Time-dependent uniaxial piezoresistive behavior of high-density polyethylene/short carbon fiber conductive composites

2004 ◽  
Vol 19 (9) ◽  
pp. 2625-2634 ◽  
Author(s):  
Q. Zheng ◽  
J.F. Zhou ◽  
Y.H. Song
Keyword(s):  
Carbon Fiber ◽  
High Density Polyethylene ◽  
Volume Fraction ◽  
High Density ◽  
Constant Stress ◽  
Time Dependent ◽  
Short Carbon Fiber ◽  
Conductive Composites ◽  
Short Carbon ◽  
Resistance Relaxation

Short carbon fiber (SCF) filled high-density polyethylene conductive composites were studied in terms of time-dependent piezoresistive behaviors. The time-dependent change of resistance under constant stress or strain was found to be the succession of the previous pressure-dependent piezoresistance. Depending on the filler volume fraction and the level of the constant stress or strain, resistance creep and resistance relaxation with different directions were observed. An empirical expression similar to the Burgers equation could be applied to fit the data for both the resistance creep and the resistance relaxation. The fitted relaxation time as a function of pressure showed that there exist two competing processes controlling the piezoresistive behavior and its time dependence. Mechanical creep and stress relaxation of the composites were also studied, and a comparison with the time-dependent resistance implied that there is a conducting percolation network attributed to the physical contacts between SCF and a mechanical network formed by the molecular entanglement or physical crosslinking of the polymer matrix and the interaction between the filler and the matrix. It is believed that the two networks dominate the electrical and the mechanical behaviors, respectively.

scholarly journals Study on the effect of carbon fiber addition on the properties of rice straw-plastic composites

BioResources ◽  
2021 ◽  
Vol 16 (2) ◽  
pp. 3411-3421
Author(s):  
Xuesong Guan ◽  
Dingguo Zhou ◽  
Mingzhu Pan ◽  
He Chen ◽  
Chunxiang Ding
Keyword(s):  
Carbon Fiber ◽  
Rice Straw ◽  
Carbon Fibers ◽  
High Density Polyethylene ◽  
High Density ◽  
Test Machine ◽  
The Matrix ◽  
Infrared Spectrometer ◽  
Short Carbon ◽  
Skeleton Structure

Short carbon fiber (SCF), rice straw powder, and high-density polyethylene (HDPE) were melted, mixed, and compounded into composites by compression molding. The effects of carbon fiber content on the mechanical properties of rice straw-high density polyethylene composites (RHCs) were studied. The carbon fibers were characterized by a universal capability test machine (UCTM), scanning electron microscope (SEM), DMA dynamic mechanical analyzer, and a Fourier infrared spectrometer. The results showed that the addition of carbon fiber was beneficial to reduce the creep of RHCs. Meanwhile, the carbon fibers were broken after strength testing. The functional group types of rice straw WPC composites did not change, and the skeleton structure of WPC materials was still retained. When the content of carbon fibers was 9%, a large number of carbon fibers were surrounded by the HDPE matrix; the fibers were broken and rarely pulled out. The results showed that good interfacial bonding took place between the carbon fibers and the composites. The maximum tensile strength of the RHC/S9 was 15.15 MPa, which was 20.7% higher than that of default RHC, and the modulus of elasticity was 52.5% higher than that of default RHC. However, due to the large content of carbon fiber, the distribution of the carbon fibers was uneven in the matrix, and the toughness was reduced.

scholarly journals Overmolding of Hybrid Long and Short Carbon Fiber Polypropylene Composite: Optimizing Processing Parameters

2021 ◽  
Vol 5 (4) ◽  
pp. 132
Author(s):  
Cahyo Budiyantoro ◽  
Heru S. B. Rochardjo ◽  
Gesang Nugroho
Keyword(s):  
Carbon Fiber ◽  
Impact Strength ◽  
Flexural Strength ◽  
Melting Temperature ◽  
Carbon Fibers ◽  
Volume Fraction ◽  
Injection Molding Process ◽  
Molding Process ◽  
Short Carbon Fiber ◽  
Short Carbon

Injection overmolding was used to produce hybrid unidirectional continuous-short carbon fiber reinforced polypropylene. Polypropylene pellets containing short carbon fibers were melted and overmolded on unidirectional carbon fibers, which act as the core of the composite structure. Four factors were varied in this study: fiber pretension applied to unidirectional fibers, injection pressure, melting temperature, and backpressure used for melting and injecting the composite pellet. This study aimed to evaluate the effect of these factors on fiber volume fraction, flexural strength, and impact strength of the hybrid composite. The relationship between factors and responses was analyzed using Box–Behnken Response Surface Methodology (RSM) and analysis of variance (ANOVA). Each aspect was divided into three levels. There were 27 experimental runs carried out, with three replicated center points. The results showed that the injection molding process parameters had no significant effect on the fiber’s volume fraction. On the other hand, melting temperature and fiber pretension significantly affected impact strength and flexural strength.

scholarly journals Effect of Geometric Parameters and Moisture Content on the Mechanical Performances of 3D-Printed Isogrid Structures in Short Carbon Fiber-Reinforced Polyamide

2021 ◽  
Author(s):  
Valerio Di Pompeo ◽  
Archimede Forcellese ◽  
Tommaso Mancia ◽  
Michela Simoncini ◽  
Alessio Vita
Keyword(s):  
Carbon Fiber ◽  
Moisture Content ◽  
Geometric Parameters ◽  
Fiber Reinforced ◽  
Compression Tests ◽  
Short Carbon Fiber ◽  
3D Printed ◽  
Carbon Fiber Reinforced ◽  
Mechanical Performances ◽  
Short Carbon

AbstractThe present paper aims at studying the effect of geometric parameters and moisture content on the mechanical performances of 3D-printed isogrid structures in short carbon fiber-reinforced polyamide (namely Carbon PA). Four different geometric isogrid configurations were manufactured, both in the undried and dried condition. The dried isogrid structures were obtained by removing the moisture from the samples through a heating at 120 °C for 4 h. To measure the quantity of removed moisture, samples were weighted before and after the drying process. Tensile tests on standard specimens and buckling tests on isogrid panels were performed. Undried samples were tested immediately after 3D printing. It was observed that the dried samples are characterized by both Young modulus and ultimate tensile strength values higher than those provided by the undried samples. Similar results were obtained by the compression tests since, for a given geometric isogrid configuration, an increase in the maximum load of the dried structure was detected as compared to the undried one. Such discrepancy tends to increase as the structure with the lowest thickness value investigated is considered. Finally, scanning electron microscopy was carried out in order to analyze the fractured samples and to obtain high magnification three-dimensional topography of fractured surfaces after testing.

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