WO2023126547A1 - Method for quantifying the viscosity of a polymeric material and viscosimeter - Google Patents
Method for quantifying the viscosity of a polymeric material and viscosimeter Download PDFInfo
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- WO2023126547A1 WO2023126547A1 PCT/ES2021/070939 ES2021070939W WO2023126547A1 WO 2023126547 A1 WO2023126547 A1 WO 2023126547A1 ES 2021070939 W ES2021070939 W ES 2021070939W WO 2023126547 A1 WO2023126547 A1 WO 2023126547A1
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N11/00—Investigating flow properties of materials, e.g. viscosity, plasticity; Analysing materials by determining flow properties
- G01N2011/0026—Investigating specific flow properties of non-Newtonian fluids
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N2203/00—Investigating strength properties of solid materials by application of mechanical stress
- G01N2203/0058—Kind of property studied
- G01N2203/0092—Visco-elasticity, solidification, curing, cross-linking degree, vulcanisation or strength properties of semi-solid materials
Definitions
- the present invention relates to methods for determining the viscosity of solid or semi-solid state polymeric materials and to viscometers.
- Viscometers and methods for quantifying viscosity are known in the prior art, for example rotational, oscillating or capillary viscometers or rheometers.
- US6023962A describes a viscometer that measures the Theological properties of polymers over a wide range of temperature, shear rate, and cure conditions.
- the described viscometer uses a reservoir onto which the polymeric material is introduced, said reservoir containing a slit through which the polymeric sample is made to flow thanks to compression on the sample. By measuring the flow rate and pressure drop across the slit and knowing the dimensions of the deposit and the slit, the rheology of the sample can be calculated.
- the object of the invention is to provide a method for the quantification of viscosity and a viscometer, as defined in the claims.
- One aspect of the invention refers to a method for quantifying the viscosity of a polymeric material in the solid or semisolid state, the method comprising the following stages: a first stage of obtaining a sample of the polymeric material with a regular prism shape based on square or rectangular, with a determined height hpref, a determined length Lpref and a determined width w, a second stage of placing the sample in a channel of a determined width, the polymeric sample being supported on a base of said channel and the width w of the sample equal to the width of the channel, a third compression stage of the sample in which the height of the polymeric sample is reduced at a speed vi ⁇ ne ai expanding the sample along the channel, and a fourth step of measuring the viscosity at an instant t as a function of the following parameters: o a pressure gradient AP between two points on the base arranged below the sample in different longitudinal positions, o the distance Lo between said two points, and or the height et and length Lt of the sample at
- a viscometer for quantifying the viscosity of a polymeric sample by means of the method of the invention, the viscometer comprising: the channel with the base to house the polymeric sample, an actuator element comprising a surface of compression configured to compress the polymeric sample at the speed of linear advance vi ⁇ ne ai, and means configured to measure the pressure supported by at least two points of the base of the channel.
- thermoplastic or thermosetting polymeric materials with high fiber content, preferably with fibers of a size greater than 25 mm, present in materials such as sheet molding compound or sheet molding compound (SMC), bulk molding compound (BMC) and glass mat thermoplastic (GMT).
- SMC sheet molding compound or sheet molding compound
- BMC bulk molding compound
- GTT glass mat thermoplastic
- the method and viscometer of the invention make it possible to obtain a more realistic simulation of the behavior of thermosetting or thermoplastic polymeric material in part production processes, mainly compression production processes, with said polymeric material.
- the method and viscometer of the invention make it possible to achieve higher shear rate values than in oscillatory and rotational rheometers, consistent with the speed values achieved in real compression production processes.
- the method and viscometer of the invention is not limited solely to small-sized samples, as usually occurs in generic viscometers of the capillary rheometer, rotational parallel plate rheometer, or oscillatory rheometers, for example. When working with these rheometers, the sample size used is not representative of reality. The method and viscometer of the invention allow the measurement of viscosity in larger sample sizes.
- Figure 1 shows a schematic representation of the first two method steps in the viscometer according to one embodiment of the invention.
- Figure 2 shows a schematic representation of the first two stages of the method in the viscometer according to another embodiment of the invention.
- Figure 3 shows a schematic representation of the expansion of a polymeric sample after a laying step.
- Figure 4 shows a schematic representation of the polymer sample of Figure 3 in a compression step.
- Figure 5 shows a schematic representation of a viscometer according to one embodiment of the invention.
- Figure 6 shows a schematic representation of the viscometer according to another embodiment of the invention.
- the method of the invention to quantify the viscosity of a polymeric material in the solid or semisolid state comprises the following stages: a first stage of obtaining a sample 300 of the polymeric material with a of a regular prism with a square or rectangular base, with a determined height hpref, a determined length Lpref and a determined width w, a second stage of placing the sample 300 in a channel 100 of a determined width, the polymeric sample being supported on a base 10 of said channel 100 and the width w of the sample 300 being the same as the width of the channel 100, a third stage of compression of the sample 300 in which the height of the polymeric sample 300 is reduced at a speed vi ne ai the sample expanding along the channel 100, that is to say expanding in a longitudinal direction of the channel 100, and a fourth step of measuring the viscosity at an instant t as a function of the following parameters: o a pressure gradient AP between two points of the base 10 arranged below the sample 300 in different
- the method of the invention allows the quantification of the viscosity at various instants t of the compression stage, with the associated advantage that having the viscosity values of the material at the shear rate values generated at each moment, they will allow to know in advance the behavior that the polymeric material will have during the production process of a piece in question. This will allow the selection of the compressor, as well as the appropriate manufacturing parameters.
- the length Lt of the sample 300 at instant t is calculated as a function of the height et of the sample 300 at said instant t, and of the initial height hpref and the initial length Lpref of the sample 300 according to the formula:
- the viscosity is obtained by the following formulas:
- Viscosity (q) - T — 7 - T —
- Vertical thrust flow Q1 Lateral advance flow Q2, and for when the polymeric sample expands in two directions in the longitudinal direction:
- Viscosity ( ]) — — . — : — - —
- the speed of the compression movement or the speed V i ine ai in which the height of the sample is reduced polymeric 300 of the compression stage is established as a function of a desired shear rate, calculating the rate V i i ne ai according to one of the following formulas:
- the method of the invention makes it possible to apply a constant or variable speed V i ne ai.
- the speed Vi, ne ai is constant.
- the method allows a range of speed vi, preferably being equal to or greater than 0.1 mm/sec and equal to or less than 100 mm/sec.
- the method of the invention allows a calculation of the viscosity when the polymeric sample 300 is expanded in a sense of the longitudinal direction represented as Q2A in Figure 1.
- the polymeric sample 300 is placed in an axial position 10A of channel 10.
- the method of the invention allows a calculation of the viscosity when the polymeric sample 300 is expanded in the two senses of the longitudinal direction, represented as Q2A and Q2B in Figure 2.
- the polymer sample 300 is preferably placed in a central position 10B of channel 10.
- the polymeric sample 300 in the rest state that is, before the placement stage and shown in Figure 3, has a height hpref equal to or less than the height of the channel 10, a length Lx less than the length of the channel 10 and a width w equal to that of the channel 10.
- the dimensions of the polymeric sample 300 are the following: a height hpref between 1 mm and 500 mm, being preferably between 10 and 20 mm. a width w between 1 mm and 2,000 mm, preferably between 25 and 50 mm. a length Lo between 5 mm and 2,000 mm, preferably between 25 and 200 mm.
- the compression stage is performed by means of an actuator element 200 that comprises a compression surface 20 configured to compress the polymeric sample 300. at the Vi ne ai speed, the linear speed corresponding to the lowering speed of the actuator element 200 and/or to the preset closing speed.
- the compression surface 20 has a size that covers a contact surface 31 of the polymeric sample 300 during the entire compression stage, that is, it has a size that covers the entire contact surface 31 of the sample. polymer sample 300 throughout the compression stage.
- the actuator element 200 exerts a force of between 1 and 1,000 Tn on the polymeric sample 300.
- the temperature of the polymeric material is tempered at a temperature between 23°C and 500°C before the compression stage. , this temperature being preferably higher than the melting temperature Tm or softening temperature Tg of the polymeric material in greater percentage by weight of the polymeric sample 300. In another embodiment, this temperature is maintained during the compression step. Depending on the part to be produced, it is also important to know the temperature that the polymeric material acquires, which is why, in a preferred embodiment, the actual temperature of the polymeric sample 300 is measured during the compression stage.
- the viscometer 500 comprises, as shown in figures 1, 2 and 5: the channel 100 with the base 10 to house the polymeric sample 300, an actuator element 200 that includes a compression surface 20 configured to compress the polymeric sample 300 at the speed vi ⁇ ne ai, and means 10a, 10b configured to measure the pressure supported by at least two points of the base 10 of the channel 100.
- the viscometer 500 includes a tool 101 in which a slot has been machined that forms the channel 10, this slot having a seat with a depth equal to or greater than the height hpref of the polymeric sample 300, a width w equal to the polymeric sample 300 and a length greater than the polymeric sample 300 that allows the expansion of the polymeric sample 300 during the compression step.
- the actuator element 200 can be a press or a hydraulic piston that has the ability to control the compression movement.
- the actuating element is configured to apply the closing speed and/or the linear advance speed Vi ⁇ ne ai and/or the preset force.
- One way to calculate the height et of the polymeric sample 300 would be knowing the distance that exists between the base of the actuator element in contact with the contact surface 31 of the polymeric sample 300 and the base 10 of the channel 100. Depending on the distance traveled by the actuator element at a time T determining the height et of the sample can be calculated.
- the compression surface 20 of the actuator element 200 and the channel 100, and more specifically the base 10 of the channel 100 are complementary, with the channel 100 and the actuator element 200 preferably facing each other and the actuator element 200 having a freedom of vertical displacement, in such a way that the actuating element moves up and down in the compression stage.
- the dimension and volume of the channel are known.
- viscometer 510 comprises channel 100 with open ends. This embodiment serves, for example, for measurements of polymeric samples 300 that expand in both directions, for example, in those embodiments where the polymeric sample is placed in a central position.
- these can be pressure sensors of different types, preferably piezoelectric or piezoresistive sensors.
- the viscometer 500 comprises means configured to heat and/or maintain the polymeric sample 300 at a specific temperature during the application of the method.
- These media can be fluid, magnetic or electrical, preferably being electrical media.
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Abstract
Description
DESCRIPCIÓN DESCRIPTION
“Método para cuantificar la viscosidad de un material polimérico y viscosímetro” “Method to quantify the viscosity of a polymeric material and viscometer”
SECTOR DE LA TÉCNICA TECHNIQUE SECTOR
La presente invención se relaciona con métodos para la determinación de la viscosidad de materiales poliméricos de estado sólido o semisólido y con viscosímetros. The present invention relates to methods for determining the viscosity of solid or semi-solid state polymeric materials and to viscometers.
ESTADO ANTERIOR DE LA TÉCNICA PRIOR STATE OF THE ART
La necesidad de aligeramiento de piezas para el sector del transporte ha acarreado consigo la necesidad del empleo de materiales poliméricos reforzados con fibras que puedan ser procesadas por métodos de moldeo tradicionales. En los procesos productivos de piezas de materiales poliméricos termoestables o termoplásticos reforzados con fibras es habitual utilizar procesos de moldeo por compresión donde el material polimérico es introducido en un molde abierto que posteriormente se comprime, de forma que el material fluye y llena la cavidad del molde. De cara a conocer el posible comportamiento del material polimérico durante este proceso, y sobre todo estimar las fuerzas de compresión es de gran ayuda disponer de información de la viscosidad de estos materiales durante el proceso de compresión. La viscosidad de los compuestos poliméricos, con o sin fibras, es una función de varios factores como la temperatura del material polimérico, la velocidad de cizalla y la presión a la que se someterá durante el proceso de compresión, el posible grado de curado alcanzado por el polímero, etc. The need to lighten parts for the transportation sector has brought with it the need to use fiber-reinforced polymeric materials that can be processed by traditional molding methods. In the production processes of parts made of fiber-reinforced thermosetting or thermoplastic polymeric materials, it is common to use compression molding processes where the polymeric material is introduced into an open mold that is subsequently compressed, so that the material flows and fills the mold cavity. . In order to know the possible behavior of the polymeric material during this process, and above all to estimate the compression forces, it is very helpful to have information on the viscosity of these materials during the compression process. The viscosity of polymeric compounds, with or without fibers, is a function of several factors such as the temperature of the polymeric material, the shear rate and pressure to which it will be subjected during the compression process, the possible degree of cure achieved by the polymer etc
En el estado de la técnica son conocidos viscosímetros y métodos para la cuantificación de la viscosidad, por ejemplo, viscosímetros o reómetros rotacionales, oscilantes o capilares. Viscometers and methods for quantifying viscosity are known in the prior art, for example rotational, oscillating or capillary viscometers or rheometers.
US6023962A describe un viscosímetro que mide las propiedades Teológicas de polímeros en un amplio rango de temperatura, velocidad de cizallamiento y condiciones de curado. El viscosímetro descrito utiliza un depósito sobre el que se introduce el material polimérico conteniendo dicho depósito una rendija por el que se hace fluir la muestra polimérica gracias a la compresión sobre la muestra. Al medir el caudal y la caída de presión a través de la rendija y conocer las dimensiones del depósito y la rendija, se puede calcular la reología de la muestra. US6023962A describes a viscometer that measures the Theological properties of polymers over a wide range of temperature, shear rate, and cure conditions. The described viscometer uses a reservoir onto which the polymeric material is introduced, said reservoir containing a slit through which the polymeric sample is made to flow thanks to compression on the sample. By measuring the flow rate and pressure drop across the slit and knowing the dimensions of the deposit and the slit, the rheology of the sample can be calculated.
EXPOSICIÓN DE LA INVENCIÓN DISCLOSURE OF THE INVENTION
El objeto de la invención es el de proporcionar un método para la cuantificación de la viscosidad y un viscosímetro, según se define en las reivindicaciones. The object of the invention is to provide a method for the quantification of viscosity and a viscometer, as defined in the claims.
Un aspecto de la invención se refiere a un método para cuantificar la viscosidad de un material polimérico en estado sólido o semisólido, comprendiendo el método las siguientes etapas: una primera etapa de obtención de una muestra del material polimérico con una forma de prisma regular con base cuadrada o rectangular, con una altura determinada hpref, una longitud determinada Lpref y una anchura determinada w, una segunda etapa de colocación de la muestra en un canal de una anchura determinada, quedando apoyada la muestra polimérica en una base de dicho canal y siendo la anchura w de la muestra igual que la anchura del canal, una tercera etapa de compresión de la muestra en la que se reduce la altura de la muestra polimérica a una velocidad vi¡neai expandiéndose la muestra a lo largo del canal, y una cuarta etapa de medición de la viscosidad en un instante t en función de los siguientes parámetros: o un gradiente de presión AP entre dos puntos de la base dispuestos debajo de la muestra en posiciones longitudinales distintas, o la distancia Lo entre dichos dos puntos, y o la altura et y la longitud Lt de la muestra en el instante t. One aspect of the invention refers to a method for quantifying the viscosity of a polymeric material in the solid or semisolid state, the method comprising the following stages: a first stage of obtaining a sample of the polymeric material with a regular prism shape based on square or rectangular, with a determined height hpref, a determined length Lpref and a determined width w, a second stage of placing the sample in a channel of a determined width, the polymeric sample being supported on a base of said channel and the width w of the sample equal to the width of the channel, a third compression stage of the sample in which the height of the polymeric sample is reduced at a speed vi¡ne ai expanding the sample along the channel, and a fourth step of measuring the viscosity at an instant t as a function of the following parameters: o a pressure gradient AP between two points on the base arranged below the sample in different longitudinal positions, o the distance Lo between said two points, and or the height et and length Lt of the sample at time t.
Otro aspecto de la invención se refiere a un viscosímetro para la cuantificación de la viscosidad de una muestra polimérica mediante el método de la invención, comprendiendo el viscosímetro: el canal con la base para alojar la muestra polimérica, un elemento actuador que comprende una superficie de compresión configurado para comprimir la muestra polimérica a la velocidad de avance lineal vi¡neai, y medios configurados para medir la presión soportada por al menos dos puntos de la base del canal. Con el método y viscosímetro de la invención se posibilita la realización de vahas medidas de viscosidad en un amplio rango de valores de velocidad de cizalla, pudiendo determinar la viscosidad en materiales poliméhcos termoplásticos o termoestabes, con altos contenidos de fibra, preferiblemente con fibras de un tamaño mayor a 25 mm, presente en materiales como en el compuesto de moldeo de láminas o el “sheet moulding compound” (SMC), el “bulk moulding compound” (BMC) y el “glass mat thermoplastic” (GMT). Another aspect of the invention refers to a viscometer for quantifying the viscosity of a polymeric sample by means of the method of the invention, the viscometer comprising: the channel with the base to house the polymeric sample, an actuator element comprising a surface of compression configured to compress the polymeric sample at the speed of linear advance vi¡ne ai, and means configured to measure the pressure supported by at least two points of the base of the channel. With the method and viscometer of the invention, it is possible to carry out various viscosity measurements in a wide range of shear rate values, being able to determine the viscosity in thermoplastic or thermosetting polymeric materials, with high fiber content, preferably with fibers of a size greater than 25 mm, present in materials such as sheet molding compound or sheet molding compound (SMC), bulk molding compound (BMC) and glass mat thermoplastic (GMT).
El método y viscosímetro de la invención permiten obtener una simulación más realista del comportamiento del material poliméhco termoestable o termoplástico en los procesos productivos de piezas, principalmente procesos productivos de compresión, con dicho material poliméhco. El método y viscosímetro de la invención permiten alcanzar mayores valores de velocidad de cizalla que en los reómetros oscilatorios y rotacionales, en coherencia con los valores de velocidades alcanzados en procesos productivos de compresión reales. The method and viscometer of the invention make it possible to obtain a more realistic simulation of the behavior of thermosetting or thermoplastic polymeric material in part production processes, mainly compression production processes, with said polymeric material. The method and viscometer of the invention make it possible to achieve higher shear rate values than in oscillatory and rotational rheometers, consistent with the speed values achieved in real compression production processes.
El método y viscosímetro de la invención no está limitado únicamente a muestras de tamaño pequeño como suele ocurrir en viscosímetros genéricos de tipo reómetro capilar, reómetro de placas paralelas rotacionales, o reómetros oscilatorios por ejemplo. Cuando se trabaja con estos reómetros el tamaño de muestra utilizar no es representativo de la realidad. El método y viscosímetro de la invención permiten la medición de la viscosidad en tamaños mayores de muestra. The method and viscometer of the invention is not limited solely to small-sized samples, as usually occurs in generic viscometers of the capillary rheometer, rotational parallel plate rheometer, or oscillatory rheometers, for example. When working with these rheometers, the sample size used is not representative of reality. The method and viscometer of the invention allow the measurement of viscosity in larger sample sizes.
Estas y otras ventajas y características de la invención se harán evidentes a la vista de las figuras y de la descripción detallada de la invención. These and other advantages and features of the invention will become apparent upon review of the figures and detailed description of the invention.
DESCRIPCIÓN DE LOS DIBUJOS DESCRIPTION OF THE DRAWINGS
La figura 1 muestra una representación esquemática de las dos primeras etapas del método en el viscosímetro según una realización de la invención. Figure 1 shows a schematic representation of the first two method steps in the viscometer according to one embodiment of the invention.
La figura 2 muestra una representación esquemática de las dos primeras etapas del método en el viscosímetro según otra realización de la invención. Figure 2 shows a schematic representation of the first two stages of the method in the viscometer according to another embodiment of the invention.
La figura 3 muestra una representación esquemática de la expansión de una muestra poliméhca tras una etapa de colocación. La figura 4 muestra una representación esquemática de la muestra polimérica de la figura 3 en una etapa de compresión. Figure 3 shows a schematic representation of the expansion of a polymeric sample after a laying step. Figure 4 shows a schematic representation of the polymer sample of Figure 3 in a compression step.
La figura 5 muestra una representación esquemática de un viscosímetro según una realización de la invención. Figure 5 shows a schematic representation of a viscometer according to one embodiment of the invention.
La figura 6 muestra una representación esquemática del viscosímetro según otra realización de la invención. Figure 6 shows a schematic representation of the viscometer according to another embodiment of the invention.
EXPOSICIÓN DETALLADA DE LA INVENCIÓN DETAILED DISCLOSURE OF THE INVENTION
Tal y como se muestra en las figuras 1 y 2, el método de la invención para cuantificar la viscosidad de un material polimérico en estado sólido o semisólido comprende las siguientes etapas: una primera etapa de obtención de una muestra 300 del material polimérico con una forma de prisma regular con base cuadrada o rectangular, con una altura determinada hpref, una longitud determinada Lpref y una anchura determinada w, una segunda etapa de colocación de la muestra 300 en un canal 100 de una anchura determinada, quedando apoyada la muestra polimérica en una base 10 de dicho canal 100 y siendo la anchura w de la muestra 300 igual que la anchura del canal 100, una tercera etapa de compresión de la muestra 300 en la que se reduce la altura de la muestra polimérica 300 a una velocidad vi¡neai expandiéndose la muestra a lo largo del canal 100, es decir expandiéndose en una dirección longitudinal del canal 100, y una cuarta etapa de medición de la viscosidad en un instante t en función de los siguientes parámetros: o un gradiente de presión AP entre dos puntos de la base 10 dispuestos debajo de la muestra 300 en posiciones longitudinales distintas, o la distancia Lo entre dichos dos puntos, y o la altura et y la longitud Lt de la muestra 300 en el instante t. As shown in figures 1 and 2, the method of the invention to quantify the viscosity of a polymeric material in the solid or semisolid state comprises the following stages: a first stage of obtaining a sample 300 of the polymeric material with a of a regular prism with a square or rectangular base, with a determined height hpref, a determined length Lpref and a determined width w, a second stage of placing the sample 300 in a channel 100 of a determined width, the polymeric sample being supported on a base 10 of said channel 100 and the width w of the sample 300 being the same as the width of the channel 100, a third stage of compression of the sample 300 in which the height of the polymeric sample 300 is reduced at a speed vi ne ai the sample expanding along the channel 100, that is to say expanding in a longitudinal direction of the channel 100, and a fourth step of measuring the viscosity at an instant t as a function of the following parameters: o a pressure gradient AP between two points of the base 10 arranged below the sample 300 in different longitudinal positions, or the distance Lo between said two points, and or the height et and the length Lt of the sample 300 at the instant t.
Por lo tanto, con el método de la invención se puede calcular la viscosidad de la muestra polimérica a una velocidad Vi¡neai determinada. En una realización preferente, el método de la invención permite la cuantificación de la viscosidad en varios instantes t de la etapa de compresión, con la ventaja asociada de que disponer de los valores de viscosidad del material a los valores de velocidad de cizalla generados en cada momento, permitirán dar a conocer de antemano el comportamiento que el material polimérico tendrá durante el proceso productivo de una pieza en cuestión. Esto permitirá seleccionar el compresor, así como los parámetros de fabricación adecuados. Therefore, with the method of the invention it is possible to calculate the viscosity of the polymeric sample at a determined speed Vi, ne ai. In a preferred embodiment, the method of the invention allows the quantification of the viscosity at various instants t of the compression stage, with the associated advantage that having the viscosity values of the material at the shear rate values generated at each moment, they will allow to know in advance the behavior that the polymeric material will have during the production process of a piece in question. This will allow the selection of the compressor, as well as the appropriate manufacturing parameters.
En una realización preferente, la longitud Lt de la muestra 300 en el instante t se calcula en función de la altura et de la muestra 300 en dicho instante t, y de la altura inicial hpref y la longitud inicial Lpref de la muestra 300 según la fórmula:
En una realización preferente, la viscosidad se obtiene mediante las siguientes fórmulas: In a preferred embodiment, the viscosity is obtained by the following formulas:
(a) cuando la muestra polimérica se expande en un sentido de la dirección longitudinal (a) when the polymer sample expands in a sense of the longitudinal direction
Viscosidad (q) =
Lpref * hpref * Vimeai * Lo * 12 Lpref * hpref * Vimeai * Lo * 12
(b) cuando la muestra polimérica se expande en los dos sentidos de la dirección longitudinal (b) when the polymer sample expands in both directions of the longitudinal direction
-AP * (et)4 -AP * (et) 4
Viscosidad (q) = - T — 7 - T — Viscosity (q) = - T — 7 - T —
Lpref * hpref * Vimeai * Lo * 6 Lpref * hpref * Vimeai * Lo * 6
Las fórmulas han sido desarrolladas teniendo en consideración lo siguiente: The formulas have been developed taking into consideration the following:
La teoría de conservación de volumen en equilibrio: The theory of conservation of volume in equilibrium:
Lpref * W * hpref = Lt * W*et La relación entre el caudal de empuje vertical Q1 y el caudal de avance lateral Q2 (reflejados en la figura 3 y 4), siendo para cuando la muestra polimérica se expande en un sentido de la dirección longitudinal: Lpref * W * hpref = Lt * W*et The relationship between the vertical thrust flow rate Q1 and the lateral advance flow rate Q2 (reflected in Figures 3 and 4), being for when the polymeric sample expands in a sense of the longitudinal direction:
Caudal de empuje vertical Q1 = Caudal de avance lateral Q2, y siendo para cuando la muestra polimérica se expande en dos sentidos de la dirección longitudinal: Vertical thrust flow Q1 = Lateral advance flow Q2, and for when the polymeric sample expands in two directions in the longitudinal direction:
Caudal de empuje vertical (Q1) = 2 * Caudal de avance lateral (Q2), en donde: Vertical thrust flow (Q1) = 2 * Lateral advance flow (Q2), where:
Ql = Lt * IV * Vnneal
Las fórmulas para el cálculo de velocidad de cizalla y tensión de cizalla utilizadas en la literatura para reómetros de capilar rectangular:
Cálculo de la viscosidad teniendo en cuenta que: Calculation of the viscosity taking into account that:
Tensión de cizalla generadagenerated shear stress
Viscosidad ( ]) = — — . — : — - — Viscosity ( ]) = — — . — : — - —
Velocidad de cizalla generada generated shear rate
En ocasiones puede ser interesante conocer la viscosidad del material en un rango de velocidad de cizalla concreta. Es por ello que, en una realización preferente, la velocidad del movimiento de compresión o la velocidad V i¡neai en la que se reduce la altura de la muestra polimérica 300 de la etapa de comprensión se establece en función de una velocidad de cizalla deseada, calculando la velocidad V i¡neai según una de las siguientes fórmulas: Sometimes it can be interesting to know the viscosity of the material in a specific shear rate range. That is why, in a preferred embodiment, the speed of the compression movement or the speed V i ine ai in which the height of the sample is reduced polymeric 300 of the compression stage is established as a function of a desired shear rate, calculating the rate V i i ne ai according to one of the following formulas:
(a) cuando la muestra polimérica se expande en un sentido de la dirección longitudinal:
(b) cuando la muestra polimérica se expande en los dos sentidos de la dirección longitudinal:
El método de la invención permite aplicar una velocidad V i¡neai constante o variable. En una realización preferente, la velocidad Vi¡neai es constante. The method of the invention makes it possible to apply a constant or variable speed V i ne ai. In a preferred embodiment, the speed Vi, ne ai is constant.
En cuanto a la velocidad de avance lineal Vi¡neai, el método permite un rango de velocidad v i¡neai, siendo preferiblemente igual o mayor a 0,1 mm/seg e igual o menor a 100 mm/seg. Regarding the speed of linear advance Vi, ne ai, the method allows a range of speed vi, preferably being equal to or greater than 0.1 mm/sec and equal to or less than 100 mm/sec.
Tal y como se ha descrito, el método de la invención permite un cálculo de la viscosidad cuando la muestra polimérica 300 se expande en un sentido de la dirección longitudinal representado como Q2A en la figura 1. En una realización preferente, la muestra polimérica 300 se coloca en una posición axial 10A del canal 10. As described, the method of the invention allows a calculation of the viscosity when the polymeric sample 300 is expanded in a sense of the longitudinal direction represented as Q2A in Figure 1. In a preferred embodiment, the polymeric sample 300 is placed in an axial position 10A of channel 10.
En otra realización, se ha descrito que el método de la invención permite un cálculo de la viscosidad cuando la muestra polimérica 300 se expande en los dos sentidos de la dirección longitudinal, representados como Q2A y Q2B en la figura 2. Para esta realización, la muestra polimérica 300 se coloca preferentemente en una posición central 10B del canal 10. En una realización preferente, la muestra polimérica 300 en estado de reposo, es decir, antes de la etapa de colocación y mostrada en la figura 3, tiene una altura hpref igual o menor a la altura del canal 10, una largura Lx menor a la largura del canal 10 y una anchura w igual a la del canal 10. En una realización preferente, las dimensiones de la muestra polimérica 300 son las siguientes: una altura hpref entre 1 mm y 500 mm, siendo preferiblemente entre 10 y 20 mm. una anchura w entre 1 mm y 2.000 mm, siendo preferiblemente entre 25 y 50 mm. una longitud Lo entre 5 mm y 2.000 mm, siendo preferiblemente entre 25 y 200 mm. In another embodiment, it has been described that the method of the invention allows a calculation of the viscosity when the polymeric sample 300 is expanded in the two senses of the longitudinal direction, represented as Q2A and Q2B in Figure 2. For this embodiment, the polymer sample 300 is preferably placed in a central position 10B of channel 10. In a preferred embodiment, the polymeric sample 300 in the rest state, that is, before the placement stage and shown in Figure 3, has a height hpref equal to or less than the height of the channel 10, a length Lx less than the length of the channel 10 and a width w equal to that of the channel 10. In a preferred embodiment, the dimensions of the polymeric sample 300 are the following: a height hpref between 1 mm and 500 mm, being preferably between 10 and 20 mm. a width w between 1 mm and 2,000 mm, preferably between 25 and 50 mm. a length Lo between 5 mm and 2,000 mm, preferably between 25 and 200 mm.
Con respecto a la etapa de compresión, en una realización preferente, tal y como se muestra en las figuras 1 y 2, la etapa de compresión se realiza mediante un elemento actuador 200 que comprende una superficie de compresión 20 configurado para comprimir la muestra polimérica 300 a la velocidad Vi¡neai, correspondiendo la velocidad lineal con la velocidad de bajada del elemento actuador 200 y/o a la velocidad de cierre preestablecido. En una realización preferente, la superficie de compresión 20 tiene un tamaño que cubre una superficie de contacto 31 de la muestra polimérica 300 durante toda la etapa de compresión, es decir, tiene un tamaño que cubre la totalidad de la superficie de contacto 31 de la muestra polimérica 300 durante toda la etapa de compresión. Regarding the compression stage, in a preferred embodiment, as shown in figures 1 and 2, the compression stage is performed by means of an actuator element 200 that comprises a compression surface 20 configured to compress the polymeric sample 300. at the Vi ne ai speed, the linear speed corresponding to the lowering speed of the actuator element 200 and/or to the preset closing speed. In a preferred embodiment, the compression surface 20 has a size that covers a contact surface 31 of the polymeric sample 300 during the entire compression stage, that is, it has a size that covers the entire contact surface 31 of the sample. polymer sample 300 throughout the compression stage.
Otro de los parámetros que pueden influir en la calidad de la pieza a fabricar es la fuerza de compresión. Es por ello que, en una realización preferente, el elemento actuador 200 ejerce una fuerza de entre 1 y 1.000 Tn sobre la muestra polimérica 300. Another of the parameters that can influence the quality of the part to be manufactured is the compression force. That is why, in a preferred embodiment, the actuator element 200 exerts a force of between 1 and 1,000 Tn on the polymeric sample 300.
Otro de los parámetros influyente en el proceso de producción es la temperatura del material polimérico, por lo que, en una realización preferente, la muestra polimérica 300 es atemperada a una temperatura de entre 23°C y 500°C antes de la etapa de compresión, siendo esta temperatura preferiblemente superior a la temperatura de fusión Tm o reblandecimiento Tg del material polimérico en mayor porcentaje en peso de la muestra polimérica 300. En otra realización, esta temperatura es mantenida durante la etapa de compresión. Dependiendo de la pieza a producir, también es importante conocer la temperatura que adquiere el material polimérico, es por ello que, en una realización preferente, se mide la temperatura real de la muestra polimérica 300 durante la etapa de compresión. Another of the influential parameters in the production process is the temperature of the polymeric material, therefore, in a preferred embodiment, the polymeric sample 300 is tempered at a temperature between 23°C and 500°C before the compression stage. , this temperature being preferably higher than the melting temperature Tm or softening temperature Tg of the polymeric material in greater percentage by weight of the polymeric sample 300. In another embodiment, this temperature is maintained during the compression step. Depending on the part to be produced, it is also important to know the temperature that the polymeric material acquires, which is why, in a preferred embodiment, the actual temperature of the polymeric sample 300 is measured during the compression stage.
Otro aspecto de la invención se refiere a un viscosímetro configurado para la cuantificación de la viscosidad de una muestra polimérica 300 mediante el método de la invención. En una realización preferente, el viscosímetro 500 comprende, tal como se muestra en las figuras 1 , 2 y 5: el canal 100 con la base 10 para alojar la muestra polimérica 300, un elemento actuador 200 que comprende una superficie de compresión 20 configurado para comprimir la muestra polimérica 300 a la velocidad vi¡neai, y medios 10a, 10b configurados para medir la presión soportada por al menos dos puntos de la base 10 del canal 100. Another aspect of the invention refers to a viscometer configured for the quantification of the viscosity of a polymeric sample 300 by means of the method of the invention. In a preferred embodiment, the viscometer 500 comprises, as shown in figures 1, 2 and 5: the channel 100 with the base 10 to house the polymeric sample 300, an actuator element 200 that includes a compression surface 20 configured to compress the polymeric sample 300 at the speed vi¡ne ai, and means 10a, 10b configured to measure the pressure supported by at least two points of the base 10 of the channel 100.
A modo de ejemplo, tal y como se muestra en la figura 5, el viscosímetro 500 comprende un utillaje 101 en el que se ha mecanizado una ranura que forma el canal 10, teniendo esta ranura un alojamiento con una profundidad igual o superior a la altura hpref de la muestra polimérica 300, una anchura w igual a la muestra polimérica 300 y una largura mayor a la muestra polimérica 300 que permita la expansión de la muestra polimérica 300 durante la etapa de compresión. El elemento actuador 200, a modo de ejemplo, puede ser una prensa o un pistón hidráulico que posee la capacidad de controlar el movimiento de compresión. El elemento actuador está configurado para aplicar la velocidad de cierre y/o la velocidad de avance lineal Vi¡neai y/o la fuerza preestablecida. By way of example, as shown in figure 5, the viscometer 500 includes a tool 101 in which a slot has been machined that forms the channel 10, this slot having a seat with a depth equal to or greater than the height hpref of the polymeric sample 300, a width w equal to the polymeric sample 300 and a length greater than the polymeric sample 300 that allows the expansion of the polymeric sample 300 during the compression step. The actuator element 200, by way of example, can be a press or a hydraulic piston that has the ability to control the compression movement. The actuating element is configured to apply the closing speed and/or the linear advance speed Vi¡ ne ai and/or the preset force.
El experto en la materia conoce distintas formas de medir los parámetros necesarios para la aplicación de las fórmulas: The person skilled in the art knows different ways of measuring the parameters necessary for the application of the formulas:
Una manera de calcular la altura et de la muestra polimérica 300 sería conociendo la distancia que existe entre la base del elemento actuador en contacto con la superficie de contacto 31 de la muestra polimérica 300 y la base 10 del canal 100. En función de la distancia recorrida por el elemento actuador en un momento T determinando se podrá calcular la altura et de la muestra.One way to calculate the height et of the polymeric sample 300 would be knowing the distance that exists between the base of the actuator element in contact with the contact surface 31 of the polymeric sample 300 and the base 10 of the channel 100. Depending on the distance traveled by the actuator element at a time T determining the height et of the sample can be calculated.
Una manera de conocer la Vi¡neai sería conociendo la velocidad de bajada lineal que se programe al pistón o elemento actuador. En una realización preferente, la superficie de compresión 20 del elemento actuador 200 y el canal 100, y más concretamente la base 10 del canal 100, son complementarios, estando el canal 100 y el elemento actuador 200 preferiblemente enfrentados y teniendo el elemento actuador 200 una libertad de desplazamiento vertical, de tal manera que el elemento actuador se desplaza de arriba abajo en la etapa de compresión. En esta realización, la dimensión y volumen del canal son conocidos. One way to know the Vi¡ ne ai would be knowing the linear descent speed that is programmed to the piston or actuating element. In a preferred embodiment, the compression surface 20 of the actuator element 200 and the channel 100, and more specifically the base 10 of the channel 100, are complementary, with the channel 100 and the actuator element 200 preferably facing each other and the actuator element 200 having a freedom of vertical displacement, in such a way that the actuating element moves up and down in the compression stage. In this embodiment, the dimension and volume of the channel are known.
En otra realización, ¡lustrada en la figura 6, el viscosímetro 510 comprende el canal 100 con los extremos abiertos. Esta realización sirve por ejemplo para las mediciones de muestras poliméricas 300 que se expanden en los dos sentidos, por ejemplo, en aquellas realizaciones en donde la muestra polimérica se coloca en una posición central. In another embodiment, illustrated in Figure 6, viscometer 510 comprises channel 100 with open ends. This embodiment serves, for example, for measurements of polymeric samples 300 that expand in both directions, for example, in those embodiments where the polymeric sample is placed in a central position.
Con respecto a los medios 10a, 10b configurados para medir la presión, estos pueden ser sensores de presión de diferente tipología, preferiblemente sensores piezoeléctricos o piezorresistivos. With respect to the means 10a, 10b configured to measure the pressure, these can be pressure sensors of different types, preferably piezoelectric or piezoresistive sensors.
Tal y como se ha descrito anteriormente, dependiendo del caso es de interés atemperar o calentar la muestra polimérica en la etapa de colocación y/o durante la etapa de compresión. En una realización preferente, el viscosímetro 500 comprende medios configurados para calentar y/o mantener la muestra polimérica 300 a una temperatura concreta durante la aplicación del método. Estos medios pueden ser fluidos, magnéticos o eléctricos, siendo preferiblemente medios eléctricos. As previously described, depending on the case, it is of interest to temper or heat the polymeric sample in the placement stage and/or during the compression stage. In a preferred embodiment, the viscometer 500 comprises means configured to heat and/or maintain the polymeric sample 300 at a specific temperature during the application of the method. These media can be fluid, magnetic or electrical, preferably being electrical media.
Claims
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1447834A (en) * | 1973-07-30 | 1976-09-02 | Du Pont | Micro-parallel plate plastometer and viscometry method |
| NO161944B (en) * | 1987-03-19 | 1989-07-03 | Elkem As | Viscometer. |
| US5269190A (en) * | 1989-01-13 | 1993-12-14 | Ole Kramer | Apparatus for the performance of rheological measurements on materials |
| US6023962A (en) | 1998-01-22 | 2000-02-15 | Cornell Research Foundation, Inc. | Reservoir-slit rheometer for the viscosity measurement of fast-reacting polymers |
| CN105300837B (en) * | 2014-06-25 | 2018-11-30 | 北京有色金属研究总院 | Method for measuring viscosity of high solid fraction metal semi-solid slurry |
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2021
- 2021-12-27 WO PCT/ES2021/070939 patent/WO2023126547A1/en not_active Ceased
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1447834A (en) * | 1973-07-30 | 1976-09-02 | Du Pont | Micro-parallel plate plastometer and viscometry method |
| NO161944B (en) * | 1987-03-19 | 1989-07-03 | Elkem As | Viscometer. |
| US5269190A (en) * | 1989-01-13 | 1993-12-14 | Ole Kramer | Apparatus for the performance of rheological measurements on materials |
| US6023962A (en) | 1998-01-22 | 2000-02-15 | Cornell Research Foundation, Inc. | Reservoir-slit rheometer for the viscosity measurement of fast-reacting polymers |
| CN105300837B (en) * | 2014-06-25 | 2018-11-30 | 北京有色金属研究总院 | Method for measuring viscosity of high solid fraction metal semi-solid slurry |
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