Low-density rotomoulded polymer foams

Bush, Stephen F.; Ademosu, O.K.

doi:10.1016/j.colsurfa.2005.01.029

Cited by 11 publications

(16 citation statements)

References 1 publication

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“…The mold featured a glass viewing window, allowing for image capture, providing a similar view to the foam height change obtained in previous publications. 13,14 However, the variable results were again observed in the foam samples because of poor heating control. To provide a more uniform and controllable heating to the samples, the hotplate was replaced with a laboratory oven, creating a method like the furnace technique applied for metal foam studies by previous researchers.…”

Section: Practical Realization Of the Conceptmentioning

confidence: 99%

“…Previous research identified that densification must be fully completed to create an optimal foam structure. 1,[12][13][14] Due to the relationship with polymer particle size and densification, 5(pp146-150) an initial study was conducted to investigate its effect on the foam structure. Table 4 sets out the settings for samples made using the new test procedure and the industrial-scale molding method.…”

Section: Study Of Effect Of Polymer Particle Size On Foam Structurementioning

confidence: 99%

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Characterization of polymer foam evolution in unpressurized melt systems

Pritchard,

Martin,

McCourt

et al. 2023

Polymer Engineering & Sci

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The evolution of foam in unpressurized melt processing techniques, such as rotational molding, is different from high‐pressure processes like injection foam molding, making comparisons difficult. This has driven the need for a dedicated technique for studying these systems. A unique test procedure was developed to capture and characterize foam evolution in test tubes under unpressurized conditions. A validation study found the procedure to be reliable, producing repeatable samples (height average (AVG) 39.69 ± 1.70 mm and density AVG 0.319 ± 0.012 g/cm3) and delivering comparable results to samples produced using the industrial rotational foam molding process. A study examined the effect of polymer particle size on the foam structures produced. Finer (>90 μm <106 μm) polymer powders produced more desirable structures, achieving 38.6% lower foam density and 43.8% taller peak foam height than coarser powders (>425 μm < 500 μm). Cycle times were much shorter (~15 min) in comparison with the industrial rotational molding process (>40 min) and required smaller amounts of materials, making it useful for rapid characterization. Future work is planned to apply the new procedure to investigate the effects of material and processing conditions on the foam structures produced under unpressurized conditions.Highlights Evaluation of existing unpressurized foam characterization methods. Rapid test procedure developed to characterize unpressurized foam evolution. Variability study of foam structures produced using the new procedure. Effect of rotational molding polymer powder and considerations for foaming. Results validated with industrial unpressurized rotationally molded samples.

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Section: Practical Realization Of the Conceptmentioning

confidence: 99%

Section: Study Of Effect Of Polymer Particle Size On Foam Structurementioning

confidence: 99%

Characterization of polymer foam evolution in unpressurized melt systems

Pritchard,

Martin,

McCourt

et al. 2023

Polymer Engineering & Sci

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“…In rotomoulding, polymer in powder form is introduced into a mould, which is then closed and rotated. If the mould temperature is set with appropriate regard to the melting temperature range of the polymer powder, a viscous molten layer is built up next to the mould surface, which gradually extends inward . To fill the interior part of the panel, special polymeric beads are introduced into the mould with the powder.…”

Section: Introductionmentioning

confidence: 99%

Impact response of polyethylene sandwich panel obtained by rotational moulding

Casavola

Moramarco

Pappalettere

2014

Fatigue Fract Eng Mat Struct

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A B S T R A C T Sandwich panels are more and more used in load bearing structures because of their high specific stiffness and high specific strength. Impact energy absorption is a characteristic required for some specific application, that is, in high-speed transportations. In this article, the impact response of a new sandwich panel made up of two polyethylene skins separated by lightweight polyethylene foam, built with an innovative manufacturing process called rotational moulding, is investigated by both the impact test and the finite element analysis. To characterize the low-velocity impact response of this new material, three homogenous polyethylene sandwich panels, 44 ± 1 mm thick, are studied under seven impact test energy levels, from 5 to 70 J. Experimental tests have allowed obtaining absorbed energy and the load-time plot for each impact energy level. Furthermore, a quantitative analysis of the damage is presented. Finally, a finite element model was implemented to evaluate the damping effect of the core. E = Young's modulus of the skin E pl = plastic modulus of the skins J = elastic volume ratio U(λ i ,η) = modified strain energy function U λ i ð Þ = foam strain energy function ϕ(η) = damage function η = damage variable λ i = principal stretches μ i , β i , α i = temperature-dependent material parameters ν = Poisson's ratio of the skins σ sn = yield stress of the skins I N T R O D U C T I O NSandwich panels, made up of two polyethylene skins separated by a lightweight polyethylene foam, could represent a good solution in many technical uses where a high damping impact effect is required (e.g. car bumpers). 1 The panel studied in the present work was built with an innovative manufacturing process called rotational moulding (or rotomoulding) whose peculiarity is the possibility of creating in a unique step the entire sandwich component, so as to obtain a better adhesion and continuity between the skins and the core. Rotomoulding is the principal process for making hollow shapes. In rotomoulding, polymer in powder form is introduced into a mould, which is then closed and rotated. If the mould temperature is set with appropriate regard to the melting temperature range of the polymer powder, a viscous molten layer is built up next to the mould surface, which gradually extends inward. 2 To fill the interior part of the panel, special polymeric beads are introduced into the mould with the powder. These beads have the characteristic to explode and to foam at a higher temperature than polymer melting temperature. This technology should permit a reduction of production time and an increase of material mechanical characteristics.Sandwich structures are known to be susceptible to impact damage by foreign objects. 3,4 The impact represents, therefore, an indispensable issue to characterize this kind Correspondence: C. Casavola.

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“…Conductive polymer foam is one of the important polymer foams. Compared with ordinary materials, polymer foams have many inherent advantages, such as low density, low thermal conductivity, good sound isolation, high specific strength, and impact resistance, which have been widely used in various fields, including aerospace, atomic energy, electric and petrochemical industry, and so on . In short, polymer foams have many meaningful applications in modern industry.…”

Section: Introductionmentioning

confidence: 99%

A conductive foam: Based on novel poly(styrene‐b‐butadiene‐co‐styrene‐b‐styrene) tri‐block copolymer filled by carbon black

Zhang

Zhou

Zhao

et al. 2014

J of Applied Polymer Sci

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In this article, a conductive foam based on a novel styrene-based thermoplastic elastomer called poly(styrene-b-butadieneco-styrene-b-styrene) tri-block copolymer S(BS)S was prepared and introduced. S(BS)S was particularly designed for chemical foaming with uniform fine cells, which overcame the shortcomings of traditional poly(styrene-b-butadiene-b-styrene) tri-block copolymer (SBS). The preparation of conductive foams filled by the carbon black was studied. After the detail investigation of cross-linking and foaming behaviors using moving die rheometer, the optimal foaming temperature was determined at 180 C with a complex accelerator for foaming agent. Scanning electron microscopy (SEM) images shown that the cell bubbles of conductive foam were around 30-50 mm. The conductivity of foams was tested using a megger and a semiconductor performance tester. SEM images also indicated that the conductivity of foams was mainly affected by the distribution of carbon black in the cell walls. The formation of the network of the carbon black aggregates had a contribution to perfect conductive paths. It also found that the conductivity of foams declined obviously with the foaming agent content increasing. The more foaming agent led to a sharp increasing of the number of cells (from 2.93 3 10 6 to 6.20 3 10 7 cells/cm 3 ) and a rapid thinning of the cell walls (from 45.3 to 1.4 mm), resulting in an effective conductive path of the carbon black no forming. The conductive soft foams with the density of 0.48-0.09 g/cm 3 and the volume resistivity of 3.1 3 10 3 22.5 3 10 5 X cm can be easily prepared in this study.

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Low-density rotomoulded polymer foams

Cited by 11 publications

References 1 publication

Characterization of polymer foam evolution in unpressurized melt systems

Characterization of polymer foam evolution in unpressurized melt systems

Impact response of polyethylene sandwich panel obtained by rotational moulding

A conductive foam: Based on novel poly(styrene‐b‐butadiene‐co‐styrene‐b‐styrene) tri‐block copolymer filled by carbon black

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