratios of these composite materials are superior to those of metallic materials. In addition, fatigue strength as well as fatigue damage tolerance of many composite laminates are excellent. For these reasons, fiber reinforced polymers have emerged as a major class of structural materials and are either used or being considered for use as substitution for metals in
many weight-critical components in aerospace, automotive, and other industries.
Traditional structural metals, such as steel and aluminum alloys, are considered isotropic, since they exhibit equal or nearly equal properties irrespective of the direction of measurement. In general, the properties of a fiber-reinforced composite depend strongly on the direction of measurement, and therefore, they are not isotropic materials. For example, the tensile strength and modulus of a unidirectional oriented fiber-reinforced polymer are maximum when these properties are measured in the longitudinal direction of fibers. At any other angle of measurement, these properties are lower.
The minimum value is observed when they are measured in the transverse direction of fibers, at 900 to the longitudinal direction. Similar angular dependence is observed for other mechanical and thermal properties, such as impact strength, coefficient of thermal expansion (CTE), and thermal conductivity. Bi- or multidirectional reinforcement yields a more balanced set of properties. Although these properties are lower than the longitudinal properties of a unidirectional composite, they still represent a considerable advantage over common structural metals on a unit weight basis.
1.4 MATERIALS
Major constituents in a fiber-reinforced composite material are the reinforcing fibers and a matrix, which acts as a binder for the fibers. The fibers to improve their wetting with the matrix as well as to promote bonding across the fiber–matrix interface. Both in turn promote a better load transfer between the fibers and the matrix. Fillers are used with some polymeric matrices primarily to reduce cost and improve their dimensional stability. Manufacturing of a composite structure starts with the incorporation of a large number of fibers into a thin layer of matrix to form a lamina (ply). The thickness of a lamina is usually in the range of 0.1–1 mm (0.004–0.04 in.). If continuous (long) fibers are used in making the lamina, they may be arranged either in a unidirectional orientation, bidirectional orientation, or in a multidirectional orientation is shown in Figure.1.
The bi or multidirectional orientation of fibers is obtained by weaving or other processes used in the textile industry. For a lamina containing unidirectional fibers, the composite material has the highest strength and modulus in the longitudinal direction of the fibers.
However, in the transverse direction, its strength and modulus are very low.
For a lamina containing bidirectional fibers, the strength and modulus can be varied using different amounts of fibers in the longitudinal and transverse directions. For a balanced lamina, these properties are the same in both directions. A lamina can also be constructed using discontinuous (short) fibers in a matrix. The discontinuous fibers can be arranged either in unidirectional orientation or in random orientation.
Discontinuous fiber-reinforced composites have lower strength and modulus than continuous fiber composites.
However, with random orientation of fibers it is possible to obtain equal mechanical and physical properties in all directions in the plane of the lamina. The thickness required to support a given load or to maintain a given deflection in a fiber-reinforced composite structure is obtained by stacking several laminas in a specified sequence and then consolidating them to form a laminate
Fig. 1.1 Basic building blocks in fiber- reinforced composites
1.5 BASIC COMPOSITE THEORY
In its most basic form a composite material is one, which is composed of at least two elements working together to produce material properties that are different to the properties of those elements on their own. In practice, most composites consist of a bulk material (the
‘matrix’), and a reinforcement of some kind, added primarily to increase the strength and stiffness of the matrix. This reinforcement is usually in fiber form.
Today, the most common man-made composites can be divided into three main groups:
1.5.1 POLYMER MATRIX COMPOSITES (PMC) These are the most common and will be discussed here.
Also known as FRP - Fiber Reinforced Polymers (or Plastics) – these materials use a polymer-based resin as the matrix, and a variety of fibers such as glass, carbon and aramid as the reinforcement. Resin systems such as epoxies and polyesters have limited use for the manufacture of structures on their own, since their mechanical properties are not very high when compared to, more metals. However, they have desirable properties, most notably their ability to be easily formed into complex shapes .Materials such as glass, aramid and boron have extremely high tensile and compressive strength but in ‘solid form’ these properties are not readily apparent. This is due to the fact that when stressed, random surface flaws will cause each material to crack and fail well below its theoretical ‘breaking point’. To overcome this problem, the material is produced in fiber form, so that, although the same number of random flaws will occur, they will be restricted to a small number of fibers with the remainder exhibiting the material’s theoretical strength. Therefore
a bundle of fibers will reflect more accurately the optimum performance of the material. However, fibers alone can only exhibit tensile properties along the fiber’s length, in the same way as fibers in a rope.
Materials used in a polymeric matrix are:
1) Thermo set polymer (resins).
2) Epoxies:
Principally used in aerospace and aircraft application.
3) Polyester, vinyl esters:
Commonly used in automobile, marine, chemical and electrical applications.
4) Phonelics:
Used in bulk moulding compounds, polyamides, polyberzimidozoles (PBI), polyphenyl-quioxialine (PPQ) for high temperature, aerospace applications.
5) Urea formaldehyde:
Used in automobile and aerospace application.
6) Melamine formaldehyde:
Used in aircraft applications
Different types of Stress vs Strain Graphs
Fig-1.2 Relationship b/w stress vs strain (a)
Fig- 1.3 Relationship b/w stress vs strain (b)
Fig-1.4 Relationship b/w stress vs strain with fiber &
resin(c)
1.5.2 THERMOSET AND THERMOPLASTIC
POLYMERS
Polymers are divided into broad categories, Thermoplastic and thermo sets. In a thermoplastic polymer, individual molecules are linear in structure with no chemical linking between them. They are held in place by weak secondary bonds such as Vander walls bonds and hydrogen bonds, with the application of neat and pressure, these inter molecular bonds in a solid thermoplastic polymer can be temporarily broken and the molecules can be moved relative to each other to flow into new position, restoring the secondary bonds between them and resulting in a new solid shape. Thus the thermoplastic polymer can be heat softened, melted and reshaped as many times as desired.
In a thermoset polymer, on the other hand, the molecules are chemical joined together by cross links, forming a rigid, and three dimensional network structures. Once these cross links are formed during the polymerization reaction the thermo set polymer cannot be melted and reshaped by the application heat and pressure. However if the number of cross links is low it may still be possible to soften them at elevated temperature.
1.5.3 METAL MATRIX COMPOSITES (MMC) Increasingly found in the automotive industry, these materials use a metal such as aluminum as the matrix, and reinforce it with fibers, or particles, such as silicon carbide. Ceramic Matrix Composites (CMC’s) - Used in very high temperature environments, these materials use a ceramic as the matrix and reinforce it with short fibers, or whiskers such as those made from silicon carbide and boron nitride. Metal matrix has advantage over polymeric matrix in application requiring a long-term resistance to serve environments, such as high temperature. The yield strength and modulus of most metal are higher than those for polymer, which is an important consideration for application requiring high transverse strength and modulus as well as compressive strength for the composite. Another advantage of using metals is that they can be plastically deformed and strengthened by a variety of thermal and mechanical treatments. However, metals have a number of advantages namely they have high specific gravity, high melting points and a tendency towards corrosion at the fiber/matrix interface. The two commonly used metal matrixes are based on aluminum and titanium. Both of these metals have comparatively low specific gravities and are available in a variety of alloy form.
1.5.4 CERAMIC MATRIX COMPOSITES (CMC) The most common ceramic fibers are silicon carbide and aluminum oxide. Silicon carbide retains its strength well above 650°c and aluminum oxide has excellent strength extension up to about 1370°c. Both fibers are suitable for reinforced metal matrixes in which carbon fibers exhibit adverse reactivates.
1.6 MATERIAL SELECTION 1.6.1 RESIN MATRIX
The resins that are used in fiber reinforced composites are sometimes referred to as ‘polymers’. All polymers exhibit an important common property in that they are composed of long chain-like molecules consisting of many simple repeating units. Man-made polymers are generally called ‘synthetic resins’ or simply ‘resins’.
Polymers can be classified under two types,
‘thermoplastic’ and ‘thermosetting’, according to the effect of heat on their properties.
Thermoplastics, like metals, soften with heating and eventually melt, hardening again
with cooling. This process of crossing the softening or melting point on the temperature scale can be repeated as often as desired without any appreciable effect on the material properties in either state. Typical thermoplastics include nylon, polypropylene and ABS, and these can be reinforced, although usually only with short, chopped fibers such as glass.
Thermosetting materials, or ‘thermosets’, are formed from a chemical reaction in situ, where the resin and hardener or resin and catalyst are mixed and then undergo a non-reversible chemical reaction to form a hard, infusible product. In some thermosets, such as phenolic resins, volatile substances are produced as by- products (a ‘condensation’ reaction). Other thermosetting resins such as polyester and epoxy cure by mechanisms that do not produce any volatile by products and thus are much easier to process (‘addition’
reactions).Once cured, thermosets will not become liquid again if heated, although above a certain temperature their mechanical properties will change significantly. This temperature is known as the Glass Transition Temperature (Tg), and varies widely according to the particular resin system used, its degree of cure and whether it was mixed correctly. Above the Tg, the molecular structure of the thermoset changes from that of a rigid crystalline polymer to a more flexible, amorphous polymer. This change is reversible on cooling back below the Tg. Above the Tg properties such as resin modulus (stiffness) drop sharply, and as a result the compressive and shear strength of the composite does too. Other properties such as water resistance and color stability also reduce markedly above the resin’s Tg. Although there are many different types of resin in use in the composite industry, the majority of structural parts are made with three main types, namely polyester, vinylester and epoxy.
Fig-1.5 Stress vs strain relationship b/w diff types of resins(d)
1.6.2 POLYESTER RESINS
Polyester resins are the most widely used resin systems, particularly in the marine industry. By far the majority of dinghies, yachts and work-boats built in composites make use of this resin system. Polyester resins such as these are of the ‘unsaturated’ type. Unsaturated polyester resin is a thermoset, capable of being cured from a liquid or solid state when subject to the right conditions. An unsaturated polyester differs from a saturated polyester such as Terylene which cannot be cured in this way. It is usual, however, to refer to unsaturated polyester resins as ‘polyester resins’, or simply as ‘polyesters’. In chemistry the reaction of a base with an acid produces a salt. Similarly, in organic chemistry the reaction of an alcohol with an organic acid produces an ester and water. By using special alcohols, such as a glycol, in a reaction with di-basic acids, a polyester and water will be produced. This reaction, together with the addition of compounds such as saturated di-basic acids and cross-linking monomers, forms the basic process of polyester manufacture. As a result there is a whole range of polyesters made from different acids, glycols and monomers, all having varying properties. There are two principle types of polyester resin used as standard laminating systems in the composites industry. Orthophthalic polyester resin is the standard economic resin used by many people.
Isophthalic polyester resin is now becoming the preferred material in industries such as arine where its superior water resistance is desirable. Figure 1.6 shows the idealised chemical structure of typical polyester.
Note the positions of the ester groups (CO - O - C) and the reactive sites (C* = C*) within the molecular chain.
Figure 1.6 – Idealized chemical structure of typical Isophthalic polyester
Most polyester resins are viscous, pale coloured liquids consisting of a solution of polyester in a monomer which is usually styrene. The addition of styrene in amounts of up to 50% helps to make the resin easier to handle by reducing its viscosity. The styrene also performs the vital function of enabling the resin to cure from a liquid to a solid by ‘cross-linking’ the molecular chains of the polyester, without the evolution of any by-products.
These resins can therefore be moulded without the use of pressure and are called ‘contact’ or ‘low pressure’
resins. Polyester resins have a limited storage life as they will set or ‘gel’ on their own over a long period of time. Often small quantities of inhibitor are added during the resin manufacture to slow this gelling action.
For use in moulding, a polyester resin requires the addition of several ancillary products.
These products are generally:
General purpose polyester resin
Catalyst
Accelerator
A manufacturer may supply the resin in its basic form or with any of the above additives already included. Resins can be formulated to the moulder’s requirements ready simply for the addition of the catalyst prior to moulding.
As has been mentioned, given enough time an unsaturated polyester resin will set by itself. This rate of polymerisation is too slow for practical purposes and therefore catalysts and accelerators are used to achieve the polymerisation of the resin within a practical time period. Catalysts are added to the resin system shortly before use to initiate the polymerisation reaction. The catalyst does not take part in the chemical reaction but simply activates the process. An accelerator is added to the catalysed resin to enable the reaction to proceed at workshop temperature and/or at a greater rate. Since accelerators have little influence on the resin in the absence of a catalyst they are sometimes added to the resin by the polyester manufacturer to create a ‘pre- accelerated’ resin. The molecular chains of the polyester can be represented as follows, where ‘B’ indicates the reactive sites in the molecule.
Schematic Representation of Polyester Resin (Uncured) With the addition of styrene ‘S ‘, and in the presence of a catalyst, the styrene crosslink’s the polymer chains at each of the reactive sites to form a highly complex three-dimensional network as follows:
Schematic Representation of Polyester Resin (Cured) The polyester resin is then said to be ‘cured’. It is now a chemically resistant (and usually) hard solid. The cross- linking or curing process is called ‘polymerisation’. It is a non-reversible chemical reaction. The ‘side-by-side’
nature of this cross-linking of the molecular chains tends to means that polyester laminates suffer from brittleness when shock loadings are applied. Great care is needed in the preparation of the resin mix prior to moulding. The resin and any additives must be carefully stirred to disperse all the components evenly before the catalyst is added. This stirring must be thorough and careful as any air introduced into the resin mix affects the quality of the final moulding. This is especially so when
laminating with layers of reinforcing materials as air bubbles can be formed within the resultant laminate which can weaken the structure. It is also important to add the accelerator and catalyst in carefully measured amounts to control the polymerisation reaction to give the best material properties. Too much catalyst will cause too rapid a gelatin time, whereas too little catalyst will result in under-cure. Colouring of the resin mix can be carried out with pigments. The choice of a suitable pigment material, even though only added at about 3%
resin weight, must be carefully considered as it is easy to affect the curing reaction and degrade the final laminate by use of unsuitable pigments.
Filler materials are used extensively with polyester resins for a variety of reasons including:
To reduce the cost of the moulding
To facilitate the moulding process
To impart specific properties to the moulding Fillers are often added in quantities up to 50% of the resin weight although such addition levels will affect the flexural and tensile strength of the laminate. The use of fillers can be beneficial in the laminating or casting of thick components where otherwise considerable exothermic heating can occur. Addition of certain fillers can also contribute to increasing the fire-resistance of the laminate.
1.6.3 VINYLESTER RESINS
Vinylester resins are similar in their molecular structure to polyesters, but differ primarily in the location of their reactive sites, these being positioned only at the ends of the molecular chains. As the whole length of the molecular chain is available to absorb shock loadings this makes vinylester resins tougher and more resilient than polyesters. The vinylester molecule also features fewer ester groups. These ester groups are susceptible to water degradation by hydrolysis which means that vinylesters exhibit better resistance to water and many other chemicals than their polyester counterparts, and are frequently found in applications such as pipelines and chemical storage tanks. The figure below shows the idealised chemical structure of a typical vinylester. Note the positions of the ester groups and the reactive sites (C* = C*) within the molecular chain.
Figure 1.7 - Idealised Chemical Structure of a Typical Epoxy Based Vinylester
The molecular chains of vinylester, represented below, can be compared to the schematic representation of polyester shown previously where the difference in the location of the reactive sites can be clearly seen:
Schematic Representation of Vinylester Resin (Uncured) With the reduced number of ester groups in a vinylester when compared to polyester, the resin is less prone to damage by hydrolysis. The material is therefore sometimes used as a barrier or ‘skin’ coat for a polyester laminate that is to be immersed in water, such as in a boat hull. The cured molecular structure of the vinylester also means that it tends to be tougher than polyester, although to really achieve these properties the resin usually needs to have an elevated temperature post cure.
Schematic Representation of Vinylester Resin (Cured) 1.6.4 EPOXY RESINS
The large family of epoxy resins represents some of the highest performance resins of those available at this time. Epoxies generally out-perform most other resin types in terms of mechanical properties and resistance to environmental degradation, which leads to their almost exclusive use in aircraft components. As a laminating resin their increased adhesive properties and resistance to water degradation make these resins ideal for use in applications such as boat building. Here epoxies are widely used as a primary construction material for high- performance boats or as a secondary application to sheath a hull or replace water-degraded polyester resins and gel coats. The term ‘epoxy’ refers to a chemical group consisting of an oxygen atom bonded to two carbon atoms that are already bonded in some way. The simplest epoxy is a three-member ring structure known by the term ‘alpha-epoxy’ or ‘1,2-epoxy’. The idealized chemical structure is shown in the figure below and is the most easily identified characteristic of any more complex epoxy molecule.
Idealised Chemical Structure of a Simple Epoxy (Ethylene Oxide)
Usually identifiable by their characteristic amber or brown coloring, epoxy resins have a number of useful properties. Both the liquid resin and the curing agents form low viscosity easily processed systems. Epoxy resins are easily and quickly cured at any temperature from 5°C to 150°C, depending on the choice of curing
agent. One of the most advantageous properties of epoxies is their low shrinkage during cure which minimizes fabric ‘print-through’ and internal stresses.
High adhesive strength and high mechanical properties are also enhanced by high electrical insulation and good chemical resistance. Epoxies find uses as adhesives, caulking compounds, casting compounds, sealants, varnishes and paints, as well as laminating resins for a variety of industrial applications.
Epoxy resins are formed from a long chain molecular structure similar to vinylester with reactive sites at either end. In the epoxy resin, however, these reactive sites are formed by epoxy groups instead of ester groups. The absence of ester groups means that the epoxy resin has particularly good water resistance. The epoxy molecule also contains two ring groups at its center which are able to absorb both mechanical and thermal stresses better than linear groups and therefore give the epoxy resin very good stiffness, toughness and heat resistant properties. The figure below shows the idealized chemical structure of a typical epoxy. Note the absence of the ester groups within the molecular chain.
Figure 1.8 - Idealised Chemical Structure of a Typical Epoxy (Diglycidyl Ether of
Bisphenol-A)
Epoxies differ from polyester resins in that they are cured by a ‘hardener’ rather than a catalyst. The hardener, often an amine, is used to cure the epoxy by an
‘addition reaction ‘where both materials take place in the chemical reaction. The chemistry of this reaction means that there are usually two epoxy sites binding to each amine site. Since the amine molecules ‘co-react’
with the epoxy molecules in a fixed ratio, it is essential that the correct mix ratio is obtained between resin and hardener to ensure that a complete reaction takes place.
If amine and epoxy are not mixed in the correct ratios, unreacted resin or hardener will remain within the matrix which will affect the final properties after cure.
To assist with the accurate mixing of the resin and hardener, manufacturers usually formulate the components to give a simple mix ratio which is easily achieved by measuring out by weight or volume.
1.7 COMPARISON OF RESIN PROPERTIES The choice of a resin system for use in any component depends on a number of its characteristics, with the following probably being the most important for most composite structures:
1 Adhesive Properties 2 Mechanical Properties
3 Degradation From Water Ingress
1.7.1 ADHESIVE PROPERTIES
It has already been discussed how the adhesive properties of the resin system are important in realising the full mechanical properties of a composite. The adhesions of the resin matrix to the fiber reinforcement or to a core material in a sandwich construction are important. Polyester resins generally have the lowest adhesive properties of the three systems described here.
Vinylester resin shows improved adhesive properties over polyester but epoxy systems offer the best performance of all, and are therefore frequently found in many high-strength adhesives. This is due to their chemical composition and the presence of polar hydroxyl and ether groups. As epoxies cure with low shrinkage the various surface contacts set up between the liquid resin and the adherents are not disturbed during the cure. The adhesive properties of epoxy are especially useful in the construction of honeycomb- cored laminates where the small bonding surface area means that maximum adhesion is required. The strength of the bond between resin and fiber is not solely dependent on the reinforcement fibers.
1.7.2 MECHANICAL PROPERTIES
Two important mechanical properties of any resin system are its tensile strength and Stiffness. Figure 22 shows results for tests carried out on commercially available polyester, vinylester and epoxy resin systems cured at 20°C and 80°C.
Figure 1.9 - Comparison of resin tensile strength &
modulus
After a cure period of seven days at room temperature it can be seen that a typical epoxy will have higher properties than a typical polyester and vinylester for both strength and stiffness. The beneficial effect of a post cure at 80°C for five hours can also be seen. Also of importance to the composite designer and builder is the amount of shrinkage that occurs in a resin during and following its cure period. Shrinkage is due to the resin molecules rearranging and re-orientating themselves in the liquid and semi-gelled phase. Polyester and vinylesters require considerable molecular rearrangement to reach their cured state and can show shrinkage of up to 8%. The different nature of the epoxy reaction, however, leads to very little rearrangement and with no volatile biproducts being evolved; typical shrinkage of an epoxy is reduced to around 2%. The absence of shrinkage is, in part, responsible for the improved mechanical properties of epoxies over polyester, as shrinkage is associated with built-in
stresses that can weaken the material. Furthermore, shrinkage through the thickness of a laminate leads to
‘print-through’ of the pattern of the reinforcing fibers, a cosmetic defect that is difficult and expensive to eliminate.
1.8 QUALITY OF EGG SHELLS
Most good quality eggshells from commercial layers contain approximately 2.2 grams of calcium in the form of calcium carbonate. About 95% of the dry eggshell is calcium carbonate weighing 5.5 grams. The average eggshell contains about 0.3% phosphorous, 0.3%
magnesium, and traces of sodium, potassium, zinc, manganese, iron and copper. If the calcium from the shell is removed, the organic matrix material is left behind. This organic material has calcium binding properties, and its organization during shell formation influences the strength of the shell. The organic material must be deposited so that the size and organization of the crystalline components (mostly calcium carbonate) are ideal, thus leading to a strong shell. The majority of the true shell is composed of long columns of calcium carbonate. There are other zones that are involved in the self-organization giving the eggshell its strength properties. Thus, shell thickness is the main factor, but not the only factor, that determines strength. At present, dietary manipulation is the primary means of trying to correct eggshell quality problems. However, the shell to organic membrane relationship is also critical to good shell quality and must be considered.
An eggshell that is smooth is desirable, as rough-shelled eggs fracture more easily. Large eggs will usually break more easily than small ones. The main reason for this is that the hen is genetically capable of placing only a finite amount of calcium in the shell. As the hen ages and the eggs get bigger, a similar amount of calcium has to be spread over a larger surface. Therefore, controlling the rate of egg weight change can influence eggshell quality as the hen ages. Controlling feed intake by changing the temperature inside the layer house influences egg size. It must be remembered that many factors can influence the amount of calcium being laid down by the hen. Just because an eggshell is thick does not necessarily mean that it is strong. Sometimes a thinner eggshell is stronger than a thicker eggshell. The reason for this is due to the shape and organization of the organic and inorganic components of the shell.
1.9 FEEDING
The importance of adequate nutrition in providing the hen what she needs to maintain adequate eggshell quality is obvious. A hen lays approximately 250 eggs per year which correspond to 20 times the quantity of calcium in her bones at any one time. Therefore, the calcium requirement of the laying hen is great. It can be calculated that during the 20 hours that are required to form an eggshell, 25 milligrams of calcium must be deposited on the egg every 15 minutes. This amount of calcium is the total amount of calcium in a normal hen's circulatory system at any given time. In addition, the
laying hen is not 100 percent efficient in extracting calcium from the available sources in the diet.
Therefore, many times the diet has to furnish in excess of 4 grams of calcium to the hen daily. Calcium availability values are sometimes not known, and it must be remembered that higher daily intakes are needed when the availability values are known to be low.
High phosphorus content in the feed and excess chlorine may have a negative effect on eggshell quality. It is possible that these two elements act negatively on eggshell quality through their influence on the acid-base balance (pH) in the blood. The importance of adequate vitamin D intake by the hen is obvious, and it is essential for proper calcium and phosphorus utilization.
However, excess vitamin D and its metabolites have not been shown to benefit eggshell quality when normal hens are already consuming adequate vitamin D. Other vitamins and trace minerals, when fed in excess of the hen's requirements, have failed to improve eggshell quality.
1.10 ENVIRONMENT
Usually, eggshell quality is not as much of a problem in cooler environments as it is in hot environments. One of the contributing factors causing poorer eggshell quality in hot weather is hens not consuming adequate feed.
This can lead to problems in body weight, egg production, egg size, and eggshell quality if measures are not taken to assure adequate daily nutrient and energy consumption. When environmental temperature becomes excessively hot, feed intake decreases, and energy becomes the first limiting factor to the hen.
Inadequate consumption of amino acids, calcium, phosphorus, and other nutrients can usually be corrected by adjusting the nutrient density of the diet. However, it must not be forgotten that in hot weather, unlike cooler weather, the laying hen has to make critical life sustaining physiological adjustments in order to cope with the increased environmental temperature.
The laying hen, through panting, resists the rise in body temperature during periods of heat stress. At the same time, the acid-base balance in the bird's blood is changed. We sometimes forget that the laying hen has to cool her body in extremely hot environments and this will shift her physiological priorities from producing eggs and maintaining an adequately calcified eggshell to that of staying alive. In such situations, maximum egg mass (egg production times egg weight) along with maximum eggshell quality are difficult to achieve with any age bird.
1.11 SCANNING ELECTRON MICROSCOPY (SEM)
Scanning Electron Microscopy - SEM - is a powerful technique in the examination of materials. It is used widely in metallurgy, geology, biology and medicine, to name a few. The user can obtain high magnification images, with a good depth of field, and can also analyse individual crystals or other features. A high-resolution
SEM image can show detail down to 25 Angstroms, or better. When used in conjunction with the closely- related technique of energy-dispersive X-ray microanalysis (EDX, EDS, EDAX), the composition of individual crystals or features can be determined.
II. EXPERIMENTAL WORK
2.1 INTRODUCTION
Hen egg shells were collected from the local hotels. To remove impurity and the interference material. The egg shells were washed several times in deionized water.
Chopped and ground egg shell waste to grinding in fine particle size was used for the acid pretreatment. The acid treatments were performed with the egg shell powder in 15 and 20% of NaOH solution maintaining the desired solid liquid ratio, to hold at room temperature for four hours. The resulting solution was diluted up to a desired level and made up the resulting with dilute NaOH solution. This solution was used for the production studies.
2.2 COMPOSITE PREPARATION
Egg-shells of hen were collected in bulk. They were cleaned mechanically by de-ionized water, dried and grinded to very fine particles. The egg shell powder is holded at room temperature. In this experiment were done in General purpose polyester resin, Calcium carbonate and egg shell powder. Calcium carbonate is used in a filler material. It taken from the Calcium carbonate and egg shell powder should be the % of weight ratio in 15 and 20%. It was taken to the 1.5% of catalyst and accelerator with mixing the resin.
The composite material is made up of GPPResin mixing with calcium carbonate and another one is made in GPPResin mixing with calcium carbonate and egg shell powder. The egg shell waste to grinding in fine particle size was used for the acid pretreatment in NaOH solution. They have been prepared to the moulding device to pouring the composite material in room temperature, and to apply the load. The moulded of composite material is holded by six hours, after it will remove the load to given by the good polymer composite specimen plate. Specimen plate size is 200*180mm.Cutting the specimen as per ASTM(American Standard Testing Material) standards for testing in tensile strength, flexural strength and impact strength.
Collection of hen Egg Shells
ASTM standards for given specimens
• Tensile test: ASTM D 638.
• Flexural test: ASTM D 790.
Size of the given specimens
• Tensile test: 150x13x3mm
• Flexural test: 125x12x3mm
III. ANALYSIS
3.1 INTRODUCTION
The egg shell polymer composite material was prepared to the specimen for as per ASTM standard. In first think the specimen is testing in GP Polyester Resin getting to the mechanical properties. The graph is drawn to the given result from mechanical properties. After that it is testing in egg shell polymer composite for the two different % of wt (15, 20).The egg shell specimen is testing to the mechanical properties and SEM analysis.
All the tests are completed to getting the results using to draw the graph.
From this tensile test for maximum tensile strength of the first specimen 49.43 Mpa at 5mm deflection during the time taken from 60sec and the second specimen 48.43 Mpa of minimum tensile strength at 3.5mm deflection during the time taken from 55 sec.
From the flexural test for minimum flexural strength of the first specimen 101.59 Mpa at 1.2 mm deflection during the time taken from 40sec and the second specimen 102.18 Mpa of maximum tensile strength at 1mm deflection during the time taken from 35sec. Max force acting on the specimen 1 & 2 are 120 N, 170 N.
The specimen was prepared to testing as per ASTM standards.
Time Length Width Thickness in sec in mm in mm in mm
1 49.43 5 60 150 13 3
2 48.43 3.5 55 150 13 3
Specimens Max Tensile strength in Mpa
Deflection in mm
Table 3.1 Tensile property (GP Resin) Time Length Width Thickness in sec in mm in mm in mm
1 101.59 1.2 40 125 13 3
2 102.18 1 35 125 13 3
Specimens Max flexural strength in Mpa
Deflection in mm
Table 3.2 Flexural property (GP Resin) Tensile property:
The effects of egg shell and egg shell with NaOH contents and particles sizes on the tensile strength of polymer composites in graph (4.3).From graph (4.3) It is evident that the tensile strength of polymer composites increased with increase in egg shell. The tensile strength will be increased in small size of egg shell particles. The Tensile strength 20%of Egg shell polymer composite is greater than the15% Egg shell, 15% Egg shell with NaOH, 20% Egg shell with NaOH. The maximum Tensile force 887N is obtained to the 20% Egg shell and the deflection is occurred in 2mm.
Flexural property:
The experimental data on the flexural strength of poly- propylene composites are illustrated graphically in graph (4.6). It is evident that at any particle size of the fillers considered, the flexural strength of the composites increased with in-crease in filler contents. Graph (4.6) also shows a general de-crease of flexural strength of the
composites as the particle size of the fillers increased.
Similar decrease in material property with increase in filler particle size was also observed for the tensile strength of the composites. The general order in the en- hancement of the flexural strength of polymer composites is egg shell powder, and filler particle size considered, the order is egg shell powder talc. The Flexural strength of 15% Egg shell polymer composite is greater than the 20% Egg shell, 15% Egg shell with NaOH, 20% Egg shell with NaOH. The maximum Flexural force 173N is obtained to the 15% Egg shell and the deflection is occurred in 1.6mm
Water absorptionproperty:
Water absorption is used to determine the amount of water absorbed under specified conditions. Factors affecting water absorption include: type of plastic, additives used, temperature and length of exposure. The data sheds light on the performance of the materials in water or humid environments.For the water absorption test, the specimens are dried in an oven for a specified time and temperature and then placed in a desiccator to cool. Immediately upon cooling the specimens are weighed. The material is then emerged in water at agreed upon conditions, often 23°C for 72 hours or until equilibrium. Specimens are removed, patted dry with a lint free cloth, and weighed.
S.No Description in % of wt Max Force(N) Max Tensile Strength (MPa)
Deflection (mm)
1 15% Egg shell 595.12 0.305 2.3
2 20% Egg shell 887 0.454 2
3 15% Egg shell with NaOH 597.46 0.306 1.8
4 20% Egg shell with NaOH 609.96 0.312 1.6
Table 3.3 Tensile property of Egg Shells
S.No Description in % of wt Max Force(N)Max Flexural Strength
(MPa) Deflection (mm)
1 15% Egg shell 173 70.97 1.6
2 20% Egg shell 66.89 27.44 3.7
3 15% Egg shell with NaOH 87.4 35.85 2.6
4 20% Egg shell with NaOH 65 26.66 2
Table 3.4 Flexural property of Egg Shells
S.No Before testing weight at gm. In 20% of Egg shell
Time duration in hour
After testing weight at gm.
1 10 72 13
2 10 72 13
3 10 72 13
Table 3.5 Water absorption of Egg shells The Graph for Tensile property:
Figure 3.1: Tensile property for the Egg Shell materials
Figure 3.2: Tensile property for the Egg Shell with NaOH materials
Figure 3.3: Tensile property for the both Egg Shell &
Egg Shell with NaOH materials The Graph for Flexural property:
Figure 3.4: Flexural property for the Egg Shell materials
Figure 3.5: Flexural property for the Egg Shell with NaOH materials
Figure 3.6: Flexural property for the both Egg Shell &
Egg Shell with NaOH materials
Morphology and particle size of the title resin combined 20%wt of egg shell materials have been illustrated from the scanning electron micrograph pictograph (Fig. 3.7).
From SEM pictograph, the materials have uniform matrix with smooth interface having perfect regular shape of homogeneous phase material. An mixture of irregularly broken scrap like shape is observed in the materials with the particle size 0.28 m. This leads to believe that we are dealing with homogeneous phase material.
Figure 3.7: scanning electron micrograph pictograph
IV. CONCLUSION
GP Polyester Resin, Calcium carbonate and Egg shell powder have been utilized successfully in preparing in two different % wt. of (15%,20%) polymer composites.
The Tensile strength, Flexural strength, SEM was tested to getting in good results for the Egg shell polymer composites. The composite specimen was found to increase with increase in egg shell powder contents, and decrease in filler particle. SEM micrographs showed that the ball milling process resulted in micrometer sized coagulated coarse grains with smooth surface, whereas attrition milled samples are characterized by the nanometer size grains. The elongation at break of the prepared composites increased in filler contents, and decreased in particle sizes. The cost of egg shell powder fillers is very less than that of the polymeric matrix. Egg shell powder is the renewable source for plastic industry.
The recovery and utilization of calcium from egg shell waste in cellulose production. The egg shell powder was cost effective and environmentally friendly technology.
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