▶ Core Performance Advantages Analysis

1. Waterproof and Moisture-proof (Core Value of Closed-Cell Structure)

Closed-cell rate ≥95%, independent and non-connected air bubbles, water absorption rate ≤1% (high-quality products ≤0.5%), far lower than traditional materials (wood >15%, asphalt board >8%). Water cannot penetrate the interior, suitable for underwater, underground, and humid environments, effectively preventing structural corrosion.

2. High Elasticity and Deformation Resistance

Compression rebound rate ≥90%, able to adapt to **±25% joint expansion and contraction**, still returning to its original shape after repeated compression.

Elongation at break ≥100%, resisting tensile stress caused by structural displacement, avoiding joint cracking.

3. Weather Resistance and Chemical Resistance

Resistant to high and low temperatures (-60℃~100℃), with no significant performance degradation after more than 10 years of outdoor use.

Resistant to acid, alkali, salt, oil, and organic solvent corrosion, suitable for complex environments such as water conservancy, chemical, and marine engineering.

Resistant to ultraviolet rays and ozone, not easy to age, powder, or crack.

4. Lightweight and Convenient Construction

Density is only 20-80. kg/m³, approximately 1/5 the weight of wood, making handling and installation easier and without increasing structural load.

It can be cut and spliced, adapting to irregular joints, resulting in high construction efficiency (saving 50% of labor time compared to traditional materials).

5. Environmental Protection and Safety

Formaldehyde-free, heavy metal-free, meets GB 18585-2020 environmental standards, and is recyclable.

Flame-retardant products can reach B1 fire resistance standards, meeting building fire protection requirements.

▶ Main application scenarios (detailed explanation by field)

Polyethylene closed-cell foam boards are used in engineering fields such as water conservancy, transportation, construction, and municipal engineering. The core application scenarios and matching types of foam are as follows:

1. Water Conservancy Engineering (Core Application Area)

Dam/Dam Expansion Joints: As a joint board, it absorbs deformation caused by temperature and water level changes in the dam, preventing leakage (using cross-linked medium-density foam board).

Energy Stilling Slope/Slope Protection Joints: Buffers water flow impact, protects the structure, and simultaneously stops water (using high-density wear-resistant type).

Tunnel/Culvert Water Stopping: Seals the lining between the lining and surrounding rock, preventing groundwater seepage (using high-elasticity waterproof type).

2. Transportation Infrastructure

Bridge Expansion Joints: Fills the joints between the main span and approach bridges, and between the beam and abutment, absorbing vibration and displacement (using cross-linked high-resilience foam board).

Highway Pavement Joints: Relieves temperature stress and prevents rainwater from seeping into the base layer and causing roadbed damage (using medium-density type).

Railway Bed Buffering: Reduces train vibration, lowers noise, and protects the track structure (using high-density elastic type).

3. Construction Engineering

Concrete Structural Joints: Sealing construction joints in walls, floors, beams, and columns to prevent leakage and air penetration (using ordinary PE or cross-linked PE).

External Wall Insulation Systems: Buffering between the insulation layer and the structure to accommodate thermal expansion and contraction (using low-density insulation).

Door and Window Installation Sealing: Elastic filling between window frames and walls to improve airtightness and watertightness (using high-elasticity closed-cell type).

4. Other Special Applications

Pipeline Engineering: Sealing pipe joints, protecting against corrosion, and buffering thermal expansion and contraction (using oil-resistant and heat-resistant type).

Packaging Industry: Cushioning packaging for precision instruments, electronic products, and fragile items (using low-density, high-elasticity type).

Sound Insulation and Noise Reduction: Sound insulation layers for building partitions, computer rooms, and vehicle interiors (using low-density porous type).

▶ Construction Techniques and Precautions

Core Construction Steps (Taking Expansion Joints in Hydraulic Engineering as an Example)

1. Pre-construction preparation

2.

1. Clean the joints: Remove debris, dust, and oil stains, ensuring the surface is dry and flat.

2. Cut the boards: Cut to the joint dimensions, leaving a 5%-10% compression allowance (to accommodate post-installation compression).

3. Inspect the boards: Ensure they are free of damage, air bubbles, and have uniform density.

3. Installation and fixing

4.

1. Embedding the joints: Gently press the foam board into the joint, ensuring a tight fit with the structures on both sides.

2. Fixing methods: Temporarily fix small joints with tape; for large projects, use steel nails or special clamps to prevent displacement.

3. Joint treatment: Use a 45° bevel joint at the board joints, applying special PE adhesive to enhance sealing.

5. Post-construction treatment

6.

1. Sealing aids: Waterstop tape and sealant can be used on the outside of the joints to form a double waterproof system.

2. Protective measures: Avoid scratches from sharp objects to prevent damage to the boards during construction.

▶ Introduction to the production process of polyethylene closed-cell foam board

Polyethylene closed-cell foam board is made primarily from high-density polyethylene (HDPE), combined with foaming agents, crosslinking agents, antioxidants, and other additives. It is manufactured through processes such as mixing, plasticizing, foaming, and shaping. Its core feature is a closed-cell structure (closed-cell rate ≥95%), characterized by low water absorption, good elasticity, aging resistance, and strong compressive and flexural strength. It is widely used for sealing expansion joints and settlement joints in water conservancy, bridge, and building construction projects. Its production process is mainly divided into chemical foaming (the mainstream method, suitable for large-scale production) and physical foaming (high-end customization, resulting in more uniform foaming). The following section focuses on the industry-standard chemical foaming extrusion process, detailing the complete production flow, key process control points, and differences in process between different product specifications.

I. Raw Material Preparation and Formulation Design 

The selection and proportioning of raw materials directly determine the core properties of the foam board, such as density, hardness, and elasticity. They must be customized according to project requirements (e.g., low/high foaming, flexible/rigid). All raw materials must be dried and purified beforehand to avoid air bubbles and voids during foaming.

1. Main Material: High-density polyethylene (HDPE) particles (melt index 0.3-5g/10min), accounting for 70%-85%. Choose grades with good temperature resistance and high melt strength to ensure that the cell walls do not easily break during foaming, forming a closed-cell structure. For some flexible foam boards, a small amount of linear low-density polyethylene (LLDPE) can be blended in to improve flexibility.

2. Blowing Agent: A chemical azo blowing agent (such as azodicarbonamide, AC blowing agent) is selected, accounting for 5%-12%, with a decomposition temperature of 180-200℃, high gas evolution (200-250mL/g), and no harmful residues after decomposition. This is the mainstream choice for polyethylene foaming. The blowing agent needs to be pulverized to 80-120 mesh beforehand to ensure uniform dispersion.

3. Additives

1. Crosslinking agent: Dicumyl peroxide (DCP), 0.5%-2%, to form a crosslinking network of polyethylene molecules, improve melt strength, prevent cell coalescence during foaming, and ensure closed-cell ratio;

2. Activator: Zinc oxide, zinc stearate, 1%-3%, to lower the decomposition temperature of the foaming agent, allowing foaming and plasticizing to proceed simultaneously, avoiding foaming lag;

3. Antioxidant: 1010+168 compound, 0.2%-0.5%, to prevent thermo-oxidative aging of polyethylene during high-temperature plasticizing and foaming, improving product weather resistance;

4. Lubricant: Stearic acid, polyethylene wax, 0.3%-1%, to improve material flowability in the extruder, preventing sticking to the barrel and die.

4. Reference for standard formulation (taking rigid closed-cell foam board with a density of 50kg/m³ as an example): HDPE particles 80%, AC foaming agent 8%, DCP 1%, activator 2.5%, antioxidant 0.5%, lubricant 1%, other additives 7%.

▶ II. Raw material mixing and granulation

The core principle is to uniformly disperse all components to form stable foaming masterbatch, avoiding uneven foaming and inconsistent cell size during subsequent extrusion. This involves two steps: high-speed mixing and granulation. Small-scale production can directly mix the powder and extrude, while large-scale production necessitates granulation to ensure process stability.

1. High-speed mixing: HDPE particles, activator, lubricant, and antioxidant are sequentially added to a high-speed mixer and mixed at 80-100℃ for 5-8 minutes to allow the additives to initially adsorb onto the surface of the polyethylene particles. The temperature is then lowered to below 60℃, and the foaming agent and crosslinking agent are added. Mixing continues for 3-5 minutes, controlling the mixing temperature to ≤70℃ to prevent premature decomposition of the foaming agent and premature reaction of the crosslinking agent.

2. Granulation: The mixed material is fed into a twin-screw granulator. The barrel temperature is controlled in sections (Zone 1: 120-140℃, Zone 2: 140-160℃, Zone 3: 160-170℃). The screw speed is 200-300 r/min. The material is plasticized and melted in the barrel but has not reached the foaming/crosslinking temperature. It is extruded into strips through the die, cooled to room temperature through a cold water bath, and then cut into 3-5 mm cylindrical foaming masterbatch by a pelletizer. The moisture content of the masterbatch must be ≤0.1%.

Testing basis

Q/CR 601-2017