Analysis Of The Problem Of PVC Material Not Forming When Used In Rotational Molding Process
## Possible reasons
1. **Material property mismatch**:
- The melting characteristics of PVC do not meet the requirements of rotational molding process
- The melt flow index (MFI) may not be suitable for rotational molding process
- Insufficient thermal stability, decomposition during rotational molding heating process
2. **Process parameter problem**:
- Improper heating temperature (too high leads to decomposition, too low cannot be fully melted)
- Rotation speed mismatch
- Inappropriate cooling rate
3. **Formula problem**:
- Improper selection or dosage of plasticizer
- Insufficient stabilizer or mismatched type
- Lubricant system is not suitable for rotational molding
## Solution suggestion
1. **Material selection**:
- Consider using PVC formula specially developed for rotational molding
- Try PVC blends or alloy materials
- It may be more appropriate to choose high molecular weight PVC
2. **Process optimization**:
- Adjust the heating curve and control the temperature in stages
- Optimize the rotation speed and rotation ratio
- Improve the cooling procedure and control the crystallization process
3. **Formula Adjustment**:
- Increase heat stabilizer content
- Adjust plasticizer system (consider using polymer plasticizer)
- Add appropriate processing aids
4. **Equipment Check**:
- Confirm that mold design and heating system are suitable for PVC
- Check the accuracy of temperature control system
## Test Recommendations
1. Conduct small-scale trials to determine the optimal process window
2. Use differential scanning calorimetry (DSC) to analyze the melting characteristics of PVC
3. Perform rheological tests to evaluate melt behavior
More specific process parameters and material specifications are required to provide more targeted recommendations.