Review of forging, stamping, and other solid‐phase forming processes

Kulkarni, Kiran

doi:10.1002/pen.760190703

Cited by 26 publications

(10 citation statements)

References 8 publications

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“…This yielded s‐rGO/PS composites with various rGO content (Figure d), and PS particles deformed into multi‐facets with rGO conductive layers sandwiched among contacting interfaces and joints. The processing temperature (100 °C) was around the glass transition temperature ( T g ) of PS, thus the PS composite processing is considered as a solid‐phase compression molding …”

Section: Resultsmentioning

confidence: 99%

Structured Reduced Graphene Oxide/Polymer Composites for Ultra‐Efficient Electromagnetic Interference Shielding

Yan

Pang

et al. 2014

Adv Funct Materials

1,063

559

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1wileyonlinelibrary.com an extremely high graphene loading is required. For example, the fi rst graphene based EMI shielding composite exhibited an EMI SE of ≈21 dB with a graphene loading of 15 wt%. [ 5 ] Ling et al. reduced the graphene loading of a polyetherimide/ graphene composite to 10 wt%, while keeping EMI SE at 20.0 dB. [ 6 ] On the other hand, an improved EMI SE, 29.3 dB, of graphene/polystyrene (PS) composite was obtained at the cost of extremely high graphene loading of 30 wt%. [ 7 ] Graphene or reduced graphene oxide (rGO) composites based on poly (methyl methacrylate), [ 8 ] water-borne polyurethane, [ 9 ] phenolic [ 10 ] were also reported in published papers, nevertheless, satisfactory EMI SE always requires abundant nanofi llers due to the homogenous dispersion structure of these composites. High nanofi ller concentrations result in high production costs and poor composite processability. Preparing CPC materials with superior EMI SE at low nanofi ller loading remains a challenge.The formation of segregated architectures can reduce the electrical percolation threshold, and improve electrical conductivity. [11][12][13][14][15] In such architectures, electrical nanofi llers are distributed only at the interfaces of polymer granules not homogeneously distributed in the whole volume of the polymer matrix. Graphene was fi rst utilized to construct segregated conductive networks in ultrahigh molecular weight polyethylene (UHMWPE) matrix, exhibiting an electrical conductivity of 0.04 S m −1 at a rather low content of 0.6 vol%. 12] A comparative study of segregated and homogeneous graphene/polycarbonate composites showed that the percolation threshold of the former composite was one third of that for the latter, and electrical conductivity was also higher by 220% at the same graphene loading of 4 wt%. [ 13 ] Segregated architectures also provide enhanced EMI SE, for example, when Cu nanowires were used as an electrical nanofi ller in PS, the segregated composites exhibited EMI SE levels of 26 and 42 dB at 10 and 13 wt% Cu loading, respectively. [ 15 ] Very recently, our group reported an in situ thermally reduced graphene/ultrahigh molecular weight polyethylene composite with a segregated structure, revealing the EMI SE of 28.3-32.4 dB at an ultralow graphene loading. [ 16 ] Although the formation of such segregated architectures could improve electrical and EMI shielding performance, one major issue of segregated architectures is that the existence of nanofi ller agglomerates at polymer granule interfaces restricts molecular diffusion between granules, leading to poor Ding-Xiang Yan , Huan Pang , Bo Li , Robert Vajtai , Ling Xu , Peng-Gang Ren , Jian-Hua Wang , and Zhong-Ming Li * A high-performance electromagnetic interference shielding composite based on reduced graphene oxide (rGO) and polystyrene (PS) is realized via highpressure solid-phase compression molding. Superior shielding effectiveness of 45.1 dB, the highest value among rGO based polymer composite, is achieved with only 3.47 vol% rGO lo...

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Section: Resultsmentioning

confidence: 99%

Structured Reduced Graphene Oxide/Polymer Composites for Ultra‐Efficient Electromagnetic Interference Shielding

Yan

Pang

et al. 2014

Adv Funct Materials

1,063

559

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“…The draw ratio was measured by cutting a sample strip of length 1 and weighing the piece. The draw ratio is then given by DR = (Ao/P)pl (1) where A0 is the cross section of the die and P , p , and 1 are the weight, density, and length of the sample, respectively. The cooling of the strip as it was being drawn was accomplished by the slit put at a fixed position in the cooling section.…”

Section: Methodsmentioning

confidence: 99%

Dimensional stability and tensile properties of drawn polystyrene composites

Nicodemo

Apicella

Nicolais

1981

J. Appl. Polym. Sci.

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SynopsisRecovery experiments above Tg and tensile tests have been performed on glass bead and' short glass fiber-polystyrene composite sheets obtained from extrusion and subsequent hot drawing. A shift procedure has been applied to the recoil data using a WLF equation. The data reported show that both dimensional stability and mechanical properties are enhanced by adding rigid fillers to the drawn thermoplastic matrix. The presence of short fibers reduces strongly the recoverable strain of the oriented material. A simple model able to predict the equilibrium values of the length reversion ratio of glass bead composites is developed and compares well with the experimental data.

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“…In the past half century a considerable amount of work1, 3, 4 has been done to develop processes different from the conventional molding process. These processes resemble more the solid‐phase metalworking process, in which the work material does not have the fluidity to give rise to the type of fluid flow observed in processes such as extrusion and injection molding 4. One advantage of polymer solid‐phase forming is that the cooling time is considerably reduced.…”

Section: Introductionmentioning

confidence: 99%

“…Another polymer solid‐phase forming technique is forging,1, 4 which utilizes compression force to shape a relatively thick material. Besides the general advantages associated with solid‐phase forming polymer forging is able to produce discrete parts, to process difficult‐to‐mold polymers, and to manufacture thick wall sections.…”

Section: Introductionmentioning

confidence: 99%

Cold forging behavior of semicrystalline polymers

Nagarajan

Yao

2005

J of Applied Polymer Sci

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ABSTRACT:Compared with molding processes, polymer solid-phase forming has several advantages. Particularly, polymer forging is able to reduce cycle time for thick parts, process difficult-to-mold materials, and enhance mechanical performance through self-reinforcment. Although much research has been carried out in the past on solid-phase forming, little has been done on polymer forging. This can be partially attributed to the lack of fundamental understanding of the process, e.g., lack of understanding on instantaneous recovery and viscoelastic recovery and lack of a modeling and simulation capability. In the present study, upsetting experiments were conducted to study the forging behavior of nylon. The instantaneous elastic recovery and the time-dependent postrecovery were found to be significantly affected by upsetting speed and dwell time. The dimensional recovery behavior of upset samples was interpreted using the Burgers model. The stress-strain data from the upsetting experiment was used in a viscoplastic simulation of forging a cylindrical hole. The simulation result about load versus forging displacement agrees well with that from the forging experiment.

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Review of forging, stamping, and other solid‐phase forming processes

Cited by 26 publications

References 8 publications

Structured Reduced Graphene Oxide/Polymer Composites for Ultra‐Efficient Electromagnetic Interference Shielding

Structured Reduced Graphene Oxide/Polymer Composites for Ultra‐Efficient Electromagnetic Interference Shielding

Dimensional stability and tensile properties of drawn polystyrene composites

Cold forging behavior of semicrystalline polymers

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