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Physics project file

Class:XII B

SUBMITTED BY–

Shalini shravan mishra

SUBMITTED TO –

MR.ashish srivastava

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INDEXSR NO. TOPIC PAGE SIGNATURE

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Introduction

UREA

FORMALDEHYDE

UREA FORMALDEHYDE PLASTIC

Composition

Classification

Thermoplastics and Thermosetting

Polymers

Biodegradability

Properties of plastics

Toxicity

Common Plastics and Uses

Experiment

Bibliography

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15 – 17

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UREAUrea,(NH2)2CO, is a colorless organic chemical

compound also known by the International Nonproprietary Name (rINN) carbamide, as established by the World Health Organization. It is highly soluble in water and has a pKa close to zero. Urea is essentially the waste produced when the body metabolizes protein.

The primary raw material used to manufacture urea is natural gas, which ties the costs directly to gas prices. Consequently, new plants are only being built in areas with large natural gas reserves where prices are lower..

Urea is a raw material used in the Urea is a raw material used in the manufacture of many chemicals, such as various manufacture of many chemicals, such as various plastics, urea-formaldehyde resins and adhesives.plastics, urea-formaldehyde resins and adhesives.    It It is also essential for making feedstock, glue, fertilizer, is also essential for making feedstock, glue, fertilizer, commercial products, and in resin production.commercial products, and in resin production.

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A gas at room te Formaldehyde   is an   organic compound   with the   formula   CH 2O or HCHO. It is the simplest   aldehyde , hence its   systematic name   methanal . The common name of the substance comes from its similarity and relation to   formic acidmperature , formaldehyde is colorless and has a characteristic pungent, irritating odor. It is an important precursor to many other materials and chemical compounds. In 2005, annual world production of formaldehyde was estimated to be 8.7 million tonnes.[3] Commercial solutions of formaldehyde in water, commonly called formol, were formerly used as disinfectants and for preservation of biological specimens.

Uses:

Industrial applications:

,   MELAMINE RESIN ,   PHENOL FORMALDEHYDE RESIN ,   POLYOXYMETHYLENE PLASTICS ,   1,4-BUTANEDIOL , AND   METHYLE FORMALDEHYDE IS A COMMON PRECURSOR TO MORE COMPLEX COMPOUNDS AND MATERIALS. IN APPROXIMATE ORDER OF DECREASING CONSUMPTION, PRODUCTS GENERATED FROM FORMALDEHYDE INCLUDE   UREA FORMALDEHYDE RESINNE DIPHENYL DIISOCYANATE . .

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urea-formaldehyde resin, any of a class of synthetic resins obtained by chemical combination of urea (a solid crystal obtained from ammonia) and formaldehyde (a highly reactive gas obtained from methane). Urea-formaldehyde resins are used mostly as adhesives for the bonding of plywood, particleboard, and other structured wood products. The chemical composition of urea and formaldehyde and the reaction by which they are polymerized into networks of permanently interlinked molecules are briefly described in the article aldehyde condensation polymer.

In industrial production, urea resins are made by the condensation of formaldehyde and urea in an aqueous solution, using ammonia as an alkaline catalyst. The condensation reaction gives a colourless, syrupy solution that can be spray-dried to a powder for later use in coatings or adhesives; it can also be mixed with cellulose filler to produce powders for molding into solid objects.

Patents for hard, transparent thermosetting resins based on urea and formaldehyde were granted to German and British chemists in the early 1920s. In 1925 the British Cyanides Company, Ltd., (now British Industrial Plastics, Ltd.) introduced light, unbreakable tableware made from its trademarked Beetle urea resin, and within two years the American Cyanamid Company had acquired the rights to produce Beetleware in the United States.

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CompositionMost organic polymers are plastics. Thevastmajority of

these polymers are based on chains of carbon atoms alone

or with oxygen, sulfur, or nitrogen as well. The backbone

is that part of the chain on the main "path" linking a

large numberof repeat units together. To customizethe

properties of a plastic, different molecular groups "hang"

fromthe backbone (usually they are "hung" as part of the

monomers before linking monomers together to form the

polymer chain).The structure of these "side chains"

influence the properties of the polymer. This fine tuning of

the properties of the polymer by repeating unit's molecular

structure has allowed plastics to become an indispensable

part ofthe twenty-first century world.

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Classification

Plastics are usually classified by their chemical structure of the polymer's backbone and side chains.

Some important groups in these classifications are the

Acrylics Polyesters Silicones Polyurethanes Halogenated plastics.

Plastics can also be classified by the chemical process used in their synthesis, such as

Condensation Polyaddition Cross-linking.

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A thermosetting plastic, also known as a thermoset, is polymer material that irreversibly cures. The cure may be done through heat (generally above 200 °C (392 °F)), through a chemical reaction (two-part epoxy, for example), or irradiation such as electron beam processing.

Thermoset materials are usually liquid or malleable prior to curing and designed to be molded into their final form, or used as adhesives. Others are solids like that of the molding compound used in semiconductors and integrated circuits (IC). Once hardened a thermoset resin cannot be reheated and melted back to a liquid form.

According to IUPAC recommendation: A thermosetting polymer is a prepolymer in a soft solid or viscous state that changes irreversibly into an infusible, insoluble polymer network by curing. Curing can be induced by the action of heat or suitable radiation, or both. A cured thermosetting polymer is called a thermoset.

Process:The curing process transforms the resin into a plastic or rubber by a cross-linking process. Energy and/or catalysts are added that cause the molecular chains to react at chemically active sites (unsaturated or epoxy sites, for example), linking into a rigid, 3-D structure. The cross-linking process forms a molecule with a larger molecular weight, resulting in a material with a higher meltingpoint. During the reaction, the molecular weight has increased to a

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point so that the melting point is higher than the surrounding ambient temperature, the material forms into a solid material.

Properties :

Thermoset materials are generally stronger than thermoplastic materials due to this three dimensional network of bonds (cross-linking), and are also better suited to high-temperature applications up to the decomposition temperature. However, they are more brittle. Since they are "set" (non-reformable), they tend not to be recyclable.

A Thermoplastic, also known as a thermosoftening plastic, is a polymer that becomes pliable or moldable above a specific temperature, and returns to a solid state upon cooling. Most thermoplastics have a high molecular weight, whose chains associate through intermolecular forces; this property allows thermoplastics to be remolded because the intermolecular interactions spontaneously reform upon cooling. In this way, thermoplastics differ from thermosetting polymers, which form irreversible chemical bonds during the curing process; thermoset bonds break down upon melting and do not reform upon cooling.Stress strain graph of thermoplastic material.

SOME OTHER TYPES OF POLYMERSSOME OTHER TYPES OF POLYMERS:1.Acrylic:

Acrylic, a polymer called poly(methyl methacrylate) (PMMA), is also known by trade names such as Lucite, Perspex and Plexiglas. It serves as a sturdy substitute for glass for such items as aquariums, motorcycle helmet visors, aircraft windows, viewing ports of submersibles, and lenses of exterior lights of automobiles

2.Nylon:

Nylon, belonging to a class of polymers called polyamides, has served as a substitute for silk in products such as parachutes, flak vests and women's stockings. Nylon fibers are useful in making fabrics, rope, carpets and strings for musical instruments. In bulk form, nylon is used for mechanical parts, including machine screws, gear wheels and power tool casings. In addition, nylon is used in the manufacture of heat-resistant composite materials.

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3.Polyethylene:

Polyethylene (or polyethene, polythene, PE) is a family of materials categorized according to their density and molecular structure. For example, ultra-high molecular weight polyethylene (UHMWPE) is tough and resistant to chemicals, and it is used to manufacture moving machine parts, bearings, gears, artificial joints and some bulletproof vests.

4.Polypropylene:

Polypropylene (PP) is useful for such diverse products as reusable plastic containers, diapers, sanitary pads, ropes, carpets, plastic moldings, piping systems, car batteries, insulation for electrical cables and filters for gases and liquids. In medicine, it is used to repair hernias and to make heat-resistant medical equipment

5.Polystyrene:

Polystyrene is manufactured in various forms that have differing applications. Extruded polystyrene (PS) is used in the manufacture of disposable cutlery, CD and DVD cases, plastic models of cars and boats, and smoke detector housings. Expanded polystyrene foam (EPS) is used in making insulation and packaging materials, such as the "peanuts" and molded foam used to cushion fragile products

6.Polyvinyl chloride:

It is used in construction industry, such as for vinyl siding, drainpipes, gutters and roofing sheets. It is also converted to flexible forms with the addition of plasticizers, thereby making it useful for items such as hoses, tubing, electrical insulation, coats, jackets and upholstery

7.Teflon:

Teflon is the brand name given by DuPont Corp. for a polymer called polytetrafluoroethylene (PTFE), which belongs to a class of thermoplastics known as fluoropolymers. It is famous as a coating for non-stick cookware.

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BiodegradabilityPlastics Waste: Environmental Issues and ChallengesThe Thermoplastics are recyclable plastics which include; Polyethylene Terephthalate (PET), Low Density Poly Ethylene (LDPE), Poly Vinyal Choloride(PVC), High Density Poly Ethylene (HDPE), Polypropylene(PP), Polystyrene (PS) etc. However, thermoset plastics contains alkyd, epoxy, ester, melamine formaldehyde, phenolic formaldehyde, silicon, urea formaldehyde, polyurethane, metalised and multilayer plastics etc. The environmental hazards due to mismanagement of plastics waste include the following aspects:

Ø . Littered plastics spoils beauty of the city and choke drains and make important public places filthy;

Ø . Garbage containing plastics, when burnt may cause air pollution by memitting polluting gases;

Ø . Garbage mixed with plastics interferes in waste processing facilities and may also cause problems in landfill operations;

Steps Involved in the Recycling Process 

Selection: The recyclers / reprocessors have to select the waste / scrap which are suitable for recycling /reprocessing.

Segregation: The plastics waste shall be segregated as per the Codes 1-7 mentioned in the BIS guidelines.

Processing: After selection and segregation of the pre-consumer waste (factory waste) shall be directly recycled. The post consumer waste (used plastic waste) shall be washed, shredded, agglomerated, extruded and granulated.

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Polymer Coated Bitumen Road:-

Ø . The coating of plastics over aggregate improves Impact, Los Angels Abrasion and Crushing Value with the increase in the percentage of plastics.

Ø . The extracted bitumen showed almost near value for Marshall stability. The entire road was having good skid resistance and texture values.

Ø . All the stretches in the roads have been found reasonably strong.

Ø . The plastic tar roads have not developed any potholes, rutting, raveling or edge flaw, even though these roads are more than four years of age.

Ø . Polymer coated aggregate bitumen mix performs well compared to polymer modified bitumen mix.

Ø . Foam plastics have better binding values.

Biodegradable Plastics:. Often queries are raised regarding biodegradability of plastics but clear-cut answer is not available about the biodegradability of plastics. In view of above, CPCB has initiated a study in collaboration with Central Institute of Plastics Engineering and Technology (CIPET) to establish the biodegradability and compostability (e.g. fragmentation rate, degradation rate and safety) of polymeric material available in India and abroad.

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When we talk of a substance being “plastic” most people would agree on its meaning. It can flow or be moulded, it is ductile or it can be shaped, but when we turn to defining “plastics” (the noun) we have problems. Almost any simple definition will exclude materials which everyone would agree should be included so we have to turn to scientific terms and start with the comment that plastics are all polymers (poly = many).

Natural polymers have been with us since time began but synthetic polymers are much more recent, their origins being traced to Alexander Parkes and his exhibits of Parkesine at the International Exhibition of London in1862. Natural polymers include shellac, tortoiseshell and horn, as well as many resinous tree saps. All these have been processed with heat and pressure into articles such as hair combs and items of jewellery for many centuries.

A polymer is simply a very large molecule made up of many smaller units joined together, generally end to end, to create a long chain. The smallest “building block” of a polymer is called a monomer (mono = one) and if all the monomers are chemically the same, then that polymer is called a homopolymer.

Monomers generally contain carbon and hydrogen with, sometimes, other elements such as oxygen, nitrogen, chlorine or fluorine. Perhaps the most common example of a synthetic homopolymer today is polyethylene or “polythene” whilst other

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common materials are polypropylene, polystyrene and poly(vinyl chloride), more commonly know as “PVC”.

Properties OF plastics:The properties of plastics are defined chiefly by the organic

chemistry of the polymersuch as

HardnessDensityResistance to heatOrganic solventsOxidation, andIonizing radiation

In particular, most plastics will melt upon heating to a few

hundred degrees Celsius. While plastics can be made

electrically conductive, with the conductivity of up to 80 kS/cm

in stretch-oriented polyacetylene,they are still no match for

most metals like copper which have conductivities of several

hundreds kS/cm.

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polymer

NameUrea formaldehyde

CAS Number 9011-05-6

Formula (C-H4-N2-O.C-H2-O)x

Major Category

Plastics & Rubber

Synonyms Formaldehyde, urea polymer; Gabrite; Hygromull; KM 2 (Polymer); Karbamol; Karbamol B/M; Kauresin K244; Kaurit 285 FL; Kaurit 420; PR 703-78; Pianizol; Piatherm; Piatherm D; Plastopal BT; Plyamine HD 1129A; Plyamine P 364BL; Poly(methi(bis(hydroxymethyl))ureylene)amer; Polynoxylin; Ponoxylan; Resamin 155F; Resamin HW 505; Resina X; S-Resin AER 20; Uformite 700; Uformite F 240N; Uloid 100; Uloid 22; [ChemIDplus]

Category Formaldehyde Resins

Description Amorphous powder; [HSDB]

Sources/Uses Amino resins are thermosetting plastics formed from the reaction of formaldehyde and an amino group, usually urea or melamine. They are used as bonding agents in plywood and particle board and wrinkle-resistance agents in textiles. They are also molded for electrical devices and various commercial and

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home applications. [LaDou (2nd ed.), p. 522-3] Urea-formaldehyde resins are used in hot-box and no-bake systems for coremaking in foundries.

Comments Amino resins are skin sensitizers. [LaDou (2nd ed.), p. 522-3] Occupational asthma reported in workers manufacturing plastic resins and foams; [Malo]

Restricted Urea-formaldehyde foam was banned in home insulation in 1982 because the release of formaldehyde was an indoor air hazard. [LaDou (2nd ed.), p. 522]

Exposure AssessmentVapor

Pressure7.28e-05 mm Hg

Lethal Concentratio

n

LC50 (rat) > 167 mg/m3/4h

Adverse EffectsSkin

SensitizerYes

Asthma Yes

Health Studies

Human Health Effects from Hazardous Substances Data Bank:POLYNOXYLIN

SOME IMPORTANT FACTSRelated Information

Diseases Occupational diseases associated with exposure to this agent:Asthma, occupational Contact dermatitis, allergic

Processes Industrial Processes with risk of exposure:Plastic Composites Manufacturing Textiles (Printing, Dyeing, or Finishing)

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Urea-Formaldehyde is everywhere and used in many manufacturing processes due to its useful properties.).

The product is widely chosen as an adhesive resin due to its high reactivity, good performance, and low price. Urea-formaldehyde resin is a chemical combination of urea and formaldehyde. Amino resins are considered a class of thermosetting resins of which urea-formaldehyde resins make up 80% produced globally. Examples of amino resins include automobile tires in order to improve the bonding of rubber to tire cord, paper for improving tear strength, molding electrical devices, molding jar caps, etc.

Agricultural use   :

Urea formaldehyde is also used in agriculture as a controlled release source of nitrogen fertilizer. Urea formaldehyde’s rate of decomposition into CO2and NH3 is determined by the action of microbes found naturally in most soils. The activity of these microbes, and, therefore, the rate of nitrogen release, is temperature dependent. The optimum temperature for microbe activity is approximately 70-90 °F (approx 20-30°C).

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Experiment:-

Objective-To prepare hard plastic (Urea –formaldehyde resin)

Introduction-Plastics are most commonly used in our daily life. Some of

them become soft on heating called Thermoplastics whereas others do not

become soft on heating called Thermosetting plastic . In this project we shall

prepare thermosetting plastic

Theory:A plastic is a synthetic material which can be molded or set into desired shape when soft, and then hardened to produce a durable article.

Plastics are of two types

1. Thermoplastics (soft plastics)2. Thermosetting plastics

Thermoplastic (soft plastic)

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A plastic which can be melted repeatedly by boiling and can be molded again and again into different shapes is called a Thermoplastic substance or thermoplastic substance.

Example Polythene Polyvinyl chloride(PVC) Nylon

………..CH2.....CH2…..CH2….CH2……………..CH2……CH2…..CH2….CH2…….

Thermosetting plastic (Hard Plastic)

A plastic substance which, once set, does not become soft on heating and cannot be molded a second time is called a thermosetting plastic or thermosetting plastic or thermosetting polymer.

Examples

Bakelite Melamine Urea –formaldehyde resin

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Material Required-

China Dish Tripod stand Bunsen burner Urea Formaldehyde

Procedure

Dissolve 5 gram of urea completely in 20ml of formaldehyde.

Heat it for 15 minutes. the solution on cooling becomes hard .

Observation:

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White hard material at the bottom of the beaker.

Result:

Hard plastic is obtained.

:Bibliography:THE PROJECT DERIVES FROM VARIOUS SOURCES.

SOME OF THEM ARE:

NCERT CHEMISTRY CLASS XIIMTG-REACTION MECHANISMS IN ORGANIC CHEMISTRY-DR. MUKUL C RAY ORGANIC CHEMISTRY-SOLOMON & FRYHLEB. BHUSHAN’S LABORATORY MANUAL

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