REINFORCED PLASTICS An ACS Symposium in Print FRANK P. GREENSPAN E I.
PROPERTIES P
RE!
JSES OF THERMOSET
Goal clccvirals dimensional stability, chemical and heat resistance Goal elccaiicsla, chemical resimnce, high strength Gmd electriralr, chcmical and heat resiatanec
Low cost, chemical rcsis-
tancc, god clcctricalr, heat resistance Goal all-around pmpcrties, case Of fabrication, low Cost, vrraatilc
Heat resistance, good CIeCtrical
TABLE I I .
Prepregs, ducting, radomes, aircraft, and miuiles Printed circuit board tooling, filament winding Decorative, clcctrieal (arc and track rcsiatancc). circuit break& Work horstdiverse mechanical and electrical applications Corrupted sheeting, rcatmg, boats, automotive, tanks and iping, aircraft, tote
Lx,,
Electrical, aerospace
THERMOPLASTICS
Nylon Polystyrene StyTme-acrylOnitrile copolymers
Polycarbonate Aerylics
TABLE 111. 1964 U. S. RESIN CONSUMPTION OF REINFORCED PLASTICS Sales, Lb. 113, 844,000°
Phcmlio Epoxide Polvertm UrCa and melamine Silieones
Class
13,322,000 201,900,000
57,605,000'. b Lern than 1 millione
Synthetic f i k -
.g., nylon, po1yentCcr
&btm
Carbon and gmphi te
Si& Paper
High purity silica and quartz whiskers
Cotton
I
A series of papers on reinforced plastics presented at an ACS National Meeting is introduced by the symposium chairman this issue of I&EC, and in issues to follow, the IOrganic :Coatings . and Plastics Chemistry Division n
of the American Chemical Society presents a series of papers from a Symposium on Chemistry of Reinforced Plastics held at Atlantic City, N. J., in September f965. This group of papers presents a review in depth of the major component materials that make up the composite that we refer to as reinforced plastics. It coven various resin systems, monomers, reinforcements such as glass, catalysts, and coupling agents representing significant areas of reinforced plastics chemical technology as they contribute to the final composite properties. In this symposium, reinforced plastics refer essentially to any combination of resin and fibrous reinforcement wherein the reinforcement is intended substantially to improve end physical properties rather than simply act as an additive or extender. Although almost any resin or plastic material can be reinforced, in practice only specific resins have achieved commercial significance. Historically, thermoset resins have dominated reinforced plastics. Several of the more prominent thermoset resins are shown in Table I, along with their outstanding properties and uses. While the properties in many cases overlap, individual resins differ quantitatively with regard to performance, and the final choice of the design engineer would be based on evaluation of the required properties as well as economic and fabrication considerations. In this series of papers, one by Earl E. Parker discusses polyester resins from the standpoint of the alkyd component, while another paper by Arthur Smith discusses the monomer aspects. A second important group of resins used for reinforced plastics, epoxy resins, is covered in a paper by J. E.
1 Random positioning offilaments in reinforced plastic is shown with greater dispersion at top and bottom of overlay. 2 Glass rovings guide though re+-in bath before being wound on a pnuessing vessel. 3 Glassfiber reinforced preform is positioned on pematchd steel mold. 4 One-piece glass fiber reinforced structural member is lifted from form. 5 Reinforced plastic pipe is rmoced from winding mandrel 18
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e
Carey, and a paper by John C. Pitzer and St. John Bain covers the thermosetting laminates based on phenolics, melamines, and acrylics. Thermoplastic resins can be reinforced with outstanding improvement of strength, heat resistance, and dimensional stability. Application areas include manu-
TABLE V.
PROCESSING AND FABRICATION
Procedure
Comments
Deicr+tion
Hand-lay-up
Polyester and epoxy; glass cloth
Spray-up
Polyesters and epoxies; chopped glass roving Glass mat (plus binder resin) shaped to contour of final mold
Preform
Prepreg
“Dry” storage stable reinforcement preimpregnated with resin, B-staged or partially advanced; phenolics, diallyl phthalates, polyesters, epoxies
Premixes
Employs premixed molding compound of resin and fibrous reinforcement-polyesters, epoxies Glass roving or strands, impregnated with resin, are wound continuously and uniformly on mandrel; polyesters, epoxies Uses atmospheric pressure, lay-up covered with cellophane or polyvinyl alcohol and vacuum drawn Variation of vacuum bag wherein pressure and heat are applied to the lay-up during cure Variation of pressure bag wherein entire lay-up is placed in steam autoclave and pressure raised u p to 700 p.s.i. Resin and reinforcement molded under heat and pressure to produce parts with excellent uniformity and surface finish; phenolics, polyesters, epoxies, diallyl phthalates
Filament winding
Vacuum bag
Pressure bag
Autoclave
Matched metal die
TABLE VI.
High strength-to-weight ratio; tanks, pipe, aerospace
Simple process-short run items-prototypes Improved resin distribution and surface finish relative to vacuum bag Can handle higher glassto-resin ratios; uniform product Fast, automated production line procedure; boats, chairs, trays, car fenders and side panels, etc.
USE OF REINFORCED PLASTICS (MILLION POUNDS)5*b
Major Market
I
7965 ( E i t d . ) i7966 (Forecast) 37 14 71 72 27
Aircraft and missiles Appliances Boats Construction Consumer goods
16
Misceilaneous Total a Source: Society of Plastics Industry. forcing agent.
20
Simplest method, minim u m equipment, inexpensive mold, short run production items; boats, aircraft, prototypes Boats, swimming pools, tank lining Economical production method-lends self to complex shapes-e.g., chairs Uniform and easy to handle-eliminates shop formulation; molded at point and time of application by standard molding processes ; electrical, sporting goods, aircraft, aerospace Housings, structural parts, electrical, tools, pipe fittings
1,
1
1
I
I
41 16 78 78 30
facture of electrical and automotive parts, with replacement of die-cast and stamped metal parts as a prime objective. The most significant thermoplastic resins lending themselves to reinforcement are listed in Table 11. The relatively new field of reinforced thermoplastics is covered in a paper by T. P. Murphy. Table I11 shows tonnage consumption of resins in the manufacture of reinforced plastics. These figures are based on recent U. S. Tariff Commission reports from which resin quantities specifically being used in reinforced plastics have been separated. Numerous reinforcements are used in the manufacture of reinforced plastics, and the selection of such materials is based on evaluation of the economics and property requirements. The materials range from those such as paper and sisal at the cost of a few cents a pound, to ablative reinforcements such as carbon and graphite fibers which cost $20 to $30 per pound, to exotic whiskers such as sapphire which cost thousands of dollars per pound. Representative reinforcing agents are listed in Table IV. The most important one listed is glass, the backbone of most industrial reinforced plastics. Robert M. McMarlin covers glass-reinforced plastics in his paper immediately following this introduction to the series. In addition to the choice of resin and reinforcing agent, we have considerable latitude in the selection of catalyst systems, mineral fillers, stabilizers, thixotropic agents, colorants, and other agents. All these have specific functions that contribute in some measure to the end property performance and influence the ease of fabrication. The subject of organic peroxides as curing agents for reinforced plastics is reviewed in this series in a paper by Orville L. Mageli and James R. Kolczynski. The contribution which silane coupling agents can make to improving the performance of certain composites is discussed in a paper in this series by James G. Marsden and Samuel Sterman. The number of fabrication techniques for reinforcedplastics manufacture is as great as the variety of materials used in the composite. Essentially, the molding or fabrication of a reinforced plastic involves the saturation of the reinforcing agent by one means or another with resin, and then curing of the resin. Some of the molding procedures used in manufacture of reinforced plastics are listed in Table V. Applications for the manufactured reinforced plastics are legion; Table VI indicates major areas of application and poundage of reinforced plastic (reinforcement plus resin) consumed for 1965 and forecast for 1966.
CHAIRMAN Frank P. Greenspan, as chairman of this symposium, planned the scope and content of the Papers presented. He is Chairman-elect of the A C S Organic Coatings and Plastics Chemistry Division, which sponsored this symposium, and is notably qualE;fied in the plasticsfield; his position is Manager, New Product Development, Cliemical Divisions, of FMC Cork. He was formerly Director of Research and Development of F M C Corp.’s Plastics Department. SYMPOSIUM
20
Includes both resin and rein-
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