Comprehensive Review of Foam Board: Materials, Processes, Properties and Applications

Foam board, also known as foam core material board or advertising board, is a lightweight flat material composed of a polymer foam core layer and a paper or plastic surface layer. This paper aims to conduct a systematic review of the material science, manufacturing process, core physical and mechanical properties, wide application fields, and future sustainable development trends of foam board. The article points out that due to its excellent specific strength, thermal insulation, processability, and cost-effectiveness, foam board plays an indispensable role in advertising promotion, architectural decoration, model making, and packaging industries. In the future, the development of high-performance biobased and recyclable foam core materials will become the research focus in this field.

1. Introduction

Foam board is a typical "sandwich" structure composite material (Sandwich Composite). Its basic structure is composed of two hard skins (Face Sheet) on the top and bottom, and a thick and lightweight core (Core) sandwiched between them. This structure is formed by laminating or directly extruding the skins and the core through adhesive layers. This structure ingeniously combines the high bending stiffness of the skins and the lightweight, heat-insulating, and buffering properties of the core, making it the ultimate application in fields requiring lightweight, high stiffness, and good surface flatness. This article will explore various aspects of this widely used material from both academic and industrial perspectives.

2. Material Composition and Manufacturing Process

2.1 Core Materials

The core properties of the foamed board mainly depend on its core material:

Polystyrene (PS): The most common type, especially Expanded Polystyrene (EPS). It is formed by heating and pre-foaming the expandable polystyrene beads in a mold and then fusing them together. It is cost-effective, easy to cut, but has a relatively rough surface and average strength.

Polyvinyl Chloride (PVC): PVC foamed board is the mainstream choice for high-end applications. It is produced using the Celuka co-extrusion foaming process, which can create closed-cell structures with a dense and smooth surface, uniform core layers. Its density range is wide, and its mechanical properties (especially impact resistance and creep resistance) and weather resistance are all superior to those of PS core materials.

Polyethylene Terephthalate Glycol (PETG): PETG foamed board is an emerging eco-friendly material. It is made by using recycled PET bottles as raw materials and foaming them. It has excellent rigidity, recyclability, and does not easily produce creasing (white stress marks appear when bending), making it a "green" solution.

Other Core Materials: Including polypropylene (PP), polycarbonate (PC), etc., to meet specific requirements for chemical resistance or heat resistance.

2.2 Surface Materials

The surface layer mainly provides surface protection, printing suitability and aesthetics.

Paper Surface Layer: The most economical choice, suitable for indoor advertising boards, self-adhesive laminations, etc. It has good ink absorption properties, but is prone to moisture damage.

Polymer Surface Layer: Such as PVC film, PET film, etc. It offers excellent waterproofness, scratch resistance and durability, suitable for outdoor signs, architectural applications and high-quality printing.

2.3 Manufacturing Process

The main process steps include:

1. Core Material Preparation: For PS, it is molded using a compression molding process; for PVC/PETG, it is extruded and foamed using a T-shaped mold. This is the core technology, where the density and cell structure of the foam are controlled by precisely regulating temperature, pressure, and the injection of foaming agents (chemical or physical).

2. Composite Lamination: The prepared core material is laminated with pre-coated adhesive-coated skin materials (roll) through a series of heated pressing rollers. Temperature, pressure, and line speed are key process parameters that directly affect the interlayer bonding strength.

3. Cooling and Shaping: The laminated sheet is shaped in the cooling section to eliminate internal stress.

4. Cutting and Trimming: Finally, it is precisely cut according to the order size.

3. Performance Characteristics Analysis

The performance of the foamed board is a direct result of its structure.

Lightness: The density is usually between 20-200 kg/m³, and its extremely high specific strength (strength/weight ratio) is its greatest advantage.

Stiffness and Straightness: The sandwich structure gives it extremely high flexural stiffness and excellent straightness, and it is not prone to deformation.

Insulation and Soundproofing: The closed-cell foam structure contains a large amount of stationary air, making it an excellent thermal insulator and sound insulator.

Processability: It is easy to cut, engrave and shape using a utility knife, laser cutter, or CNC router. The PVC and PETG core materials can also be thermally bent using a hot air gun.

Printability and Decorativeness: The surface skin is easy to undergo post-processing such as digital UV printing, screen printing, and laminating.

4. Application Areas

Advertising and Exhibitions: It is the core material for posters, display boards, promotional signs, and POP display stands.

Architecture and Industry: It is used as insulation panels for buildings, partitions for bathrooms and kitchens, back panels for cabinets, and as core materials for composite panels (such as wind turbine blades).

Model and Prototype Making: Architects, engineers, and product designers widely use it to create concept models, scale models, and functional prototypes due to its ease of rapid processing.

Packaging Industry: It is used to make high-value protective packaging, liners, and display boxes, providing structural support and cushioning protection.

Creativity and Education: It is often used in artistic creation, school projects, and DIY handicrafts.

5. Challenges and Future Trends

Although foam boards are widely used, they still face challenges and opportunities for development:

1. Environmental Sustainability: Traditional PS and PVC materials are difficult to biodegrade and have poor recycling channels. Future research will focus on:

Biobased Plastics: Develop foam boards with core materials such as PLA.

Closed-loop Recycling: Promote materials like rPETG that use recycled components and establish a complete recycling and reuse system.

Biodegradable Additives: Research the addition of degrading agents to reduce environmental burden.

2. High Performance: Through nanomodification (such as adding nanocellulose, clay) and other methods, while maintaining lightness, further enhance their mechanical properties and flame retardancy.

3. Intelligent Manufacturing and Customization: Combined with 4.0 technology, develop intelligent production lines based on digital models to achieve small batch, multi-variety, and rapid response customized production.

6. Conclusion

Foam board, as a classic lightweight composite material, has achieved considerable scientific and technological maturity. Its outstanding properties stem from its ingenious sandwich structure design and material combination. From the low-cost PS board to the high-performance PVC board, and then to the environmentally friendly PETG board, the product range meets the diversified demands of the market. Looking to the future, research in this field will inevitably focus on the theme of sustainable development. By developing new environmentally friendly materials, optimizing manufacturing processes, and establishing a circular economy model, the foam board industry will be pushed towards a greener and higher-performance direction, continuing to consolidate its important position in numerous industrial and consumer sectors.