Study on the Orientation Mechanism of High-Strength Liquid Crystal Polymer Spinning Fiber Han Zhifang (Chengdu Branch of the Chinese Academy of Sciences, Chengdu S10041) Stretch flow orientation, steady orientation movement and unsteady movement. The Lagrangian method was used to study the stability of axisymmetric spinning elongation. It is concluded that the molecular orientation of the liquid crystal polymer in the spinning process is more stable than the crucible, and its orientation motion has high resistance to dissolving orientation, and it is easier to form a high degree of orientation. This is to produce high strength and high modulus fibers, films and The basis of the molded product.
Day stability analysis, an important application of molecular orientation liquid crystal polymers in anti-dissolving orientation 1 melt spinning is the production of high-strength, high-modulus fibers, such as Kevlar-type fibers. Another important application is the use of liquid crystals in display technology.
Currently, liquid crystal displays have been widely used in computers. However, the rheological basis and applied basic research of liquid crystal polymers lag behind their development and application. For example, the mechanism of production of high-strength and high-modulus fibers by liquid crystal polymer materials remains to be further studied. At the same time, in the process of extrusion of liquid crystal helium molecules, the phenomenon of back extruding swell has been shown, which is significantly different from the general polymer melt. In the liquid crystal continuum mechanics, in order to describe its molecular orientation characteristics, the introduction of a vector to the vector that characterizes the dominant orientation of molecules in a neighborhood of any point acts on the liquid crystal polymer, which can either produce fluid motion or induce orientation. Vector (orientator vector) orientation motion. The main characteristic of the main chain or side chain type liquid crystal polymer is that the molecular chain orientation is easily formed under the action of the external force field. Actual 1) National Natural Science Foundation Project B test shows that when the liquid crystal polymer fluid passes through the spinneret, die or flow channel, even if orientation is obtained at low shear rate, general polymer can be achieved without post-stretching. The degree of orientation achieved after stretching. Therefore, by using the properties of liquid crystal polymers, ie, thermotropic liquid crystal polymers or composite materials blended therewith, high-strength, high-modulus fibers can be produced. (l) For liquid crystal polymer spinning, flow vectors are set. The velocity field is in the following form. In the vector and velocity fields (2) and (3), the vector transfer equation (1) is converted to dnzdnzdnz. The liquid crystal polymer orientation motion is much smaller than the fluid velocity, so the transport The inertial term in the equation can be omitted, ie the partial derivative of time can be used in place of its full differential, so the vector equation derived from the transport equation can be simplified to the steady-state liquid crystal polymer spinning elongation flow, which is derived from the above equation. Because it is the main stretching direction, a reasonable steady-state flow solution is the following two solutions, = 1, = 0. The initial vector when extruded from the spinneret hole should be parallel to the unit vector of the stretching direction, so the first one The solution is reasonable. 3 Unsteady orientation motion For the unsteady liquid crystal helium molecular spinning elongation flow, the integral is obtained from equation (5). If the initial condition is nzt=0 =1, there must be As0. Corresponding to the stationary flow solution = 1, nr =0. The non-unsteady theory of the vector-transport equation is based on the idea that when the initial time vector is the unit of the main tensile direction, it will continue to keep the direction vector for the direction of time. Now suppose that in the past (the liquid crystalline polymer has the anti-disorientation property in the spinning process, and the general cerium molecule does not have the property, this is a new concept proposed in this study. The stable molecular orientation degree is the liquid crystal polymer or its The burial explanation of the strength and the moduli of the yttrium modulus made by the composite material is a special property caused by the anisotropy of the liquid crystal polymer.
4 Stability analysis In this paper, the stability of liquid crystal polymer spinning will be studied using the Lagrangian method of fluid dynamics. This method was successfully applied to the study of the stability of viscoelastic fluid sheet in equation (2) and formula ( 3) Under the equation (4), the basic solution for the flow can be given by equation (7). The sum of the components of the vector component and the disturbance value represents the disturbance component. It can be understood that the amount of perturbation is caused by the de-orientation of the liquid crystal polymer when extruded from the spinneret hole. Linearization of the unsteady-orientation equation of motion (13) results in that the first term in the equation is the material derivative and the coefficient of the second term is independent of time. Therefore, in the Lagrangian coordinate, the solution of the equation can be set to In the following form, f = r = t is Lagrange coordinates. Substituting equation (15) into equation (14) yields that the full differential in the equation in the Lagrangian coordinate system can be replaced by partial differential, ie, the integral equation is used to derive the solution to the ordinary differential equation. Let i = If P(f) = P, the integral constant can be determined. Because A, fc, and t are all positive, -6Afct is negative. Therefore, the perturbation amplitude P(t) decays with time and can be oriented along the major axis without post-stretching the molecular orientation. The molecular orientation is stable and is not influenced by the disorientation. Spinning stretches differ. This conclusion is consistent with the previous conclusions, but also further confirmed the above conclusions. However, it should be pointed out that the basic equation (13) in the above stability study has taken into account the characteristics of axisymmetric symmetry, that is, it belongs to a two-dimensional space problem. The conclusion of this paper is derived under the following conditions: the stretch rate is constant, and the orientation motion has no substantial effect on the fluid motion. If you need to further study the problem, you should consider the stretching rate is not constant, the orientation of the movement of the fluid movement, you must study the fluid movement equation and the orientation equation of motion. Obviously, this study pointed out the main direction of the problem, namely that the orientation motion in the spinning liquid stretching molecules of liquid crystal molecules has the energy to maintain the orientation of the main stretching direction. Based on the following conclusions, the liquid crystal polymer spinning has a higher stability in the orientation of stretched molecules, and it is easier to form a 篼 orientation degree in the sliver, which is to produce high-strength and high-modulus fibers, films and molded products. The above conclusions are consistent with the current application of liquid crystal polymers.
PP plastic, polypropylene, commonly known as "baijiao",Scientific name: polypropylene.
Description:
PP Plastic is a kind of semi crystalline material. It is more hard than PE and has a higher melting point. Due to the high crystallinity, the surface of the material stiffness and resistance to scratch characteristics very well. PP Plastic don't have the problem of environmental stress cracking.Polypropylene (PP Plastic) is a semi-crystalline thermoplastic.PP Plastichas high impact resistance, strong mechanical properties, resistance to many organic solvents and acid and alkali corrosion.
PP Plastic is widely used in industry and is one of the most common polymer materials.
Australian COINS are also made of polypropylene.
Polypropylene bonding:
K-720 is suitable for polypropylene PP plastic adhesion, suitable for large area plate lamination, high transparency, suitable for PP adhesion PP, PP adhesive PC, PP adhesive ABS,PP adhesive PVC, PP adhesive acrylic, PP sticky metal, PP stick wood.
K-7007 adhesion performance is roughly the same as k-720, light yellow and more economical.
K-620 is adhesive small area polypropylene PP glue, must be used with the k-650 treatment agent, the instant positioning, the strength is high.
Advantages:
1. Low density;
2. Heat resistance ;
3. Non deformation;
4. High stiffness;
5. High surface strength;
6. Good chemical stability;
7. Nontoxic and safe.
Disadvantage:
The main disadvantage of the fault polypropylene is that the high temperature rigidity is not enough, and the low temperature is brittle.
Poor environmental tolerance, outdoor use, easy to turn yellow and brittle.
Tensile strength of anisotropy, the products are easy to deform, continuous use of low temperature, high creep performance, and long - term load.
Poor printing performance.
Application:
1,Valve part, drinking water and sewage water pipe,
2,Sealing element, spraying carrier,
3,Corrosion-resistant trough and barrel, industrial applications that have acid and alkali-resistant requirement; wastewater and gas discharge equipment for industrial purpose,
4,Scrubbing tower, clean room, semiconductor plant and other related industrial equipment and machinery, food machinery and chopping board,
5,Electroplating process, toy part
Combustion characteristics: PP Plastic easy to burn, polypropylene from continue to burn after the fire, with the top of the flame is yellow, the bottom made in blue, with a small amount of smoke generated, burning melt dripping, and oil.
Specification: the thickness of PP sheet material can be produced from 0.3mm to 2mm, and the PP sheet material is of rolling material and width of 500-1000mm.
The thickness of the plate can be produced from 2mm to 200mm. The specification is 600*1200mm 1000*1000mm 1000* 2000mm. Other specifications can be customized as needed,and The diameter of the PP rod can be produced from 2mm to 250mm, the length is 1 meter, PP rod can be ordered to be more than 3 meters in length.
Color: white and black, other colors can be customized
Modified varieties: PP sheet have various enhancers and other auxiliaries can be added to make modified varieties, depending on the requirements
Storage methods:
Keep in tight, cool and dry place to ensure good ventilation
Product certification: most environmental certification reports and safety reports for raw materials, such as SGS report, CTI report, UL report, MSDS safety information, etc.
Pp Plastic Rod,Polypropylene Plastic Rod,Extruded Polypropylene Plastic Rod,Pp Plastic Welding Rods
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