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        # Understanding Polyethylene Grades: LDPE, LLDPE, and HDPE Guide

        

**Topic:** Explainer

        

From flexible packaging films in local markets to high-pressure water pipes, polyethylene grades (LDPE, LLDPE, HDPE) are essential. Under **IS 7328:2020** quality standards, selecting the correct density and molecular weight distribution is key to achieving target tear strength and puncture resistance.

        
        
        
        
        
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          ## Frequently Asked Questions

          
### Is BIS ISI marking legally required for polyethylene resin imports?

No. The Department of Chemicals and Petrochemicals (DCPC) officially rescinded the Polyethylene Quality Control Order on November 12, 2025 (Gazette Notification S.O. 5136(E)), eliminating mandatory ISI marking for resin procurement. However, prime virgin resin must still conform to IS 7328 specifications to pass finished-product quality audits.

### Why is LLDPE blended with LDPE in blown film extrusion?

LLDPE provides high tensile and puncture resistance, but has low melt strength, making the blown bubble unstable. Blending 10-20% LDPE improves bubble stability and ease of processing without reducing physical properties.

### What is the difference between PE 80 and PE 100?

These are pipe-grade HDPE classifications. PE 100 has a higher Minimum Required Strength (MRS) of 10 MPa at 50 years, allowing for pipes with thinner walls and higher pressure ratings compared to PE 80 (MRS 8.0 MPa).

### What is ESCR?

Environmental Stress Crack Resistance (ESCR) is the resistance of PE to crack propagation under stress in contact with active agents (like detergents or oils). HDPE has lower ESCR than LLDPE due to its high crystallinity.

### Can I use LDPE for high-pressure pipes?

No. LDPE does not have the required tensile strength or hydrostatic design basis. Pressure pipes must use high-density PE 80 or PE 100 grades.

        
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By NBT Technical Desk · Updated 2026-07-04

        

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