A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes

Llewelyn, Gethin; Rees, Andrew; Griffiths, Christian; Jacobi, Martin

doi:10.3390/polym11111896

Cited by 16 publications

(11 citation statements)

References 41 publications

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“…107,108 Also, the addition of talc to polyolefins in MIM has been seen to improve the polymer melt viscoelasticity and promote crystallisation of the polymer matrix. [109][110][111][112] Other nucleating agents that have been shown to enhance the crystallisation of polyolefins are that of GFs, 14 nanoclay 113 and also 1,3:2,4 bis-O-(4methylbenzylidene)-D-sorbitol gelling agent (MD). 114 Wang et al 115 incorporated 0.2 degree of substitution (DS) of cellulose nanofiber (CNF) to isotactic PP.…”

Section: Materials Alterationmentioning

confidence: 99%

Advances in microcellular injection moulding

Llewelyn

Rees

Griffiths

et al. 2020

Journal of Cellular Plastics

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Injection moulding is a well-established replication process for the cost-effective manufacture of polymer-based components. The process has different applications in fields such as medical, automotive and aerospace. To expand the use of polymers to meet growing consumer demands for increased functionality, advanced injection moulding processes have been developed that modifies the polymer to create microcellular structures. Through the creation of microcellular materials, additional functionality can be gained through polymer component weight and processing energy reduction. Microcellular injection moulding shows high potential in creating innovation green manufacturing platforms. This review article aims to present the significant developments that have been achieved in different aspects of microcellular injection moulding. Aspects covered include core-back, gas counter pressure, variable thermal tool moulding and other advanced technologies. The resulting characteristics of creating microcellular injection moulding components through both plasticising agents and nucleating agents are presented. In addition, the article highlights potential areas for research exploitation. In particular, acoustic and thermal applications, nano-cellular injection moulding parts and developments of more accurate simulations.

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Section: Materials Alterationmentioning

confidence: 99%

Advances in microcellular injection moulding

Llewelyn

Rees

Griffiths

et al. 2020

Journal of Cellular Plastics

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show abstract

“…Polymer foams can develop a different geometry, such as open cells or closed cells, depending on the raw materials and the method used for their creation. Polymeric foams—because of their advantages—can fit in different fields, such as packaging, thermal insulation systems, sporting equipment and automotive parts [ 5 , 6 ]. Polymeric foams find applications also in food packaging, providing lightweight insulating properties to the package [ 7 ].…”

Section: Introductionmentioning

confidence: 99%

Injection Molded PP Foams Using Food Ingredients for Food Packaging Applications

et al. 2021

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A new approach to the creation of polypropylene (PP) based foaming materials was developed using food grade foaming agents that were coated on the PP pellets. More specifically, sodium bicarbonate and organic acids were used to coat PP pellets using either polyethyleneoxide (PEO) or lipid esters as coating stabilizers. In order to overcome the problem of the thermal decomposition of sodium bicarbonate at temperatures lower than the PP melting temperature, which makes the direct foaming during melt mixing impossible, the proposed methodology was proved quite efficient. Thus, new PP masterbatches were prepared, where the foaming agents were incorporated as coating at PP pellets at contents up to 10%, and initially used in Lab scale injection machines in order to find the best combination of materials that resulted in the production of foamed articles. Subsequently selected material combinations were tested in an industrial scale injection molding machine, where an optimization of the injection parameters was attempted. The outcome of this was the production of PP articles with significantly increased void fraction, up to 14%, decreased thermal conductivity, up to 20%, and various pore sizes as was observed via microscopic examination using SEM and CLSM.

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“…In another study, Llewelyn et al used a hybrid foaming method by utilizing a physical blowing agent (super critical nitrogen) and a chemical blowing agent to produce polypropylene (PP) foam, with and without talc filler, by low-pressure foam-injection molding (FIM). Through a hybrid foaming method with low pressure (FIM), foams with high cell density and superior homogeneous cell structure were produced [ 89 ]. To produce inhomogeneous foams, using chemical blowing was most effective, as a larger skin wall thickness was obtained.…”

Section: Recent Processes To Produce Functionally Graded Foamsmentioning

confidence: 99%

“…Apart from foams based on thermoplastic polymers, thermoset polymers and elastomers have also been successfully used to produce foams with controlled structure (and therefore properties). Song et al [ 89 ] mixed a biobased epoxy resin (Greenpoxy 56) and an amine-based hardener using a hand-held mixer for 20 min in order to produce an air-in-resin liquid foam. The biobased polymer foams were formed in self-standing tubes.…”

Section: Recent Processes To Produce Functionally Graded Foamsmentioning

confidence: 99%

Recent Progress in Processing Functionally Graded Polymer Foams

2020

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Polymer foams are an important class of engineering material that are finding diverse applications, including as structural parts in automotive industry, insulation in construction, core materials for sandwich composites, and cushioning in mattresses. The vast majority of these manufactured foams are homogeneous with respect to porosity and structural properties. In contrast, while cellular materials are also ubiquitous in nature, nature mostly fabricates heterogeneous foams, e.g., cellulosic plant stems like bamboo, or a human femur bone. Foams with such engineered porosity distribution (graded density structure) have useful property gradients and are referred to as functionally graded foams. Functionally graded polymer foams are one of the key emerging innovations in polymer foam technology. They allow enhancement in properties such as energy absorption, more efficient use of material, and better design for specific applications, such as helmets and tissue restorative scaffolds. Here, following an overview of key processing parameters for polymer foams, we explore recent developments in processing functionally graded polymer foams and their emerging structures and properties. Processes can be as simple as utilizing different surface materials from which the foam forms, to as complex as using microfluidics. We also highlight principal challenges that need addressing in future research, the key one being development of viable generic processes that allow (complete) control and tailoring of porosity distribution on an application-by-application basis.

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A Novel Hybrid Foaming Method for Low-Pressure Microcellular Foam Production of Unfilled and Talc-Filled Copolymer Polypropylenes

Cited by 16 publications

References 41 publications

Advances in microcellular injection moulding

Advances in microcellular injection moulding

Injection Molded PP Foams Using Food Ingredients for Food Packaging Applications

Recent Progress in Processing Functionally Graded Polymer Foams

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