Polystyrene ADVANTAGES & DIS ADVANTAGES

Forms produced

Properties
Density of EPS	16–640 kg/m3
Young's modulus (E)	3000–3600 MPa
Tensile strength (st)	46–60 MPa
Elongation at break	3–4%
Notch test	2–5 kJ/m2
Glass transition temperature	100 °C
Vicat B	90 °C
Linear expansion coefficient (a)	8×10−5 /K
Specific heat (c)	1.3 kJ/(kg·K)
Water absorption (ASTM)	0.03–0.1
Decomposition	X years, still decaying

Polystyrene is commonly injection molded, vacuum formed, or extruded, while expanded polystyrene is either extruded or molded in a special process. Polystyrene copolymers are also produced; these contain one or more other monomers in addition to styrene. In recent years the expanded polystyrene composites with cellulose and starch have also been produced. Polystyrene is used in some polymer-bonded explosives

ADVANTAGES

1.      Handling with easy.

2.      Brick is light weight.

3.      The cost is economical.

4.      Resistance to earthquake shacking.

5.      Used in tallest building.

6.      Using for parapet wall ,  partician wall.

7.      The mostly used for non loading bearing wall structures.

8.      Manufacturing is easy.

DIS ADVANTAGES

1.It is only used in temporary structure.

2. Not for high strength resistance.

3. Load bearing capacity is normal.

4.Compression strength is normal of brick.

5.Not using for unframed structures.

Diamant (1986)

The insulating material having very low value on thermal inertia where by the flammable is inversely proportional to the thermal conductivity (stec and hull 2010).when the EPS is subjected to high temperature, the cell walls started to soften and collapse se the cellular structure which the foam started to contract. According to (bynum,2001) (Papadopoulos,2005) (A1-homoud 2005)) as cited in vaou and panias , 2010 when the EPS is subjected to direct sunlight or temperature higher than 80⁰c the EPS started to breaks down gradually and reacts with common solvent.

Gurman et al ., (2004)

It also gives of the carbon monoxide (co),carbon dioxide (co₂) water and soot (black smoke) (doroudiani and omidian,2010).

Teo et al (1997)

During the mixing of the virgin with recycled pre expansion and molding stage , the pentane gas is being impregnated into EPS beads and causes the virgin to expand. Unlike for the recycled EPS which has already breaks it cells during grinding process at this stage very less pentane gas left hence the recycle has no longer expand. Acierno et al (2010) A nearer place needed to recycle the EPS waste. Maharana et al ,(2007)

EPS has becomes an alternative to traditional plastic commodity and it is an eco friendly polymer. There are two type of polystyrene mainly solid PS and the EPS . The solid PS such as coffee cups can recycle and synthesis its properties to original resin, which can be used for other application such as video cassette cases and office equipment . National polystyrene recycling company had revealed that the PS foam egg cartons can be recycling in to so many times.  Gnip et al (2008)

                             

EPS also good in packaging product having shock absorbing properties, low cost and case of processing (International Trade Center UNCTAD/WTO).EPS also being used as insulating materials in construction. Building material due to its characteristics which having long term compressive stress.

Kan and demirboga,(2009)

            This phenomenon can develop more reliable models for predicting creep strain development by extrapolation and consistency. As leen started by doroudiani and omidian,2010 Eps is an attractive material because of low in material usage , less costly during installation , good performance and resist to moisture. Another characteristic of Eps it has low value of thermal conductivity. Unmodified EPS foams have a cellular microstructure with closed cell membranes made of EPS and its density is typically less than 50 kg/m³.Maharana et al (2007

Therefore there are several factors that need to be considered mainly the availability of waste product how much the amount of waste is being generated. Recycling has been the concern including eco-efficiency, corporate social responsible and how quality and traceability of product is been taken in to account. Hamad et al (2010)

            Polymeric materials are a unique product whereby it exhibit different durability based on its backbone of a chain. world nowadays produce this product massively in order to fulfill the needs and requirements of packing industry. As this product continuously increase , the total amount of plastics that ends up in waste stream is in a similar trend. This has lead towards the increment cost of landfill disposal. Vilapana and karlsson (2008)

Therefore it is important to optimize the waste by applying various practical approaches such as prevention , minimization , reuse are recovery. Papadopoulos (2008)

                    

Previous research has proved that this EPS product can improve the heat impact by having a very low thermal conductivity value. Melo et al (2009) Basically , the EPS from packaging is white. Naguchi et al (1998)

Basically , the EPS from packaging is white in material and it has two types mainly clean post consumer or dirty post consumer. This box normally used in order to sustain the temperature level in its box. The other accepted polystyrene materials are serving school trays, polystyrene cups , plates and bowls , packaging used to protect electronic and computers , egg cartons , and small packaging of peanuts. Melo et al (2009)

            There are three methods used to recycling the EPS. Mechanical recycling usually requires the combination of high temperatures & shear stress (energy consumption) the chemical recycling usually requires depolymerisation of the recycle material through solvolysis and thermal catalytic. 

Explain about polystyrene is flammable

Polystyrene is flammable.

In chemical terms, polystyrene is a long chain hydrocarbon wherein alternating carbon centers are attached to phenyl groups (the name given to the aromatic ring benzene).Polystyrene's chemical formulais (C8H8) it contains the chemical elements carbon and hydrogen.

The material's properties are determined by short-range van DerWaals attractions between polymers chains. Since the molecules are long hydrocarbon chains that consist of thousands of atoms, the total attractive force between the molecules is large. When heated (or deformed at a rapid rate, due to a combination of viscoelastic and thermal insulation properties), the chains are able to take on a higher degree of conformation and slide past each other. This intermolecular weakness (versus the high intramolecular strength due to the hydrocarbon backbone) confers flexibility and elasticity. The ability of the system to be readily deformed above its glass transition temperature allows polystyrene (and thermoplastic polymers in general) to be readily softened and molded upon heating.

Extruded polystyrene is about as strong as an unalloyed aluminum, but much more flexible and much lighter (1.05 g/cm³ vs. 2.70 g/cm³ for aluminum).

Polystyrene (PS) a synthetic aromatic polymer made from the monomer styrene. Polystyrene can be solid or foamed. General-purpose polystyrene is clear, hard, and rather brittle. It is an inexpensive resin per unit weight. It is a rather poor barrier to oxygen and water vapor and has a relatively low melting point. Polystyrene is one of the most widely used plastics, the scale of its production being several billion kilograms per year. Polystyrene can be naturally transparent, but can be colored with colorants. Uses include protective packaging (such as packing peanuts and CD and DVD cases), containers (such as "clamshells"), lids, bottles, trays, tumblers, and disposable cutlery.

As a thermoplastic polymer, polystyrene is in a solid (glassy) state at room temperature but flows if heated above about 100 °C, its glass transition temperature. It becomes rigid again when cooled. This temperature behavior is exploited for extrusion (as in Styrofoam) and also for molding and vacuum forming, since it can be cast into molds with fine detail.

Polystyrene is very slow to biodegrade and is therefore a focus of controversy among environmentalists. It is increasingly abundant as a form of litter in the outdoor environment, particularly along shores and waterways, especially in its foam form, and also in increasing quantities in the Pacific Ocean.

Polymerization

Polystyrene results when styrene monomers interconnect. In the polymerization, the carbon-carbon pi bond (in the vinyl group) is broken and a new carbon-carbon single (sigma) bond is formed, attaching another styrene monomer to the chain. The newly formed sigma bond is much stronger than the pi bond that was broken, thus it is very difficult to depolymerize polystyrene. About a few thousand monomers typically comprise a chain of polystyrene, giving a molecular weight of 100,000–400,000.

A 3-D model would show that each of the chiral backbone carbons lies at the center of a tetrahedron, with its 4 bonds pointing toward the vertices. Consider that the -C-C- bonds are rotated so that the backbone chain lies entirely in the plane of the diagram. From this flat schematic, it is not evident which of the phenyl (benzene) groups are angled outward from the plane of the diagram, and which ones are inward. The isomer where all of the phenyl groups are on the same side is called isotactic polystyrene, which is not produced commercially. Atactic polystyrene

The only commercially important form of polystyrene is atactic, in which the phenyl groups are randomly distributed on both sides of the polymer chain. This random positioning prevents the chains from aligning with sufficient regularity to achieve any crystallinity. The plastic has a glass transition temperature T_g of ~90 °C. Polymerization is initiated with free radicals.

Syndiotactic polystyrene

Ziegler-Natta polymerization can produce an ordered syndiotactic polystyrene with the phenyl groups positioned on alternating sides of the hydrocarbon backbone. This form is highly crystalline with a T_m of 270 °C (518 °F). Syndiotactic polystyrene resin is currently produced under the trade name XAREC by Idemitsu corporation. Syndiotactic polystyrene is prepared by combining a metallocene catalyst with a styrene monomer to generate a polystyrene chain with a syndiotactic structure.

Degradation

Polystyrene is very chemically inert, being resistant to acids and bases but is easily dissolved by many chlorinated solvents, and many aromatic hydrocarbon solvents. Because of its resilience and inertness, it is used to fabricate many objects of commerce. It is attacked by many organic solvents, which dissolve the polymer. Foamed polystyrene is used for packaging chemicals.

Like all organic compounds, polystyrene burns to give carbon dioxide and water vapor. Polystyrene, being an aromatic hydrocarbon, typically combusts incompletely as indicated by the sooty flame.

Biodegradation

Methanogenic consortia have been shown to degrade styrene as sole carbon source (Grbić-Galić et al. 1990). In this case styrene degraded to a range of organic intermediates and carbon dioxide. Taking the carbon dioxide figures as a representation of the amount of styrene that had completely degraded to gas as is of interest here, rates of styrene degradation ranged from 0.14 to 0.4 a⁻¹. This is an order of magnitude faster than the most rapid rate of polystyrene degradation identified (Kaplan et al. 1979, Sielicki et al. 1978). It is consistent with the T2GGM polystyrene degradation model (Quintessa and Geofirma 2011b), which considers the rate-limiting step for polystyrene degradation to be the breakup of polystyrene, rather than the degradation of styrene.

Pseudomonas putida is capable of converting styrene oil into the biodegradable plastic PHA.^[15][16] This may be of use in the effective recycling of Polystyrene foam, otherwise thought to be non-biodegradable.

Mealworms have been shown to be able to eat polystyrene and degrade it within their larval gut.