Pultrusion process developments

This paper will describe briefly the pultrusion process developed and built locally, its reliability or performance, the quality of prepreg combined with the controlling parameters and finally the preliminary results on its usage as laminates and reinforcement in thermoplastic composites. 

Pultrusion process development of a graphite reinforced PEI thermoplastic composite. 4tb annual Conf. of Reinforced... 

Pulforming n. A modified pultrusion process developed to produce a changing volume/ shape. 

Wilson, M.L., Backley, J.D., Dickerson, G.E., Johnson, G.S., Taylor, E.C. and Covington III, E.W. (1989) Pultrusion process development of a graphite reinforced polyetherimide thermoplastic composite. Proceedings of the 44th Annual Conference, Society of Plastics Industry, Reinforced Plastics / Composite Institute, Dallas, Texas, USA, February 10, Paper Session 8-D. 

DeFosse, M., Material and Process Developments (Pultrusions) Promise New Applications, MP, Jun. 2002. 

Initial modelling on predicting velocity profiles in pultrusion dies was carried out by Gorthala et al. (1994). Here a two-dimensional mathematical model in cylindrical co-ordinates with a control-volume-based finite-difference method was developed for resin fiow, cure and heat transfer associated with the pultrusion process. Raper et al. 

Development of Long-Fibre Prepreg via Pultrusion Process. 453... 

Dow has developed a pultrusion simulation modeling (PSM) service designed to help fabricators achieve higher levels of productivity and reliability. Process variables such as pull speed, part and die temperature, heater output and pulling force can affect the quality of pultruded components. The PSM tool allows fabricators to predict processing performance for specific applications, and is accurate to within 10% of actual performance. The tool has been validated in customer trials and allows the pultrusion process to be optimized quickly. 

Dow, using Fulcrum thermoplastic composites technology and Isoplast thermoplastic polyurethanes, have developed a new thermoplastic pultrusion process. 

A rectangular model based on Darcy s law for predicting the degree of impregnation (or the void content, respectively) during the pultrusion process was developed in [8]. It leads to the following equation for the void content X, ... 

As a result, technology has been developed to enable the use of long fibres (around 2 mm) in a thermoplastic resin matrix. These are produced, not by classical physical mixing, but by a process analogous to the pultrusion process with thermosetting resin matrices, with internal lubrication additives to counteract the chopping effect of injection moulding. Similar effects have been measured with other fibres, such as aramid and carbon, and with other matrices, such as polypropylene and poly(phenylene sulphide). 

Like the pultrusion process, the selection of a suitable thermoplastic matrix material mainly depends on the desired mechanical properties and the desired long-term service temperature. The range of usable matrix materials starts with standard polymers such as polyethylene (PE) or polypropylene (PP) and ends with high performance polymers such as polyetherimide (PEI) or poyletheretherketone (PEEK). Recent developments have shown that the processing of reactive thermoplastic materials is possible as well (CBT). For some physical properties of common matrix materials see Table 8.2. °... 

A numerical model has been developed by Viola etaL (1990) to optimize the operating parameters of a pultrusion line. Their model incorporates a onedimensional finite difference simulation of the pultrusion process. Based on given target parameters, the model primarily optimizes the temperature set points along the die. 

A mathematical relationship between the DOC profile across the cross-section of a pultruded part and the die-heater temperatures was established by Li et al. (2002b).The relationship was employed to optimize the die-heating profile such that a near-uniformly cured component could be obtained finally. The algorithm was implemented for simulation of pultrusion process using the three-dimensional finite element/nodal control volume (FE/NCV) approach developed by Joshi and Lam (2001). 

The same authors (Carlone et al., 2007) further developed a hybrid approach, based on genetic algorithms and simplex method, to optimize the accuracy of pultrusion process using a finite difference scheme. 

Carlone and Palazzo (2008) developed a computational modelling of microwave assisted pultrusion. This model is based on an electromagnetic submodel, meant to evaluate the electric field distribution and the heat generation rate due to the microwave source and on a thermochemical submodel, used to determine the temperature and degree of cure distributions. The performed simulations revealed the relevance of design of the microwave cavity, the curing die, and the importance of the dielectric properties of the materials in microwave pultrusion process. 

Byun, J. H., Lee, S. K. and Kim, B. S. (1996), Development of hraided-pultrusion process and structure-property relationships for tubular composites , Acta Metallurgica Sinica, 9(6), 555-564. 

Carlone, R, Palazzo, G. S. and Pasquino, R. (2(X)6), Pultrusion manufacturing process development by computational modelling and methods , Mathematical and Computer Modelling, 44(7-8), 701-709. 

Fig. 10. Time-temperature profile for pultrusion process and development of conversion along the process. Temperature, conversion. From Ref. 55.

Pultrusion is a manufacturing process that converts fibre reinforcements and resin matrices into finished composite parts. Unlike other processes, pultrusion enables continuous production in a highly automated and low-labour process that uses a heated die to give shape to the composite part. These features mean that, of the different manufacturing processes developed in the last five decades, pultrusion offers the best productivity/cost ratio (Zureick and Scott, 2000). 

Carlone P, Palazzo G S and Pasquino R (2006) Pultrusion manufacturing process development by computational modeling and methods. Math Computer Model 44 701-709. 

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