{"id":54146,"date":"2026-07-13T15:29:17","date_gmt":"2026-07-13T13:29:17","guid":{"rendered":"https:\/\/www.citribel.com\/2026\/07\/13\/monosodium-citrate-as-an-endothermic-blowing-agent-for-plastic-foaming\/"},"modified":"2026-07-13T15:29:17","modified_gmt":"2026-07-13T13:29:17","slug":"monosodium-citrate-as-an-endothermic-blowing-agent-for-plastic-foaming","status":"publish","type":"post","link":"https:\/\/www.citribel.com\/de\/2026\/07\/13\/monosodium-citrate-as-an-endothermic-blowing-agent-for-plastic-foaming\/","title":{"rendered":"Monosodium citrate as an endothermic blowing agent for plastic foaming"},"content":{"rendered":"\t\t
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Monosodium citrate as an endothermic blowing agent for plastic foaming<\/h1>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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Lightweight materials are increasingly important in the plastics industry. By reducing material density, manufacturers can lower raw material use, reduce product weight and develop materials with specific functional or aesthetic properties.<\/p>

One way to achieve this is through material foaming. During this process, small gas bubbles are created inside a polymer, resulting in a cellular structure. The choice of blowing agent plays an important role in controlling gas generation, cell structure, surface quality and the overall performance of the finished product.<\/p>

Monosodium citrate can be used as an endothermic chemical blowing agent in combination with sodium bicarbonate. It offers controlled gas release, broad polymer compatibility and a decomposition profile that makes it suitable for a wide range of plastic-processing applications.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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What is a chemical blowing agent?<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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Blowing agents are added to polymers to create gas during processing. As the temperature rises, the blowing agent decomposes or reacts, releasing gases that form small bubbles within the polymer matrix.<\/p>

These bubbles create a cellular structure that reduces the density of the material. Depending on the formulation and processing conditions, foaming can also influence characteristics such as:<\/p>

  • Material weight<\/li>
  • Surface appearance<\/li>
  • Impact resistance<\/li>
  • Thermal and acoustic insulation<\/li>
  • Material consumption<\/li>
  • Dimensional stability<\/li><\/ul>

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    Chemical blowing agents are commonly used in extrusion and injection moulding, but they can also be applied in compression moulding, blow moulding and rotational moulding.<\/p>

    Gas generation alone, however, is not enough to ensure a high-quality foam. The gas must be released at the right moment and at a controlled rate, while the polymer must be able to retain the developing cell structure during expansion.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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    How does monosodium citrate work?<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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    Monosodium citrate is generally used together with sodium bicarbonate. When heat is applied during polymer processing, an acid-assisted chemical and thermal decomposition takes place.<\/p>

    This reaction primarily releases:<\/p>

    • Carbon dioxide<\/li>
    • Water vapour

      <\/li><\/ul>

      The gases expand within the polymer matrix and create a foamed structure.<\/p>

      Because the reaction absorbs heat, monosodium citrate is classified as an endothermic blowing agent<\/strong>. This controlled, heat-absorbing reaction supports a gradual release of gas and can help create fine, uniform cells.<\/p>

      Compared with some exothermic blowing agents, endothermic systems can offer improved processing control, reduced risk of uncontrolled gas generation and better surface quality in the finished product.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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      Why use monosodium citrate in plastic foaming?<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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      Monosodium citrate offers several practical and technical advantages as part of an endothermic blowing-agent system.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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      Controlled gas release<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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      Its endothermic decomposition supports a gradual and more controllable release of gas during processing. This can help reduce the formation of irregular or oversized cells and contribute to a more homogeneous foam structure.<\/p>

      Monosodium citrate has a decomposition temperature of approximately 217\u00b0C<\/strong>, depending on formulation and processing conditions. Its reported gas yield is approximately 185\u2013240 ml per gram<\/strong>.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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      Fine and uniform cell structures<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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      Controlled gas generation can support the formation of smaller and more evenly distributed cells.<\/p>

      A fine cellular structure may contribute to:<\/p>

      • Improved surface appearance<\/li>
      • More consistent density reduction<\/li>
      • Better dimensional control<\/li>
      • Reduced risk of visible defects<\/li>
      • More uniform mechanical properties

        <\/li><\/ul>

        At active loadings of approximately 0.5\u20131% in the polymer<\/strong>, density reductions of around 12\u201332%<\/strong> may be achieved, depending on the polymer, formulation, processing method and operating conditions.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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        Clean decomposition profile<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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        The reaction releases carbon dioxide and water vapour rather than nitrogen- or ammonia-containing gases associated with certain alternative blowing agents.<\/p>

        This can help limit undesirable residues, odours or by-products in the finished material. It may also reduce the risk of deposits or contamination within processing equipment.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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        Suitable for coloured and translucent materials<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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        Monosodium citrate is supplied as colourless crystals or powder. It can therefore be incorporated into opaque and translucent products without significantly interfering with the intended product colour.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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        Particle size and gas-release behaviour<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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        Particle size influences how quickly monosodium citrate dissolves or reacts within the formulation.<\/p>

        A finer powder generally reacts more rapidly because of its larger available surface area. A coarser granular product may provide a different reaction and gas-release profile.<\/p>

        This gives formulators additional flexibility when adapting the blowing-agent system to:<\/p>

        • Processing temperature<\/li>
        • Residence time<\/li>
        • Polymer viscosity<\/li>
        • Desired cell size<\/li>
        • Production speed<\/li>
        • Target density reduction

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          Citribel supplies monosodium citrate in granular and powder forms, allowing manufacturers to select a particle-size profile suited to their processing requirements.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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          Compatible polymers<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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          Monosodium citrate can be used with a broad range of thermoplastics, particularly when the polymer-processing window corresponds with the decomposition behaviour of the blowing-agent system.<\/p>

          Typical processing temperatures range from approximately 160 to 270\u00b0C<\/strong>.<\/p>

          Compatible polymers may include:<\/p>

          • Acrylonitrile butadiene styrene (ABS)<\/li>
          • Ethylene-vinyl acetate (EVA)<\/li>
          • Polyamide (PA)<\/li>
          • Polybutylene terephthalate (PBT)<\/li>
          • Polycarbonate (PC)<\/li>
          • Polyethylene, including LDPE, LLDPE and HDPE<\/li>
          • Polyethylene terephthalate (PET)<\/li>
          • Polyoxymethylene (POM)<\/li>
          • Polyphenyl ether (PPE)<\/li>
          • Polyphenylene oxide (PPO)<\/li>
          • Polyphenylene sulfide (PPS)<\/li>
          • Polypropylene (PP)<\/li>
          • Polystyrene, including GPPS and HIPS<\/li>
          • Polyvinyl chloride (PVC)<\/li>
          • Styrene-acrylonitrile resin (SAN)<\/li>
          • Thermoplastic olefin (TPO)<\/li>
          • Thermoplastic polyurethane (TPU)<\/li><\/ul>

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            The optimal dosage and processing parameters depend on the polymer, equipment, masterbatch formulation and desired foam properties.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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            Applications of foamed plastics<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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            Endothermic blowing agents can be used in a variety of plastic products and processing techniques.<\/p>

            Typical applications include:<\/p>

            • Food-contact packaging<\/li>
            • Labels<\/li>
            • Fine sheet products<\/li>
            • Films and boards<\/li>
            • Profiles<\/li>
            • Monofilaments<\/li>
            • Injection-moulded components<\/li>
            • Extruded plastic products<\/li>
            • Lightweight technical parts

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              Foaming can help manufacturers reduce material use while maintaining the required geometry and functionality of the final product.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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              Food-contact and industrial applications<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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              Citribel\u2019s monosodium citrate complies with food-purity requirements and is known as food additive E331<\/strong>. It is allergen-free, odourless and non-flammable.<\/p>

              This makes it relevant for the production of materials intended for food-contact applications, subject to the requirements and compliance assessment of the complete final formulation.<\/p>

              Monosodium citrate is also registered under REACH, supporting its use in industrial applications.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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              Monosodium citrate for lightweight plastic materials<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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              Monosodium citrate offers a combination of controlled decomposition, clean gas generation and broad polymer compatibility.<\/p>

              When used together with sodium bicarbonate, it can support:<\/p>

              • Controlled endothermic foaming<\/li>
              • Fine and uniform cellular structures<\/li>
              • Reduced material density<\/li>
              • Improved surface quality<\/li>
              • Lower material consumption<\/li>
              • Application in a broad range of thermoplastics

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                Its performance can be adapted through dosage, particle size and processing conditions, giving formulators flexibility when developing lightweight plastic products.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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                Looking for monosodium citrate for polymer processing?<\/h3>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t
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                Citribel produces monosodium citrate in Belgium through its distinctive surface-fermentation process.<\/p>

                Contact our team to discuss the most suitable grade and particle-size profile for your plastic-processing application.<\/p>\t\t\t\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t

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                Contact us:<\/h2>\t\t\t\t<\/div>\n\t\t\t\t<\/div>\n\t\t\t\t
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