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济南科邦空压机配件弹性性能的详细介绍
Time:2018-07-23 15:13:18       来源:http://www.jnkbjx.com/      

橡胶的这些优点和局限性反映其分子水平的物理结构。这是折叠和扭结的聚合链的三维网络,其间分散着交叉链和有限数量的自由空间。在热能激励下,链段能够围绕一些键并以随机方式旋转。当橡胶伸展时,这些链逐步地被拉直,引起橡胶的超常延展性。同时,由于旋转的链段的横向热运动,存在抗拉直的能力。这种热运动易于将橡胶的两头拉在一起。这一抗拉伸的能力决定弹性模量,结果是弹性模量随热能,即温度的增加而增大。杨氏模量随温度增加的值被人们认同为焦耳一高夫效应。弹性体的应变能∥可从统计热力学简单式导出:
These advantages and limitations of rubber reflect their physical structure at molecular level. This is a three-dimensional network of folding and kinking polymerization chains, which are dispersed with cross links and limited number of free spaces. Driven by thermal energy, the segments can revolve around some key and rotate in a random way. When rubber is stretched, these chains are gradually straightened, causing the rubber to be super ductile. At the same time, due to the transverse thermal movement of the rotating segment, there is the ability to resist straightening. This thermal movement is easy to pull the two ends of the rubber together. The tensile modulus determines the modulus of elasticity, and the result is that the modulus of elasticity increases with the increase of heat energy. The value of Young modulus increases with temperature is recognized as Joule GF effect. The strain energy of elastomers can be derived from statistical thermodynamics.
w =0.5NkT(^i+^;+^;一3) (1一1)
W =0.5NkT (^i+^; + square; 3) (1, 1)
式中,A一等为三个方向上的伸展比(应变长度/未应变长度);kT为单位热能(k为渡耳兹曼常数);Ⅳ为单位体积的振动链段数(N/2为交叉链密度);r为绝对温度。量0.5 Nkr等于材料的剪切模量,杨氏模量E=2(1+p)G。
In the formula, A 1 is the extension ratio in three directions (strain length / strain length); kT is unit thermal energy (k is the tzmann constant); IV is the number of vibrational segments per unit volume (N/2 as the cross chain density); R is the absolute temperature. The amount of 0.5 Nkr is equal to the shear modulus of the material, and the young modulus E=2 (1+p) G.
橡胶的弹性模量与大多数工程材料的弹性模量很不相同。因此,抵抗伸展的弹性阻力直接起因于克服分子间的吸引力所做的功,因此随温度的升高而减小。
The elastic modulus of rubber is quite different from that of most engineering materials. Therefore, the resistance to stretching is directly caused by the work done to overcome the attraction between molecules, and thus decreases with the increase of temperature.
济南科邦浪潮空压机配件橡胶中,链的热运动仅在有自由空间时才可能:这是上面提到的自由体积。但是,自由体积的存在也提供流体分子因橡胶吸人流体而向橡胶内部扩散的机会,从而引起膨胀:弹性体与某一特定流体接触时膨胀的趋势通过能量进行支配。内聚能密度(CED)是完全分离一种材料(弹性体或液体等)的组成分子所需的能量。如果弹性体和液体内聚能密度值很类似,那么,就会发生膨胀。实际中,所用的量道常是/CED,“溶解度”参数占。各种液体或弹性体的6值可在参考文献中找到。不幸的是,烃类和弹性体在相同范围内倾向于具有7 -t0(cal/em3)o's的溶解度参数,结果具有高的膨胀风险:水的值大约为23,极性化合物女口甲醇的值界于该值和烃类之间;因此这些介质引起膨胀的可能性极小。对于
济南空压机
The thermal movement of the air compressor accessories rubber in Ji'nan is only possible when there is free space. This is the free volume mentioned above. However, the existence of free volume also provides the opportunity for the diffusion of fluid molecules to the interior of rubber due to rubber suction fluid, which causes expansion: the expansion trend of the elastomer in contact with a particular fluid is dominated by energy. Cohesive energy density (CED) is the energy required to completely separate the constituent molecules of a material, such as an elastomer or liquid. If the bulk density of elastomers and liquids is very similar, then expansion will occur. In practice, the quantity used is usually /CED, and the "solubility" parameter takes up. The 6 values of various liquids or elastomers can be found in references. Unfortunately, hydrocarbons and elastomers tend to have the solubility parameters of 7 -t0 (cal/em3) o's in the same range, which results in a high expansion risk: the value of water is about 23, and the value of the methanol of polar compounds is between this value and hydrocarbon; therefore, the possibility of swelling is minimal. about
液体的可混合组合,8与成分的浓度成比例。
The mixture of liquids, 8, is proportional to the concentration of the components.
弹性体复合材料中的自由体积在空间和时间上不是静止的;它的快速振动的链填满一处自由体积并在别处开辟体积时被动态保持着。如果温度依次降低,该动态过程首先放慢,然后停止,材料变得很坚硬。这解释了玻璃态转变温度的存在。高于t时,橡胶性能像液体,低于j时,其性能像过冷液体,即玻璃。在该玻璃态,链被链间的范德瓦尔键刚性锁定,但这些链相对较弱,因此玻璃态和橡胶态之间的转变是可逆的。聚合体链的化学结构影响t,例如,更松散的单体要求有较大的自由体积,而这不常发生,从而提高了t。增塑剂倾向于增加自由体积,从而降低T。。填充物往往具有相对小的影响。
The free volume in the elastomer composite is not static in space and time; its fast vibrating chain fills with a free volume and is kept dynamically when the volume is opened elsewhere. If the temperature decreases in turn, the dynamic process slows down first, then stops, and the material becomes very hard. This explains the existence of the glass transition temperature. When t is above the rubber, the performance of the rubber is like liquid, and its performance is like super cold liquid, namely glass, when it is lower than j. In the glassy state, the chains are locked by the Van Derwal bonds between the chains, but these chains are relatively weak, so the transition between the glassy state and the rubber state is reversible. The chemical structure of the polymer chain affects T, for example, looser monomers require larger free volume, which does not occur frequently, thus increasing t. Plasticizer tends to increase free volume, thereby reducing T. The filler often has a relatively small effect.

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