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The purpose of this paper was to synthesise a thermally expandable microsphere (TEMS) with fast thermal response property and small expansion temperature range, and investigate the factors affecting the expansion properties of the microspheres.

A new kind of TEMS with fast thermal response property was synthesised by suspension polymerisation method, using acrylonitrile, ethyl methacrylate and methacrylic acid as the main monomers; Mg(OH)₂ as the main dispersing agent; and isooctane or n-hexane or n-pentane as the blowing agent.

The TEMS possessed the best expansion capacity when encapsulated isooctane and n-hexane were about 18.5 Wt.%. The expansion process of the TEMS could be finished by raising the temperature to 18°C from the expansion onset, much less than the reported 30-50°C. The morphology of the TEMS turned from sphere to irregular concave shape following the content increase of the blowing agent.

A new kind of TEMS composed of acrylonitrile/ethyl methacrylate/methacrylic acid as the polymer shell was synthesised. These TEMS showed the fastest thermal response speed reported.

The purpose of this paper is to review the new trends in plastic additives, with special focus on developments in food packaging materials.

Phenomenological research has brought awareness and increased insight into the role of various plastic additives on the packaging of foods. The approach is based on the current trends and the industrial protocols for the additives used in plastic polymer processing for the development of food packaging materials.

Packaging of foodstuffs is a dynamic process which continually responds to the changes in supply and demand which are the result of adaptations to the varying demands of the consumer, changes in retail practices, technological innovations, new materials and developments in legislation, especially, with respect to environmental concerns. A wide range of additives is available for enhancing the performance and appearance of food packaging, as well as improving the processing of the compound. Polymer additives are important areas of innovation for packaging materials.

The paper reviews and summarizes the recent developments in the functionality of different additives, along with their advantages and disadvantages, currently being used to enhance the properties of food packaging materials that can positively influence the environment within the packaging for the increased demand for raw or processed foods.

This paper aims to understand the effect of extrusion conditions on the degree of foaming of polylactic acid (PLA) during three-dimensional (3D) printing. It was also targeted to optimize the slicing parameters for 3D printing and to study how the properties of printed parts are influenced by the extrusion conditions.

This study used a commercially available PLA filament that undergoes chemical foaming. An extrusion 3D printer was used to produce individual extrudates and print samples that were characterized using an optical microscope, scanning electron microscope and custom in-house apparatuses.

The degree of foaming of the extrudates was found to strongly depend on the extrusion temperature and the material feed speed. Higher temperatures significantly increased the number of nucleation sites for the blowing agent as well as the growth rate of micropores. Also, as the material feed speed increased, the micropores were allowed to grow bigger which resulted in higher degrees of foaming. It was also found that, as the degree of foaming increased, the porous parts printed with optimized slicing parameters were lightweight and thermally less conductive.

This study fills the gap in literature where it examines the foaming behavior of individual extrudates as they are extruded. By doing so, this work distinguishes the effect of extrusion conditions from the effect of slicing parameters on the foaming behavior which enhances the understanding of extrusion of chemically foamed PLA.

In the present article, the authors have conducted a review on some of the recent developments given in the literature pertaining to the passive protection of concrete structures using intumescent coatings. Here, the main thrust is placed on the spalling phenomenon of concrete elements when exposed to elevated temperatures and fires.

In this context, it has been long established that prolonged thermal insult on concrete members will lead to egress of water, both physically bound as well as those present as water of hydration within the concrete matrix, in the form of steam through microchannels and associated pathways of least resistance, often resulting in the flaking of the surface of the structure. The latter process can ultimately lead to the exposure of the ferrous-based reenforcement elements, for instance, to higher temperatures, thus inducing melting. This, in turn, can result in substantial loss of strength and load-bearing capacity of the structural element that is already undergoing disintegration of its base matrix owing to heat/fire. Even though spalling of concrete structures has long been recognized as a serious problem that can often lead to catastrophic failure of infrastructures, such as buildings, bridges and tunnels, the utility of intumescent coating as a mitigation strategy is relatively new and has not been explored to its fullest possible extent. Therefore, in the latter parts of the review, the authors have endeavored to discuss the different types of intumescent coatings, their modes of actions and, in particular, their wider applicability in terms of protecting concrete elements from detrimental effects of severe or explosive spalling.

Given that spalling of concrete components is still a very serious issue that can result in loss of lives and destruction of critical infrastructures, there is an urgent need to formulate better mitigating strategies, through novel means and methods. The use of the intumescent coating in this context appears to be a promising way forward but is one that seems to be little explored so far. Therefore, a more systematic investigation is highly warranted in this area, especially, as the authors envisage a greater activity in the building and commissioning of more infrastructures worldwide incommensurate with augmented economic activities during the post-COVID recovery period.

The authors have conducted a review on some of the recent developments given in the literature pertaining to the passive protection of concrete structures using intumescent coatings. The authors have also included the results from some recent tests carried out at the facilities using a newly commissioned state-of-the-art furnace.

The main purpose of this paper is to present and compare two different models for bubble growth and foam formation and to conduct a thorough assessment in terms of their numerical implementation and prediction accuracy.

The two models are assessed and validated against experimental measurements. The first model is known as a single bubble growth model and treats the foaming process as a single bubble growing in a large pool with enough gas available for growth, while the second model (cell model) takes into account the finiteness of gas supply availability as well as the effects of surrounding bubbles. The models are based on the application of the conservation of continuity and momentum principles and on constitutive equations to represent the viscosity of the melt. The models are numerically implemented using a finite difference scheme and their predictions are compared against experimental measurements.

The results demonstrate that the single bubble model predicts an infinite bubble growth with time due to the assumption of unlimited supply of the blowing agent. Meanwhile the cell model gives an equilibrium bubble size because it accounts for gas depletion. From this work, it was concluded that the cell model is the best model that adequately describes experimental data.

The problem of bubble growth and foam formation is of great importance in the process industry as it plays a key role in diverse technological fields such as the production of foamed plastics.

The findings here are important for the appropriate modeling of bubble growth and foam formation and for scheduling and optimizing the process. A simple model will suffice for the early stage of the process while a cell model is more appropriate for the entire duration of the process.

Attagel 50 is a processed form of the mineral attapulgite, and can be used in both aqueous and organic systems as a suspending, thickening or thixotropic agent. Typical uses are as a suspending and sag control agent in adhesives, plastics and sealants, as a suspending and flatting agent in paints, and as a stabilising or thickening agent in emulsions.

The second in a two‐part series, describes various applications of calcium stearate in resins and resinous polymers. Focuses in particular on its use in polypropylenes and stynenes (e.g. as a slip agent, a dispersing agent, a light stabilizer, or a nucleating agent) and in polyvinyl chlorides (e.g. as a pure‐proofing agent, to enhance ageing and heat resistance or as a non‐toxic stabilizer against acid, heat and light). Also considers the different applications of various stearate blends.

Amides made from animal and vegetable oil fatty acids and the fatty acids of fats, by reaction with ammonia or various amines, have several uses in the processing and production of many polymers, e.g. anti‐static agents, anti‐blocking agents, slip agents, and mould release agents etc., and this article reviews the various amides available for these outlets.