Polystyrene

Polystyrene


Iran’s petrochemical industry was established in late 1950s. Availability of enormous hydrocarbon reserves and also having an exemplary domestic market, the industry rapidly developed in the ensuing years. Since its inception, the industry has travelled a long and challenging road from its humble origins to become a significant source in the global petrochemical market. The genesis of petrochemical industry in Iran dates back 1964, when the National Petrochemical Company (NPC) was set up to plan for the development of this high-potential industry.

Jam Empire Trading (JET) Company is a prominent manufacturer, supplier and exporter of several petrochemical products in the Middle East. Having extended existence in international markets, Jam Empire Trading (JET) Company is able to present its services in all aspects of this business, from consultation to exporting. Polystyrene is one of the Jam Empire Trading (JET)’s specialties which makes us distinguished from our rivals, as we are able to find the most proper product for our customers among plethora of products promptly.

What is Polystyrene?


Polystyrene is a thermoplastic resin made by the polymerization of styrene as the sole monomer and it may contain small portions of stabilizers, lubricants, fillers, pigments, and dyes. It also may be copolymerized with other unsaturated compounds. When this is done, it is usually called a modified compound, high-impact, or super high-impact styrene.
Styrene was first isolated by scientists in 1831, which makes it one of the oldest materials in the plastics family.
However, it was not until 1938 that it first appeared in the plastics industry in the United States. Since then, its acceptance as an extremely well qualified material is demonstrated by the fact that over a million pounds (453,600 kg) a year are used in the production of a tremendous variety of products ranging from toys to fluorescent lighting panels.
The material is supplied to the fabricator in the form of pellets ranging in size from 0.03125 inch (794 μm) to 0.125 inch (3.2 mm) in diameter. The pellets are packed in heavy waterproof paper bags of 50 lb (23 kg) capacity or 200 lb (91 kg) capacity cardboard drums.


Polystyrene is a versatile plastic used to make a wide variety of consumer products. As a hard, solid plastic, it is often used in products that require clarity, such as food packaging and laboratory ware. When combined with various colorants, additives or other plastics, polystyrene is used to make appliances, electronics, automobile parts, toys, gardening pots and equipment and more. Polystyrene also is made into a foam material, called expanded polystyrene (EPS) or extruded polystyrene (XPS), which is valued for its insulating and cushioning properties. Foam polystyrene can be more than 95 percent air and is widely used to make home and appliance insulation, lightweight protective packaging, surfboards, foodservice and food packaging, automobile parts, roadway and roadbank stabilization systems, and more.
Polystyrene is made by stringing together, or polymerizing, styrene, a building-block chemical used in the manufacture of many products. Styrene also occurs naturally in foods such as strawberries, cinnamon, coffee and beef.


Styrene readily polymerizes to polystyrene by a relatively conventional free radical chain mechanism. Either heat or initiators will begin the polymerization. Initiators thermally decompose, thereby forming active free radicals that are effective in starting the polymerization process. Typically, initiators used in the suspension process include benzoyl peroxide and di-tert-butyl per-benzoate.
Potassium persulfate is a typical initiator used in emulsion polymerizations. In the presence of inert materials, styrene monomer will react with itself to form a homopolymer. Styrene monomer will react with a variety of other monomers to form a number of copolymers. Polystyrene is an odorless, tasteless, rigid thermoplastic. Pure polystyrene has the following structure.


Figure 1. Pure Polystyrene

The homopolymers of styrene are also referred to as general purpose, or crystal, polystyrene. Because of the brittleness of crystal polystyrene, styrene is frequently polymerized in the presence of dissolved polybutadiene rubber to improve the strength of the polymer. Such modified polystyrene is called high-impact, or rubber-modified, polystyrene. The styrene content of high-impact polystyrene varies from about 88 to 97 percent. Where a blowing (or expanding) agent is added to the polystyrene, the product is referred to as an expandable polystyrene. The blowing agent may be added during the polymerization process (as in the production of expandable beads), or afterwards as part of the fabrication process (as in foamed polystyrene applications).

Different Grades of Polystyrene


Products made of Polystyrene are produced by almost every process of fabrication known to the plastics industry. By far, the greatest quantity used is in the injection molding and extrusion processes. This material is extremely versatile under the extreme conditions of processing, which makes it very popular when the need arises for a material which must be produced with a minimum amount of difficulties. Polystyrene is not generally thought of as a compression molding material, but under certain conditions this process can be used.
The vacuum forming process uses vast quantities of the high-impact type of Polystyrene sheets in the manufacture of large-size, heavy-gage products. Great amounts of the thinner gages are used for the display and packaging industry.
A large volume of Polystyrene is produced for the Polystyrene foam business for production of large blocks of ready-made foam material. There are also Polystyrene beads, which are caused to foam within a heated mold. Styrene is also used in the manufacture of adhesives and paints.


The decision about which of the many different types and brands of material to use for a particular product and the choice of fabrication method is not a very easy one to make. Many variables are involved in each of the many processes and in the economics of the different methods. It is always a wise move to consult with persons well qualified in the field of plastics materials, who have a good knowledge of the fabrication methods, before any definite decisions are reached.
Because of the design of certain products, it is sometimes necessary to produce the part in two or more sections and then bond them together. This is not difficult with Polystyrene, as many types are available that allow for fast, easy bonding. Usually, when two pieces are joined together by certain solvents, the resultant weld is as strong or stronger than any other portion of the molded part.
Another very important characteristic of Polystyrene is that parts may be decorated by many methods, including spray painting, silk screening, roller coating, hot stamping, vacuum metallizing, and dip coating. The
various methods used to decorate plastics have certain characteristics that should dictate their particular use.
Most Polystyrene articles are decorated with fast air-drying lacquers.
Spray painting is accomplished with the use of stencil-type masks particularly adapted to painting uneven surfaces with more than one color. This method is quite extensively used in the toy industry and has become fully automated.
Silk screening is used with very good results in the vacuum forming and sign industries because it is well adapted for flat and large radii surfaces. Hot stamping is well suited for use on Polystyrene parts and is often used on advertising novelties. It can be done with or without color.


Vacuum metallizing is an excellent method for decorating, but care should be taken regarding the surface to be metallized. Dipping is not often used. Extreme care must be taken when decorating by this method because the solvents in the paint may cause swelling or softening of the parts. It is suggested to seek the advice of an expert in this field before any decision on decorating is made.
The optical properties of Polystyrene are good and, when there are no fillers or additives, it is a crystal clear material. When it contains fillers or additives, it becomes either translucent or opaque. Color can be added to obtain the amount of light transmission required, or the depth of opaqueness desired.


Polystyrene has very good dielectric properties, as is characteristic of most of the other thermoplastics. It is used quite extensively for television and stereo cab-inets and parts, battery cases, and many other electrical applications where good dielectrics are necessary. Polystyrene has an exceptionally low power factor. Although articles made of Polystyrene hold their dimensions very well when used properly, care should be taken not to overestimate its qualities.
Polystyrene is not generally an outdoor material and should not be used in places where it might be too exposed. It also might be well to remember that the surface of general purpose or normal styrene is very hard and is easily scratched. It is a brittle material and if broken, the edges are jagged and sharp. This is not always true of the modified types, since that is one of the reasons for modification. Polystyrene is classified as slow burning, but it will burn and should never be held over an open flame. However, blends have been developed to withstand high heats, up to and above the boiling point of water. Progress has been made to make this material selfextinguishing.
There are many applications in the home where this material will not be adversely affected, such as food containers, refrigerator door liners, wall tile, furniture drawers, or decorative room dividers. Most of these materials should not be used with citrus fruit rinds, turpentine, gasoline, or fingernail polish. These can cause staining or disfiguration and make the product unsuitable for use. Blends of Polystyrene may have fillers, such as fiberglass or rubber. These fillers give added strength to the end product, thereby making this low-priced material equal to or better than many of the higher-priced materials for specific items.
Polystyrene products tend to attract dust particles. This is because of the static electricity built up in the article during the process of fabrication. However, many products are available that help to destaticize and, in some instances, eliminate the static electricity completely. To keep articles made of Polystyrene clean, it is recommended that they be washed in lukewarm water with a mild soap or detergent using a soft cloth. A point to remember is that a product is only as good as the material and workmanship that go into it. Polystyrene has been used in the plastics industry for many years, and the production use of this material has increased tremendously every year. It is quite apparent that Polystyrene will be one of the basic materials of the plastics industry for many years to come.

Specifying and purchasing polystyrene thermal insulation can be complicated because there are multiple product types with distinctive physical properties. Using the ASTM International standard applicable to polystyrene can provide useful guidance.

ASTM C578


The U.S. product standard for polystyrene thermal insulation is ASTM C578, “Standard Specification for Rigid, Cellular Polystyrene Insulation.” It applies to expanded polystyrene (EPS) and extruded polystyrene (XPS) products. Within ASTM C578, there are Types I through XV classification designations. Type III was deleted because the product no longer is available. Seven type classifications describe EPS products, and seven describe XPS products.

EPS


EPS products are identified by ASTM C578’s Types I, II, VII, IX, XI, XIV and XV. The types are characterized by distinctive physical properties, including density and compressive strength. The figure shows common types, minimum and nominal densities, and minimum compressive strengths for EPS. EPS complying with ASTM C578, Type XI (0.75 nominal density) generally is not intended for use in roofing applications.
NRCA recommends EPS used as rigid board roof insulation have a minimum nominal density of 1.25 pounds per cubic foot, such as that complying with ASTM C578, Type VIII. Designers should specify EPS with higher density and compressive strength values to meet specific project requirements.

XPS


XPS products are identified by ASTM C578’s Types IV, V, VI, VII, X, XII and XIII. The types are characterized by distinctive physical properties, including density and compressive strength. The figure shows common types, minimum densities and compressive strength values for XPS.
XPS complying with Type XII or XIII generally is not intended for use in roofing applications. NRCA recommends XPS used as rigid board roof insulation have a minimum compressive strength of 15 pounds per square inch (psi), which complies with ASTM C578, Type X. Designers should specify XPS with higher compressive strength values to meet specific project requirements. Type VI (40 psi), Type VII (60 psi) or Type V (100 psi) products may be used in protected membrane roof systems and plaza deck applications where high compressive strength values may be desirable.

Specifying recommendations


When using polystyrene, NRCA recommends specifiers identify the specific polystyrene product desired using the ASTM C578 designation and applicable type classification. Also, specifiers should clearly indicate their desired board sizes and thicknesses in project specifications based on a project’s specific requirements. Additional information regarding polystyrene thermal insulation is contained in The NRCA Roofing Manual: Membrane Roof Systems—2015. NRCA members can access the manual free on shop.nrca.net or via the NRCA app. 123

Table 1. Physical Properties of different types of EPS and XPS


*Indicates a product type typically not used in roof assemblies


Polystyrene Production


Batch Process


Various grades of polystyrene can be produced by a variety of batch processes. Batch processes generally have a high conversion efficiency, leaving only small amounts of unreacted styrene to be emitted should the reactor be purged or opened between batches. A typical plant will have multiple process trains, each usually capable of producing a variety of grades of polystyrene. Figure 2 is a schematic representation of the polystyrene batch bulk polymerization process, and the following numbered steps refer to that figure. Pure styrene monomer (and comonomer, if a copolymer product is desired) is pumped from storage (1) to the feed dissolver (2). For the production of impact-grade polystyrene, chopped polybutadiene rubber is added to the feed dissolver, where it is dissolved in the hot styrene. The mixture is agitated for 4 to 8 hours to complete rubber dissolution. From the feed dissolver, the mixture usually is fed to an agitated tank (3), often a prepolymerization reactor, for mixing the reactants. Small amounts of mineral oil (as a lubricant and plasticizer), the dimer of alpha-methylstyrene (as a polymerization regulator), and an antioxidant are added. The blended or partially polymerized feed is then pumped into a batch reactor (4). During the reactor filling process, some styrene vaporizes and is vented through an overflow vent drum (5). When the reactor is charged, the vent and reactor are closed. The mixture in the reactor is heated to the reaction temperature to initiate (or continue) the polymerization. The reaction may also be begun by introducing a free radical initiator into the feed dissolver (2) along with other reactants. After polymerization is complete, the polymer melt (molten product) containing some unreacted styrene monomer, ethylbenzene (an impurity from the styrene feed), and low molecular weight polymers (dimers, trimers, and other oligomers), is pumped to a vacuum devolatilizer (6). Here, the residual styrene monomer, ethylbenzene, and the low molecular weight polymers are removed, condensed (7), passed through a devolatilizer condensate tank (9), and then sent to the byproduct recovery unit. Overhead vapors from the condenser are usually exhausted through a vacuum system (8). Molten polystyrene from the bottom of the devolatilizer, which may be heated to 250 to 280°C (482 to 536°F), is extruded (10) through a stranding die plate (a plate with numerous holes to form strands), and then immersed in a cold water bath. The cooled strands are pelletized (10) and sent to product storage (11).

Continuous Process


As with the batch process, various continuous steps are used to make a variety of grades of polystyrene or copolymers of styrene. In continuous processes, the chemical reaction does not approach completion as efficiently as in batch processes. As a result, a lower percentage of styrene is converted to polystyrene, and larger amounts of unreacted styrene may be emitted from continuous process sources.



Figure 2. Simplified flow diagram of a batch polystyrene process.

A typical plant may contain more than one process line, producing either the same or different grades of polymer or copolymer.
A typical bulk (mass) continuous process is represented in Figure 6.6.3-2. Styrene, polybutadiene (if an impact-grade product is desired), mineral oil (lubricant and plasticizer), and small amounts of recycled polystyrene, antioxidants, and other additives are charged from storage (1) into the feed dissolver mixer (2) in proportions that vary according to the grade of resin to be produced. Blended feed is pumped continuously to the reactor system (3) where it is thermally polymerized to polystyrene. A process line usually employs more than one reactor in series. Some polymerization occurs in the initial reactor, often referred to as the prepolymerizer. Polymerization to successively higher levels occurs in subsequent reactors in the series, either stirred autoclaves or tower reactors.
The polymer melt, which contains unreacted styrene monomer, ethylbenzene (an impurity from the styrene feed), and low molecular weight polymers, is pumped to a vacuum devolatilizer (4). Here, most of the monomer, ethylbenzene, and low molecular weight polymers are removed, condensed (5), and sent to the styrene recovery unit (8 and 9). Noncondensables (overhead vapors) from the condenser typically are exhausted through a vacuum pump (10). Molten polystyrene from the bottom of the devolatilizer is pumped by an extruder (6) through a stranding die plate into a cold water bath.

 


Figure 3. Simplified flow diagram of a continuous polystyrene process.

The solidified strands are then pelletized (6) and sent to storage (7). In the styrene recovery unit, the crude styrene monomer recovered from the condenser (5) is purified in a distillation column (8). The styrene overhead from the tower is condensed (9) and returned to the feed dissolver mixer. Noncondensables are vented through a vacuum system (11).
Column bottoms containing low molecular weight polymers are used sometimes as a fuel supplement.

Polystyrene Applications


Polystyrene is the fourth largest thermoplastic by production volume. It is used in applications in the following major markets (listed in order of consumption): packaging, consumer/institutional goods, electrical/electronic goods, building/construction, furniture, industrial/machinery, and transportation.
Packaging applications using crystal polystyrene biaxial film include meat and vegetable trays, blister packs, and other packaging where transparency is required. Extruded polystyrene foam sheets are formed into egg carton containers, meat and poultry trays, and fast food containers requiring hot or cold insulation. Solid polystyrene sheets are formed into drinking cups and lids, and disposable packaging of edibles. Injection molded grades of polystyrene are used extensively in the manufacture of cosmetic and personal care containers, jewelry and photo equipment boxes, and photo film packages. Other formed polystyrene items include refrigerator door liners, audio and video cassettes, toys, flower pots, picture frames, kitchen utensils, television and radio cabinets, home smoke detectors, computer housings, and profile moldings in the construction/home-building industry.
Homopolymers and copolymers can be produced by bulk (or mass), solution (a modified bulk), suspension, or emulsion polymerization techniques. In solution (or modified bulk) polymerization, the reaction takes place as the monomer is dissolved in a small amount of solvent, such as ethylbenzene.


Suspension polymerization takes place with the monomer suspended in a water phase. The bulk and solution polymerization processes are homogenous (taking place in one phase), whereas the suspension and emulsion polymerization processes are heterogeneous (taking place in more than one phase). The bulk (mass) process is the most widely used process for polystyrene today. The suspension process is also common, especially in the production of expandable beads. Use of the emulsion process for producing styrene homopolymer has decreased significantly since the mid-1940s.

Amphiphilic block copolymers have a long history as industrial surfac-tants. The major types of block copolymers, such as those made from ethylene oxide (EO) and propylene oxide (PO) or EO and styrene, are cheap and easy to tailor-make for specific applications.
Polymer containing PPO as the hydrophobic partner are by far the most studied and used, but the use of a more hydrophobic segment in the block copolymer becomes important for other applications, such as emulsion polymerization. Thus, PS-b-PEO copolymers are preferred for this purpose. EO-styrene block copolymers have also been used to formulate water-in-oil microemulsions. Such microemulsions have been used as minireactors for polymerization of acrylamide, for example. Amphiphilic polymers containing polystyrene blocks are also effective stabilizers for emulsion. This application is related to the previously mentioned emulsion polymerization, but in this case the emulsion is formed by intimate mixing of two immiscible liquid phases and not by polymerization of a hydrophobic monomer in aqueous phase in order to prepare latexes. It is important in this case that the hydrophobic (polystyrene) block is long enough to ensure steric stabilization of the non-aqueous phase but not too long, to avoid bridging flocculation.
Due to the permanently hydrophobic nature of the polystyrene, its high glass transition temperature and its toxicity in living organisms, applications as drug carriers and drug delivery systems does not seem to be practicable for PS-based amphiphilic block copolymers.
Nevertheless, the ability of such polymer to solubilize hydrophobes in their PS core (e.g.: benzene, hexane) makes them suitable systems for applica-tion in separation systems, as alternative to liquid-liquid extractions.
Due to the affinity of the PS block for components of crude oil, and the rheological and interfacial properties of amphiphilic block copolymers, poten-tial application of PS containing amphiphilic block copolymers for enhanced oil recovery can also be envisaged. This potential, however, at the present day has not been fully disclosed yet.

Polystyrene Aggregate Concrete (PAC):

Polystyrene aggregate concrete (PAC) is the material of lightweight with varying densities in the range of 1000 to 2000 kg/m3 and are produced by replacing partially coarse aggregate with reference of the normal weight concrete mixtures that is of equal volume chemically coated with PS beads. It can be used for both structural and non-structural applications due to its very attracting properties such as lightweight, thermal properties, insulating capacity, durable character and eco-friendly nature. All these characteristics are dependent on the amount of expanded PS used in an aggregate form.
According to the structural application such as the structural self-weight, the foundation size can be reduced by decreasing the density. But yet many studies reported the data related to the PAC of lower strength only. In order to enlarge the utility of PAC and also to compete with both structural as well as functional demands, a series of PAC of 1410-2100 kg/m3 densities with corresponding strengths of at least 17 MPa has been designed.

PS-Mediated Inorganic Composites:

PS is generally studied as an organic substance for the synthesis of composites along with other inorganic materials. For example, Caruso using a layer-by-layer method prepared PS-silica composite particles with the core-shell structure and the formed structure found to exhibit morphological properties. Similarly, Huang and Tang have prepared PS coated Fe3O4 particles of spherical shape to be used as magnetic and structural properties.
Lenoble et al. Synthesized a PS matrix loaded with MnO2 and studied on retention of As(V) and simultaneous of As(III) oxidation as well as the waste on this medium was analyzed.
In a similar study, the formation of PS shell on the surface of ZnO (modified with oleic acid) by the microemulsion polymerization found to have water initiator as potassium persulfate (KPS) [26]. Pan and co-workers fabricated PS-supported ZrO2 composites and studied their effect on the sorption enhancement of Pb(II) ions from water. It was observed from the studies that the fabrication of ZrO2 with PS gave a specific result which had an influence on its use. The photoactive TiO2 particles are utilized in two ways, i.e. in the form of suspension or immobilization on a surface. The practical application of photoactive nanoparticles appears to be very difficult due to the lack of sophisticated and economical filtration procedures for the separation of suspended particles in the reaction medium after long treatment periods. In search of suitable filtration procedure, the immobilization of TiO2 onto a surface is considered to overcome the disadvantages appeared in the treatment processing. However, the immobilization process seems to reduce the photocatalytic activity due to an increased amount of distance between the immobilized particle and the surface layer which is at the peak of degradation.

PS in Different Metallic Membranes:

There was a study about DC electrical conductivity of nano-composite Polystyrene–Titanium–Arsenate (PS-Ti-As) membrane and found that the conductivity is dependent of the temperature. It was observed that the conductivity increased with an increase of temperature until 100C, after that it decreased during 120-160°C. These changes expected to be due to the loss of dopant HCl, as the dopant molecules are responsible for blocking the chemical reactions associated with it. It is also noticed that the perm-selectivity is attaining a value between zero and unity are dependent on the external electrolyte concentration for the PS-Ti-As membrane and the electrolyte pair. The formed membrane is crystalline in nature and exhibited significant toxicological effects towards the H9c2 cardiomyoblasts due to the maintenance of cationic charge by the PS in the membrane. These cationic polymers due to their electron deficient character tries to absorb the electrons quickly from the intracellular components like DNA, protein etc. and mediate many toxic responses through the initiation of free radical oxidative stress.

PS in Electronics:

The electronic industry uses PS in the manufacturing of televisions and in computers as different types of emerging trends which follows the norms for its use such as combination of function, form and aesthetics and a high performance as well as cost ratio. With the advancement of disposable cutlery, the life of individual has become very easy and comfortable as the sheet or molded form of PS is serving and the enormous utility in the production of plastic cutlery which is once used and thrown away.
It is also the preferred choice nowadays as media enclosures, cassette tape and jewelry boxes for protecting CD’s and DVD cases and many devices that are used in the information technology sector. PS is fit for manufacturing various household appliances like blenders, air conditioners, refrigerators, hot air and microwave ovens, hand-held vacuum cleaners. The increased uses of PS in the industrial sector is due to its easy production processing, capability of imparting an easy and clear cut end of the appliances while meeting almost all the end product requirements. The consumer goods such as kitchen and bathroom accessories, lawn accessories are found to be produced by inculcating PS in the process of synthesis and manufacture. The availability of PS in economical prices compared with many other polymers and convenient to processing into desired shapes and sizes are especially making it to use in toys and other playing accessories, injection-molding, extrusion, thermoforming and smoke detecting alarms when the fire flares up.

PS in Automotives:

PS in automotives are quiet randomly used for various purposes by making of use of its characteristics such as thermal stability at a broader temperature range, high mechanical strength along with other elements, conductivity when used in ionic form, economical, recyclable, moisture free, etc. The commonly manufactured products in the automobile industry includes the bumper cores, boot in-fills, void fillers, roof liners, head rests, head impact, knee bolsters, side-impact protection, car seating, sun visors, car air conditioning liners, under bonnet battery liners, under bonnet sound deadening and material handling dunnage.

PS in Food Packaging:

PS is used as an insulator and food protector in the food packing process. The various
food items like meat, fish, eggs, dairy products, salads, cold drink carry out meals can be prevented from decomposition/spoiling by packing it in PS material and is an easy and less expensive way of preserving food. Only because of PS role in packaging industry in terms of the goods packaging, refrigeration and transportation in developed countries ensured that only a 2% of food is that gets spoiled when compared with developing or underdeveloped countries where PS revolution has not started. The PS packaging materials are versatile and can serve as disposables for food having rigid packing and are recyclable. To transport other consumer goods and health care products (pharmaceuticals, neutraceuticals, etc) across the countries, they are packed in boxes along with PS as a supporting materials and also to provide insulation and protection from various external factors like moisture, air and temperature by maintaining its properties at all conditions.

PS in Construction:

PS resin, a long chain hydrocarbon has an excellent insulation capacity and so it can be used in building and construction industry as for insulating the ceilings, walls, floors, roofing, siding, panels, bath and shower units, in addition to lighting and plumbing fixtures to get rid of external temperature differences and humidity. The PS resin of chemical compound are mainly required for lighting and plumbing fixtures, panels and slidings used during the construction purposes. The polymers also find its utility in soundproofing walls of buildings due to its properties of good processing ability and excellent performances at all climatic conditions.

PS in Medical Sector:

PS has a wide range of utility in medical field. The use of PS advances the technology to
the patient and physician as its versatility had made it to be more suitable for use in the medical field. It is highly preferable for making medical equipment due to its excellent clarity which helps in good visibility and outstanding sterilization process. PS resins are used in the manufacturing of disposable medical appliances which includes the tissue culture plates, trays for conducting test, petri dishes, test tubes and kits for housing test which is involved in biomedical research. Many diagnostic test equipment and components made up of PS such as medical cups, medical keyboards, plastic boxes, vaginal dilator speculum are also under everyday use.

PS in Crafts: PS uses are also highly influencing the art and crafts sector. Extruded PS or Styrofoam is a special form of the polymer having closed cell which is used for art and craft projects. The material or the equipment are easily cut into various shapes and sizes for ornamenting it to amazing craft pieces which is of excellent beauty. Craft materials such as candle holders and ornaments for decorating Christmas Tree are generally made of Styrofoam. For making and manufacturing the model of architectural designs, PS is mainly used which can be replace in convenience for corrugated cardboards.