Jacketed Mixer High Speed Mixer

Routes from raw materials to finished products illustrating different compounding techniques with PVC compounds20 is then granulated or pelleted. This can be carried out as part of the continuous compounding process, whereas a mass mixed in an internal mixer may be either fed to an extruder-pelletiser, which extrudes strands which are then cut up into pellets, to an extruder-slabber, which produces a sheet subsequently fed to a dicing machine, or to a two-roll mill, which also...

Organic Inorganic

Classification of fillers in polymer compounds Particulate fillers are divided into two types, 'inert' fillers and reinforcing fillers. The term inert filler is something of a misnomer as many properties may be affected by incorporation of such a filler. For example, in a plasticised PVC compound the addition of an inert filler will reduce die swell on extrusion, increase modulus and hardness, may provide a white base for colouring, improve electrical insulation properties and...

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In commercial practice the resin is condensed to a point close to the hydrophobe point and then either applied to the substrate, or converted into a moulding powder, before proceeding with the final cure. In a typical process a jacketed still fitted with a stirrer and reflux condenser in charged with 240 parts 37 w w (40 w v) formalin and the pH adjusted to 8.0-8.5 using sodium carbonate solution with the aid of a pH meter. One hundred and twenty six parts of melamine (to give a melamine...

2000 3000 4000 5000 6000 Wavelength In I

Light transmission of acrylic polymer (5 in thick moulded Diakon. Parallel light beam normally incident on surface). (Reproduced by permission of ICI) incorporated to 'let out' the light at that point. The optical properties of poly(methyl methacrylate) have been exploited in the development of optical fibres. Poly(methyl methacrylate) is a good electrical insulator for low-frequency work, but is inferior to such polymers as polyethylene and polystyrene, particularly at high...

189 Applications

Consumption of poly amide plastics in the late 1990s has been estimated at about 1 300 000 t.p.a. Western Europe and the United States each have about 42 of this market and Japan about 16 . This is probably about 20 of the total production of polyamide materials and virtually all of the rest of polyamide production goes into fibres where the market is shared very roughly equally between nylons 6 and 66. The large-scale production of these materials enables them to be available at a...

129 Miscellaneous Products

This chapter has so far dealt with the major fields of use of vinyl chloride polymers, namely plasticised PVC homopolymer, unplasticised PVC, including impact-modified grades, and copolymers particular based on vinyl acetate. There are, however, five particular special forms of vinyl chloride polymer which merit separate consideration, namely crystalline PVC, after-chlorinated PVC (often known as CPVC) and certain graft copolymers and two vinyl-chloride-based copolymers. The development of...

303 Miscellaneous Protein Plastics

Casein is the only protein that has achieved commercial significance as a plastics raw material. Many other proteins are readily available in many vegetable material residues which arise from such processes as the extraction of oils and starches from seeds. It would be advantageous to countries possessing such residues if plastics could be successfully exploited commercially. Although plastics materials have been produced they have failed to be of value since they are invariably dark in colour...

16 Raw Materials For Plastics

Today, the plastics industry is heavily integrated with the oil industry. In fact a popular view is that it would not be able to produce plastics if oil were not available. This is very different from the situation 40-50 years ago when the plastics industry was being described as a 'scavenger of raw materials'. Before World War II the most important class of thermoplastics, the cellulosics, were produced from vegetable sources, cellulose being an important constituent of vegetable matter. From...

Pr

1 ( d< 2 aiig-W ((U) 4 xnR3 ' 4 kR3 ' d log t, 3 ' + 1 4Q where AP is the pressure drop between the ends of the capillary of length L and radius R and Q is the volumetric output. The term n', the flow behaviour index, is defined by and is usually a function of shear rate. Equations (8.3) to (8.6) are forms of the Rabinowitsch equation. In practice n' changes only slowly with changes in y and it is possible to postulate that over a range of shear rates it is constant. If equation (8.7) is...

Styreneacrylonitrile And Related Copolymers

The commercial success of ABS polymers has led to the investigation of many other polyblend materials. In some cases properties are exhibited which are superior to those of ABS and some of the materials are commercially available. For example, the opacity of ABS has led to the development of blends in which the glassy phase is modified to give transparent polymers whilst the limited light aging has been countered by the use of rubbers other than polybutadiene. Notable among the alternative...

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Whilst these are usually vulcanised, unvulcanised high green strength rubbers have been used in the construction industry and for pit liner systems. In such applications they act more like plastics than rubbers. High elasticity is also not utilised in the main application of chlorosulphonated polyethylenes, in wire and cable coating, which consume about 40 of output. The combination of heat and oil resistance has led to widespread use as sheathing for nuclear power cables,...

74 Lubricants And Flow Promoters

The term lubricant or lubricating agent is often encountered to describe certain additives incorporated into plastics materials. There are, however, various types of lubricants with varying functions and it is important to distinguish between them. The three main types are (1) Materials which reduce the friction of mouldings and other finished products when these are rubbed against adjacent materials which may or may not be of the same composition. The most well-known examples here are graphite...

326 A Simple Pathwaybased Noncomputer Selection System

In this section a selection procedure will be developed for injection moulding, since this process is used for the widest range of materials. The choice available for other processes such as, for example, compression moulding, filament winding and vacuum forming, is much more restricted. The approach described will be less mechanistic than the systems described in the two previous sections, requiring the prospective user to be aware of the properties of the various materials available. Because...

141

Because of difficulties in their measurement, published figures for a given polymer can range up to 3 on either side of the average figure quoted. More comprehensive data are given in reference 7. Because of difficulties in their measurement, published figures for a given polymer can range up to 3 on either side of the average figure quoted. More comprehensive data are given in reference 7. Table 5.5 Solubility parameters and partial polarities (P) of some common solvents Table 5.5 Solubility...

82

Underwriters' Laboratories Thermal Index ratings are 105 C for electrical, 90 C for mechanical without impact and 90 C (copolymer) 85 C (homopolymer) for mechanical with impact. Underwriters' Laboratories Thermal Index ratings are 105 C for electrical, 90 C for mechanical without impact and 90 C (copolymer) 85 C (homopolymer) for mechanical with impact. Prolonged exposure to ultraviolet light will induce surface chalking and reduce the molecular weight, leading to gradual embrittlement. As with...

73 Plasticisers And Softeners

It has been common practice to blend plasticisers with certain polymers since the early days of the plastics industry when Alexander Parkes introduced Parkesine. When they were first used their function was primarily to act as spacers between the polymer molecules. Less energy was therefore required for molecular bond rotation and polymers became capable of flow at temperatures below their decomposition temperature. It was subsequently found that plasticisers could serve two additional...

64 Electronic Applications Of Polymers

Whilst plastics materials have been associated with electrical and electronic applications since the early days of the electrical industry, developments over the past 20 years have been particularly spectacular. Amongst applications that may be mentioned are (1) Encapsulation of semiconductors. The usual material is epoxide resin (see Chapter 26) and the preferred method transfer moulding. It has been estimated that by 1980 annual production of such encapsulated parts exceeded 10 billion units....

163

(NB The data compares a syndiotactic material with a melt index of 30 and an isotactic material with an index of 0.3. This should however not invalidate the large differences seen in such properties as modulus, impact strength and opacity.) (NB The data compares a syndiotactic material with a melt index of 30 and an isotactic material with an index of 0.3. This should however not invalidate the large differences seen in such properties as modulus, impact strength and opacity.) 260 Aliphatic...

133 Tetrafluoroethylenehexafluoropropylene Copolymers

These materials were first introduced by Du Pont in 1956 and are now known as Teflon FEP resins. (FEP fluorinated ethylene-propylene.) Subsequently other commercial grades have become available (Neoflon by Daikin Kogyo and Teflex by Niitechim, USSR). These copolymers may be regarded as the first commercial attempt to provide a material with the general properties of PTFE and the melt processability of the more conventional thermoplastics. The commercial polymers are mechanically similar to PTFE...

304 Derivatives Of Natural Rubber

The chemistry and technology of natural rubber were considered briefly in Chapter 11. In this chapter some non-elastomeric derivatives will be reviewed. The most important of these is ebonite, which may be considered as the world's earlier thermosetting plastics material. It is obtained by vulcanising (natural) rubber with large quantities of sulphur. Whereas ordinary vulcanised rubber as used in tyres contains normally only 2-3 of sulphur a typical rubber sulphur ratio for ebonite is 68 32....

162 Preparation Of The Monomer

In 1786 William Nicholson wrote A Dictionary of Practical and Theoretical Chemistry. In this work Nicholson mentions that a chemist named Neuman, on distillation of storax (a balsam derived from the tree Liquambar orientalis), had produced a fragrant 'empyreumatic oil'. In 1839 E. Simon1 carried out some similar experiments, apparently quite independently, and again obtained this essential oil which he called styrol. In 1845 M. Glenard and R. Boudault2 reported on the production of styrol (now...

1613 Stereoregular Polystyrene

Polystyrene produced by free-radical polymerisation techniques is part syndio-tactic and part atactic in structure and therefore amorphous. In 1955 Natta16 and his co-workers reported the preparation of substantially isotactic polystyrene using aluminium alkyl-titanium halide catalyst complexes. Similar systems were also patented by Ziegler17 at about the same time. The use of n-butyl-lithium as a catalyst has been described.18 Whereas at room temperature atactic polymers are produced,...

053

The so-called flow temperature cannot be considered to be either the processing temperature or the maximum service temperature. It is obtained using the highly arbitrary Rossi-Peakes flow test (BS 1524) and is the temperature at which the compound is forced down a capillary of fixed dimensions by a fixed load at a specified rate. It is thus of use only for comparison and for quality control purposes. Since the rates of shear and temperatures used in processing are vastly different from those...

234

Chemical properties, 76-109 aging and weathering, 99 chemical bonds, 76-80 chemical reactivity, 95-6 diffusion and permeability, 100-103 effects of thermal, photochemical and high-energy radiation, 96-8 fire and plastics, 104-109 polymer solubility, 80-94 toxicity, 103-104 Chemical reactivity, 95-6 Chewing gum, 866 Chicle, 866 Chloroacrylate polymers and copolymers, 421-3 Chlorofluorocarbons (CFCs), 417, 797 Chloroprene rubbers (CR), 295-6 Chlorosulphonated polyethylene (Hypalon), 23, 241...

Ygh

Although the nitrile-containing polymers failed to become significant, the fluorine-containing polymers have found commercial application. Commonly referred to as fluorosilicones and with the ASTM designation FVMQ, they were first introduced by Dow Corning in 1953 as LS-53 and are now also supplied by General Electric and Shinetsu. The commercial materials usually contain a small amount about 0.2 of methyl vinyl siloxane as a cure site monomer, whilst the fluorosilicone component can range from...

Photostructural Lacquers

A variety of methods have been used to produce these polymers but the use of chemical or electrochemical oxidative polymerisation has been particularly important. Whilst the doping operation may follow the polymerisation stage, in the case of polypyrrole an excess charge may be formed during the oxidative polymerisation stage. Where doping is carried out subsequent to polymerisation, oxidising agents such as AsF5, SbF5, NOPF6 and FeCl3 have been used successfully. The properties and...

Info

The transitions at - 123 C in the methyl butene and methyl pentene polymers have been ascribed to both side-chain and main-chain mechanisms. Reproduced, with minor revisions in the light of data now available, from chapter on 'The Glass Transition, Melting Point and Structure' by the author in Polymer Science edited by Professor A. D. Jenkins,4 with permission of North-Holland Publishing Company. The transitions at - 123 C in the methyl butene and methyl pentene polymers have been ascribed to...

316

With a somewhat lower level of heat resistance but with many properties that make them of interest as engineering materials alongside the polycarbonates, polysulphones, poly phenylene sulphides and polyketones are the so-called polyarylates which are defined as polyester from bis-phenols and dicarboxylic acids. One such material is the copolymer first marketed by the Japanese company Unitika in 1974 as U-Polymer and more recently by the Belgian company Solvay as Arylef and Union Carbide as...

44 Factors Affecting The Crystalline Melting Point

To a large extent the factors which determine the position of the glass transition temperature of a polymer chain stiffness and intermolecular forces also determine the melting point of a crystalline polymer. In Figure 4.10 a rough correlation is seen between the glass transition and melting points of a number of crystalline polymers. The glass transition temperature of many polymers is about two-thirds that of the crystalline melting point when measured in K. An important exception to this...

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1 Separate data for butyl rubber not available after 1983, but it is believed to be in decline. 2 Data for synthetic rubber production exclude production from the one-time USSR, Central Europe and Socialist Countries of Asia. 3 Data for thermoplastic rubber see Chapter 31 are excluded. 1 Separate data for butyl rubber not available after 1983, but it is believed to be in decline. 2 Data for synthetic rubber production exclude production from the one-time USSR, Central Europe and Socialist...

23 Further Consideration Of Addition Polymerisation

Bulk Polymerisation Technique

Addition polymerisation is effected by the activation of the double bond of a vinyl monomer, thus enabling it to link up to other molecules. It has been shown that this reaction occurs in the form of a chain addition process with initiation, propagation and termination steps. -COO.CH2.CH CH - COO.CH,.CH CH Diallyl Phthalate Figure 2.11 The initiation stage may be activated by free-radical or ionic systems. In the following example a free-radical system will be discussed. In this case a material...