DD236048A1 - METHOD AND DEVICE FOR PRODUCING HOMOGENEOUS SPRAYING BODY - Google Patents

Abstract

The invention relates to the fields of technology in which polymers are processed and from the smallest amounts of sample rheological and mechanical characteristics for application engineering investigations in laboratory and industrial practice are required. The aim and object is to provide a method and a device for the production of homogeneous Spritzgußpruefkoerper from small sample quantities for the determination of mechanical characteristics and the detection of rheological characteristics of the still molten sample amount by capillary rheometer or miniature processing machines with piston plasticization. The object is achieved in that the inhomogeneous sample material is pressed by the piston of the capillary rheometer or the mini-processing machine by a static mixing or dispersing and then the thermally and materially homogeneous material via a Meßduese while recording the parameters for the rheological characteristic in the Pruefkoerperformhohlraum is injected. According to the invention, the device according to FIG. 1 consists of a capillary rheometer or a micro-processing machine with piston plastification, a downstream temperature-controlled mixing chamber with mixing or dispersing element and mixing nozzle equipped with transducers, which is followed by a temperature-controllable injection molding tool having a test specimen cavity.

Description

For this 1 page drawing

Field of application of the invention

The invention relates to a method and an apparatus for producing homogeneous Spritzgußprüfkörper, especially from small sample quantities. It is primarily used in polymer processing in conjunction with capillary and micro-machining machines with piston plastification in laboratory and industrial practice.

Characteristic of the known technical solutions

The application-technological characterization of very small amounts of polymer material is becoming increasingly important with the increasing development of new polymer materials or mixtures of polymers with other materials.

The dominant method for the production of test specimens from small amounts of specimens is the pressing method (Schmiedel, H., Schiefer, H .: Hochpolymere and their testing, VEB Fachbuchverläg Leipzig, 1972, Author collective: Examination of high polymer materials, fundamentals and test methods, VEB Deutscher Verlag for basic industry, Leipzig, 1977).

However, due to the lack of homogeneity, the specimens produced by the pressing process do not provide any characterization results that are relevant to practice.

This also applies to specimens made on micromachining machines with piston plastification.

For application-technical characterization often only so much material is present that this rheologically or in the solid state can be mechanically characterized, for the processing and materials technician but a correlation of studies in the molten and solid state of material on the same material is of great interest.

Also known are extensive mold filling studies using special forms on capillary rheometers to investigate the shear and extensional flows in the mold cavity during injection molding (Schmidt, LR: Injection Molding of Glass-Filled Polypropylene: Mold Filling Studies, in Platzer, N .: Copolymers, Polyblends and Composites, Advance in Chemistry Series, Vol. 142, 175). The investigations are characterized by a high metrological effort, u.a. the tracer technique to illustrate the flows, high-speed cameras to record the complete deformation history of tracers and IR thermometers for temperature registration.

With devices of this kind, it is not possible:. ',

1. Perform form filling studies with material and thermally homogeneous material;

2. Produce materially homogeneous test specimens in order to ensure targeted application-technological investigations. In conducting an experimental study, Han and coworkers (Han, CD, et al .: Journal of Applied Polymer Science, Vol.21, 1977, pp.353-379) switch a static mixer (kenics) between piston and mold cavity of a plastic processing machine to improve mixing performance.

For test specimen production, a larger sample quantity is needed; d. H. a Prüfkörperherstellung with small sample quantities is not possible; Even a Theological material identification of the still molten sample amount is not possible. It is also known that mixing elements (Kenics mixing elements) for mixing intensification are incorporated in dispersion studies in the cylinders of capillary rheometers (Vanoene, H .: Journal of Colloid and Interface Science, Vol.40, Sept. 1972, No.3, p.448- 467).

Subject of the investigations are the dispersion formations. There is no Prüfkörperherstellung for application technology examination of the mixtures; Also, due to the use of multiple Kenics mixing elements, a larger sample size is required.

The known methods and devices for the production of test specimens, in particular from the smallest sample quantities, do not guarantee material homogeneity of the specimens. The characterization results obtained by means of these test specimens are thus only conditionally suitable for application-technical statements.

The state of the art and methods for reological characterization is embodied by conventional rheometers and viscometers (Walters, K .: Rheometry: Industrial Applications, John Wiley & S .;, Ltd. 1980, Whorlow, R.W .:

Rheological Techniques, Ellis Harwood & Halsted Press, 1980); in the application of a simultaneous production of homogeneous specimens for application engineering studies is not known.

Object of the invention

The object of the invention is the production of material homogeneous Spritzgußprüfkörper for determining mechanical characteristics of smallest sample quantities and the detection of the Theological characteristics of the still molten sample amount.

Explanation of the essence of the invention

The invention has for its object to provide a method and an apparatus which make it possible to produce materially homogeneous Spritzgußprüfkörper for application engineering examinations from small sample quantities by means of capillary or mini-processing machines with Kolbenplastifizierung.

According to the invention, the object is achieved in that the inhomogeneous sample material is transferred in the plasticizing of a capillary rheometer or a miniature processing machine with piston plasticization in the molten state and by the piston of the capillary rheometer or the micro-processing machine by a static mixing or dispersing in which it is due to multiply high directionally changed strain and shear stresses undergoes thermal and material homogenization, is pressed and then the thermal and material homogeneous material is injected via a measuring nozzle with simultaneous inclusion of the parameter for determining theological characteristic in the Prüfkörperformcohlraum in which it is cooled defined.

As a device for carrying out the method is a Kapillarrheometer or a mini-processing machine with piston plasticization application.

The capillary rheometer or the micro-processing machine with piston plasticization is a temperature-controlled mixing chamber downstream of the positive or pressure in the direction of pressure, in which there are a static mixing or dispersing element and a measuring nozzle. The measuring nozzle is located in the pressure direction behind the static mixing or dispersing element; is designed as a rheometer nozzle and equipped with transducers for pressure and temperature.

The mixing chamber is positively or positively downstream in the pressure direction of an injection mold with the corresponding Prüfkörperformcohlraum; the injection mold is tempered. At the entrance of the Prüfkörperformhohlraumes pressure and temperature sensors are also mounted.

By means of the piston of the capillary rheometer or the micro-machining machine with piston plastification, the molten sample material is pressed by the static mixing or dispersing element at a defined temperature for influencing the degree of mixing or dispersion. Due to the strength of the stresses, in particular the elastic elongation, the mixing or dispersing effect can be adjusted in a targeted manner as a function of the flow and deformation properties.

Thereafter, the thermally and materially homogeneous material passes through the measuring nozzle with simultaneous inclusion of the parameters for the determination of theological value (throughput, pressure drop, temperature) in the Prüfkörperformcohlraum. By means of suitable heating or cooling devices, the injection molding tool is purposefully tempered in accordance with the respective application-technical examination, a process-relevant cooling rate is realized during solidification; this will u.a. influenced the orientation state. The shape and geometry of the injection molding tool with tempering device and the Prüfkörperformhohlraum therein is designed so that a maximum of characteristics and information can be obtained during the Formfüllvorganges and with the corresponding specimen.

Based on the use of small sample quantities, the geometric dimensions of the mixing or dispersing element, in particular its cavities, are kept small; the expansion and shear stresses simultaneously and / or alternateseld realized in a confined space.

embodiment

The invention will be explained in more detail by way of example.

Fig. 1 shows an embodiment of the apparatus for carrying out the method for producing homogeneous Spritzgußprüfkörper, consisting of a capillary rheometer 1 with downstream mixing chamber 2, in which a static mixing or dispersing element 3 and designed as a Rheometerdüse measuring nozzle 4, with the transducers 5 is equipped for pressure and temperature; the mixing chamber 2 is equipped with a heating band 6. The mixing chamber 2 is downstream of an injection mold 7 with the Prüfkörperformhohlraum 8 in the pressure direction; the injection molding tool 7 is located in a tempering 9.

Injection test specimens were prepared from polyethylene-chalk mixtures with 5.10 and 20 percent by volume chalk; where once worked with and without the other used mixing or dispersing 3. The temperatures of rheometer 1 and mixing chamber 2 were 200 ° C .; the injection mold 7 was with the tempering 9 to 50 ^c C.

tempered. .

The injection rate was 3.8 cm ³ / min in all cases; the piston pressure was measured via the force measuring device of the rheometer 1. The determination of the parameters for the determination of the theological parameters was carried out via the measuring nozzle 4 and the transducers 5.

The mechanical characteristic values determined on the injection-molded test specimen by means of tensile testing are shown in Table 1 in addition to the theological characteristics.

Table 1: Rheology and mechanical properties of PE-chalk mixtures

Chalk share (V-%) Mixed segment Viscosity (Pa s) Tensile strength (MPa) Elongation at break (%) Modulus of elasticity (MPa) 0 without 150 25.3 82 987 5th without 165 20.3 31 1 150 With 198 23.5 45 Λ 130 10 without 197 18.5 12.5 1200 With 236 21.8 33.5 2240 20 without 252 12 3.2 1690 With 302 17.3 8.7 1680

Claims (4)

claims: 1. A method for producing homogeneous Spritzgüßprüfkörper by Kapillarrheometer or miniature processing machines with Kolbenplastifizierung, in the plasticizing the sample material is transferred to the molten state, characterized in that the molten sample material is exposed to a high, multiply directionally changed strain and shear stress and then a defined nozzle flow from which parameters for the determination of theological parameters are simultaneously recorded and which are subsequently injected into a test specimen mold cavity and solidified under defined cooling conditions. 2. Apparatus for carrying out the method according to item 1, characterized in that the capillary rheometer (1) or the miniature processing machine with Kolbenplastifizierung via a heating bath (6) temperature-controlled mixing chamber (2) in the pressure direction, a static mixing or dispersing ( 3), which has the smallest cavities and a measuring nozzle (4) are located and this one via a temperature control (9) temperature-controlled injection molding tool (7) with Prüfkörperformhohlraum (8) are downstream. 3. Device according to item 2, characterized in that the static mixing or dispersing element (3) interchangeable, the measuring nozzle (4) and the downstream injection molding tool (7) with the Prüfkörperformhohlraum (8) may have different geometric shapes and dimensions and respectively are interchangeable. 4. The device according to item 2 and 3, characterized in that the measuring nozzle (4) with Wandgängigen or in recesses provided transducers (5) is provided for pressure and temperature.