Anisotropic and heterogeneous thermal expansion of polyethylene foam blocks: Effect of thermal treatments

Rodríguez‐Pérez, M. A.; González-Peña, J.I.; Saja, J.A. de

doi:10.1016/j.eurpolymj.2007.07.025

Cited by 14 publications

(10 citation statements)

References 25 publications

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“…This interesting effect is known to occur with the compression‐moulding technique 6, 16, 27. In the last stage of foaming, the foams fill a closed mould.…”

Section: Resultsmentioning

confidence: 99%

“…For this reason only results for sheets 1, 2, 3 and 4 are included. This well‐known effect6, 16, 27 is due to the foaming process and in particular is a consequence of the expansion of the material at atmospheric pressure in a closed mould during the last stage of foaming. The areas of the foam block that make contact with the mould walls (sheets 1 and 7) due to this physical constraint (expansion is limited by the mould wall) expand to a lesser extent giving sheets of higher density.…”

Section: Resultsmentioning

confidence: 99%

“…The foams under study were produced from low‐density polyethylene using a compression‐moulding process. A detailed description of this process has been published elsewhere 6, 16, 27…”

Section: Materials and Thermal Treatmentsmentioning

confidence: 99%

“…That study showed significant modifications of both structure and density. In addition, the influence of thermal treatments on thermal expansion has also been considered 27. However, as far as we know, the influence of thermal treatments on other important physical properties, such as elastic modulus, collapse stress, energy absorbed or thermal conductivity, has not been previously reported.…”

Section: Introductionmentioning

confidence: 99%

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Modifying the structure and properties of polyethylene foams using thermal treatments

Rodríguez‐Pérez

González-Peña

Saja

2009

Polymer International

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BACKGROUND: The physical properties of polymer foams depend on many factors: density, cellular structure, matrix polymer morphology, etc. Therefore, these properties can be adapted by appropriate control of the structure. However, this simple and attractive concept has some limitations because the cellular structure of foams cannot be fully controlled during manufacturing. Therefore, in order to make possible the control of properties, it is highly desirable to develop simple procedures, such as thermal treatments, to modify the cellular structure. In the work reported, low-density polyethylene foams were thermally treated at temperatures below the melting temperature of the base polymer. The cellular structure, polymer base morphology and several thermal and mechanical properties were studied before and after the thermal treatments. RESULTS: It is shown that the anisotropy of the cellular structure is reduced by using adequate treatments. This modification of the structure influences physical properties that are sensitive to the cell shape, such as thermal expansion, elastic modulus and collapse stress.CONCLUSION: A simple procedure to allow further control of the structure and properties of polyethylene-based foams has been presented. The use of adequate thermal treatments is able to modify the cellular structure and hence the physical properties of these materials.

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“…This interesting effect is known to occur with the compression‐moulding technique 6, 16, 27. In the last stage of foaming, the foams fill a closed mould.…”

Section: Resultsmentioning

confidence: 99%

Section: Resultsmentioning

confidence: 99%

“…The foams under study were produced from low‐density polyethylene using a compression‐moulding process. A detailed description of this process has been published elsewhere 6, 16, 27…”

Section: Materials and Thermal Treatmentsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Modifying the structure and properties of polyethylene foams using thermal treatments

Rodríguez‐Pérez

González-Peña

Saja

2009

Polymer International

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“…Improving thermal stability of the foams is important in some final applications of the materials such as thermoforming [2]. Other properties that are improved by crosslinking the matrix are resistance to chemicals, stability against weathering and ultraviolet radiation; mechanical properties are also positively affected by crosslinking [5, 6].…”

Section: Introductionmentioning

confidence: 99%

Production and Characterization of crosslinked low‐density polyethylene foams using waste of foams with the same composition

Sáiz

Saja

Rodríguez‐Pérez

2011

Polymer Engineering & Sci

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A process to recover residues of crosslinked polyolefin foams is described in this paper. Low‐density foam scraps coming from discarded products or cuts from secondary manufacturing processes are heated and pressed to obtain a new material. The main target to reach with the used recovering process was to keep the density of the recycled specimens as low as possible, and similar to that of the starting products. The structure and properties of both recovered and virgin commercial materials with similar densities have been analyzed. It has been found that due to the recovering process cell size slightly decreased and at the same time the cells become orientated. Mechanical properties of recovered foams were lower than those of commercial products, even though thermal conductivity remained in the range of the values presented by virgin products, and recovered products were better sound absorbers than virgin foams. It is concluded that due to its low density and good balance of properties the recovered materials can substitute virgin materials in applications in which the key properties are excellent thermal insulation, good acoustic absorption, and medium compressive strength. POLYM. ENG. SCI., 2011. © 2011 Society of Plastics Engineers

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Polymer‐Based Nano‐Composites for Thermal Insulation

Fraleoni‐Morgera

Chhikara

2019

Adv Eng Mater

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The growing need for efficient energy use prompts for effective thermally insulating materials. Nano‐composites represent an important class of materials able to fulfill these needs, enabling both sizeable energy savings and specific applications where thermal insulation has to be coupled to mechanical robustness and lightness, like in automotive and aerospace applications. In view of these developments, this review summarizes the topic of polymer‐based nano‐composites for thermal insulation. The theme is introduced overviewing the features of the matrix‐filler interfaces and of the available models of thermal conductivity, with a mention of the most used types of polymeric matrices. The main three different types of polymer‐based nano‐composites for thermal insulation, that is, polymeric nano‐foams, syntactic foams and all‐solid nano‐composites, are then reviewed. For each class of material, the thermal insulation performance of selected examples is highlighted, with explicit reference to the material's structure and constitutional peculiarities (like type or size of the filler, specific filler surface functionalizations, etc). A resuming table reporting the thermal insulation performance of selected composites is also included in the review. Finally, an outlook on the possible developments in the field is given.

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Anisotropic and heterogeneous thermal expansion of polyethylene foam blocks: Effect of thermal treatments

Cited by 14 publications

References 25 publications

Modifying the structure and properties of polyethylene foams using thermal treatments

Modifying the structure and properties of polyethylene foams using thermal treatments

Production and Characterization of crosslinked low‐density polyethylene foams using waste of foams with the same composition

Polymer‐Based Nano‐Composites for Thermal Insulation

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