JPH06212018A - Polymer-based material having composite functions - Google Patents

Abstract

PURPOSE:To provide the polymer-based composite functional material imparted with material-reinforcing and vibration-insulating properties at high temperatures and with a self-repairing function for inner damages. CONSTITUTION:This multi-functional polymer-based composite material capable of responding to changes in outside environments is characterized by incorporating the shape-memorizing alloy material-fibrous elements 2 of low temperature side martensite phase with a polymeric matrix 1 at <= a reverse transformation temperature, thereby permitting to enhance the strength and vibration resistance of the matrix material and simultaneously enabling the self closure of the inner cracks, cavities, etc., of the composite material by the utilization of a shape memory contraction force which is produced by always measuring the electric resistances of the buried fibers and the changes of a pressure (strain) sensor adhered to the surface of the composite material and subsequently applying an electric current to the buried fibers to heat the fibers at the time of an abnormal trouble. Especially, the polymer-based composite functional material having the high performances is characterized by mixing and arranging the shape-memorizing alloy material-fibrous elements in the matrix, where the shape-memorizing alloy material-fibrous elements have metal crystalline substances produced by rapidly cooling and coagulating the melted alloy at a rate of 10<2> to 10<6> deg.C/sec.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION The present invention not only improves strength and anti-vibration property, but also enables self-repair of stress and temperature inside the material as well as internal damages and defects such as cracks and cavities. The present invention relates to the development of a high-order polymer-based composite functional material which is capable of responding to the above, and the material itself has the above multiple functions.

[0002]

2. Description of the Related Art In a polymer (polymer) matrix composite material, glass fibers and carbon fibers are mixed and arranged inside a plastics base material, and the weight and high corrosion resistance peculiar to the polymer are further increased and the strength is further increased. Is widely used as. For example, building materials, ships / boats, automobiles / vehicles, constituent materials of mechanical structures such as aviation / space, pipes / tanks, corrosion-resistant equipment / devices, electric / electronic parts, and miscellaneous goods.

Further, a polymer material generally has a high damping ability (damping characteristic). Recently, sound absorbing / sound insulating materials, vibration damping materials, and industrial applications that utilize this function have been increasing. For example, damping steel plates, anti-vibration rubber, foamed plastics (foamed polyurethane, etc.)
Is a typical example.

In one version, the polymer material has a large damping ability (loss coefficient = damping) on the order of 2 to 3 (100 to 100 times) as compared with the metal material, but the maximum area is Generally, it is near the glass transition temperature at 100 ° C. or higher, and the damping ability in the glass region on the lower temperature side and the rubber region on the higher temperature side is not so high, and the broadening of the glass transition region is plasticized and copolymerized. And so on. But,
The current situation is that the high damping capacity up to room temperature, which is the operating temperature of building materials, has not progressed at all due to the inherent structural problems of polymers. In the glass transition region, which exhibits high damping (damping) properties, the polymer softens and its strength drops sharply, making it possible as a structural material consisting of a polymer alone in that temperature region to have both strength and damping properties. The reality is that sex is still small.

The transmission loss (damping loss) of a material is generally affected by the rigidity, mass and internal friction of the member. An example thereof is shown in FIG. 1. At extremely low frequencies (fo and below), the total rigidity is governed, and in the middle vibration range (fo to fn), the resonance (fn) caused by the material fixing conditions is affected. In a higher frequency range (fn or more), the transmission loss (damping loss) is dominated by the mass and increases with the increase of the mass. At that time, a resonance point (fc) is generated due to the elastic modulus of the material, and the transmission loss is reduced in the narrow frequency portion.

Therefore, in practice, glass fiber or carbon fiber, which has higher rigidity than that of the polymer base material, is mixed to increase the rigidity in the low frequency range or increase the mass in the high frequency range.
Measures for increasing the density by filling e ₂ O ₃ or ZnO powder have been devised. However, as can be seen from FIG. 1, increasing the internal friction of the material itself can improve the transmission loss (damping loss) in almost all frequency regions. However, it can be said that it is an effective means for improving the vibration damping property.

Recently, in the industries such as the aircraft industry, nuclear power generation, chemical plants, etc., where there is a possibility of serious damage due to social and environmental problems due to sudden destruction, only the above-mentioned high strength and anti-vibration property are provided. Not only that, stress and temperature inside the material can be constantly monitored (= self-diagnosis) by acquiring signals from the material side itself, and further internal damage / defects such as cracks and cavities can be reduced (= self-repairability). It is expected that a higher-order polymer-based composite functional material that can respond to such changes in external environmental temperature and stress and that the material itself has the above-mentioned multiple functions.

[Problems to be Solved by the Invention]

In the present invention, there have been material problems to be solved in order to improve the materials of the above-mentioned various polymer materials and to prevent damage to component equipment and members using the materials and accidents. The strength up to the middle temperature range, ensuring high damping at low to medium temperature range, grasping the internal state (temperature / stress) of the polymer material in use, self-diagnosis function, internal defects during use -It aims to incorporate high-dimensional material function additions into polymer materials, such as the self-healing function of damage.

Means for Solving the Invention

In the present invention, the high-dimensional material function imparted to the above-mentioned various polymer (polymer) -based materials is added to the shape memory alloy-based element (fiber, fine particles, thin film, etc.) on or inside the polymer surface. ) Is mixed and arranged to produce a composite material. That is, the material strength and rigidity are improved with the increase in temperature from low temperature due to the transformation phenomenon that generally occurs in shape memory alloy systems, the change in the electrical resistance of the material itself, and the effect of strengthening the shrinkage of the shape memory element inside the polymer matrix, the polymer, The polymer-based composite functional material of the present invention can be realized by material design utilizing a synergistic effect that combines the difference in rigidity between the base material and the shape memory element and the high damping property of the mixed shape memory element itself. .

[0010]

In general, the shape memory phenomenon of the alloy system is caused by the thermoelastic martensite (M) transformation. This is not due to a crystal slip due to dislocation formation, but due to a shearing movement accompanied by the movement of the phase boundary surface and the twin interface accompanying the heat absorption. Much smaller siblings (variants) are formed. It can reversibly return to its original crystalline structure state by external heat or absorption of stress-strain energy.
This is the cause of manifestation of the shape memory effect. Unlike the martensitic transformation M phase that occurs by quenching in steel, etc., the low temperature M phase in the shape memory alloy system is softer than the stable austenite (A) matrix at high temperature by 1/2 to 1/3 and is deformed. It's easy. That is, the rigidity of the shape memory alloy increases by about 2 to 3 times as the temperature goes from low to high. In addition, in this case, if pre-strain is applied to restrain the deformation, a large recovery force of about 2 to 3 times is obtained. The material strengthening phenomenon associated with this temperature rise is very different from the high-temperature low-strength / softening phenomenon in ordinary metal materials. By utilizing this unique phenomenon (= thermoelastic martensite transformation), polymer-based composite High damping properties can be realized by utilizing the material reinforcement of the material and the difference in rigidity inside the composite material.

The respective transformation temperatures in the thermoelastic transformation of the shape memory alloy are shown below by the symbols. End of low temperature martensitic transformation, start temperature Mf, Ms, start of stable parent phase austenite transformation (reverse transformation) on high temperature side, end temperature A
Call s, Af. The development of material properties with temperature changes in these shape memory alloy systems is summarized in FIG. Further, in the low temperature martensite phase, fine twin transformation phase and sibling crystals (variants) are formed, and their boundaries are very mobile due to external heat and stress and interfere with each other. At this time, the hysteresis of the stress-strain curve in the low temperature martensite phase becomes very large, and the strain energy is absorbed inside the material and is dissipated to the outside as heat. It has high friction and becomes a high damping material. It is shown by a black mark in FIG. 3 that a series of shape memory alloys have extremely great characteristics in both damping ability and strength as compared with general metallic materials. For this reason, shape memory alloy (SMA) -based material, which is a thermoelastic phase change alloy, is one of the important issues for vibration control and noise suppression, which has recently become an important issue as an environmental problem for machines and structures. It is possible to find the possibility as a constituent material element.

Further, shape memory alloys are generally intermetallic compounds.
Therefore, it is brittle and hard, and its wear resistance generally tends to be high.

Now, a process for strengthening the polymer-based shape memory fiber composite material of the present invention by utilizing the large recovery force associated with the shape memory phenomenon is schematically shown in FIG. When a polymer composite material embedded with a shape memory TiNi alloy that has been subjected to elongation strain (ε in the figure) in the low temperature martensite phase state is heated to the austenite (A) region, the internal TiNi fiber undergoes reverse transformation and shrinks. Since compressive stress is generated inside the base material and the rigidity of the TiNi fiber is improved, it can be understood that the composite material can be reinforced synergistically.

If the composite material of the present invention is placed at a low temperature of Mf or lower after heating and heat treatment for strengthening shape memory, the damping property as the M phase should appear again, but it is not affected by the ambient temperature. In order to impart the vibration damping property, it is necessary to mix the second SMA element having a high transformation temperature. Further, in order to improve the fracture toughness and strength of this material, it is effective to add carbon fiber or the like as the third mixing element.

[0015]

EXAMPLE FIG. 5 shows an example of the active closing action of the shape memory TiNi fiber reinforced composite material for an aircraft wing, etc., to the internal damage cracks / defects of the example of the present invention. Detecting deformation or pressure signal above the set value from the strain gauge or piezoelectric element PVDF film on the surface of the composite material, the TiNi fiber is electrically heated, and the TiNi fiber contracts.
It is possible to close cracks and cavities as defects.
If the polymer is a base material, use its insulating properties to
As shown in Fig. 6, it is possible to nondestructively grasp the generated stress, strain, temperature state, etc. inside the composite material from the electric resistance change accompanying the phase transformation of the buried fiber, and the buried fiber itself is used as a sensor. Can also be used.

FIG. 7 shows Ti in the epoxy polymer matrix.
An external view of a composite material plate in which Ni-based long fibers are arranged was used to measure the dynamic characteristics of the surface-applied strain gauge output and its damping property when one end was freely vibrated. As shown in FIG. 8, a clear increase in the damping property of the displacement amplitude on the composite plate surface was confirmed. Further, as shown in FIG. 9, the TiNi alloy ribbon produced by the single roll liquid rapid solidification (melt / span) method has a significantly improved damping (inner wear) property as compared with the conventional melt / processing method. It is possible, and it is found that the temperature is about 10 times higher than that of the polycarbonate (PC) material near room temperature. In this way, the tan in the alloy ribbon is obtained by the rapid solidification method.
δ is greatly improved, and is optimal as a shape memory element for forming a composite material.

[0017]

Since the present invention is constructed as described above, the following effects can be obtained. INDUSTRIAL APPLICABILITY The polymer-based composite functional material of the present invention is a polymer (polymer) -based material that undergoes an unavoidable decrease in strength with an increase in temperature in a form that takes advantage of the phase transformation and material functional characteristics of the embedded shape memory alloy element. Not only can it be suppressed, but also high vibration damping due to the difference in rigidity between the polymer base material and the shape memory element, as well as self-diagnosis utilizing the change in electrical resistance of the embedded element itself, or abnormalities during accidents, etc. A self-healing function can be imparted by detecting the temperature rise by itself and shrinking the internal shape memory alloy element to close a crack.

Therefore, various polymer-based materials, such as building materials, boats, ships, aircraft, etc., for which the material strength improvement and weight reduction at high temperatures are required, and noise and vibration problems are becoming serious. Widely used as a material for constructing mechanical structures such as space, automobiles, vehicles, and large chemical plants, pipes / tanks, corrosion-resistant equipment / devices, electrical / electronic parts, mechanical / electronic parts such as miscellaneous goods, vibration control, and sound absorbing mats. It can be used.

[Brief description of drawings]

[Figure 1] Relationship between transmission loss, mass, elastic modulus (rigidity), and internal friction

FIG. 2 High strength and high vibration damping of shape memory alloy type material (black circles in the figure)

FIG. 3 Material properties of shape memory alloy (SMA) with temperature change

FIG. 4 Material design and processing process of shape memory composite material

FIG. 5: Example of active closure of intrinsic crack in polymer-based shape memory fiber reinforced composite material

FIG. 6: Strain amount and electric resistance change of polymer-based shape memory TiNi long fiber composite material

FIG. 7: Example of composite material in which shape memory actuator fibers are embedded in carbon / epoxy matrix (cantilever)

FIG. 8: Improvement of vibration damping in polymer-based shape memory composite material

FIG. 9: Internal wear (tan) in liquid rapidly solidified TiNi alloy
δ) rise

[Explanation of symbols]

 1 Shape memory alloy element (fiber) 2 Polymer matrix 3 Strain gauge

Claims (5)

[Claims] 1. A polymer-based composite material in which at least one or more shape memory alloy materials having a temperature not higher than the reverse transformation end temperature are arrayed and attached to the surface of the base material or attached or arranged and mixed in the base material. 2. At least one kind of shape memory alloy material element, which has been subjected to plastic elongation at a temperature below the transformation end point, is arranged on the surface of the base material by bonding, attachment or arrangement in the base material.
Mixed polymer matrix composites 3. A base material for a shape memory alloy-based material element having a metal crystallinity, which is obtained by rapidly solidifying the melt of the alloy-based metal in the range of 10 ² to 10 ⁶ ° C./sec in producing a shape memory alloy. The metal-based composite material according to claim 1, wherein the metal-based composite material is mixed and arranged in the interior. 4. At least one kind of first shape memory alloy which is provided with plastic elongation at a temperature below the reverse transformation end point, and reverse transformation start above the reverse transformation end point of the first shape memory alloy. The metal matrix composite material according to claim 1, 2 or 3, wherein at least one kind of second shape memory alloy having dots is mixed. 5. The polymer-based composite material according to claim 1, wherein carbon fibers are mixed as the third composite reinforcing material element.