Detailed Comparison of PVC Structural Foam vs. PET and PU Foams Across Various Performance Metrics

With the industrial popularization of composite sandwich structures, PVC, PET, and PU structural foams have become widely used mainstream core materials in the fields of wind power, marine, and rail transit. These three types of structural foams differ significantly in water absorption, mechanical load-bearing, temperature resistance, and process adaptability. Many composite processing enterprises easily confuse their performance characteristics when selecting materials. Today, the editorial team of Swainor New Materials will demonstrate the comparison of PVC structural foam against PET and PU foams from multiple core performance dimensions. Let's take a look.

I. Comparison of Basic Physical and Water Absorption Properties

1. PVC Structural Foam: It belongs to a closed-cell rigid foaming system with a high proportion of closed cells. Its water absorption rate at room temperature is relatively low, and moisture penetration is slow in seawater and high-humidity environments. The density range covers 60kg/m³ to 250kg/m³. The dimensional stability of the panels is good, and the deformation amplitude after water absorption is small.

2. PET Structural Foam: Also a closed-cell structure, its water absorption rate is slightly higher than that of PVC. It has strong chemical inertness, stable performance in acid and alkali corrosion resistance, and its high-temperature tolerance range is slightly better than that of conventional PVC foam.

3. PU Polyurethane Structural Foam: Mostly semi-closed-cell or a combination of open-cell structures, its overall water absorption rate is significantly higher than that of PVC and PET. Long-term immersion can easily lead to internal water absorption, weight gain, and delamination. It is only suitable for dry indoor, low-humidity working conditions.

II. Comparison of Mechanical Load-Bearing Performance

Compressive strength, bending modulus, and shear strength are core indicators of sandwich structures, directly determining the load-bearing capacity of components.

PVC foam has balanced shear strength, stable compressive and bending performance, and outstanding fatigue load resistance, making it suitable for long-term alternating stress components.

PET foam has higher rigidity, and its compressive modulus advantage is obvious at high densities. However, its toughness is relatively weak, and it is more prone to brittle cracking upon impact.

Ordinary PU foam has relatively low shear strength and large deformation under high-load conditions, making it only suitable for light interior decoration and non-load-bearing decorative panels.

III. Temperature Resistance and Forming Process Adaptability

Conventional PVC structural foam has a long-term service temperature range of approximately -40°C to 80°C, adaptable to medium and low-temperature vacuum infusion and hand lay-up molding. Modified high-temperature resistant grades can withstand short-term prepreg curing temperatures within 120°C.

PET foam has a higher heat resistance upper limit, withstanding short-term high-temperature curing at 130°C to 150°C, suitable for high-temperature prepreg production lines.

PU foam has the weakest heat resistance, easily softening and shrinking at high temperatures, and is only suitable for room-temperature hand lay-up and low-temperature bonding processes.

IV. Chemical Resistance and Weathering Aging Performance

PVC has stable resistance to seawater salt spray and weak acids and alkalis. Its mechanical properties degrade slowly after long-term outdoor UV exposure, making it highly adaptable for offshore wind power and marine exposed components.

PET has a wider range of chemical solvent resistance and good UV resistance, but the overall procurement cost of raw materials is relatively high.

General-purpose PU foam has poor weather resistance, easily yellowing and chalking under outdoor exposure, and insufficient seawater corrosion resistance, rarely used in marine working conditions.

V. Processing and Cost Differences

All three can be processed by grooving, milling, and cutting.

PVC panels have stable homogeneity, less processing chipping, and balanced comprehensive procurement and processing costs.

PET raw material prices are relatively high, resulting in higher overall investment.

PU raw material unit prices are low, but with high loss and limited applicable scenarios.

The above details the comparison of PVC structural foam against PET and PU foams. Each of the three structural foams has its own performance advantages, and there is no universal core material. Enterprises need to select materials reasonably based on working condition humidity, stress load, forming temperature, and usage environment. For offshore wind power and hull load-bearing sandwich structures, PVC structural foam can be prioritized; for high-temperature prepreg production lines, PET structural foam is suitable; for indoor light decorative components, PU structural foam can be selected. For material samples, parameter comparison, and process adaptation consultation, please contact Swainor New Materials for professional technical support.