Question

can someone help me find this information?

Pre-Laboratory Exercise: Plastics Identification I. List four properties that you will use in lab to determine the identity of the polymer samples 2. Describe the density test. What observation will help you determine the density of each polymer? What precautions should be taken in placing the sample in the solutions? 3. Write the name and abbreviation for the six recyclable polymers 2 huetn deisity polyetayene.HDpz poulene: PP 4. Given the list of wavenumber ranges in the experiment, identify the main functional VI groups and the identity of the IR spectra below. Identify peaks (the peaks point downward.) that are #30% transmittance (large absorption values). Any unique peaks may also be noted. Appendix -41 Experiment 18 lastic Identification Objectives To learn some physical and chemical properties of plastics . To Identify unknown plastic samples Prior Reading Chemistry: The Central Science Section 12.8: Polymeric Solids pp. 490-496 Introduction From plastic jugs to toys, from jet canopies to patches for heart surgery plastics have changed our containers, our possessions and our economy. The everyday use of plastics slowly became popular in the 1960's. It was thought to be an up and coming industry. Little did the scientists know then just how enormous the plastics industry would become. Plastics are not only used for all types of bags and containers, but also for adhesives, building material, and clothing. These plastics belong to a group of chemicals known as polymers. Polymers are long chains of molecules with a repeating unit (poly- meaning more than one and -mer meaning unit). In this category there are also natural polymers such as cotton and rubber and acrylics such as adhesives and hardeners. The properties of these substances differ just as the properties of other compounds. Polymers can be classified by their formability as thermoplastics (a polymer that melts upon heating) or thermosets (a polymer that does not melt but hardens then Experiment 18-1 decomposes upon heating). This is one way to determine what types of plastics are recyclable and for what types of products. Thermoplastics can be melted and reshaped while thermosets can only be ground up to be used as a type of "filler" for another substance. Also, if a container is to be recycled, it cannot be used to store a food product even if it once held food. Just as substances can be observed through physical state changes, polymers can be observed or analyzed while they transform during transitional phases. The graph below is an example of a transitional diagram of a polymer. 0 Temperatune dealized modulus-temperature behavior of an amorphous polymer At low temperatures, a polymer is in the glassy state (1). One such polymer at room temperature would be your stiffer, common plastics. The next phases is the glass transition (2). At this point the polymer starts to become viscous; therefore, its properties change. An example of a polymer in this stage would be latex paint. The paint is flexible, yet does not flow like a liquid. The third stage is the rubber plateau (3). The elastic properties of this transition stage come from the chains having more energy due to temperature, but not enough for viscous flow. The fourth phase is rubbery flow (4). In this stage, the polymer is elastic but does not return to its original form. The last phase is viscous flow (5). This stage exhibits no elastic properties but due to the long entangling chains this stage does give the polymer lubricating abilities, more than a typical liquid. Many types of polymers exhibit these properties at room temperature, which yields the vast number of product applications. The different properties also come about by the structure of the polymer and size of the chains involved. For a substance to be considered a polymer, the molecular weight must be close to 25,000 gmol. Dealing with Experiment 18-2 polymers is quite different from dealing with the structures of basic inorganic and organic structures. For a given polymer, the repeating unit will be the same but the chain length can vary by controlling the reaction, or mechanism. Even though the chain lengths can vary, if the basic unit is the same, it is still referred to as that polymer. Think of spaghetti noodles. Even though the noodles can be broken into very small pieces, it is still considered to be spaghetti. Spaghetti also aids in the understanding of the physical state. A polymer can be amorphous or crystalline: the amorphous state represented by cooked spaghetti and the crystalline state represented by uncooked spaghetti Amorphous polymers begin to soften at a point known as Tg which is the glass transition. The melting point of a polymer is Tr. Therefore, a heating curve can be drawn for a polymer. It should be noted that a thermoset will not have a Tr because it does not melt. Another form of identification is density. The shape and number of chains will dictate the density of the substance. Crystalline polymers which are more structured in nature will tend to have a higher density. An amorphous polymer will tend to have a lower density. Fillers can be added to change the density of a substance. An example of crystalline(A) and amorphous (B)regions are given below. A substance may be amorphous or partially crystalline. A polymer cannot be completely crystalline due to the large size of the chains. Polymers can also be classified by their molecular weight. Since the density has more to do with the shape of the chain, the molecular weight may not always indicate the density of the polymer. Other properties such as viscous flow can also be used to classify polymers. Due to the popularity of plastics there are mass quantities of this material, the topic of recycling must also be discussed. Many plastics can be recycled in many ways, some of the possibilities were mentioned above. On a given container, there will be the symbol of the polymer and a recycle code. Most of the plastic products that we use are composed of approximately six-eight polymers (listed below). In the table below (with the exception of the first polymer) the vinyl monomers are characterized by the general structure CH2 CHR where R represents any side group. The resulting polymers would have repeating chains of CH-CH-) where n is the number of repetitions. Experiment 18-3 Procedure Before coming to lab collect at least 4 plastic samples, 2 of thin plastic such as wrappers and 2 of thicker plastic such as plastic flatware or a toothbrush. Each set of partners will only use 4 samples, two thick and two thin, but unless there is collaboration in collecting samples it would be wise to bring four samples for each person. After coming to lab, the number of samples can be reduced to three per partnership. The fourth sample will be an unknown provided by the TA. First assign an identification number to each sample. The first four letters of their ID should be the initials of the partners. After the initials should be a number identifying which sample it is (ie. CFKQ1). Next record the origin of the sample and the examine it and record your observations. Density Obtain 15 to 20 mL of each of the first four density solutions(0.915, 0.95, 1.00 and 1.15 g/mL) in labeled 30 and 50 mL beakers (keep these solutions until all testing is completed). If after testing, it is found that the last three density solutions (1.22, 1.33, or 1.45 g/mL) are needed, they may be used by placing a clean plastic sample in the solution provided. Do not remove these solutions from their jars. The plastic should be cut into an approximate 2 cm by 2 cm size sample and placed in the 1.00 g/mL solution. The decision on the density will be based on whether the sample sinks or floats. Be careful not to have air bubbles on the plastic. The same sample may be used in other solutions if the sample is wiped of carefully between solutions. When determining an unknown the density test is usually quite reliable Solubility Place a drop of ethyl acetate on one of the samples, stir with a stirring rod for a few minutes and then wipe off with a paper towel. If the residue is now opaque or is sticky, some sample has dissolved. There is also hot xylene available in the hood for solubility testing. This should be used only as if the sample is not soluble in ethyl acetate. The xylene is not to be removed from the hood. Do not touch the xylene or plastic samples that have been treated with it. Just place your sample in the container, stir and observe. Always keep the xylene covered with a watch glass except when inserting or removing a sample. Record all your observations on the data sheet. Experiment 18-5 Chlorine test In a hood heat a piece of copper wire, touch it to the sample of plastic. Place the copper wire with the plastic on it into the flame. If it imparts a green color to the flame there is chlorine in the sample. Behavior in a flame Hold a piece of plastic with crucible tongs and slowly place it into the flame in the hood. Record observations noting whether it shrinks back from the flame, melts drips, burn smokes etc. Remove it from the flame and note whether it continues to burn. If it does, note the intensity of burning, smoking, dripping, etc. and record all your observations on the data sheet. This test can be difficult to judge and should not be used as the only basis for identifying an unknown. IR Spectra should be recorded for a collected sample that would provide the most useful information for identification. To get useable spectrum from a thicker piece of plastic it will be necessary to make it thinner. One way to do this is to take a 1 em by1 cm sample an place it in middle of a 5 cm by 10 cm piece of aluminum foil folded in half. Refold the foil over the sample and press it with an iron on the hot plate. If the plastic doesn't become soft and flatten out, use a hotter setup. If the plastic seems to decompose use a cooler setting. The thinner you can get your sample the better the spectrum will be. Another way to reduce thickness is to tear it at an angle. This is particular useful for soft drink containers. The sample does not have to be transparent to give a good spectrum. It will be necessary to mount the sample to a cardboard holder prior to running the IR spectra. Obtain one of the holders from the assistant. Mount a sample that is approximately 2 cm by 2 cm on the holder with two small pieces of tape. Be careful that the tape does not extend over the hole in the cardboard and that the plastic is centered over the hole. After recording the spectra remove the sample from the holder and return the holder to the assistant. Make tentative IR identification by finding and writing down the characteristics absorptions in the unknown spectrum. The "peaks' from an IR are read as downward dips in the spectra. Then compare these spectra with spectra of knowns Experiment 18-6 posted in the lab. If there are differences between the spectra of the known and the unknown be sure to note them. This can give information on additives or fillers that may be present. Spectra for the unknown will be provided Useful information for identification Density Solubility Behavior Groups for Useful IR ID non-aromatic C-H Plastic low density 0.91-0.95 hot xylene burn in and out of flame polyethylene high density 0.95-0.98 hot xylene polyethylene in a Flame drips like candle flame, drips like candle from flame from flame from flame burn in and out of non-aromatic C-H non-aromatic C-H non-aromatic C-H, chlorine polypropylene 0.89-0.92 ethyl acetate extinguishes when removed poly(vinyl 1.35-1.42 ethyl acetate extinguishes when removed chloride poly(vinylidene 1.67-1.85 ethyl acetate extinguishes when removed non-aromatic C-H, chlorine chloride) polytetrafluoro-22 does not burm fluorine non-aromatic C-H, aromatic C-H non-aromatic C-H, nitrile non-aromatic C-H, ester ethylene polystyrene 104.106 ethyl acetate! burns with lots of black smoke and soot polyacrylo- nitrile poly(vinyl acetate) poly(vinyl alcohol) polyacrylates 1.2 water alcohol non- aromatic C-H, ester polycarbonate 1.25 poly(ethylene 1.35 1.5 ester teraphthalate) cellulose non-aromatic C-H, aromatic C-H ester alcohol nylon 0.97-1.15 non-aromatic C-H, ester the absence of information in the table indicates that the plastic will burm, but no information is easily obtained from its burning Experiment 18-7 Groups with useful Caracteristic Absorption information IR information alcohols non-aromatic compounds C-H band between 3000 and 2800 cm, which is usually intense because of strong, broad band O-H between 3500 and 3300 cm the large number of C-H bond in the polymers C-H band between 3100 and 3000 en. Although this C-H band is weak, polystyrene shows a strong band in this region because of the large number of aromatic C-H bonds in the molecule. Polystyrene also shows a characteristic pattern of four relatively weak bands between 2000 and 1600 em. Teraphthlates do not show this pattern between 2000 and 1600 em moderately strong C-N band between 2400 and 2200 em aromatic compounds nitriles strong C-O band between 1820 and 1680 cm, and a strong C-O band between 1300 and 1000 cm strong C-F band between 1400 and 1200 cm, but note that many other bonds and combination of bonds also have strong absorptions in this region. strong C-CI band between 800 and 600 cm, but note that many other bonds and combination of bonds also have strong absorptions in this region. esters fluorine-containing chlorine-containing Experiment 18-8

Answer 1

Qi-Ans:- denh h cou hơn, et pobmer Sample at lab scale following on diteet Llame Idenbh cahon ot dittrent paly mer en buing charatasishc et buu lock - fume colour -én charalaisko 7 whe point on the bajis 4. ら FTIR Dansǐ5 Densiケot a substance is lis mass per unj-volume, bot Densily of a Subs mast used as 3. and unit is glee or suppo le , we want tofmdoul ter hensi et unkmo poljmn > cut the speurn on 20×20 mm in Size nsiy t Salution and Negut +u specimon wt in soluton ond vugat in know Dew¡ケSoken X Dena,of known Soluf pre caution > Avoida.hu bul,led on speu mon Sample or Spemen ordol not be touteb en siele

) High Densilj polyeinylow HOPC A) Low nens polystyren s pag propylane Pp at ) 300 0-2300 or), С-H bond dur- lenge rondo"Y 2) 8o6 600 cm, l due ts c-cl bond bond due o large pumber c unit