共查询到19条相似文献,搜索用时 203 毫秒
1.
《现代塑料加工应用》2016,(5)
利用差示扫描量热仪(DSC)研究了聚醚醚酮(PEEK)和PEEK/碳纤维(CF)复合材料的非等温结晶行为,采用Avrami,Ozawa和Mo方程对PEEK/CF复合材料的非等温动力学进行分析,获得相关非等温动力学参数,并利用Kissinger方程计算其结晶活化能。结果表明:Avrami方程和Mo方程能很好描述PEEK/CF复合材料的非等温结晶过程;PEEK/CF复合材料的非等温结晶活化能为79.99kJ/mol。 相似文献
2.
通过偏光显微镜和差示扫描量热仪(DSC)研究了碳纤维(CF)和滑石粉对聚酰胺6(PA6)结晶行为的影响。结果表明,CF的加入在PA6和CF的界面诱发横晶,CF和滑石粉在PA6基体中起到了异相成核作用,改变PA6的成核机理和晶体生长方式,提高了起始结晶温度和结晶速率。结晶速率随普等温结晶温度的升高而下降。当冷却速率增大时,起始结晶温度下降,结晶度增大。 相似文献
3.
4.
5.
6.
改性多壁碳纳米管/PET纳米复合材料的非等温结晶行为 总被引:2,自引:0,他引:2
采用原位复合方法制备出纯PET、MWNTs-COOH/PET和MWNTs-OH/PET纳米复合材料.通过红外测试发现PET以共价键形式接枝到碳纳米管上;用扫描电镜(SEM)观察了改性碳纳米管在PET基体中的分散性;通过差示扫描量热法(DSC)研究3种纳米复合材料的非等温结晶行为,使用Jeziomy法和莫志深法分析3种样品的非等温结晶动力学.结果表明:COOH/OH官能化MWNTs可以较好地分散在PET基体中并且能够作为一种有效的成核剂,改变PET的成核机理;同时可以使PET在较高的温度下结晶,提高了PET的结晶速率并且MWNTs-COOH/PET复合材料起始结晶时间更早,而MWNTs-OH/PET复合材料结晶速率更快. 相似文献
7.
8.
利用自行设计的浸渍装置,通过熔融浸渍法制备了连续碳纤维增强聚酰胺6(PA6/LCF)复合材料。研究了LCF对PA6/LCF复合材料结晶行为的影响。结果表明,LCF的加入对PA6基体具有异相成核作用,增容剂苯乙烯马来酸酐共聚物(SMAH)和聚丙烯接枝马来酸酐(PP-g-MAH)的加入均能促进LCF对PA6基体的异相成核作用。PA6的等温结晶均相成核和异相成核共存,PA6/LCF复合材料则以异相成核结晶为主。非等温结晶研究表明,随着冷却速率的增加,PA6,PA6/LCF复合材料的结晶速率变大,半结晶时间降低。 相似文献
9.
PP/PET/POE-g-MAH共混合金的等温结晶动力学特性 总被引:1,自引:0,他引:1
应用差示扫描量热法(DSC),研究了加入不同份数增容剂POE-g-MAH的PP/PET共混合金及纯PP的等温结晶行为,采用Avrami方程处理等温结晶过程,计算结晶动力学参数。结果表明,随着结晶温度的升高各体系的结晶速率下降,结晶速率常数K、n降低,半结晶时间t1/2延长。同一温度下PET有明显的异相成核作用,提高了基体的结晶速率;POE-g-MAH的加入降低了基体的结晶速率,并且随着增容剂含量的增加,基体的结晶速率逐渐下降。纯PP的等温结晶过程具有异相成核与均相成核的机理,共混合金的等温结晶过程属于异相成核机理。 相似文献
10.
11.
The tendency of carbon fiber to nucleate the zation of poly(etherettterlcetone) (PEEK) has been evaluated by DSC and other techniques. As the carbon fiber content was increased, the supercooling necessary for PEEK crystallization decreased. The repeated melting (at 396°C) of the same PEEK sample results in a decrease of the number of nuclei for crystallization. At equivalent thermal histories, PEEK with carbon fiber was found to have a higher nucleation density than PEEK itself. The surface of carbon fibers and nuclei in the PEEK matrix compete for crystallization growth. As the holding time in melt was increased, the number of matrix spherulites formed on cooling decreased, hence a more pronounced transcrystalline region was developed. Correspondingly, the composites preheated in the melt for 100 min showed about two times the transverse tensile strength and strain-to-failure of those preheated for only 30 min. Corresponding fracture surface produced in tension showed that the former samples had a greater matrix adhesion to the carbon fiber than the latter. A strong interfacial bond is thus developed by crystallization on carbon fiber surface. Destroying nuclei in the PEEK matrix by long preheating enhances crystallization on the carbon fiber. 相似文献
12.
The influence of the degree of crystallinity on interfacial properties in carbon and SiC two‐fiber reinforced poly(etheretherketone) (PEEK) composites was investigated by the two‐fiber fragmentation test. This method provides a direct comparison of the same matrix conditions. The tensile strength of the PEEK matrix and the interfacial shear strength (IFSS) of carbon or SiC fiber/PEEK exhibited the maximum values at around 30% crystallinity, and then showed a decline. The tensile modulus increased continuously with an increase in the degree of crystallinity. Spherulite sizes in the PEEK matrix became larger as the cooling time from the crystallization temperature increased. Transcrystallinity of carbon fiber/PEEK was developed easily and more densely than with SiC fiber/PEEK. This might have occurred because the unit cell dimensions of the crystallite in the fiber axis direction on the carbon surface was more suitable for making nucleation sites. The IFSS of carbon fiber/PEEK was significantly higher than that of SiC fiber/PEEK because it formed transcrystallinity of IFSS more favorably. 相似文献
13.
The objective of this work was to investigate the effects of molding conditions (molding temperature, residence time at melt temperature, and cooling rate) on the crystallization behavior and the fiber/matrix interaction in PEEK/carbon composites made from both prepreg and commingled forms. In order to investigate the crystallization behavior of the PEEK matrix, the molding process was simulated by differential scanning calorimetric analysis, DSC. The results show that the prepreg and commingled systems do not have the same matrix morphology; prepreg tape was found to be at its maximum of crystallinity, whereas the commingled system was found to be only partially crystalline. The results show that processing must be carried out at a temperature sufficiently high to destroy the previous thermal history of the PEEK matrix; this is an essential requirement to produce efficient fiber/matrix adhesion in the commingled fabric system. Optical microscopic observations also suggest that matrix morphology near the fibers is dependent on the melting conditions; a well-defined transcrystalline structure at the interface is observed only when the melt temperature is sufficiently high. However, the high temperature of molding can easily result in degradation of the PEEK matrix such as chain scission and crosslinking reactions. Thermal degradation of the matrix during processing is found to affect the crystallization behavior of the composites, the fiber/matrix adhesion, and the matrix properties. This effect is more important in the case of a commingled system containing sized carbon fibers because the sizing agent decomposes in the molding temperature range of PEEK/carbon composites. This produces a decrease of the matrix crystallinity and an elimination of the nucleating ability of the carbon fibers. A transition between cohesive and adhesive fracture is observed when the cooling rate increases from 30°C/min to 71°C/min for the composite made from the commingled fabric. This critical cooling rate is found to closely correspond to a change in the mechanism of crystallization of the PEEK matrix. 相似文献
14.
Nan-ying Ning 《Polymer》2007,48(25):7374-7384
In this work, halloysite nanotubes (HNTs), a new type of inexpensive filler, were used for the modification of polypropylene (PP). HNTs were first surface treated by methyl, tallow, bis-2-hydroxyethyl, quaternary ammonium, then melt mixed with PP. Scanning electron microscope (SEM) was used to examine the dispersion of HNTs in PP matrix. Differential scanning calorimetry (DSC), polarized light microscope (PLM), dynamic melt rheometry and wide angle X-ray diffraction (WAXD) were employed to investigate the crystallization behavior of the prepared PP/HNT composites. The mechanical properties were evaluated by Instron and impact tests. SEM results revealed that HNTs could be well-dispersed in PP matrix and had a good interfacial interaction with PP, even up to a high content of 10 wt%. DSC data indicated that HNTs could serve as a nucleation agent, resulting in an enhancement of the overall crystallization rate and the non-isothermal crystallization temperature of PP. PLM showed a constant spherulite growth rate and a decreased spherulite size at given isothermal crystallization temperature, suggesting that nucleation and growth of a spherulite are two independent processes. The result obtained by dynamic melt rheometry indicated that HNTs mainly promoted nucleation and had not much influence on the growth of PP crystallization. Nevertheless, by fast cooling the samples, almost constant spherulite size can be obtained for both pure PP and PP/HNT composites due to the limited nucleation effect of HNTs on PP crystallization. WAXD showed that HNTs mainly facilitated α-crystal form of PP. Though a good dispersion of HNTs in PP matrix was observed, out of our expectation, not much enhancement on mechanical properties of PP/HNT composites had been achieved, and this could be mainly ascribed to the constant crystallinity and spherulite size of PP as well as the small length/diameter ratio of HNTs. 相似文献
15.
采用硅烷偶联剂(KH-550)对纳米氧化锌进行了表面改性,通过熔融共混法制备了聚丁二酸丁二醇酯(PBS)/纳米氧化锌复合材料,利用扫描电子显微镜、热重分析仪、差示扫描量热仪等对复合材料的力学性能、热性能和非等温结晶性能进行了研究分析,并通过Ozawa-Flynn-Wall方法分析了复合材料的热降解行为。结果表明,纳米氧化锌能提高PBS的拉伸强度和弯曲强度,但降低了其冲击强度;改性后的纳米氧化锌可以提高其与PBS的界面相容性,并提高其在PBS基体中的分散性能,不同程度地提高了复合材料的力学性能;纳米氧化锌提高了PBS的结晶速率,降低了其热解反应活化能。 相似文献
16.
The interfacial interactions of carbon fiber (CF)-reinforced polymer composites is a key factor affecting the overall performance of the material. In this work, we prepared a sulfonated poly(ether sulfone)–graphene oxide mixed sizing agent to modify the interface of CF/PEEK composites and improve the interfacial properties between the PEEK matrix and CF. Results showed that the mechanical and interfacial properties of CF/PEEK composites are improved by the sizing agent. Specifically, the flexural strength, flexural modulus and interlaminar shear strength of the materials reached 847.29 MPa, 63.77 GPa, and 73.17 MPa, respectively. Scanning electron microscopy confirmed markedly improved adhesion between the resin matrix and fibers. This work provides a simple and effective method for the preparation of high-performance CF/PEEK composites, which can improve the performance of composites without degrading the mechanical property of pristine CF. 相似文献
17.
A carbon fiber (CF)/polyetheretherketone (PEEK) composite was manufactured using hybrid fabrics composed of CF and PEEK fiber. The fiber/matrix interface was modified by low temperature oxygen plasma treatment. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform attenuated total reflection infrared spectroscopy (FTIR-ATR) were used to relate the roughness and the functionality of the CF surface with the interfacial adhesion strength of the CF/PEEK composite. Scanning electron micrographs showed that plasma treatment increased the roughness of the CF surface up to 3 min of plasma treatment time; and prolonged treatment resulted in overall smoothing. XPS results confirmed that increasing treatment time marginally increased surface functionality: treatment for more than 5 min decreased the surface functionality by removing the active site of the CF surface. In addition, flexural strength and interlaminarshear strength (ILSS) of the CF/PEEK composite were measured. Their maximum values were observed at 3 min of plasma treatment time as a result of surface roughening by plasma etching. The SEM results were correlated with mechanical properties of the CF/PEEK composite. 相似文献
18.
采用注射成型法制备了铜/低密度聚乙烯/甲基乙烯基硅橡胶(Cu/LDPE/MVQ)复合材料和低密度聚乙烯/甲基乙烯基硅橡胶(LDPE/MVQ)复合材料,采用差示扫描量热法(DSC)研究了复合材料的非等温结晶行为。结果表明,随着冷却速率的加快,复合材料的结晶度逐渐增大。铜颗粒在复合材料中作为异相成核点,同时阻碍着LDPE分子链的运动。 相似文献