Pultrusion
“Pultrusion is a continuous process for manufacture of composite materials with constant cross-section. Reinforced fibers are pulled through a resin, possibly followed by a separate preforming system, and into a heated die, where the resin undergoes polymerization. Many resin types may be used in pultrusion including polyester, polyurethane, vinylester and epoxy.”
“The technology is not limited to thermosetting polymers. More recently, pultrusion has been successfully used with thermoplastic matrices such as polybutylene terephthalate (PBT) either by powder impregnation of the glass fiber or by surrounding it with sheet material of the thermoplastic matrix, which is then heated.”
(Wikipedia, Pultrusion, 7/25/2011)
“There are pultrusion processing methods known in the art in which heat-cured, pultruded, composite structures can be produced at moderate to high production rates. However, generally, a limitation of pultrusion processes is that a pultrusion process is adapted only to produce straight elongated parts of uniform cross-section. This is due in part to the nature of the process itself and in part due to the thermoset resins that are most often used. Because the process operates by pulling long continuous reinforcing fibers through the various unit operations, it naturally forms elongated composites in which the reinforcing fibers are aligned in the direction of the pultrusion. Once cured, thermoset resins cannot be subsequently thermoformed or shaped in any other manner, yet it is necessary to cure the thermoset resin at the die in order to bind the fibers together and to create the desired cross-sectional shape.”
“Usually, in these processing methods a resin system is employed that sacrifices structural performance for rapid processing. Therefore, conventional pultruded structures are generally unsuitable for primary structural applications due to their less than optimal structural performance. Lower structural performance is due to non-optimal fiber orientations in the fabric and the necessity of using rapid curing resins that have non-optimal structural performance.”
[Hillermeier and Friedrick, US Patent 7,867,568 (1/11/2011)]
Composites Processing
Extrusion
Injection Pultrusion
Processing
Recent US Patents
11/29/2011
8,066,922
Method and device for the production of a plastic profile
Jansen, Weidler and Hoffmann of Thomas and Technik + Innovation, Germany produced curved profiles by putlrusion using moving curved dies. (RDC 12/5/2011)
11/29/2011
8,066,836
Prepeg pultrusion
Fanucci and Bystricky of Kazak Composites, Massachusetts, did continuous pultrusion by introducing prepreg material, comprising fibers infiltrated with a partially cured resin, with a barrier layer between surfaces of the prepreg material and facing inner surfaces of the die. The prepreg material and the barrier layers are continuously pulled through the pultrusion die. The barrier layer is removed from each surface of the prepreg material after exiting the die. (RDC 12/5/2011)
9/27/2011
8,024,908
Pultruded utility structures
Williams, Illinois, has developed a pultrusion process for utility structures in different colors, environmentally safe, aesthetic pleasing and resistant to damage from weather, animals, insects and resistant to corrosion. The pultruded utility structure includes utility pole, a lighting pole, a structural support, an architectural design element (interior or exterior), a marine dock element or a fencing element, etc. (RDC 7/27/2011)
9/27/2011
8,025,754
Method of making a reinforcing mat for a pultruded part
Davies, Fritz and Beer of the Pella Corporation, Iowa, developed a method of preparing a reinforcing structure for pultruded parts where the reinforcing structure is pulled through a pultrusion die in a continuous longitudinal pull direction. First reinforcing fibers are arranged in a transverse direction and attached to a permeable transport web of staple fibers so that that the first reinforcing fibers oriented in the direction transverse are at least 30% of a volume of the reinforcing material. (RDC 9/29/2011).
1/11/2011
7,867,568
Continuous pultrusion process for producing high performance structural profiles
Hillermeier and Friedrich of Airbus, Germany, developed a continuous pultrusion process for producing structural profiles wherein a) one or more textile sheets are impregnated with a resin composition comprising a combination of (i) at least one epoxy resin which is a tri- or tetrafunctional epoxy resin and (ii) a curing agent system comprising at least two types of reactive groups of different reactivity b) the impregnated textile sheets are subjected to heat to cause a partial reaction between the at least one epoxy resin and the curing agent system, so that the viscosity of the resin composition is increased, and c) the partially reacted impregnated resin composition is gelled using heat and/or pressure. (RDC 7/22/2011)
1/11/2011
7,866,249
Method of manufacture of pultruded non-metallic damage-tolerant hard ballistic laminate
Booher of Techdyne, Arizona has developed a lightweight and highly effective armor in which engineered ballistic broad goods are encased in exacting alignment within a specialized housing, composed of a polymeric composite, which is simultaneously formed around the dry broad goods by pultrusion. The product finds use as protective armoring for vehicles, personal armor, siding and roofing for existing structures, and structural panels for construction of ballistic resistant structures. (RDC 7/22/2011)
Recent Journal Articles
Mathematical modeling for the pultrusion of polymethyl methacrylate based composites
(2228–2233)Journal of Applied Polymer Science 123 #4 (2012)
Chen of the Chinese Culture University, Taiwan, used a mathematical model accounting for the heat transfer and heat generation during the reaction of polymethyl methacrylate (PMMA) composites during the pultrusion of glass fiber reinforced composites. The equations of continuity and energy balance, coupled with a kinetic expression for the reaction system were solved using a finite difference method to calculate the temperature profiles in the thickness direction in a rectangular pultrusion die. A kinetic model, , was proposed to describe the reaction behavior of a PMMA resin. Kinetic parameters for the model were found from isothermal differential scanning calorimetry (DSC) scans using a multiple regression technique. The theoretical predicted values of temperature profiles along the pultrusion die length were in good agreement with experimental data. (RDC 11/2/2011)