scholarly journals Resin Transfer Moldable Fluorinated Phenylethynyl-Terminated Imide Oligomers with High Tg: Structure–Melt Stability Relationship

Polymers ◽  
2021 ◽  
Vol 13 (6) ◽  
pp. 903
Author(s):  
Weijie Hong ◽  
Lili Yuan ◽  
Yanping Ma ◽  
Chao Cui ◽  
Haoyang Zhang ◽  
...  
Keyword(s):  
Glass Transition ◽  
Density Functional ◽  
Resin Transfer Molding ◽  
Cure Kinetics ◽  
Processing Temperature ◽  
Scanning Calorimetry ◽  
Transfer Molding ◽  
13C Nuclear Magnetic Resonance ◽  
Nmr Characterization ◽  
Tg Structure

Phenylethynyl-terminated aromatic polyimides meet requirements of resin transfer molding (RTM) and exhibits high glass transition temperature (Tg) were prepared. Moreover, the relationship between the polyimide backbones structure and their melting stability was investigated. The phenylethynyl-terminated polyimides were based on 4,4’-(hexafluorosiopropylidene)-diphthalic anhydride (6FDA) and different diamines of 3,4’-oxydianiline (3,4’-ODA), m-phenylenediamine (m-PDA) and 2,2’-bis(trifluoromethyl)benzidine (TFDB) were prepared. These oligoimides exhibit excellent melting flowability with wide processing temperature window and low minimum melt viscosities (< 1 Pa·s). Two of the oligoimides display good melting stability at 280–290 °C, which meet the requirements of resin transfer molding (RTM) process. After thermally cured, all resins show high glass transition temperatures (Tgs, 363–391 °C) and good tensile strength (51–66 MPa). The cure kinetics studied by the differential scanning calorimetry (DSC), 13C nuclear magnetic resonance (13C NMR) characterization and density functional theory (DFT) definitely confirmed that the electron-withdrawing ability of oligoimide backbone can tremendously affect the curing reactivity of terminated phenylethynyl groups. The replacement of 3,4’-ODA units by m-PDA or TFDB units increase the electron-withdrawing ability of the backbone, which increase the curing rate of terminated phenylethynyl groups at processing temperatures, hence results in the worse melting stability.

Uncertainty Modeling of Residual Stress Development in Polymeric Composites Manufactured With Resin Transfer Molding Process

2007 ◽  
Author(s):  
Kuang-Ting Hsiao
Keyword(s):  
Residual Stress ◽  
Resin Transfer Molding ◽  
Parametric Uncertainty ◽  
Polymeric Composite ◽  
Cure Kinetics ◽  
Polymeric Composites ◽  
Molding Process ◽  
Stress Development ◽  
Transfer Molding ◽  
Rtm Process

Resin Transfer Molding (RTM) is an advanced process to manufacture high quality thermoset polymeric composites. The quality of the composite depends on the resin infusion stage and the cure stage during the RTM process. The resin curing is a complex exothermic process which involves resin mechanical property evolution, resin volume shrinkage, thermal expansion, heat transfer, and chemical reaction. Since the fibers and resin have many differences in their physical properties, the composite cure stage inevitably introduces the undesired residual stress to the composite parts. As the residual stress could sometimes generate local matrix failure or degrade the performance of the composite, it is important to model and minimize the residual stress. This paper presents a model to predict the residual stress development during the composite cure process. By slightly disturbing the manufacturing parameters such as the mold heating cycle and the cure kinetics of polymer, the variations of residual stress development during the RTM process can be modeled and compared. A parametric uncertainty study of the residual stress development in the polymeric composite manufactured with RTM will be performed and discussed.

A Numerical Study of Integrated Direct Cure Kinetics Characterization and Control for Resin Transfer Molding (RTM)

Materials ◽  
2005 ◽  
Author(s):  
Kuang-Ting Hsiao
Keyword(s):  
Control System ◽  
Numerical Study ◽  
Resin Transfer Molding ◽  
Cure Kinetics ◽  
Mold Temperature ◽  
Fiber Preform ◽  
Transfer Molding ◽  
Cure Cycle ◽  
Numerical Case Study

In Resin Transfer Molding (RTM), the fiber preform is first placed inside a mold cavity and is subsequently impregnated with liquid resin. After mold filling, the resin starts to cure and bind the fiber preform into a solid composite part. The cure cycle will affect the residual stress built during RTM and must be controlled. Traditionally, the cure cycle control is achieved through three steps: offline resin cure kinetics characterization, offline cure cycle optimization, and mold temperature control. Different from other traditional cure cycle control approaches, this paper presents an investigation to achieve an integrated cure kinetics characterization-control system by combining a newly developed direct cure kinetics characterization method with online cure cycle optimization. A methodology to seamlessly combine these components for a practicable online cure characterization-control system will be presented and demonstrated by a numerical case study. The accuracy and reliability of this methodology will be examined and discussed based on the results of the numerical case study.

A new m-xylylene bismaleimide-based high performance resin for vacuum-assisted infusion and resin transfer molding

2019 ◽  
Vol 53 (22) ◽  
pp. 3063-3072
Author(s):  
Sergey Evsyukov ◽  
Ronald Klomp-de Boer ◽  
HD Stenzenberger ◽  
Tim Pohlmann ◽  
Matthijs ter Wiel
Keyword(s):  
High Performance ◽  
Resin Transfer Molding ◽  
Ternary Eutectic ◽  
Melt Processing ◽  
Processing Temperature ◽  
Resin Infusion ◽  
Bismaleimide Resin ◽  
Transfer Molding ◽  
Low Viscosity ◽  
Processing Techniques

A novel low-melting, low-viscosity, one-part bismaleimide resin based on m-xylylene bismaleimide has been developed and examined for application in vacuum-assisted resin infusion. The resin is a fully formulated system comprising a ternary eutectic BMI mixture blended with bis-( o-propenylphenoxy)benzophenone and 2,2'-bis(3-allyl-4-hydroxyphenyl)propane as co-monomers. The resin offers enhanced properties for melt processing techniques. The formulation strategy and chemistry is presented and discussed in detail. For resin infusion and/or resin transfer molding technologies, the melt processing temperature of the resin is in the range of 90–110℃. Processing data of the uncured and mechanical properties of cured neat resin are provided. The resin shows a Tgof 285℃ when post-cured at 250℃ for 6 h. Finally, a 400 × 500 mm2carbon fabric laminate was successfully molded for demonstration by a VARI process. The microscopic study reveals no voids and no laminate surface imperfections. The VARI processing details are presented and discussed.

scholarly journals Preparation of High-Performance Carbon Fiber-Reinforced Epoxy Composites by Compression Resin Transfer Molding

Materials ◽  
2018 ◽  
Vol 12 (1) ◽  
pp. 13 ◽  
Author(s):  
Zeyu Sun ◽  
Jie Xiao ◽  
Lei Tao ◽  
Yuanping Wei ◽  
Shijie Wang ◽  
...  
Keyword(s):  
Carbon Fiber ◽  
High Performance ◽  
Bending Strength ◽  
Volume Fraction ◽  
Resin Transfer Molding ◽  
Epoxy Composites ◽  
Scanning Calorimetry ◽  
Transfer Molding ◽  
Molding Method ◽  
Compression Resin Transfer Molding

To satisfy the light weight requirements of vehicles owing to the aggravation of environmental pollution, carbon-fiber (CF)-reinforced epoxy composites have been chosen as a substitute for traditional metal counterparts. Since the current processing methods such as resin transfer molding (RTM) and compression molding (CM) have many limitations, an integrated and optimal molding method needs to be developed. Herein, we prepared high-performance composites by an optimized molding method, namely compression resin transfer molding (CRTM), which combines the traditional RTM and CM selectively and comprehensively. Differential scanning calorimetry (DSC) and rotational rheometry were performed to optimize the molding parameters of CRTM. In addition, metallurgical microscopy test and mechanical tests were performed to evaluate the applicability of CRTM. The experimental results showed that the composites prepared by CRTM displayed superior mechanical properties than those of the composites prepared by RTM and CM. The composite prepared by CRTM showed up to 42.9%, 41.2%, 77.3%, and 5.3% increases in tensile strength, bending strength, interlaminar shear strength, and volume fraction, respectively, of the composites prepared by RTM. Meanwhile, the porosity decreased by 45.2 %.

scholarly journals Surface Modification of Bamboo Fibers to Enhance the Interfacial Adhesion of Epoxy Resin-Based Composites Prepared by Resin Transfer Molding

Polymers ◽  
2019 ◽  
Vol 11 (12) ◽  
pp. 2107 ◽  
Author(s):  
Dong Wang ◽  
Tian Bai ◽  
Wanli Cheng ◽  
Can Xu ◽  
Ge Wang ◽  
...  
Keyword(s):  
Surface Modification ◽  
Epoxy Resin ◽  
Condensation Reaction ◽  
Resin Transfer Molding ◽  
Coupling Agents ◽  
Scanning Calorimetry ◽  
Thermal Stabilities ◽  
Transfer Molding ◽  
Bamboo Fibers ◽  
The Impact

Bamboo fibers (BFs)-reinforced epoxy resin (EP) composites are prepared by resin transfer molding (RTM). The influence of BFs surface modification (NaOH solution or coupling agents, i.e., KH550 and KH560) on interfacial properties of BFs/EP composites is systematically investigated. The synergistic effect of hydrolysis, peeling reaction of BFs, and the condensation reaction of hydrolyzed coupling agents are confirmed by FTIR. Scanning electron microscopy (SEM) and atomic force microscopy (AFM) reveal that the interfacial compatibility of NaOH- and silane-modified BFs/EP composites was significantly improved. KH550-modified BFs/EP composite renders optimal tensile, flexural, and impact strength values of 68 MPa, 86 MPa, and 226 J/m. The impact resistance mechanism at the interface of BFs/EP composites was proposed. Moreover, the dynamic mechanical properties, creep behavior, and differential scanning calorimetry of BFs/EP composites have also been carried out to understand thermal stabilities. Overall, the surface-modified BFs-reinforced EP composites exhibited superior interfacial bonding.

scholarly journals Effects of End-Caps on the Atropisomerization, Polymerization, and the Thermal Properties of ortho-Imide Functional Benzoxazines

Polymers ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 399 ◽  
Author(s):  
Kan Zhang ◽  
Yuqi Liu ◽  
Zhikun Shang ◽  
Corey Evans ◽  
Shengfu Yang
Keyword(s):  
Thermal Properties ◽  
Density Functional ◽  
Structural Information ◽  
Steric Structure ◽  
Polymerization Process ◽  
Scanning Calorimetry ◽  
Thermally Activated ◽  
13C Nuclear Magnetic Resonance ◽  
Oxazine Ring ◽  
End Caps

A new type of atropisomerism has recently been discovered in 1,3-benzoxazines, where the intramolecular repulsion between negatively charged oxygen atoms on the imide and the oxazine ring hinders the rotation about the C–N bond. The imide group offers a high degree of flexibility for functionalization, allowing a variety of functional groups to be attached, and producing different types of end-caps. In this work, the effects of end-caps on the atropisomerism, thermally activated polymerization of ortho-imide functional benzoxazines, and the associated properties of polybenzoxazines have been systematically investigated. Several end-caps, with different electronic characteristics and rigidities, were designed. 1H and 13C nuclear magnetic resonance (NMR) spectroscopy and density functional theory (DFT) calculations were employed to obtain structural information, and differential scanning calorimetry (DSC) and in situ Fourier transform infrared (FT-IR) spectroscopy were also performed to study the thermally activated polymerization process of benzoxazine monomers. We demonstrated that the atropisomerization can be switched on/off by the manipulation of the steric structure of the end-caps, and polymerization behaviors can be well-controlled by the electronic properties of the end-caps. Moreover, a trade-off effect were found between the thermal properties and the rigidity of the end-caps in polybenzoxazines.

scholarly journals Thermal and Cure Kinetics of Epoxy Molding Compounds Cured with Thermal Latency Accelerators

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
Chean-Cheng Su ◽  
Chien-Huan Wei ◽  
Bo-Ching Li
Keyword(s):  
Low Temperatures ◽  
Thermal Characteristics ◽  
Cure Kinetics ◽  
Molding Process ◽  
Scanning Calorimetry ◽  
Transfer Molding ◽  
Molding Compounds ◽  
Higher Temperature ◽  
Kinetics Of ◽  
Rubber State

The cure kinetics and mechanisms of a biphenyl type epoxy molding compounds (EMCs) with thermal latency organophosphine accelerators were studied using differential scanning calorimetry (DSC). Although the use of triphenylphosphine-1,4-benzoquinone (TPP-BQ) and triphenylphosphine (TPP) catalysts in biphenyl type EMCs exhibited autocatalytic mechanisms, thermal latency was higher in the TPP-BQ catalyst in EMCs than in the TPP catalyst in EMCs. Analyses of thermal characteristics indicated that TPP-BQ is inactive at low temperatures. At high temperatures, however, TPP-BQ increases the curing rate of EMC in dynamic and isothermal curing experiments. The reaction of EMCs with the TPP-BQ latent catalyst also had a higher temperature sensitivity compared to the reaction of EMCs with TPP catalyst. In resin transfer molding, EMCs containing the TPP-BQ thermal latency accelerator are least active at a low temperature. Consequently, EMCs have a low melt viscosity before gelation, and the resins and filler are evenly mixed in the kneading process. Additionally, flowability is increased before the EMCs form a network structure in the molding process. The proposed kinetic model adequately describes curing behavior in EMCs cured with two different organophosphine catalysts up to the rubber state in the progress of curing.

Cure Kinetics of High Performance Epoxy Molding Compounds

2014 ◽  
Vol 1024 ◽  
pp. 151-154
Author(s):  
Chean Cheng Su ◽  
Cheng Fu Yang ◽  
Chien Huan Wei
Keyword(s):  
Kinetic Model ◽  
High Performance ◽  
Resin Transfer Molding ◽  
Cure Kinetics ◽  
Molding Process ◽  
Transfer Molding ◽  
Molding Compounds ◽  
Higher Temperature ◽  
Kinetics Of ◽  
Rubber State

The reaction of EMCs with the triphenylphosphine-1,4-benzoquinone (TPP-BQ) latent catalyst also had a higher temperature sensitivity compared to the reaction of EMCs with triphenylphosphine (TPP) catalyst. In resin transfer molding, EMCs containing the TPP-BQ thermal latency accelerator are least active at a low temperature. Consequently, EMCs have a low melt viscosity before gelation, and the resins and filler are evenly mixed in the kneading process. Additionally, the rheological property, flowability, is increased before the EMC form a network structure in the molding process. The proposed kinetic model adequately describes curing behavior in EMCs cured with two different organophosphine catalysts up to the rubber state in the progress of curing.

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