Void Formation and Growth in Thermoplastic Processing

Roychowdhury, Suranjan; Gillespie, John W.; Advani, Suresh G.

doi:10.1007/978-94-011-2874-2_7

Cited by 14 publications

(5 citation statements)

References 15 publications

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“…Conditions: kW/m 2 ; dwell power ϭ 70 time ϭ seconds; dwell ؇C; weld kPa. 30 temperature ϭ 260 pressure ϭ 690 mean, was attributed to thermal uniformity of the LMS welds. The highest lap shear strengths were obtained in the second weld step, which experienced a longer time for polymer interdiffusion of the weld interface.…”

Section: Processing Quality and Performance Of Large-scale Resistanmentioning

confidence: 99%

“…Past research has demonstrated the feasibility of using vacuum bag technology to provide lower pressure, on the order of ( psi), to large area fusion bonds. 29 0.1 MPa Ϸ 14.7 However, insufficient pressure may induce void formation 30 and deconsolidation 17 of the laminated adherends during welding. Furthermore, pressure is a critical parameter in determination of the final bondline thickness of the welded joints, as in the case of adhesively bonded joints.…”

Section: Pressure Requirementsmentioning

confidence: 99%

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Scaling issues in resistance-welded thermoplastic composite joints

McKnight

Holmes

Gillespie

et al. 1997

Adv. Polym. Technol.

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Resistance welding has been demonstrated as a viable technique for joining thermoplastic composites. Extensive research has been conducted in previous studies on the processing and postprocessing evaluation of coupon‐sized resistance welded specimens using this thermoplastic fusion bonding technique. This work focuses on the manufacturing and evaluation of large‐scale resistance welds used to join carbon fiber (CF)/polyetheretherketone (PEEK) thermoplastic composite parts. Applications using the present resistance welding technology are assessed, and potential applications of resistance welding are discussed. The sequential resistance welding process is introduced as an approach to large‐scale welding that increases joint quality and performance while maintaining modest pressure and weld power requirements. The single‐step and alternate multiple‐step (sequential) techniques are implemented for large‐scale resistance welds of CF/PEEK adherends comolded with polyetherimide (PEI) (i.e., the Thermabond® process). Nondestructive ultrasonic evaluation, mechanical testing, fractography, and microscopy show that: (1) a higher weld uniformity was obtained with the multiple‐step weld than the single‐step weld; and (2) uneven heating and overheating were minimized by reducing the heating element length within the bond region through the use of the sequential resistance welding process. The different welding techniques produce a large variation in lap shear strength; direct comparison of the weld quality and lap shear strength shows that the sequential resistance welding process yields a superior bond. With the principles developed in this investigation, resistance welding can be used to join large‐scale thermoplastic composite parts with consistent, high levels of performance and quality. © 1997 John Wiley & Sons, Inc. Adv in Polym Techn 16: 279–295, 1997

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Section: Processing Quality and Performance Of Large-scale Resistanmentioning

confidence: 99%

Section: Pressure Requirementsmentioning

confidence: 99%

Scaling issues in resistance-welded thermoplastic composite joints

McKnight

Holmes

Gillespie

et al. 1997

Adv. Polym. Technol.

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show abstract

“…During the fabrication process, the sample with the high ratio fiber content to matrix may having the area which is poorly wetted with resin. The area with poorly wetted with resin experienced the fiber pull-out and when load is applied to the composite surface, it will significantly be promoted to composite failure [18,19]. Therefore, it is important to determine the optimum ratio of fiber to matrix in fabricating the composite samples.…”

Section: Correlation Of Impact Properties Due To Manufacturing Defectsmentioning

confidence: 99%

Correlation of manufacturing defects and impact behaviors of kenaf fiber reinforced hybrid fiberglass/Kevlar polyester composite

Suriani

Sapuan

Ruzaidi

et al. 2021

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In this study, the impact properties of kenaf fibre reinforced hybrid fiberglass/Kevlar polymeric composite was investigated. In this study, a new fiber arrangement based on kenaf bast fiber as reinforcement to the hybrid fiberglass/Kevlar fiber and polyester as matrix used to fabricate the hybrid polymeric composite. Five different types of samples with different of kenaf fiber content based on volume fraction (0, 15, 45, 60 and 75%) to hybrid fiberglass/Kevlar polymer composites were manufactured. 0% of kenaf fiber has been used as control sample. The results showed that hybridization has improved the impact properties. These results were further supported through SEM micrograph of the manufacturing defects of the polymer composite. Based on literature work, manufacturing defects that occurs in composite system reduced the mechanical properties of the material. Therefore, in this research the correlation of impact behaviors and manufacturing defects of kenaf fiber reinforced hybrid fiberglass/Kevlar polymeric composite has been successfully done. As conclusion, the highest manufacturing defects determined in the composites during the fabrication significantly lowest the results of impact behavior.

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“…When a vacuum is applied, bubble nucleation takes place instantaneously, followed by bubble growth. While it is difficult to differentiate bubble nucleation from bubble growth, it is useful to take advantage of the characteristic nucleation time t c , which is defined as [6] where D is the diffusion coefficient of the gas phase in a polymer resin. Bubble nucleation is a type of phase transformation from liquid to gas, of which the essential driving force is the difference in free energy between the liquid and gas phases.…”

Section: Theorymentioning

confidence: 99%

“…Hence, it is critical to understand the underlying mechanism as to how bubbles are formed and grow depending on imposed processing conditions. With the exception of the foaming process, minimizing bubble formation is, in general, required for maintaining the desirable physical properties and securing the long‐term durability of polymer and composite products [6]. Consequently, the robust control of bubble formation and growth is needed to accomplish the consistent and stable processing of polymers and polymer composites.…”

Section: Introductionmentioning

confidence: 99%

Bubble development in a polymeric resin under vacuum

Sul¹,

Youn²,

Song³

2012

Polymer Engineering & Sci

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Understanding the gas diffusion and evaporation behavior in a polymeric resin under vacuum is of great importance because many types of polymer and composite products are manufactured by applying a vacuum to the production system. This article proposes a theoretical model that can describe bubble growth under vacuum by combining the mechanisms of gas diffusion and evaporation. To confirm such a model, we carried out experimental analyses including evaporation experiments with a bell jar or a tube as well as vacuum‐assisted resin transfer molding (VARTM). Particularly in the VARTM process, it was identified that many bubbles were nucleated and grew at the fiber‐matrix interface due to the applied vacuum pressure. Those results suggest that more attention should be paid to vacuum‐assisted material processing to prevent bubbles from existing in the final products. POLYM. ENG. SCI., 2012. © 2012 Society of Plastics Engineers

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Void Formation and Growth in Thermoplastic Processing

Cited by 14 publications

References 15 publications

Scaling issues in resistance-welded thermoplastic composite joints

Scaling issues in resistance-welded thermoplastic composite joints

Correlation of manufacturing defects and impact behaviors of kenaf fiber reinforced hybrid fiberglass/Kevlar polyester composite

Bubble development in a polymeric resin under vacuum

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