scholarly journals Effect of Temperature on the Mechanical Properties and Polymerization Kinetics of Polyamide-6 Composites

Polymers ◽  
2020 ◽  
Vol 12 (5) ◽  
pp. 1133 ◽  
Author(s):  
Mei-Xian Li ◽  
Dasom Lee ◽  
Gyu Hee Lee ◽  
Seung Mo Kim ◽  
Goichi Ben ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Model Fitting ◽  
Polyamide 6 ◽  
Reaction Model ◽  
Polymerization Kinetics ◽  
Thermoplastic Composites ◽  
Effect Of Temperature ◽  
Carbon Fiber Composites ◽  
Scanning Calorimetry ◽  
Kinetics Of

This work reports the preparation of carbon fiber reinforced thermoplastic composites via the in situ anionic ring opening polymerization of ε-caprolactam. Vacuum assisted resin transfer molding was used to fabricate polyamide-6/carbon fiber composites at different molding temperatures. As a result, the higher polymerization of ε-caprolactam was observed with the condition at 140 °C for satisfactory impregnation. Regarding molding temperature, the physical properties of polyamide-6/carbon fiber were observed that the bending and impact strengths at 140 °C were higher than those to at other molding temperatures. The polymerization kinetics of polyamide-6 was analyzed using differential scanning calorimetry by experimentally acquiring kinetic parameters according to model fitting approaches. Polymerization and crystallization, which occur simultaneously throughout the whole process, were separated using Gaussian and Maxwell–Boltzmann distributions to study polymerization kinetics. The result of the developed model was in good agreement with the experimental data for the presented first order autocatalytic reaction model.

Comparison and characterization of discontinuous carbon fiber liquid-molded nylon to hydroentanglement/compression-molded composites

2019 ◽  
Vol 33 (8) ◽  
pp. 1078-1093 ◽  
Author(s):  
Siddhartha Brahma ◽  
Selvum Pillay ◽  
Haibin Ning
Keyword(s):  
Carbon Fiber ◽  
Mechanical Performance ◽  
Weight Fraction ◽  
Polyamide 6 ◽  
Compression Molding ◽  
Fiber Composites ◽  
Strength Properties ◽  
Processing Temperature ◽  
Carbon Fiber Composites ◽  
Scanning Calorimetry

This article looks at liquid molding of polyamide 6 (PA6) via vacuum assisted resin transfer molding (VARTM) of discontinuous recycled carbon fiber composites. Its mechanical, thermal, and optical characterization is compared to hydroentanglement/compression molding. Liquid-molded composites show consistent improvement in their tensile and impact properties at three different weight fractions in comparison to hydroentanglement/compression molding. There was roughly a 10 and 13% increase in its tensile strength, modulus, and impact strength properties at 30 and 40% weight fractions and almost a 120% increase at 50% weight fraction. Fourier-transform infrared spectroscopy and differential scanning calorimetry data show that the caprolactam was synthesized to PA6 and was comparable to commercial grade PA6 used in this research. Scanning electron microscopy studies show poor wet out in the case of hydroentanglement/compression molding as compared to VARTM. The combination of better mechanical performance and lower processing temperature (165°C) shows promise in being a viable method to process PA6-based recycled fiber composites.

scholarly journals Synthesis and Polymerization Kinetics of Rigid Tricyanate Ester

Polymers ◽  
2021 ◽  
Vol 13 (11) ◽  
pp. 1686
Author(s):  
Andrey Galukhin ◽  
Roman Nosov ◽  
Ilya Nikolaev ◽  
Elena Melnikova ◽  
Daut Islamov ◽  
...  
Keyword(s):  
Kinetic Analysis ◽  
Single Step ◽  
Polymerization Kinetics ◽  
Scanning Calorimetry ◽  
Modulated Differential Scanning Calorimetry ◽  
Diffusion Controlled ◽  
Polymerization Product ◽  
The One ◽  
Kinetics Of

A new rigid tricyanate ester consisting of seven conjugated aromatic units is synthesized, and its structure is confirmed by X-ray analysis. This ester undergoes thermally stimulated polymerization in a liquid state. Conventional and temperature-modulated differential scanning calorimetry techniques are employed to study the polymerization kinetics. A transition of polymerization from a kinetic- to a diffusion-controlled regime is detected. Kinetic analysis is performed by combining isoconversional and model-based computations. It demonstrates that polymerization in the kinetically controlled regime of the present monomer can be described as a quasi-single-step, auto-catalytic, process. The diffusion contribution is parameterized by the Fournier model. Kinetic analysis is complemented by characterization of thermal properties of the corresponding polymerization product by means of thermogravimetric and thermomechanical analyses. Overall, the obtained experimental results are consistent with our hypothesis about the relation between the rigidity and functionality of the cyanate ester monomer, on the one hand, and its reactivity and glass transition temperature of the corresponding polymer, on the other hand.

scholarly journals Non-Isothermal Crystallization Kinetics of Injection Grade PHBV and PHBV/Carbon Nanotubes Nanocomposites Using Isoconversional Method

2020 ◽  
Vol 4 (2) ◽  
pp. 52
Author(s):  
Thaís Larissa do Amaral Montanheiro ◽  
Beatriz Rossi Canuto de Menezes ◽  
Larissa Stieven Montagna ◽  
Cesar Augusto Gonçalves Beatrice ◽  
Juliano Marini ◽  
...  
Keyword(s):  
Carbon Nanotubes ◽  
Crystallization Kinetics ◽  
Isothermal Crystallization ◽  
Model Fitting ◽  
Polarized Light ◽  
Isoconversional Method ◽  
Degree Of Crystallinity ◽  
Gamma Aminobutyric Acid ◽  
Scanning Calorimetry ◽  
Kinetics Of

Carbon nanotubes (CNT)-reinforced polymeric composites are being studied as promising materials due to their enhanced properties. However, understanding the behavior of polymers during non-isothermal crystallization is important once the degree of crystallinity and crystallization processes are affected when nanoparticles are added to matrices. Usually, crystallization kinetics studies are performed using a model-fitting method, though the isoconversional method allows to obtain the kinetics parameter without assuming a crystallization model. Therefore, in this work, CNTs were oxidized (CNT-Ox) and functionalized with gamma-aminobutyric acid (GABA) (CNT-GB) and incorporated into a poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) matrix. The influence of the addition and functionalization of CNT in the crystallization kinetics of PHBV was evaluated using the isoconversional method with differential scanning calorimetry (DSC), and by polarized light optical microscopy (PLOM) and Shore D hardness. The incorporation and functionalization of CNT into PHBV matrix did not change the Šesták and Berggren crystallization model; however, the lowest activation energy was obtained for the composite produced with CNT-GB, suggesting a better dispersion into the PHBV matrix. PLOM and Shore D hardness confirmed the results obtained in the kinetics study, showing the smallest crystallite size for CNT-containing nanocomposites and the highest hardness value for the composite produced with CNT-GB.

scholarly journals Influence of process parameters on the tensile properties of DREF-3000 friction spun hybrid yarns consisting of waste staple carbon fiber for thermoplastic composites

2017 ◽  
Vol 89 (1) ◽  
pp. 32-42 ◽  
Author(s):  
Mir Mohammad Badrul Hasan ◽  
Stefanie Nitsche ◽  
Anwar Abdkader ◽  
Chokri Cherif
Keyword(s):  
Carbon Fiber ◽  
Process Parameters ◽  
Polyamide 6 ◽  
Fiber Reinforced Composites ◽  
Thermoplastic Composites ◽  
Reinforced Composites ◽  
Influence Of Process Parameters ◽  
Low Weight ◽  
Carbon Fiber Reinforced Composites ◽  
The Relationship

Due to their excellent strength, rigidity, and damping properties, as well as low weight, carbon fiber reinforced composites (CFRCs) are being widely used for load bearing structures. On the other hand, with an increased demand and usage of CFRCs, effective methods to re-use waste carbon fiber (CF) materials, which are recoverable either from process scraps or from end-of-life components, are attracting increased attention. In this paper, hybrid yarns consisting of waste staple CF (40 and 60 mm) and polyamide 6 staple fibers (60 mm) are manufactured on a DREF-3000 friction spinning machine with various process parameters, such as spinning drum speed, suction air pressure, and core–sheath ratio. The relationship between different textile physical properties of the hybrid yarns, such as tensile strength, elongation, and evenness with different spinning parameters, core–sheath ratio, and input CF length is revealed.

Non-Isothermal Crystallisation Kinetics of Polyamide 6/Mesoporous Silica Nanocomposites

2007 ◽  
Vol 15 (7) ◽  
pp. 561-567
Author(s):  
Qingyuan Hu ◽  
Xiangling Ji ◽  
Yunfeng Lu
Keyword(s):  
Differential Scanning Calorimetry ◽  
Mesoporous Silica ◽  
Polyamide 6 ◽  
Nucleating Agents ◽  
Scanning Calorimetry ◽  
Crystallisation Kinetics ◽  
Silica Nanocomposites ◽  
Crystallisation Process ◽  
Isothermal Crystallisation ◽  
Kinetics Of

Non-isothermal crystallisation kinetics of a polyamide 6/mesoporous silica nanocomposite (PA6-MS) has been investigated by differential scanning calorimetry (DSC) at different cooling rates. Mandelkern, Jeziorny-Ziabicki and Ozawa methods were applied to describe this crystallisation process. The analyses show that the mesoporous silica particles act as nucleating agents in the composite and that the Avrami exponent n varies from 3.0 to 4.6. The addition of mesoporous silica influenced the mechanism of nucleation and the growth of polyamide 6 (PA 6) crystallites.

scholarly journals Polymerization Kinetics of Cyanate Ester Confined to Hydrophilic Nanopores of Silica Colloidal Crystals with Different Surface-Grafted Groups

Polymers ◽  
2020 ◽  
Vol 12 (10) ◽  
pp. 2329
Author(s):  
Andrey Galukhin ◽  
Guzel Taimova ◽  
Roman Nosov ◽  
Tatsiana Liavitskaya ◽  
Sergey Vyazovkin
Keyword(s):  
Colloidal Crystals ◽  
Active Role ◽  
Reaction Model ◽  
Proton Donor ◽  
Cyanate Ester ◽  
Polymerization Process ◽  
Scanning Calorimetry ◽  
Significant Acceleration ◽  
Kinetics Of ◽  
Silica Colloidal Crystals

This study investigates the kinetics of confined polymerization of bisphenol E cyanate ester in the nanopores of the three types of silica colloidal crystals that differ in the concentration and acidity of the surface-grafted proton-donor groups. In all three types of pores, the polymerization has released less heat and demonstrated a very similar significant acceleration as compared to the bulk process. Isoconversional kinetic analysis of the differential scanning calorimetry measurements has revealed that the confinement causes not only a dramatic change in the Arrhenius parameters, but also in the reaction model of the polymerization process. The obtained results have been explained by the active role of the silica surface that can adsorb the residual phenols and immobilize intermediate iminocarbonate products by reaction of the monomer molecules with the surface silanols. The observed acceleration has been quantified by introducing a new isoconversional-isothermal acceleration factor Zα,T that affords comparing the process rates at respectively identical conversions and temperatures. In accord with this factor, the confined polymerization is 15–30 times faster than that in bulk.

Non-isothermal Cure Kinetics of Polybenzoxazine/Carbon Fiber Composites by Phase Change Theory

2005 ◽  
Vol 13 (6) ◽  
pp. 599-605
Author(s):  
Chunling Xin ◽  
Xiaoping Yang ◽  
Dingsheng Yu
Keyword(s):  
Carbon Fiber ◽  
Marked Change ◽  
Activation Energies ◽  
Curing Temperature ◽  
Avrami Equation ◽  
Published Data ◽  
Carbon Fiber Composites ◽  
Scanning Calorimetry ◽  
Cure Reaction ◽  
Apparent Activation Energies

The cure of benzoxazines (BA-a) and benzoxazine/carbon fiber (BA-a/CF) composites was monitored by non-isothermal differential scanning calorimetry (DSC) at various heating rates. The characteristic temperatures of BA-a and BA-a/CF were analysed. The results showed that the initial cure temperature of BA-a/CF was lower than that of BA-a at the same heating rate. Various kinetic parameters and apparent activation energies for both curing systems were obtained by using a modified version of the Avrami equation. For BA-a, the apparent activation energy was 116.8 kJ/mol, which agreed well with the published data. For BA-a/CF, the results showed that the plot of Avrami rate constant vs. 1/T was not a straight line for the whole curing temperature range, but it displayed a marked change in slope at around 220 oC. The apparent activation energies at primary and second section were 105.6 kJ/mol and 224.8 kJ/mol respectively. The cure reaction of benzoxazines was not only catalysed by carbon fiber, but also was retarded by it.

scholarly journals Enhanced Performance of Ultrasonic Welding of Short Carbon Fiber Polymer Composites Through Control of Morphological Parameters

2019 ◽  
Vol 142 (1) ◽  
Author(s):  
Tae Hwa Lee ◽  
Hua-Tzu Fan ◽  
Yang Li ◽  
Daniel Shriver ◽  
Jorge Arinez ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
Nylon 6 ◽  
Ultrasonic Welding ◽  
Thermoplastic Composites ◽  
Degree Of Crystallinity ◽  
Weld Strength ◽  
Morphological Parameters ◽  
Scanning Calorimetry ◽  
Short Carbon Fiber ◽  
Short Carbon

Abstract Ultrasonic welding (USW) is one of the joining technologies that can be applied to short carbon fiber thermoplastic composites. In this study, the USW of Nylon 6 reinforced by short carbon fibers created using injection molding is used to investigate the USW process without energy directors. In addition to process parameters and performance parameters, a new category of parameters is introduced to characterize the behavior of base materials to control USW without energy directors. These parameters, named morphological parameters, are the degree of crystallinity (DoC) and the ratio of the crystalline phases of Nylon 6 (α/γ ratio). One method of controlling the morphological parameters is annealing. A design of experiments is carried out using 5 replicates and 7 annealing temperatures above the glass transition temperature (Tg) and below the melting temperature (Tm) of Nylon 6 to investigate the influence of annealing on the morphological parameters. The DoC and α/γ ratio are measured for each replicate by utilizing differential scanning calorimetry and X-ray diffraction. The results show that the DoC becomes uniform and the α/γ ratio increases after annealing. Consequently, the variation in weld strength decreases and the average weld strength increases by controlling the morphological parameters through annealing.

scholarly journals Studies of dehydration kinetics of Li2SO4·H2O by the master plots method

2007 ◽  
Vol 5 (1) ◽  
pp. 341-348
Author(s):  
Tang Wanjun ◽  
Chen Donghua
Keyword(s):  
Standard Deviation ◽  
Model Fitting ◽  
Isoconversional Method ◽  
Scanning Calorimetry ◽  
Exponential Factor ◽  
Air Atmosphere ◽  
Master Plots Method ◽  
Fitting Method ◽  
Master Plots ◽  
Kinetics Of

AbstractThe kinetics of Li2SO4·H2O dehydration in static air atmosphere was studied on the basis of nonisothermal measurements by differential scanning calorimetry. Dehydration data were subjected to an integral composite procedure, which includes an isoconversional method, a master plots method and a model-fitting method. Avrami-Erofeev equation was found to describe all the experimental data in the range of conversion degrees from 0.1 to 0.9. The determined activation energy equals 65.45 kJ·mol−1 with standard deviation ±0.47 kJ·mol−1. The estimated value of parameter m in Avrami-Erofeev equation is 2.15 with standard deviation ±0.11. Also, the obtained pre-exponential factor is 7.79×105 s−1 with standard deviation ±0.55×105 s−1. The results show that the present integral composite procedure gives self-consistent kinetic parameters.

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