How To Choose Rotational Molding Raw Materials
1. Material properties
Thermal stability:
During the rotational molding process, the material needs to be heated at high temperatures for a long time, so it must have good thermal stability to prevent performance degradation.
Most rotational molding materials are stabilized with antioxidants to reduce the negative impact of prolonged heating on material properties.
Melt flowability:
The melt viscosity of the material must be low enough to impregnate the inner mold surfaces and melt into a homogeneous mass. This is usually measured by the melt flow rate (MFR). For commonly used rotational molding materials such as polyethylene, the MFR is generally between 2 and 8g/10min (2.16kg, at 190°C).
Impact strength:
Good impact strength is an important indicator for judging whether the material is suitable for low-temperature rotational molding products. Materials are usually required to maintain good impact resistance at temperatures as low as -40°C.
Environmental stress cracking resistance (ESCR):
The material should have the ability to withstand long-term contact with stress cracking media. It is generally believed that materials with ESCR values exceeding 1000h are acceptable.
Flexural strength and tensile strength:
Depending on the material's final application requirements, materials need to be selected with sufficient bending and tensile strength. For example, engineering plastics such as nylon and polycarbonate have high strength.
Elongation at break:
The elongation at break of the material should be high to meet most application requirements.
2. Cost considerations
The cost of raw materials is an important factor in the selection process. Polyethylene is widely used in the rotational molding industry because of its low cost and easy processing, accounting for the majority of the rotational molding raw material market.
However, for high-end applications or special needs, higher cost engineering plastics or other specialty materials may need to be considered.
3. Application environment
Different application environments have different requirements for material performance. For example, rotational molding products for outdoor use need to have excellent light resistance and weather resistance; rotational molding products that come into direct contact with the human body need to pay attention to the safety of the materials.
According to the specific application scenarios and needs, select materials that can meet the corresponding performance requirements.
4. Processing performance
The material's processability is also an important consideration in the selection process. Materials that are easy to grind and have good fluidity and heat transfer properties make it easier to control quality and improve production efficiency during the rotational molding process.
5. Environmental protection and sustainability
As environmental awareness increases, more and more companies are paying attention to the environmental performance and sustainability of raw materials. Choosing recyclable, degradable or low-pollution raw materials can help companies achieve green production and sustainable development.
In summary
Choosing appropriate rotational molding raw materials requires comprehensive consideration of material performance, cost, application environment, processing performance, environmental protection and sustainability. During the specific selection process, it is recommended to conduct detailed analysis and comparison based on the specific needs of the product and market conditions to select the most suitable raw materials