Plastics dimension stability and acoustic performance

Material is the material basis for the product design, injection tooling material physical and chemical properties of basically determine the performance of products and goods value. Therefore, understanding the performance of the material, choose the right material, can be said to be the product design the first step to success. Each kind of material to judge whether from the technical or economic point of view, are inevitable limitations, more or less, so, is necessary during material is introduced to the designer to special tips. To understand the limitations of the material, help to material selection and product design to the best of its director, avoid the short.

change the size of the plastic material or dimensional stability and the composition, structure, rigid material itself, as well as shown in the hygroscopicity, thermal expansion and so on. Usually, good in thermoplastic plastics, thermosetting plastic engineering plastic is better than common plastic. In addition, dimensional stability are also associated with molding process conditions. For some plastic parts molding after annealing, or wet processing, can be used in a certain extent, inhibit the size in the process of change.

foam cup considered material with sound-absorbing properties, some rigid foam board so is often used for building wall materials. In addition, the high concentration of filled with relatively dense, such as lead, iron, and the powder of these compounds and fiber composite plastic, also have excellent acoustic impedance. Actual acoustic resistance of plastic materials, but also because of the frequency of the sound, some scholars think it is proper to more than 2000 hz frequency, acoustic impedance, of course, should also be related to the thickness of the material.

in higher dimensional stability requirements applicable occasions, we should pay attention to select good rigidity, affected by the ambient temperature and humidity changes smaller materials. Add mineral filler in plastics materials, or by using glass fiber reinforced material, can increase the size of the material stability, moreover in parts of the structure design, reasonable design is also necessary. Swelling caused by water absorption, moisture absorption, some are the size of the permanent and irreversible changes, such as aging chemical changes caused by the material belongs to the size of the permanent changes.

sound incident to some kind of material, the sound part of the incident by material surface reflection, the other part is absorbed by materials, the rest is through the material. Through the voice of the less than the incident sound called a sound insulation. Which has the function of sound insulation, sound-absorbing materials could be called acoustic resistance materials. Excellent acoustic resistance material can prevent the harm of noise on people. Polymer due to the high damping property of mechanical vibration and silent resistance materials available.

plastics are organic compounds, under the conditions of use, it is difficult to keep the size of the absolute stability, influence the stability of the injection molding processing parts size for many reasons, including the use of the environment in the process of water absorption, moisture absorption, expansion and contraction caused by temperature change, the erosion of organic solvent, swelling; Load under the action of bending, creep, plasticizer and other volatile components contained in the material composition, dissipation of residual internal stress caused by the release of warping, distortion, after the change in the size of the crystallization process, and the changes of material caused by aging factors such as light, oxygen, etc.

you can use a material internal friction values measured acoustic resistance capability. The experiment proved that only near the glass transition temperature, polymer materials within the larger. Used to be quiet, therefore, resistance of polymer materials, first ask its glass transition temperature near the use temperature. If required acoustic resistance materials in a wide temperature range with high internal friction values, should choose the multiphase polymer composites, such as more than two kinds of polymer blend, multiple copolymer and a variety of homopolymer laminated material.

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