Reinforced thermoplastic sheets

Reinforced Thermoplastic Sheet. This process uses precombined sheets of thermoplastic resin and glass fiber reinforcement, cut into blanks to fit the weight and size requirements of the part to be molded. The blanks, preheated to a specified temperature, are loaded into the metal mold and the material flows under mol ding pressure to fiU the mold. The mold is kept closed under pressure until the temperature of the part has been reduced, the resin solidified, and demolding is possible. Cycle time, as with thermosetting resins, depends on the thickness of the part and the heat distortion temperature of the resin. Mol ding pressures are similar to SMC, 10—21 MPa (1500—3000 psi), depending on the size and complexity of the part. 

In use are stamping compression molding presses. Plastic used can be TS sheet molding compounds (SMCs) and stampable reinforced thermoplastic sheet (STX) material (STX is a registered tradename Azdel Inc., Shelby, NC). It is usually composed of a glass fiber-thermoplastic RTP (Chapter 15). 

TS plastics in reinforced sheets and compounds are usually used. Also used are reinforced thermoplastic sheets and compounds. With TSs compression molding (CM) can use preheated material (dielectric heater, etc.) that is placed in a heated mold cavity. The mold is closed under pressure causing the material to flow and completely fill the cavity. Chemical crosslinking occurs solidifying the TS molding material. 

Figure 5.54 Processing sequence for compression stamping glass fiber reinforced thermoplastic sheets...

Similar results can be achieved by hot stamping, in which blanks of reinforced thermoplastics sheets are preheated in an oven and placed between matched metal moulds in a heated press. 

With regard to methods of fabrication, all processes in Table 1.1 that are applicable to unfilled, unmodified thermoplastics can also be used for discontinuous systems (with the exception of expandable bead molding). In addition to thermoforming, hot stamping of reinforced thermoplastic sheets mostly containing randomly oriented continuous or discontinuous fibers is used for the production of large semistructural parts. Fillers can also be used in the thermoset processes in Table 1.1, often in combination with the primary continuous fiber reinforcement. The content and inherent properties of the additive, as well as its physical/chemical interactions with the matrix, are important parameters controlling the processability of the composite. 

Capacity for Making Fiber Glass-Reinforced Thermoplastic Sheet is Doubled by Azdel Inc., Shelby, NC, USA. Reinforced Plastics Newsletter 18 4, February 21, 1994. 

Material to be molded is placed in a matched-metal-die mold cavity and the mold closed. The part is formed by compressing the material under heat and pressure until the resin is cured or sufficiently cool to allow removal. Suitable for she (SMC) or bulk molding compounds (BMC), jH-eforms, w resin applied to reinfracemoit in the mold (wet system molding) or reinforced thermoplastic sheet (hot stamping). 

Christie, G.R. (1997) Numerical modelling of fibre-reinforced thermoplastic sheet forming. University of Auckland, PhD dissertation. 

Pickett, A.K., Queckborner, T, de Luca, P. and Haug, E. (1995) An explicit finite element solution for the forming prediction of continuous fibre-reinforced thermoplastic sheets. Composites Manufact., 6(3/4), 237-244. 

Martin, T.A., Bhattacharyya, D. and Pipes, R.B. (1992) Deformation chciracter-istics and formabUity of fiber-reinforced thermoplastic sheets. Composites Manufact., 3, 165-172. 

Mander S J, Bhattacharyya D and Collins I F (1995) Roll Forming of Fiber Reinforced Thermoplastic Sheet Proc Tenth Int Conf Compos Mater, vol. Ill, (Eds. Poursartip A and Street K) Woodhead Publishing Ltd, Cambridge, UK, pp. 413-420. 

Dykes R J, Mander S J and Bhattacharyya D (2000) Roll Forming Continuous Fiber-Reinforced Thermoplastic Sheets Experimental Analysis, Composites Part A 31 1395-1407,... 

Di Pede S and Woodhams R T (1990) Deep drawing self-reinforced thermoplastic sheet, Polym Eng Sci 30 1185-1199. 

Peter H. Hofer, A. R. Tavorozzi, and G. J. Wagerson, Stamping Adzell—A Reinforced Thermoplastic Sheet , Society of Automotive Engineers, Inc., 690009 (January 13-17,1969). 

A. D. Osborne and F. W. Maine, Reinforced Thermoplastic Sheet for Thermoforming , 29th Annual Technical Conference, Reinforced Plastics/Composites Institute, The Society of the Plastics Industry, Inc., Washington, DC, 1974. 

STP standard temperature pressure STX stampable reinforced thermoplastic sheet (Azdel tradename)... 

This investigation has yielded a number of findings relating to the deformation behavior of knitted fabric-reinforced thermoplastic sheets, as well as conclusions regarding practical forming issues. It has also delved into the underlying mechanisms responsible for its unique behavior, both essential for the development and future use of these types of materials. 

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