36 results about "Crystallization of polymers" patented technology

The invention discloses a method for improving the mechanical properties of liquid crystal polymer products, which belongs to the technical field of polymer composite materials. In the method, the liquid crystal polymer products are subjected to heat treatment under a protective atmosphere. The temperature of the heat treatment is 250°C and the time is 6 hours; the heat treatment During the heating process, when the ambient temperature is below 100°C, the temperature is raised at a rate of 5°C / min; when the temperature is 100-200°C, the temperature is raised at a rate of 2°C / min; During the cooling process of heat treatment, when the ambient temperature is 250‑50 °C, the temperature is lowered at a rate of 1 °C / min. The method is simple and easy to operate, can improve the crystallization inhomogeneity of polymer molecules, obtain LCP products with stable crystal structure, can eliminate the internal stress of the products, and make the parts less prone to brittle cracks or mechanical damage during use, improving the Mechanical properties of LCP products.

The invention relates to a method for preparing a polymer crystal, and belongs to the field of ultraviolet polymerization method. The method is characterized in that: the method comprises three polymerization reactions according to the following three directions: (1) mixing a photopolymerizable monomer and small amount of an initiator according to a certain ratio, followed by carrying out polymerization under the ultraviolet irradiation; (2) mixing two photopolymerizable monomers and small amount of an initiator according to a certain ratio, followed by carrying out polymerization under the ultraviolet irradiation through copolymerization reaction; (3) dissolving a photopolymerizable monomer in a certain amount of a solvent, followed by adding small amount of an initiator according to a certain ratio to carry out polymerization under the ultraviolet irradiation; then the prepared photopolymerizable system is placed at a low temperature less than -80-0 DEG C to enable the prepared photopolymerizable system to be converted from the transparent liquid to the crystal, then 30-80 mW / cm<2> of the ultraviolet is adopted to carry out irradiation for 1-50 minutes to obtain the polymer crystal. The method provided by the present invention is easy to be controlled, has simple steps, simple post treatment operation, and no pollution to environment.

The invention discloses a method for predicting retention time of a gas phase chromatogram based on a macromolecule crystallization behavior derivation retention equation. The method comprises the following processes: deducing a retention equation curve which contains temperature and capacity factors based on macromolecule crystallization behavior, wherein the curve can be set up by only using three known data points which contain temperature and capacity factors of a compound at corresponding temperature; setting virtual dead time for a chromatographic column at a random temperature point according to measured retention time at a constant temperature; determining the capacity factor of the compound at the random temperature point through differentiating and integrating the whole chromatographic column according to the set retention equation curve; and predicting the retention time of the compound on the chromatographic column under a temperature-programming condition by using the data, and comparing the predicted retention time with an actually-measured value. The method for predicting the retention time of the gas phase chromatogram based on the macromolecule crystallization behavior derivation retention equation disclosed by the invention has the following advantages that: the number of adopted data points is few, and the number of experiments is reduced; the dead time has no need of measuring, and the process for predicting is simplified; and the predicting accuracy is high, and the application range is wide.

The invention discloses a composite material and a high molecular positive temperature coefficient thermistor made of the composite material. The composite material includes a high molecular crystalline polymer, a conductive filler and a compatibilizer; the high molecular crystalline polymer occupies a composite The weight percentage of the material is 5-15 wt%, the conductive filler occupies 70-95 wt% of the composite material, and the compatibilizer occupies 0.5-2 wt% of the composite material; the conductive filler is a mixture of carbide and metal tungsten, and the metal tungsten occupies the weight of the conductive filler Percentage 2~6wt%; compatibilizer is ethylene-vinyl alcohol copolymer, thermistor comprises two layers of conductive layers and a composite material layer, composite material layer is placed between two layers of conductive layers, composite material layer is made of composite material The thermistor has the characteristics of low initial resistance, and at the same time, it can still maintain low resistance characteristics after multiple high and low temperature cycles, which meets the stability of lithium batteries.

One embodiment of the present invention provides polymer crystalline materials containing crystals of the polymer and satisfying the following requirements (I) and (II) or the following requirements (I) and (III): (I) the polymer crystalline materials a crystallinity of 70% or greater; (II) the crystals are 300 nm or less in size; and (III) the crystals have a number density of 40 μm−3 or greater. This allows an embodiment of the present invention to provide polymer crystalline materials which are excellent in properties such as mechanical strength, heat tolerance, and transparency or, in particular, polymer crystalline materials, based on a general-purpose plastic such as PP, which is excellent in properties such as mechanical strength, heat tolerance, and transparency.

The invention provides a biaxial uniaxial tension device for in-situ structure detection in combination with the scattering of X-rays and an experimental method of the biaxial uniaxial tension device. The device comprises a high-precision servo motor (1), a torque sensor (2), a precise gear (3), a heating furnace (3), a reverse tension shaft (5) and a Labview software control system (6). A guide rail, the precise gear (3) and a reverse tension rod are adopted for transmission. The rotating speed of the servo motor (1) and the rotational displacement are controlled by the Labview to realize precise displacement and speed tension control. The temperature distribution of the heating furnace (3) is uniformed and the thermal degradation at high temperature of samples is reduced by forced nitrogen flow. A temperature monitoring point is preset in the heating furnace (3) and a temperature controller is adopted to precisely control the temperature. Temperature jump is realized between two heating furnaces (3) of different temperature. The device has the advantages of small volume, light mass, simplicity in disassembling and installing and the like, is particularly suitable for the combination of synchrotron radiation experimental line stations and is a good device for studying the crystallization of polymer melt induced by a flow field.

Provided is a piezoelectric element in which the piezoelectricity is easily utilized by converting shear deformation into expansion and contraction deformation. The piezoelectric element is characterized by comprising an electric layer containing a helical chiral polymer crystal showing piezoelectricity, a first electrode layer, a second electrode layer, a first connection part provided on the side of the first electrode layer opposite to the piezoelectric layer, and a second connection part provided on the side of the second electrode layer opposite to the piezoelectric layer, when viewed in the thickness direction of the piezoelectric layer, an overlapping portion where the piezoelectric layer, the first electrode layer, and the second electrode layer overlap each other has a circular shape, and when viewed in the thickness direction of the piezoelectric layer, the first connection portion and the second connection portion overlap the center of the overlapping portion.

The present invention relates to a polyethylene terephthalate composite material and a preparation method thereof. The method comprises that: 40 weight portions to 80 weight portions of polyethylene terephthalate, 0.1 weight portions to 4 weight portions of macromolecule nucleating agent testa liquid crystal, 1 weight portion to 6 weight portions of macromolecule crystallization accelerator, and 0.5 weight portions to 1 weight portion of other processing aids are stirred and mixed at a high speed; the mixture is then sent into a double-screw extruder through a material feeder of precise measurement. Then 10 weight portions to 50 weight portions of intensifier is filled into the double-screw extruder through the material feeder of precise measurement. The product can be prepared after plasticization, melting, compounding, and then extruding, bracing, cooling, pelletizing and drying. Compared with the prior art, the present invention has the characteristics of improving the crystallization rate of polyethylene terephthalate, widening the application scope, meeting the demands of engineering plastics for polyethylene terephthalate.