ASSIGNMENT 2

TITLE:

POLYMER BLEND

MEMBER:

NUR AMIRA FAZIRA BINTI AHMAD (A146096)

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1. Short essay on polymer blend include advantage and disadvantage of it.

A polymer blend or polymer mixture is a member of a class of materials analogous to

metal alloys, in which at least two polymers are blended together to create a new material with

different physical properties.

Generally, there are five main types of polymer blend: thermoplastic–thermoplastic

blends; thermoplastic–rubber blends; thermoplastic–thermosetting blends; rubber– thermosetting

blends; and polymer–filler blends, all of which have been extensively studied. Polymer blending

has attracted much attention as an easy and cost-effective method of developing polymeric

materials that have versatility for commercial applications. In other words, the properties of the

blends can be manipulated according to their end use by correct selection of the component

polymers . Today, the market pressure is so high that producers of plastics need to provide better

and more economic materials with superior combinations of properties as a replacement for the

traditional metals and polymers. Although, plastic raw materials are more costly than metals in

terms of weight, they are more economical in terms of the product cost. Moreover, polymers are

corrosion-resistant, possess a light weight with good toughness (which is important for good fuel

economy in automobiles and aerospace applications), and are used for creating a wide range of

goods that include household plastic products, automotive interior and exterior components,

biomedical devices, and aerospace applications

The advantage of polymer blend is one main practical application of polymers is through the use of multicomponentpolymer systems, such as polymer blends, and there are a variety of reasons to utilize them.Polymer blends are physical mixtures of two or more polymers that do not have chemical bonding between them and have become a chief means for advancing and constructing polymeric materials.A main reason polymer blends are used are to improve the chemical and physical properties of commercial polymers through the blending with other polymers.Some of the attractive features of polymer blends are that they can lower cost and addvalue.

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Polymer blends may result in an overall reduction of cost as a relatively inexpensive polymer can be added to a more expensive commercial polymer. The properties of polymers may also be enhanced with polymer blends. Properties that can be altered are heat distortion temperature (HDT), toughness, modulus, chemical resistance, and processability of the commercial polymer to make it more ideal for a given application.3 Also, polymer blends can be made in different compositions, and with differing compositions there are different properties that result. Lastly, polymer blends may be implemented more quickly and economically for a given application instead of looking into the chemistry of new polymers.

In addition, advantages to using polymer blends include impact modification when rubber is incorporated; improved environmental stress crack resistance; possible anti-slip, anti-block, and low coefficients of friction; and various commercial products can result from property compromise with elastomers. Some advantages of single phase blends include HDT enhancement, improved processability, plasticizer permanence, and no weld-line strength deterioration. Single phase blends also retain optical clarity, which is necessary in packaging and optical applications. Advantages to using two phase blends involve the ability to be used in rubber-toughened plastics, composites, and recycled polymer mixtures.As it can be seen, the degree of miscibility of a blend can have either advantages or disadvantages depending on the application.

2. Recent development in polymer blend

The study of blend properties is very important to find its new application in the field of

biomedical and pharmacy. The example is journal (Hadi et al 2015) which focused on Improving Tensile Strength of Polymer Blends as Prosthetic Foot Material Reinforcement by Carbon Fiber. Prosthetic Foots or artificial limbs,

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are fabricated devices that provide amputees with a replacement for their missing limb, restoring some function, The development of polymer blend materials has, in recent years, led to technological advances across a wide range of applications in modern orthopedic medicine and prosthetic devices. The basic of this research new polymer blend self-cure PMMA/SR which can be used in manufacturing the prosthetic foot with a reasonable cost and satisfying mechanical properties accepted. Improvement tensile strength of this polymer blends for this application, one of the simple improve tensile strength of PMMA/SR polymer blend reinforcement by carbon fiber CF.

Polymer blends (PMMA:SR) 90:10; 80:20; 70:30; 60:40; 50:50 were prepared reinforcements each one by carbon fibers from 5-15% (CF), then tensile strength test was carried out for prepared specimens, and effect of reinforcement by carbon fibers on tensile strength of polymer blends were determined as one improvement for prosthetic foot material.

PMMA and SR were used as polymer blends for this research as suitable material for prosthetic foot, PMMA is a linear thermoplastic polymer. Experiments were performed in order to improve the tensile strength properties for polymer blends as prosthetic foot material by reinforcement with short carbon fibers, this improvement as tensile strength, modulus of elasticity, increase as reinforcement material increase, elongation decrease as reinforcement material increase, while increase as rubber content increase for polymer blends, tensile strength, elasticity, decreases as rubber content increase, and used cold cure polymers blends for simple molding process with improvement the tensile properties by reinforcement is very comparative blends that can be used for prosthetic foot applications, spatially the lower cost for this polymer materials.

Next is research that focus on the polymer blends and nanocomposite systems for articular cartilage tissue engineering applications. Among these polymers, natural polymers could provide some properties such as

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biocompatibility, biodegradability, low toxicity, and cell signaling whereas synthetic polymers provide some other properties such as mechanical and physical properties and thermal stability. But many of them do not provide sufficient mechanical properties to continuously support the formation of cartilage tissue

Polymer blending is a well-known technique whenever property modification is required, because this inexpensive technology enables materials with full set of tailored properties and improved specific properties [104]. The main reason of blending is to widen the range of properties while obviating their drawbacks. Usually the combination of natural polymers with synthetic polymers preserves the advantages of polymers. In this research polymer is blend with chitosan and collagen. collagen/hyaluronan/chitosan and hydroxyapatite/collagen/chondroitin sulfate nanocomposite are some examples of this classification. Sometimes, synthetic polymers, such as polyvinyl alcohol, are mixed with othersynthetic ones to modify its drawbacks such as poor bioactivity. It must be borne in mind that the engineered articular cartilage should match the mechanical functionality of the native tissue. Therefore, engineered articular cartilages should have properties such as anisotropic, nonlinear, viscoelastic, and inhomogeneity.

Reference :

Hadi A,N & Oleiwi J,K. 2015. Improving Tensile Strength of Polymer Blends as Prosthetic Foot

Material Reinforcement by Carbon Fiber. Material Sci En.4. 1000158.

Doulabi A,H & Mequanint K & Mohammadi H. 2014. Blends and Nanocomposite Biomaterials for Articular Cartilage Tissue Engineering. Materials. 7. 5327-5355.

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3. Characterization technique of polymer blend

The example of characterization technique of polymer blend is by Scanning electron microscopy.The cryogenically fractured surface and smooth cut surface of the blend samples were investigated using a Jeol ESEM scanning electron microscopy (SEM) system, with an accelerating voltage of 20 kV. Next is Atomic force microscopy.The AFM images of the cut surface of the samples were taken in tapping mode by a Dimension3100 Nanoscope V (Veeco, USA). Silicon-SPM sensors (Budget Sensors, Bulgaria) with a spring constant of ca.40N/mand resonance frequency of .280kHz were used. The tip radius is lower than10nm.

The other example is Transmission electron microscopy.To assess the quality of filler dispersion and morphological details, the NR/NBR nanocomposites were investigated by means of Transmission electron microscopy (TEM) (JEM-2100 HRTEM). The micrographs were obtained in point to point resolution 0.194 nm, operating at an accelerating voltage of 200 kV. Ultrathin sections of bulk specimens Cryocut specimens (~100nm thickness) prepared using an ultra-microtome (Leica, Ultracut UCT) were placed on a 300 mesh Cu grids (35mm diameter) and were analysed without staining.

X-ray diffraction also one of popular tools used in characterization technique in polymer blend.X-ray diffraction (XRD) experiments were performed directly on the organically modified clay powder sand on the clay filled samples. Inorder to findout the spacing between the clay layers, X-ray diffraction of NR/NBR nanocomposite was conducted using the XRD:SIEMMENS D 5000 with radiations Cu K alpha at 40 kV and 30mA.

Beside that, Tensile properties is also used in carazterization polymer blend. The tensile testing of the blends was carried out in a Universal

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Testing Machine (T50KT), Tensile properties of the samples were measured using universal testing machine (Tinius Olsen) with a cross-head rate at 500mm/min according to ASTM D 412-98 at a room temperature (25 ± 2°C). Five dumbbell shaped samples of each system were used to determine the young’s modulus, tensile strength and elongation at break. Tensile modulus was taken as the slope of theinitial linear region of the stress-strain curve.

At last is Stress relaxation measurements. The stress relaxation measurements of the blend nanocomposites were carried out in a Universal Testing Machine (T50KT). Stress relaxation measurements were carried out to study the effect of different parameters that influence the NR/NBR nanocomposite such as, loading, filler polarity, blend composition, mixing conditions, nature of filler, temperature and preparation methods. A Tinius Olsen testing machine (H50KT) fitted with an environmental chamber, was used to carry out the viscoelastic testing. The environmental chamber was capable of temperature control. After the environmental chamber was equilibrated to the desired temperature (70oC), the specimen was gripped between two sets of jaws 12 mm apart and then was further allowed to equilibrate to the conditions within the chamber, for a period of 30 – 40 minutes. Once equilibrated, a tensile stress was applied to the specimen by moving the upper grip at a constant rate (500 mm min-1 crosshead speed). When the desired initial strain of 50% had been reached, movement of the grip

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