Feedstocks for Polymers

Fermentation-derived organic acids and their esters are potentially important chemical feedstocks for polymers and specialty polymers, but most significantly as alternative solvents for industrial and consumer applications. For example, lactate esters are derived from renewable carbohydrate raw materials such as cornstarch. They exhibit much lower toxicity compared with halogenated hydrocarbons and ethylene glycol ethers and are environmentally benign. Some studies suggested that lactate ester solvents have the potential of replacing petroleum-based solvents... 

Oxidation of naphthalene gives phthalic acid, which can also be obtained by air oxidation of o-xylene. Phthalic acid is an important feedstock for polymers and plasticizers and so, once again, the fragrance industry is piggy-backing on a larger industry to obtain... 

Most of the fibers and resins currently available on the market are derived from petroleum. There are two major problems associated with using petroleum as the feedstock for polymers. First, it is a non-renewable (non-sustainable) resource and at the current rate of consumption, by some estimates, it is expected to last for only 50-60 years [1]. Also, the current petroleum consumption rate is estimated to be 100,000 times the rate of natural generation rate [1]. Second, most fibers and resins made using petroleum are non-degradable. Although this is desirable in many applications from the durability point of view, at the end of their life, they are not easy to dispose of. Discarded... 

This text discusses how and why major chemicals are manufactured. Intertwined in these discussions are concepts such as separation techniques, cost, conversion, transport, byproduct formation, and other items critical to industrial chemistry. Many of the major chemicals are discussed. Also discussed are several different industries. Most of the largest volume organic chemicals that are produced are made as feedstocks for polymers. For this reason, polymer chemistry is given special attention. The text discusses many of the major industrial polymers including their synthesis and properties. A background in polymer science is also presented so that the reader becomes familiar with some important concepts such as glass transition. 

This has prompted research activities all over the world to find alternative feedstocks for polymers. Agricultural by-products and forest products have become more attractive these days as renewable resources for polymers and plastics additives. Plant exudates such as gum arable, gum ghatti, gum karaya, gum tragacanth etc. have been used in textiles, cosmetics and pharmaceuticals mainly as emulsifiers and thicknersl. Other types of gums from seed such as guar gum have similarly been used. But these have not been utilized as the raw material for polymer manufacture. 

In life cyde assessments, the problem arises that production systems may have more than one output. For instance, mineral oil refinery processes may generate not only feedstock for polymer production but also gasoline, kerosene, heavy fuel oil, and bitumen. In the case of multi-output processes, extractions of resources and emissions have to be allocated to the different outputs. There are several ways to do so [31]. Major ways to allocate are based on physical units (in the case of refineries, for example, energy content, hydrogen content, or weight of outputs) or on monetary value (price). There may also be allocation on the basis of substitution. In the latter case, the environmental burden of a coproduct is established on the basis of another similar product. Different kinds of allocation may lead to different outcomes of life cyde inventories. The outcome of the inventory stage is a list with all extractions of resources and emissions of substances causally linked to the functional unit considered. 

It may be expected that cumulative fossil fuel demand linked to a nanocomposite life cyde will be a major determinant of the environmental impact [33] of nanocomposite life cyde. Apart from the case that crops are used as feedstock for polymer production, cumulative fossil fuel demand may even be the main determinant of the overall environmental burden [33]. 

If a linear mbber is used as a feedstock for the mass process (85), the mbber becomes insoluble in the mixture of monomers and SAN polymer which is formed in the reactors, and discrete mbber particles are formed. This is referred to as phase inversion since the continuous phase shifts from mbber to SAN. Grafting of some of the SAN onto the mbber particles occurs as in the emulsion process. Typically, the mass-produced mbber particles are larger (0.5 to 5 llm) than those of emulsion-based ABS (0.1 to 1 llm) and contain much larger internal occlusions of SAN polymer. The reaction recipe can include polymerization initiators, chain-transfer agents, and other additives. Diluents are sometimes used to reduce the viscosity of the monomer and polymer mixture to faciUtate processing at high conversion. The product from the reactor system is devolatilized to remove the unreacted monomers and is then pelletized. Equipment used for devolatilization includes single- and twin-screw extmders, and flash and thin film evaporators. Unreacted monomers are recovered for recycle to the reactors to improve the process yield. 

Natural gas Hquids represent a significant source of feedstocks for the production of important chemical building blocks that form the basis for many commercial and iadustrial products. Ethyleae (qv) is produced by steam-crackiag the ethane and propane fractions obtained from natural gas, and the butane fraction can be catalyticaHy dehydrogenated to yield 1,3-butadiene, a compound used ia the preparatioa of many polymers (see Butadiene). The / -butane fractioa can also be used as a feedstock ia the manufacture of MTBE. 

About 35% of total U.S. LPG consumption is as chemical feedstock for petrochemicals and polymer iatermediates. The manufacture of polyethylene, polypropylene, and poly(vinyl chloride) requires huge volumes of ethylene (qv) and propylene which, ia the United States, are produced by thermal cracking/dehydrogenation of propane, butane, and ethane (see Olefin polymers Vinyl polymers). 

Propjiene [115-07-17, CH2CH=CH2, is perhaps the oldest petrochemical feedstock and is one of the principal light olefins (1) (see Feedstocks). It is used widely as an alkylation (qv) or polymer—ga soline feedstock for octane improvement (see Gasoline and other motor fuels). In addition, large quantities of propylene are used ia plastics as polypropylene, and ia chemicals, eg, acrylonitrile (qv), propylene oxide (qv), 2-propanol, and cumene (qv) (see Olefin POLYMERS,polypropylene Propyl ALCOHOLS). Propylene is produced primarily as a by-product of petroleum (qv) refining and of ethylene (qv) production by steam pyrolysis. 

Sucrose acrylate derivatives can be converted into polymers and hydrogels that can be used as flocculants, water adsorbents, bioimplantables, and dmg dehvery devices (42). Sucrose ethers have appHcations as surfactants and surface coatings, and as feedstocks for synthesis of polyurethane foams and... 

Since the bulk of butadiene is recovered from steam crackers, its economics is very sensitive to the selection of feedstocks, operating conditions, and demand patterns. Butadiene supply and, ultimately, its price are strongly influenced by the demand for ethylene, the primary product from steam cracking. Currently there is a worldwide surplus of butadiene. Announcements of a number of new ethylene plants will likely result in additional butadiene production, more than enough to meet worldwide demand for polymers and other chemicals. When butadiene is in excess supply, ethylene manufacturers can recycle the butadiene as a feedstock for ethylene manufacture. 

Most of the propylene polymerized by this process is used in motor gasoline ("Polymer Gasoline"). However, an appreciable portion of the C7, C, and C,2 olefins find use as feedstocks for production of Oxo alcohols. 

Ethene and propene are produced as bulk feedstocks for the chemical (polymer) industry and therefore their purities are important parameters. In particular, H2S and COS are compounds which may not only cause corrosion problems in processing equipment, but also may have detrimental effects on the catalysts in use. Eurthermore, air pollution regulations issued by, among others, the US Environmental Protection Agency (EPA) require that most of the sulfur gases should be removed in order to minimize Sulfur emissions into the atmosphere. Therefore, these compounds have to be determined to the ppb level. 

Conjugated dienes are among the most significant building blocks both in laboratories and in the chemical industry [1], Especially, 1,3-butadiene and isoprene are key feedstocks for the manufacture of polymers and fine chemicals. Since the discovery of the Ziegler-Natta catalyst for the polymerizations of ethylene and propylene, the powerful features of transition metal catalysis has been widely recognized, and studies in this field have been pursued very actively [2-7]. 

Propylene, a light olefin, is like ethylene one of the most important feedstocks for the petrochemical industry. In recent years the main way to obtain propylene and ethylene has been via cracking of naphtha. For this reason the cost of the corresponding polymers, mainly polypropylene and polyethylene, depends on the international oil price. One big challenge for modem chemistry is to look for an alternative production of feedstocks that is independent of the oil-industry. 

Solid PET feedstock for the SSP process is semicrystalline, and the crystalline fraction increases during the course of the SSP reaction. The crystallinity of the polymer influences the reaction rates, as well as the diffusivity of the low-molecular-weight compounds. The crystallization rate is often described by the Avrami equation for auto-accelerating reactions (1 — Xc) = cxp(—kc/"), with xc being the mass fraction crystallinity, kc the crystallization rate constant and n a function of nucleation growth and type. 

End uses. Its a little curious that the two major end uses for EG are so different. One is -a consumer product the other is a feedstock for more complicated chemistry. The reasons have to do with two separate properties of EG, one physical property, one chemical property. Because of EG s low freezing point, it is the main ingredient in automotive antifreeze. Because it is so chemically reactive, it is used as a monomer in making polyester polymers and PET, the plastic in the ubiquitous water and drink bottles. 

What are some of the obstacles to using polymer-intensive plants as feedstocks for the preparation... 

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