108-589: Theodorus Gerardus Jozef Jansen ( Dutch pronunciation: [ˈteːjoː ˈjɑnsə(n)] ; born 14 March 1948) is a Dutch artist. In 1990, he began building large mechanisms out of PVC that are able to move on their own and, collectively, are titled Strandbeest . The kinetic sculptures appear to walk. His animated works are intended to be a fusion of art and engineering . He has said that "The walls between art and engineering exist only in our minds." Some of his creations are reported to incorporate primitive logic gates for collision detection with obstacles such as
216-459: A catalyst . Laboratory synthesis of biopolymers, especially of proteins , is an area of intensive research. There are three main classes of biopolymers: polysaccharides , polypeptides , and polynucleotides . In living cells, they may be synthesized by enzyme-mediated processes, such as the formation of DNA catalyzed by DNA polymerase . The synthesis of proteins involves multiple enzyme-mediated processes to transcribe genetic information from
324-599: A health hazard in their own right, it dissolves in moisture and breaks down onto surfaces, particularly in areas where the air is cool enough to breathe, so would not be inhaled. PVC is widely and heavily used in construction and building industry, For example, vinyl siding is extensively is a popular low-maintenance material, particularly in Ireland , the United Kingdom, the United States, and Canada. The material comes in
432-441: A lower critical solution temperature phase transition (LCST), at which phase separation occurs with heating. In dilute solutions, the properties of the polymer are characterized by the interaction between the solvent and the polymer. In a good solvent, the polymer appears swollen and occupies a large volume. In this scenario, intermolecular forces between the solvent and monomer subunits dominate over intramolecular interactions. In
540-409: A 4-metre (13 ft)-wide flying saucer that was filled with helium . It was launched over Delft in 1980 on a day when the sky was hazy. Light and sound came from the saucer. Because the saucer was black against a light sky, its size was difficult to determine. The police even stated that it was 30 meters wide, and some people swore they saw a halo around it. Jansen has claimed that this project "caused
648-498: A bad solvent or poor solvent, intramolecular forces dominate and the chain contracts. In the theta solvent , or the state of the polymer solution where the value of the second virial coefficient becomes 0, the intermolecular polymer-solvent repulsion balances exactly the intramolecular monomer-monomer attraction. Under the theta condition (also called the Flory condition), the polymer behaves like an ideal random coil . The transition between
756-641: A clear correlation between dioxin formation and chloride content and indicate that PVC is a significant contributor to the formation of both dioxin and PCB in incinerators. In February 2007, the Technical and Scientific Advisory Committee of the US Green Building Council (USGBC) released its report on a PVC avoidance related materials credit for the LEED Green Building Rating system. The report concludes that "no single material shows up as
864-417: A commitment to eliminate the use of cadmium (previously used as a part component of heat stabilizers in window profiles) and phase out lead-based heat stabilizers (as used in pipe and profile areas) such as liquid autodiachromate and calcium polyhydrocummate by 2015. According to the final report of Vinyl 2010 , cadmium was eliminated across Europe by 2007. The progressive substitution of lead-based stabilizers
972-466: A compound by the incorporation of additives (but not necessarily all of the following) such as heat stabilizers , UV stabilizers , plasticizers, processing aids, impact modifiers, thermal modifiers, fillers, flame retardants , biocides , blowing agents and smoke suppressors, and, optionally, pigments. The choice of additives used for the PVC finished product is controlled by the cost performance requirements of
1080-408: A degree of crystallinity approaching zero or one will tend to be transparent, while polymers with intermediate degrees of crystallinity will tend to be opaque due to light scattering by crystalline or glassy regions. For many polymers, crystallinity may also be associated with decreased transparency. The space occupied by a polymer molecule is generally expressed in terms of radius of gyration , which
1188-587: A deviation from a simple linear chain. A branched polymer molecule is composed of a main chain with one or more substituent side chains or branches. Types of branched polymers include star polymers , comb polymers , polymer brushes , dendronized polymers , ladder polymers , and dendrimers . There exist also two-dimensional polymers (2DP) which are composed of topologically planar repeat units. A polymer's architecture affects many of its physical properties including solution viscosity, melt viscosity, solubility in various solvents, glass-transition temperature and
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#17328558952111296-464: A flexible quality. Plasticizers are also put in some types of cling film to make the polymer more flexible. The attractive forces between polymer chains play a large part in determining the polymer's properties. Because polymer chains are so long, they have many such interchain interactions per molecule, amplifying the effect of these interactions on the polymer properties in comparison to attractions between conventional molecules. Different side groups on
1404-580: A gasket-sealed joint. The most common type of gasket utilized in North America is a metal-reinforced elastomer, commonly referred to as a Rieber sealing system. PVC is often used as the insulating sheath on electrical cables . PVC is chosen because of its good electrical insulation, ease of extrusion , and resistance to burn. In a fire, PVC can form hydrogen chloride fumes; the chlorine serves to scavenge free radicals , making PVC-coated wires fire retardant . While hydrogen chloride fumes can also pose
1512-479: A given application, the properties of a polymer can be tuned or enhanced by combination with other materials, as in composites . Their application allows to save energy (lighter cars and planes, thermally insulated buildings), protect food and drinking water (packaging), save land and lower use of fertilizers (synthetic fibres), preserve other materials (coatings), protect and save lives (hygiene, medical applications). A representative, non-exhaustive list of applications
1620-402: A high surface quality and are also highly transparent so that the laser properties are dominated by the laser dye used to dope the polymer matrix. These type of lasers, that also belong to the class of organic lasers , are known to yield very narrow linewidths which is useful for spectroscopy and analytical applications. An important optical parameter in the polymer used in laser applications
1728-576: A near-riot". He said that the machine was never found, and that it probably landed somewhere in Belgium. He later repeated the project over Paris. Jansen's painting machine was developed in 1984–86 in Delft, and it was a somewhat larger project than his flying saucer. It consisted of a tube with a light cell situated at its end. When darkness was detected, the machine would begin to spray paint, creating painted silhouettes of people standing in front of it. This machine
1836-401: A polymer behaves as a continuous macroscopic material. They are classified as bulk properties, or intensive properties according to thermodynamics . The bulk properties of a polymer are those most often of end-use interest. These are the properties that dictate how the polymer actually behaves on a macroscopic scale. The tensile strength of a material quantifies how much elongating stress
1944-421: A polymer is its first and most important attribute. Polymer nomenclature is generally based upon the type of monomer residues comprising the polymer. A polymer which contains only a single type of repeat unit is known as a homopolymer , while a polymer containing two or more types of repeat units is known as a copolymer . A terpolymer is a copolymer which contains three types of repeat units. Polystyrene
2052-433: A polymeric material can be described at different length scales, from the sub-nm length scale up to the macroscopic one. There is in fact a hierarchy of structures, in which each stage provides the foundations for the next one. The starting point for the description of the structure of a polymer is the identity of its constituent monomers. Next, the microstructure essentially describes the arrangement of these monomers within
2160-536: A process called reptation in which each chain molecule is constrained by entanglements with neighboring chains to move within a virtual tube. The theory of reptation can explain polymer molecule dynamics and viscoelasticity . Depending on their chemical structures, polymers may be either semi-crystalline or amorphous. Semi-crystalline polymers can undergo crystallization and melting transitions , whereas amorphous polymers do not. In polymers, crystallization and melting do not suggest solid-liquid phase transitions, as in
2268-407: A range of colors and finishes, including a photo-effect wood finish, and is used as a substitute for painted wood, mostly for window frames and sills when installing insulated glazing in new buildings; or to replace older single-glazed windows, as it does not decompose and is weather-resistant. Other uses include fascia , and siding or weatherboarding . This material has almost entirely replaced
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#17328558952112376-534: A rare disease. Since that time, studies of PVC workers in Australia, Italy, Germany, and the UK have all associated certain types of occupational cancers with exposure to vinyl chloride, and it has become accepted that VCM is a carcinogen. PVC produces HCl and carbon dioxide upon combustion. Studies of household waste burning indicate consistent increases in dioxin generation with increasing PVC concentrations. According to
2484-427: A result, they typically have lower melting temperatures than other polymers. When a polymer is dispersed or dissolved in a liquid, such as in commercial products like paints and glues, the chemical properties and molecular interactions influence how the solution flows and can even lead to self-assembly of the polymer into complex structures. When a polymer is applied as a coating, the chemical properties will influence
2592-846: A rigid solid to a soft gel, and almost 90% of all plasticizer production is used in making flexible PVC. The majority is used in films and cable sheathing. Flexible PVC can consist of over 85% plasticizer by mass, however unplasticized PVC (UPVC) should not contain any. The most common class of plasticizers used in PVC is phthalates, which are diesters of phthalic acid . Phthalates can be categorized as high and low, depending on their molecular weight. Low phthalates such as Bis(2-ethylhexyl) phthalate (DEHP) and Dibutyl phthalate (DBP) have increased health risks and are generally being phased out. High-molecular-weight phthalates such as diisononyl phthalate (DINP) and diisodecyl phthalate (DIDP) are generally considered safer. While DEHP has been medically approved for many years for use in medical devices, it
2700-456: A statistical distribution of chain lengths, the molecular weight is expressed in terms of weighted averages. The number-average molecular weight ( M n ) and weight-average molecular weight ( M w ) are most commonly reported. The ratio of these two values ( M w / M n ) is the dispersity ( Đ ), which is commonly used to express the width of the molecular weight distribution. The physical properties of polymer strongly depend on
2808-465: A system of triangles and connecting links which convert the rotation of an axle into a stepping motion of six or more legs. This allows the strandbeesten to travel over sand much more efficiently than if it were to travel on wheels. What was at first a rudimentary "breed" has evolved slowly, with the help of evolutionary computation techniques, into a generation of kinetic sculptures that can react to their environment to some degree. According to Jansen, he
2916-537: A tendency to form amorphous and semicrystalline structures rather than crystals . Polymers are studied in the fields of polymer science (which includes polymer chemistry and polymer physics ), biophysics and materials science and engineering . Historically, products arising from the linkage of repeating units by covalent chemical bonds have been the primary focus of polymer science. An emerging important area now focuses on supramolecular polymers formed by non-covalent links. Polyisoprene of latex rubber
3024-432: A variety of different but structurally related monomer residues; for example, polynucleotides such as DNA are composed of four types of nucleotide subunits. A polymer containing ionizable subunits (e.g., pendant carboxylic groups ) is known as a polyelectrolyte or ionomer , when the fraction of ionizable units is large or small respectively. The microstructure of a polymer (sometimes called configuration) relates to
3132-405: A wide-meshed cross-linking between the "main chains". Close-meshed crosslinking, on the other hand, leads to thermosets . Cross-links and branches are shown as red dots in the figures. Highly branched polymers are amorphous and the molecules in the solid interact randomly. An important microstructural feature of a polymer is its architecture and shape, which relates to the way branch points lead to
3240-407: Is autocatalytic . Many diverse agents have been used including, traditionally, derivatives of heavy metals (lead, cadmium). Metallic soaps (metal "salts" of fatty acids such as calcium stearate ) are common in flexible PVC applications. PVC is a thermoplastic polymer. Its properties are usually categorized based on rigid and flexible PVCs. The heat stability of raw PVC is very poor, so
3348-458: Is water-resistant , used for its weather-resistant qualities in coats, skiing equipment, shoes, jackets , and aprons . The two main application areas for single-use medically approved PVC compounds are flexible containers and tubing: containers used for blood and blood components, for urine collection or for ostomy products and tubing used for blood taking and blood giving sets, catheters, heart-lung bypass sets, hemodialysis sets etc. In Europe
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3456-629: Is 46 percent lower than conventional produced PVC. So the use of recycled material leads to a significant better ecological footprint . The global warming potential is 39 percent lower. In November 2005, one of the largest hospital networks in the US, Catholic Healthcare West , signed a contract with B. Braun Melsungen for vinyl-free intravenous bags and tubing. In January 2012, a major US West Coast healthcare provider, Kaiser Permanente , announced that it will no longer buy intravenous (IV) medical equipment made with PVC and DEHP-type plasticizers. In 1998,
3564-814: Is a substance or material that consists of very large molecules, or macromolecules , that are constituted by many repeating subunits derived from one or more species of monomers . Due to their broad spectrum of properties, both synthetic and natural polymers play essential and ubiquitous roles in everyday life. Polymers range from familiar synthetic plastics such as polystyrene to natural biopolymers such as DNA and proteins that are fundamental to biological structure and function. Polymers, both natural and synthetic, are created via polymerization of many small molecules, known as monomers . Their consequently large molecular mass , relative to small molecule compounds , produces unique physical properties including toughness , high elasticity , viscoelasticity , and
3672-479: Is a crucial physical parameter for polymer manufacturing, processing, and use. Below T g , molecular motions are frozen and polymers are brittle and glassy. Above T g , molecular motions are activated and polymers are rubbery and viscous. The glass-transition temperature may be engineered by altering the degree of branching or crosslinking in the polymer or by the addition of plasticizers . Whereas crystallization and melting are first-order phase transitions ,
3780-410: Is a long-chain n -alkane. There are also branched macromolecules with a main chain and side chains, in the case of polyethylene the side chains would be alkyl groups . In particular unbranched macromolecules can be in the solid state semi-crystalline, crystalline chain sections highlighted red in the figure below. While branched and unbranched polymers are usually thermoplastics, many elastomers have
3888-402: Is a white, brittle solid. It is soluble in ketones , chlorinated solvents, Dimethylformamide , THF and DMAc . PVC was synthesized in 1872 by German chemist Eugen Baumann after extended investigation and experimentation. The polymer appeared as a white solid inside a flask of vinyl chloride that had been left on a shelf sheltered from sunlight for four weeks. In the early 20th century,
3996-400: Is also commonly present in polymer backbones, such as those of polyethylene glycol , polysaccharides (in glycosidic bonds ), and DNA (in phosphodiester bonds ). Polymerization is the process of combining many small molecules known as monomers into a covalently bonded chain or network. During the polymerization process, some chemical groups may be lost from each monomer. This happens in
4104-418: Is also confirmed in the same document showing a reduction of 75% since 2000 and ongoing. This is confirmed by the corresponding growth in calcium-based stabilizers, used as an alternative to lead-based stabilizers, more and more, also outside Europe. Some of the most crucial additives are heat stabilizers. These agents minimize loss of HCl , a degradation process that starts above 70 °C (158 °F) and
4212-457: Is also used to produce thin, colored, or clear, adhesive -backed films referred to simply as "vinyl". These films are typically cut on a computer -controlled plotter (see vinyl cutter ) or printed in a wide-format printer . These sheets and films are used to produce a wide variety of commercial signage products, vinyl wraps or racing stripes on vehicles for aesthetics or as wrap advertising , and general purpose stickers . PVC fabric
4320-512: Is an average distance from the center of mass of the chain to the chain itself. Alternatively, it may be expressed in terms of pervaded volume , which is the volume spanned by the polymer chain and scales with the cube of the radius of gyration. The simplest theoretical models for polymers in the molten, amorphous state are ideal chains . Polymer properties depend of their structure and they are divided into classes according to their physical bases. Many physical and chemical properties describe how
4428-481: Is an example of a natural polymer, and the polystyrene of styrofoam is an example of a synthetic polymer. In biological contexts, essentially all biological macromolecules —i.e., proteins (polyamides), nucleic acids (polynucleotides), and polysaccharides —are purely polymeric, or are composed in large part of polymeric components. The term "polymer" derives from Greek πολύς (polus) 'many, much' and μέρος (meros) 'part'. The term
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4536-728: Is called, is produced by chlorination of aqueous solution of suspension PVC particles followed by exposure to UV light which initiates the free-radical chlorination. Phthalates, which are incorporated into plastics as plasticizers, comprise approximately 70% of the US plasticizer market; phthalates are by design not covalently bound to the polymer matrix, which makes them highly susceptible to leaching. Phthalates are contained in plastics at high percentages. For example, they can contribute up to 40% by weight to intravenous medical bags and up to 80% by weight in medical tubing. Vinyl products are pervasive—including toys, car interiors, shower curtains, and flooring—and initially release chemical gases into
4644-428: Is composed only of styrene -based repeat units, and is classified as a homopolymer. Polyethylene terephthalate , even though produced from two different monomers ( ethylene glycol and terephthalic acid ), is usually regarded as a homopolymer because only one type of repeat unit is formed. Ethylene-vinyl acetate contains more than one variety of repeat unit and is a copolymer. Some biological polymers are composed of
4752-409: Is defined, for small strains , as the ratio of rate of change of stress to strain. Like tensile strength, this is highly relevant in polymer applications involving the physical properties of polymers, such as rubber bands. The modulus is strongly dependent on temperature. Viscoelasticity describes a complex time-dependent elastic response, which will exhibit hysteresis in the stress-strain curve when
4860-451: Is easier to handle, resists corrosion and abrasion, and may be color-coded for increased visibility. It is found in a variety of industries and environments both indoor and out. Molded PVC is used to produce phonograph, or "vinyl," records . PVC piping is a cheaper alternative to metal tubing used in musical instrument making; it is therefore a common alternative when making wind instruments, often for leisure or for rarer instruments such as
4968-459: Is produced by polymerization of the vinyl chloride monomer (VCM), as shown. About 80% of production involves suspension polymerization . Emulsion polymerization accounts for about 12%, and bulk polymerization accounts for 8%. Suspension polymerization produces particles with average diameters of 100–180 μm, whereas emulsion polymerization gives much smaller particles of average size around 0.2 μm. VCM and water are introduced into
5076-435: Is the change in refractive index with temperature also known as dn/dT. For the polymers mentioned here the (dn/dT) ~ −1.4 × 10 in units of K in the 297 ≤ T ≤ 337 K range. Most conventional polymers such as polyethylene are electrical insulators , but the development of polymers containing π-conjugated bonds has led to a wealth of polymer-based semiconductors , such as polythiophenes . This has led to many applications in
5184-563: Is the main constituent of wood and paper. Hemoglycin (previously termed hemolithin ) is a space polymer that is the first polymer of amino acids found in meteorites . The list of synthetic polymers , roughly in order of worldwide demand, includes polyethylene , polypropylene , polystyrene , polyvinyl chloride , synthetic rubber , phenol formaldehyde resin (or Bakelite ), neoprene , nylon , polyacrylonitrile , PVB , silicone , and many more. More than 330 million tons of these polymers are made every year (2015). Most commonly,
5292-690: Is the temperature of the combustion gases. Oxygen concentration also plays a major role on dioxin formation, but not the chlorine content. Several studies have also shown that removing PVC from waste would not significantly reduce the quantity of dioxins emitted. The EU Commission published in July 2000 a Green Paper on the Environmental Issues of PVC" A study commissioned by the European Commission on "Life Cycle Assessment of PVC and of principal competing materials" states that "Recent studies show that
5400-425: Is used in construction for pipes, doors and windows. It is also used in making plastic bottles, packaging, and bank or membership cards. Adding plasticizers makes PVC softer and more flexible. It is used in plumbing, electrical cable insulation, flooring, signage, phonograph records , inflatable products, and in rubber substitutes. With cotton or linen, it is used in the production of canvas . Polyvinyl chloride
5508-611: The European Chemicals Bureau of the European Commission released a final draft risk assessment of BBzP which found "no concern" for consumer exposure including exposure to children. Lead compounds had previously been widely added to PVC to improve workability and stability but have been shown to leach into drinking water from PVC pipes. In Europe the use of lead-based stabilizers has been discontinued. The VinylPlus voluntary commitment which began in 2000, saw European Stabiliser Producers Association (ESPA) members complete
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#17328558952115616-535: The U.S. Consumer Product Safety Commission (CPSC) arrived at a voluntary agreement with manufacturers to remove phthalates from PVC rattles, teethers, baby bottle nipples and pacifiers. Polymer A polymer is a substance composed of macromolecules. A macromolecule is a molecule of high relative molecular mass, the structure of which essentially comprises the multiple repetition of units derived, actually or conceptually, from molecules of low relative molecular mass. A polymer ( / ˈ p ɒ l ɪ m ər / )
5724-423: The contrabass flute . An instrument that is almost exclusively built from PVC tube is the thongophone , a percussion instrument that is played by slapping the open tubes with a flip-flop or similar. PVC is also used as a raw material in automotive underbody coating. PVC can be usefully modified by chlorination, which increases its chlorine content to or above 67%. Chlorinated polyvinyl chloride , (CPVC), as it
5832-542: The DNA to RNA and subsequently translate that information to synthesize the specified protein from amino acids . The protein may be modified further following translation in order to provide appropriate structure and functioning. There are other biopolymers such as rubber , suberin , melanin , and lignin . Naturally occurring polymers such as cotton , starch , and rubber were familiar materials for years before synthetic polymers such as polyethene and perspex appeared on
5940-535: The European Directives on End-of-Life Vehicles , Packaging and Waste Electric and Electronic Equipment). Since June 2011, it is followed by VinylPlus, a new set of targets for sustainable development. Its main target is to recycle 800,000 tonnes per year of PVC by 2020 including 100,000 tonnes of "difficult to recycle" waste. One facilitator for collection and recycling of PVC waste is Recovinyl. The reported and audited mechanically recycled PVC tonnage in 2016
6048-556: The Russian chemist Ivan Ostromislensky and Fritz Klatte of the German chemical company Griesheim-Elektron both attempted to use PVC in commercial products, but difficulties in processing the rigid, sometimes brittle polymer thwarted their efforts. Waldo Semon and the B.F. Goodrich Company developed a method in 1926 to plasticize PVC by blending it with various additives, including the use of dibutyl phthalate by 1933. Polyvinyl chloride
6156-448: The U.S. EPA dioxin inventory, landfill fires are likely to represent an even larger source of dioxin to the environment. A survey of international studies consistently identifies high dioxin concentrations in areas affected by open waste burning and a study that looked at the homologue pattern found the sample with the highest dioxin concentration was "typical for the pyrolysis of PVC". Other EU studies indicate that PVC likely "accounts for
6264-427: The addition of a heat stabilizer during the process is necessary in order to ensure the product's properties. Traditional product PVC has a maximum operating temperature around 60 °C (140 °F) when heat distortion begins to occur. As a thermoplastic, PVC has an inherent insulation that aids in reducing condensation formation and resisting internal temperature changes for hot and cold liquids. Roughly half of
6372-441: The adhesion of the coating and how it interacts with external materials, such as superhydrophobic polymer coatings leading to water resistance. Overall the chemical properties of a polymer are important elements for designing new polymeric material products. Polymers such as PMMA and HEMA:MMA are used as matrices in the gain medium of solid-state dye lasers , also known as solid-state dye-doped polymer lasers. These polymers have
6480-429: The air. Some studies indicate that this outgassing of additives may contribute to health complications, and have resulted in a call for banning the use of DEHP on shower curtains, among other uses. In 2004 a joint Swedish-Danish research team found a statistical association between allergies in children and indoor air levels of DEHP and BBzP ( butyl benzyl phthalate ), which is used in vinyl flooring. In December 2006,
6588-434: The backbone in a variety of ways. A copolymer containing a controlled arrangement of monomers is called a sequence-controlled polymer . Alternating, periodic and block copolymers are simple examples of sequence-controlled polymers . Tacticity describes the relative stereochemistry of chiral centers in neighboring structural units within a macromolecule. There are three types of tacticity: isotactic (all substituents on
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#17328558952116696-403: The best across all the human health and environmental impact categories, nor as the worst" but that the "risk of dioxin emissions puts PVC consistently among the worst materials for human health impacts." In Europe the overwhelming importance of combustion conditions on dioxin formation has been established by numerous researchers. The single most important factor in forming dioxin-like compounds
6804-421: The case of water or other molecular fluids. Instead, crystallization and melting refer to the phase transitions between two solid states ( i.e. , semi-crystalline and amorphous). Crystallization occurs above the glass-transition temperature ( T g ) and below the melting temperature ( T m ). All polymers (amorphous or semi-crystalline) go through glass transitions . The glass-transition temperature ( T g )
6912-453: The chain gives a few percent crystallinity that is influential on the properties of the material. About 57% of the mass of PVC is chlorine . The presence of chloride groups gives the polymer very different properties from the structurally related material polyethylene . At 1.4 g/cm , PVC's density is also higher than structurally related plastics such as polyethylene (0.88–0.96 g/cm ) and polymethylmethacrylate (1.18 g/cm ). About half of
7020-433: The consumption of PVC from medical devices is approximately 85,000 tons each year. Almost one third of plastic-based medical devices are made from PVC. PVC has been applied to various items such as: bottles, packaging films, blister packs , cling wraps , and seals on metal lids. PVC may be extruded under pressure to encase wire rope and aircraft cable used for general purpose applications. PVC coated wire rope
7128-469: The continuously linked backbone of a polymer used for the preparation of plastics consists mainly of carbon atoms. A simple example is polyethylene ('polythene' in British English), whose repeat unit or monomer is ethylene . Many other structures do exist; for example, elements such as silicon form familiar materials such as silicones, examples being Silly Putty and waterproof plumbing sealant. Oxygen
7236-536: The degree of crystallinity may be expressed in terms of a weight fraction or volume fraction of crystalline material. Few synthetic polymers are entirely crystalline. The crystallinity of polymers is characterized by their degree of crystallinity, ranging from zero for a completely non-crystalline polymer to one for a theoretical completely crystalline polymer. Polymers with microcrystalline regions are generally tougher (can be bent more without breaking) and more impact-resistant than totally amorphous polymers. Polymers with
7344-400: The driving force for mixing is usually entropy , not interaction energy. In other words, miscible materials usually form a solution not because their interaction with each other is more favorable than their self-interaction, but because of an increase in entropy and hence free energy associated with increasing the amount of volume available to each component. This increase in entropy scales with
7452-432: The end use specification (underground pipe, window frames, intravenous tubing and flooring all have very different ingredients to suit their performance requirements). Previously, polychlorinated biphenyls (PCBs) were added to certain PVC products as flame retardants and stabilizers. Among the common plastics , PVC is unique in its acceptance of large amounts of plasticizer with gradual changes in physical properties from
7560-417: The field of organic electronics . Nowadays, synthetic polymers are used in almost all walks of life. Modern society would look very different without them. The spreading of polymer use is connected to their unique properties: low density, low cost, good thermal/electrical insulation properties, high resistance to corrosion, low-energy demanding polymer manufacture and facile processing into final products. For
7668-527: The free energy of mixing for polymer solutions and thereby making solvation less favorable, and thereby making the availability of concentrated solutions of polymers far rarer than those of small molecules. Furthermore, the phase behavior of polymer solutions and mixtures is more complex than that of small molecule mixtures. Whereas most small molecule solutions exhibit only an upper critical solution temperature phase transition (UCST), at which phase separation occurs with cooling, polymer mixtures commonly exhibit
7776-401: The glass transition is not. The glass transition shares features of second-order phase transitions (such as discontinuity in the heat capacity, as shown in the figure), but it is generally not considered a thermodynamic transition between equilibrium states. In general, polymeric mixtures are far less miscible than mixtures of small molecule materials. This effect results from the fact that
7884-415: The individual chains more strongly in position and resist deformations and matrix breakup, both at higher stresses and higher temperatures. Copolymers are classified either as statistical copolymers, alternating copolymers, block copolymers, graft copolymers or gradient copolymers. In the schematic figure below, Ⓐ and Ⓑ symbolize the two repeat units . Monomers within a copolymer may be organized along
7992-451: The latter case, increasing the polymer chain length 10-fold would increase the viscosity over 1000 times. Increasing chain length furthermore tends to decrease chain mobility, increase strength and toughness, and increase the glass-transition temperature (T g ). This is a result of the increase in chain interactions such as van der Waals attractions and entanglements that come with increased chain length. These interactions tend to fix
8100-436: The length (or equivalently, the molecular weight) of the polymer chain. One important example of the physical consequences of the molecular weight is the scaling of the viscosity (resistance to flow) in the melt. The influence of the weight-average molecular weight ( M w {\displaystyle M_{w}} ) on the melt viscosity ( η {\displaystyle \eta } ) depends on whether
8208-417: The load is removed. Dynamic mechanical analysis or DMA measures this complex modulus by oscillating the load and measuring the resulting strain as a function of time. Transport properties such as diffusivity describe how rapidly molecules move through the polymer matrix. These are very important in many applications of polymers for films and membranes. The movement of individual macromolecules occurs by
8316-436: The market. Many commercially important polymers are synthesized by chemical modification of naturally occurring polymers. Prominent examples include the reaction of nitric acid and cellulose to form nitrocellulose and the formation of vulcanized rubber by heating natural rubber in the presence of sulfur . Ways in which polymers can be modified include oxidation , cross-linking , and end-capping . The structure of
8424-413: The material will endure before failure. This is very important in applications that rely upon a polymer's physical strength or durability. For example, a rubber band with a higher tensile strength will hold a greater weight before snapping. In general, tensile strength increases with polymer chain length and crosslinking of polymer chains. Young's modulus quantifies the elasticity of the polymer. It
8532-444: The number of particles (or moles) being mixed. Since polymeric molecules are much larger and hence generally have much higher specific volumes than small molecules, the number of molecules involved in a polymeric mixture is far smaller than the number in a small molecule mixture of equal volume. The energetics of mixing, on the other hand, is comparable on a per volume basis for polymeric and small molecule mixtures. This tends to increase
8640-444: The overwhelming majority of chlorine that is available for dioxin formation during landfill fires." The next largest sources of dioxin in the U.S. EPA inventory are medical and municipal waste incinerators. Various studies have been conducted that reach contradictory results. For instance a study of commercial-scale incinerators showed no relationship between the PVC content of the waste and dioxin emissions. Other studies have shown
8748-713: The partially negatively charged oxygen atoms in C=O groups on another. These strong hydrogen bonds, for example, result in the high tensile strength and melting point of polymers containing urethane or urea linkages. Polyesters have dipole-dipole bonding between the oxygen atoms in C=O groups and the hydrogen atoms in H-C groups. Dipole bonding is not as strong as hydrogen bonding, so a polyester's melting point and strength are lower than Kevlar 's ( Twaron ), but polyesters have greater flexibility. Polymers with non-polar units such as polyethylene interact only through weak Van der Waals forces . As
8856-422: The physical arrangement of monomer residues along the backbone of the chain. These are the elements of polymer structure that require the breaking of a covalent bond in order to change. Various polymer structures can be produced depending on the monomers and reaction conditions: A polymer may consist of linear macromolecules containing each only one unbranched chain. In the case of unbranched polyethylene, this chain
8964-399: The polymer and create gaps between polymer chains for greater mobility and fewer interchain interactions. A good example of the action of plasticizers is related to polyvinylchlorides or PVCs. A uPVC, or unplasticized polyvinylchloride, is used for things such as pipes. A pipe has no plasticizers in it, because it needs to remain strong and heat-resistant. Plasticized PVC is used in clothing for
9072-426: The polymer at the scale of a single chain. The microstructure determines the possibility for the polymer to form phases with different arrangements, for example through crystallization , the glass transition or microphase separation . These features play a major role in determining the physical and chemical properties of a polymer. The identity of the repeat units (monomer residues, also known as "mers") comprising
9180-540: The polymer can lend the polymer to ionic bonding or hydrogen bonding between its own chains. These stronger forces typically result in higher tensile strength and higher crystalline melting points. The intermolecular forces in polymers can be affected by dipoles in the monomer units. Polymers containing amide or carbonyl groups can form hydrogen bonds between adjacent chains; the partially positively charged hydrogen atoms in N-H groups of one chain are strongly attracted to
9288-403: The polymer is above or below the onset of entanglements . Below the entanglement molecular weight , η ∼ M w 1 {\displaystyle \eta \sim {M_{w}}^{1}} , whereas above the entanglement molecular weight, η ∼ M w 3.4 {\displaystyle \eta \sim {M_{w}}^{3.4}} . In
9396-583: The polymerization of PET polyester . The monomers are terephthalic acid (HOOC—C 6 H 4 —COOH) and ethylene glycol (HO—CH 2 —CH 2 —OH) but the repeating unit is —OC—C 6 H 4 —COO—CH 2 —CH 2 —O—, which corresponds to the combination of the two monomers with the loss of two water molecules. The distinct piece of each monomer that is incorporated into the polymer is known as a repeat unit or monomer residue. Synthetic methods are generally divided into two categories, step-growth polymerization and chain polymerization . The essential difference between
9504-484: The presence of PVC has no significant effect on the amount of dioxins released through incineration of plastic waste ." In Europe, developments in PVC waste management have been monitored by Vinyl 2010, established in 2000. Vinyl 2010's objective was to recycle 200,000 tonnes of post-consumer PVC waste per year in Europe by the end of 2010, excluding waste streams already subject to other or more specific legislation (such as
9612-405: The reactor along with a polymerization initiator and other additives. The contents of the reaction vessel are pressurized and continually mixed to maintain the suspension and ensure a uniform particle size of the PVC resin. The reaction is exothermic and thus requires cooling. As the volume is reduced during the reaction (PVC is denser than VCM), water is continually added to the mixture to maintain
9720-403: The replacement of Pb-based stabilisers in 2015. In the early 1970s, the carcinogenicity of vinyl chloride (usually called vinyl chloride monomer or VCM) was linked to cancers in workers in the polyvinyl chloride industry. Specifically workers in polymerization section of a B.F. Goodrich plant near Louisville, Kentucky , were diagnosed with liver angiosarcoma also known as hemangiosarcoma ,
9828-437: The same side), atactic (random placement of substituents), and syndiotactic (alternating placement of substituents). Polymer morphology generally describes the arrangement and microscale ordering of polymer chains in space. The macroscopic physical properties of a polymer are related to the interactions between the polymer chains. When applied to polymers, the term crystalline has a somewhat ambiguous usage. In some cases,
9936-462: The sandy beach environment in which Jansen releases them. The sculptures are also able to store air pressure in order to propel themselves in the absence of wind. Jansen's more sophisticated creations are able to detect when they have entered water and are then able to move away from it. One model is capable of anchoring itself to the earth if an approaching storm is sensed. A 2016 episode of The Simpsons , " The Nightmare After Krustmas ", featured
10044-598: The sea. Jansen was born in Scheveningen in the Netherlands. He grew up with a talent for both physics and art, and studied physics at the Delft University of Technology . Jansen left the university in 1974 without a degree. While at Delft, Jansen was involved in many projects that involved both art and technology, including a paint machine and a flying-saucer machine. In 1979 Jansen started using cheap PVC pipes to build
10152-512: The size of individual polymer coils in solution. A variety of techniques may be employed for the synthesis of a polymeric material with a range of architectures, for example living polymerization . A common means of expressing the length of a chain is the degree of polymerization , which quantifies the number of monomers incorporated into the chain. As with other molecules, a polymer's size may also be expressed in terms of molecular weight . Since synthetic polymerization techniques typically yield
10260-448: The states is known as a coil–globule transition . Inclusion of plasticizers tends to lower T g and increase polymer flexibility. Addition of the plasticizer will also modify dependence of the glass-transition temperature T g on the cooling rate. The mobility of the chain can further change if the molecules of plasticizer give rise to hydrogen bonding formation. Plasticizers are generally small molecules that are chemically similar to
10368-473: The strandbeesten and Jansen. He provided the voice for his cartoon character. PVC Polyvinyl chloride (alternatively: poly(vinyl chloride) , colloquial : vinyl or polyvinyl ; abbreviated: PVC ) is the world's third-most widely produced synthetic polymer of plastic (after polyethylene and polypropylene ). About 40 million tons of PVC are produced each year. PVC comes in rigid (sometimes abbreviated as RPVC) and flexible forms. Rigid PVC
10476-452: The suspension. PVC may be manufactured from ethylene , which can be produced from either naphtha or ethane feedstock. The polymers are linear and are strong. The monomers are mainly arranged head-to-tail, meaning that chloride is located on alternating carbon centres. PVC has mainly an atactic stereochemistry , which means that the relative stereochemistry of the chloride centres are random. Some degree of syndiotacticity of
10584-686: The term crystalline finds identical usage to that used in conventional crystallography . For example, the structure of a crystalline protein or polynucleotide, such as a sample prepared for x-ray crystallography , may be defined in terms of a conventional unit cell composed of one or more polymer molecules with cell dimensions of hundreds of angstroms or more. A synthetic polymer may be loosely described as crystalline if it contains regions of three-dimensional ordering on atomic (rather than macromolecular) length scales, usually arising from intramolecular folding or stacking of adjacent chains. Synthetic polymers may consist of both crystalline and amorphous regions;
10692-555: The two is that in chain polymerization, monomers are added to the chain one at a time only, such as in polystyrene , whereas in step-growth polymerization chains of monomers may combine with one another directly, such as in polyester . Step-growth polymerization can be divided into polycondensation , in which low-molar-mass by-product is formed in every reaction step, and polyaddition . Newer methods, such as plasma polymerization do not fit neatly into either category. Synthetic polymerization reactions may be carried out with or without
10800-580: The use of cast iron for plumbing and drainage , being used for waste pipes, drainpipes, gutters and downspouts . PVC is known as having strong resistance against chemicals, sunlight, and oxidation from water. Polyvinyl chloride is formed in flat sheets in a variety of thicknesses and colors. As flat sheets, PVC is often expanded to create voids in the interior of the material, providing additional thickness without additional weight and minimal extra cost (see closed-cell PVC foamboard ). Sheets are cut using saws and rotary cutting equipment. Plasticized PVC
10908-492: The world's PVC production capacity is in China , despite the closure of many Chinese PVC plants due to issues complying with environmental regulations and poor capacities of scale. The largest single producer of PVC as of 2018 is Shin-Etsu Chemical of Japan , with a global share of around 30%. The product of the polymerization process is unmodified PVC. Before PVC can be made into finished products, it always requires conversion into
11016-431: The world's PVC resin manufactured annually is used for producing pipes for municipal and industrial applications. In the private homeowner market, it accounts for 66% of the household market in the US, and in household sanitary sewer pipe applications, it accounts for 75%. Buried PVC pipes in both water and sanitary sewer applications that are 100 mm (4 in) in diameter and larger are typically joined by means of
11124-540: Was 568,695 tonnes which in 2018 had increased to 739,525 tonnes. One approach to address the problem of waste PVC is also through the process called Vinyloop . It is a mechanical recycling process using a solvent to separate PVC from other materials. This solvent turns in a closed loop process in which the solvent is recycled. Recycled PVC is used in place of virgin PVC in various applications: coatings for swimming pools, shoe soles, hoses, diaphragms tunnel, coated fabrics, PVC sheets. This recycled PVC's primary energy demand
11232-473: Was also attached to a large piece of wood that was hoisted against a wall, where it would move back and forth to create 2-D images of everything in the room. Since 1990, Jansen has been creating strandbeesten ( Dutch for "beach animals", singular strandbeest - see also English cognate strand ), which are moving kinetic structures, sometimes wind-propelled, that resemble walking animals, described by Jansen as artificial life. All of his models are based on
11340-605: Was coined in 1833 by Jöns Jacob Berzelius , though with a definition distinct from the modern IUPAC definition. The modern concept of polymers as covalently bonded macromolecular structures was proposed in 1920 by Hermann Staudinger , who spent the next decade finding experimental evidence for this hypothesis. Polymers are of two types: naturally occurring and synthetic or man made . Natural polymeric materials such as hemp , shellac , amber , wool , silk , and natural rubber have been used for centuries. A variety of other natural polymers exist, such as cellulose , which
11448-499: Was inspired by The Blind Watchmaker by Richard Dawkins . Jansen has said "I make skeletons that are able to walk on the wind. Over time, these skeletons have become increasingly better at surviving the elements such as storms and water and eventually I want to put these animals out in herds on the beaches, so they will live their own lives." Constructed from PVC piping, wood, fabric airfoils, and zip ties, Jansen's sculptures are constantly being improved and are designed to function in
11556-483: Was permanently banned for use in children's products in the US in 2008 by US Congress; the PVC-DEHP combination had proved to be very suitable for making blood bags because DEHP stabilizes red blood cells, minimizing hemolysis (red blood cell rupture). However, DEHP is coming under increasing pressure in Europe. The assessment of potential risks related to phthalates, and in particular the use of DEHP in PVC medical devices,
11664-742: Was subject to scientific and policy review by the European Union authorities, and on 21 March 2010, a specific labeling requirement was introduced across the EU for all devices containing phthalates that are classified as CMR (carcinogenic, mutagenic or toxic to reproduction). The label aims to enable healthcare professionals to use this equipment safely, and, where needed, take appropriate precautionary measures for patients at risk of over-exposure BaZn stabilisers have successfully replaced cadmium-based stabilisers in Europe in many PVC semi-rigid and flexible applications. In Europe, particularly Belgium, there has been
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