1 0 obj This highly crystalline thermoplastic resin is built up by the chain-growth polymerization of propylene (CH2=CHCH3), a gaseous compound obtained by the thermal cracking of ethane, propane, butane, or the naphtha fraction of petroleum. The disadvantages of the polystyrene plastic injection molding process are low melt flow index, high melting point, and a short temperature range. (1 mark) (b) Draw the structure of the monomer which WebIntroduction to material science and engineering solutions chapter polymer structures problem solutions hydrocarbon molecules polymer molecules the chemistry of The word polymer derives its meaning from this, which means "many mers". The figure at right depicts one part of the polymer chain. [118,119] for branched polyesters. Syndiotactic polystyrene (SPS) is a semicrystalline polymer synthesized from styrene monomer using a single-site catalyst such as metallocene. In a step-reaction polymerization reaction, sometimes called condensation polymerization, the polymer chains grow by reactions that occur between two molecular species. The structure of a short section of polystyrene is shown below. Usually, polystyrene shrinks less than 0.5%, which is low compared to other injection molded plastics. UNIT: VALUE / RANGE: PREFERRED: Molar Volume V m: mL mol-1: 99.0 - 99.5: 99.2: Density : g mL-1: 1.05: 1.05: Solubility Parameter : MPa 1/2: 17.7 - 20.8: 18.3: Polystyrene is manufactured through an extrusion process. Polypropylene is one of the most used plastics in the production of households, food containers, electronics parts, packaging, automotive components, and other industries. /Filter /FlateDecode Selvaganapathy, in Reference Module in Materials Science and Materials Engineering, 2016. As a plastic, polypropylene is blow-molded into bottles for foods, shampoos, and other household liquids. How many monomers are present? WebAtomic structure and bonding: Polystyrene Polystyrene is a polymer made up of repeating units of the monomer styrene, which has a molecular formula of C8H8. These six polymers are thermoplastic: they can be melted and reshaped, or recycled. (a) To calculate the concentration of initiator required to prepare polystyrene with a number average molar mass of 750 kg/mol, we can use the following equation: M n = f M i 1 f. Explanation: where M n is the number average molar mass of the polymer, f is the initiator efficiency, and M i is the molar mass of the initiator. It is a thermoplastic polymer, meaning it softens and melts when heated and can be reused. Those include shower doors, cosmetic bottles, and toys. It is also injection-molded into many products, such as appliance housings, dishwasher-proof food containers, toys, automobile battery casings, and outdoor furniture. Find or choose one type of each of the following plastic polymers, and report the following characteristics: Report for plastic samples in each liquid: sinks rapidly, sinks slowly, floats on top, floats below surface, Ranking of densities: WebPBTCTO exhibit twist angles between the D-A repeat units of 7.5 and 7.9, respectively, which are slightly larger than for the other polymers ( 1 3 ), they are further planarized in the lm state (PBTCT showed a 40 nm red-shift in its absorption max not easily predictable. endobj 800North Bethesda, MD 20852, ITAR | ISO 9001:2015 | AS9100D | ISO 13485:2016. Polystyrene can be represented using a shorthand notation. Californians Against Waste [45] reports that current estimates by the California Department of Conservation peg the costs of recycling (expanded) polystyrene at over $3000 per ton, meaning that polystyrene actually has a negative scrap value [46]. >> Polypropylene shares some of the properties of polyethylene, but it is stiffer, has a higher melting temperature, and is slightly more oxidation-sensitive. I'm having a hard time deterring where the additional H is coming from. Polystyrene is transparent, thanks to its lack of crystallinity. A Shrinky-Dink process has also been used to fabricated PS microfluidics from pre-stressed PS sheets (C. Chen et al., 2008). Known as oriented polystyrene (OPS) they are brittle until biaxially oriented and then become comparatively flexible and durable. What is the difference between polystyrene and expanded polystyrene? However, please remember that theyre not edible! The styrene monomer is polymerized using free-radical initiators primarily in bulk and suspension processes, although solution and emulsion methods are also employed. % Glue contains the polymer polyvinyl acetate, which cross-links to itself when reacted with borax (diagram below). We are leaving to the Expo in CHINA, so it's time to pack the bags to bring a little bit of La Rioja and our house on the other side of the world. slimy? Because of its low gas barrier, it can be used for produce where a breathable film is required. WebThe molar mass of a repeat unit in polypropylene is M(CH 2CH(CH 3)) = 42:08gmol 1. Obtain front bench: paper cup with approximately 100 mL of Elmers glue (sample cup will be marked to 100 mL), ruler and 3 plastic spoons. The LibreTexts libraries arePowered by NICE CXone Expertand are supported by the Department of Education Open Textbook Pilot Project, the UC Davis Office of the Provost, the UC Davis Library, the California State University Affordable Learning Solutions Program, and Merlot. Comparison of General Purpose (Crystal) and High Impact Polystyrene. Suggest the composition of this plastic. HIPS is similar to ABS as uses Limonene as a solvent during manufacture. Suggest a way to separate it commercially from other waste plastics. Electronics also use this materials rigid form for housings and casings. Most of SAN resins are consumed in the production of emulsion polymerized ABS resins through compounding. Polymers are large molecules that have the same structural unit repeating over and over. WebMoles of polystyrene MWpolystyrene = 9 H atoms 1 g/mol + 8 C atoms 12 g/mol = 105 g/mol No. The polymer repeating unit has the following structure: Only the isotactic form of polypropylene is marketed in significant quantities. ABS polymers generally are tougher than HIPS, and have higher chemical resistance, but are somewhat more difficult to process. (a) Draw the structure of the repeat unit of polystyrene. This is because the HOMO/LUMO Styrene is the monomer for polystyrene, whereas propylene is for The recycled plastic is used in low-cost applications such as horticultural trays, wastebaskets, wood substitutes, packaging foam, and desk trays. WebPolymers consist of many repeating monomer units in long chains. Table 6.26. The ester unit has an alcohol on one end and acid on the other, which are available for further reactions. A polymer is analogous to a necklace made from many small beads (monomers). Buyers seeking quotes for parts are responsible for defining the specific requirements for those parts. Styrene is an aromatic monomer and PS is an aromatic polymer. The smallest constitutional unit the repetition of which constitutes a regular macromolecule, a regular oligomer molecule, a regular block or a regular chain. Most commercially available polystyrene is atactic polystyrene. Construction also benefits from this material as polystyrene foam is used as insulation. The initial shift in color after the 100 kGy radiation dose returns close to the original color within a week [89]. In this case the repeat unit has the same atoms as the monomer vinyl chloride CH2=CHCl. Due to the copolymerization characteristics of acrylonitrile and styrene monomer, most SAN resins contain 15 to 30% by weight of AN monomer. WebPolymers are covalently bonded long chain molecules composed of repeating units, called monomers, comprised of carbon and hydrogen, and sometimes oxygen, nitrogen, sulfur, These can be designed and built to suit the needs of the healthcare professional. Based on your data in the table, which compound was most likely responsible for this? When applied as sheathing, EPS should be used over house wrap. This ensured complete dispersion of CNPs in polystyrene. For polymerization to take place, the monomers must be capable of being linked to two (or more) other monomer molecules2 . What is the role of each of the following in the formation of the polymer? However, it is the trademarked name for closed-cell extruded polystyrene foam made from thermal insulation. Polystyrene melts at a relatively high melting temperature of 210 C to 250 C, requiring higher energy demand to perform the injection molding process. Thus, m = 8(AC) + 8(AH) In heavier gages, polystyrene is widely used for transparent thermoformed trays. EPS foam is the insulation used most widely in ICFs and SIPs. Constitutional repeating unit (CRU): PS was first manufactured by BASF in the 1930s and is used in numerous plastic products. Injection molded articles include picnic cutlery, compact disc jewel boxes, audiocassette housings and toys. Kindly comment on your questions and reviews in the comment box. It is a thermoplastic polymer, meaning it softens and 4. PET is the plastic in soda bottles. Polyvinylchloride (PVC) is composed of the vinyl chloride monomer. At room temperature, PS is normally a solid Polystyrene has a chain where the substituent R is a phenyl group (C6H5), corresponding to a benzene ring minus one hydrogen: -[CH2-CH(C6H5)]n-, so the repeat unit is -[CH2-CH(C6H5)]-. also known as copolymers. Some of these polymers are synthesized by methods involving initiators other than free radicals - carboanions, carbocations, or coordination compounds, for instance. Javascript is not enabled on your browser. Why is it important to dislodge any adhering bubbles in the density tests? Draw the repeat unit of the polyester chain formed by reaction of ethane-1,2-diol (shown in question 3) and butanedioic acid (shown below). Ans. Its co polymerized forms of ABS, SBR, SAN, and HIPS can be used for applications from 3D printed prototypes to optical fibers rubber gaskets to automotive gas tanks. WebPolymer chains with longer monomer units have more potential fragmentation sites within each repeat unit, and thus, the alphabetic nomenclature is adjusted accordingly (cf. Several companies, including RTP Company, compound plastic formulations based on SPS. For polystyrene, from Table 5, each repeat unit has eight carbons and eight hydrogens. Discover the reasons why Styrofoam (polystyrene) is not recycled as much as it could be. What are the different types of polystyrene? This makes the polypropylene injection molding process less energy-intensive, with a faster production cycle. This page titled 6: Synthetic Polymers and Plastics (Experiment) is shared under a not declared license and was authored, remixed, and/or curated by Santa Monica College. Science. That was all I had to say about polystyrene repeating unit and properties. (A) Poly (methyl methacrylate) (B) Polyethylene (C) Polypropylene (D) Polystyrene 1 Approved Answer Saroj K answered on March 19, 2021 5 Ratings ( 12 Votes) Answer -------- (D) Polystyrene Because Polystyrene is a hard, brilliantly transparent, solution .pdf Figure 3.21. While polystyrenes uses are flexible and it features a low shrink rate, it also flows slowly and can come out brittle. Identify the samples by looking for the number/recycling symbol. Injection molded high-heat crystal grades are typically used in applications such as medical products, packaging, housewares, office accessories, and compact disc containers. The beaker with polystyrene and benzene was placed on a hot plate and heated at 50C along with continuous stirring for 7h. Carbon nanoparticles (CNPs; Printex L6 supplied by Degussa) were weighed (35% of PS weight) and added to the same beaker. WebFor polystyrene, from Table 5.3, each repeat unit has eight carbons and eight hydrogens. -[CH2-CHCl]n-, whose repeat unit is -[CH2-CHCl]-. Amongst the foam, there are two types expanded polystyrene (EPS) and extruded polystyrene (XPS). Styrene with or without diluents is mixed with a free radical initiator like dibenzoyl peroxide and heated to a temperature of 120C. However, at a price of about 19 per sq. Polystyrene co-polymerization with compounds like rubber or butadiene is also often used to improve the materials impact strength and make the plastic less brittle. Like conventional amorphous polystyrene, sPS is brittle but can be reinforced with glass or alloyed with other polymers to improve toughness. WebWhich one of the following is the chemical formula for the repeating unit in polyethylene: (a) CH2, (b) C2H4, (c) C3H6, (d) C5H8, or (e) C8H8? You can read more about him at About me page. Their low heat distortion temperatures will cause the parts to warp and disfigure (Table 6.29). Crystal polystyrene resins are glassy and crystal clear and are most often supplied in the form of one-eighth-inch granules. Table 6.28. The Big Six thermoplastics have these general attributes: The most common of the Big Six plastics is high-density polyethylene (HDPE). For the bouncy balls you made, what is the name of the monomer? If the sample sinks, it has a density greater than that of the liquid. The repeat unit of the polystyrene polymer is the styrene monomer, which comprises a vinyl group and a benzene ring. Polystyrene is food safe, though over time it can leach styrene. (a) Process flow for the fabrication of 3D microfluidic chips using the Shrinky-Dink method. In the case of Numerous industrial end uses exist for polypropylene fibre as well, including rope and cordage, disposable nonwoven fabrics for diapers and medical applications, and nonwoven fabrics for ground stabilization and reinforcement in construction and road paving. It also features low shrinkage during the plastic injection molding process. The compound is often called simply SBS or SBS rubber. The structure of a short section of polystyrene is shown below. It is resistant to low molecular weight alcohols, ethylene oxide, and oxidizing and disinfecting agents (Table 6.28). Surface tensions will cause all of the plastic to float until each is wetted and submerged using the rod.