[← Back to Knowledge Hub](/knowledge-hub)

        # Understanding PVC Resin: How It's Made, Its Types, K-Values, and Industrial Uses

        

**Topic:** Explainer

        

Unplasticized and plasticized PVC products form the backbone of infrastructure in India, Asia, and Africa. Sourcing the correct suspension PVC resin  -  based on K-value and apparent density  -  is critical for pipe and cable manufacturing. Conforming to Bureau of Indian Standards **IS 17658:2021** (specification for PVC resins), NBT distributes prime domestic resins like [Reliance RELPVC SG-5](/products/resins/resin-reliance-sg5) and [Chemplast Sanmar SG-5](/products/resins/resin-chemplast-sg5) to ensure optimal processing.

        
        
        
        
        
---

          ## 

          

        
---

        
---

          ## 

          

        
---

        
---

          ## 

          

        
---

        
---

          ## 

          

        
---

        
---

          ## 

          

        
---

        
---

          ## 

          

        
---

        
---

          ## 

          

        
---

        
---

          ## 

          

        
---

        
---

          ## 

          

        
---

        
---

          ## 

          

        
---

        
---

          ## 

          

        
---

        
        
---

          ## Frequently Asked Questions

          
### What is the difference between K-value and inherent viscosity of PVC?

Both measure molecular weight indirectly through solution viscosity, but they use different equations. K-value (Fikentscher) is the standard for PVC. Inherent viscosity (IV) in dl/g is also used by some manufacturers. K-value of 67 corresponds approximately to IV of 0.87 dl/g in cyclohexanone at 25°C.

### Can I use K-70 resin in an extruder designed for K-65?

Yes, but with adjustments. K-70 has higher melt viscosity and requires 5-10°C higher processing temperatures and approximately 15-25% higher motor torque. Check your extruder motor amperage limit before processing K-70 to avoid motor overload.

### What is the VCM limit for PVC in food packaging?

EU Food Contact Regulation requires ≤1 mg/kg in finished PVC article (not resin) and ≤2 ppm in the resin itself. IS 17658:2021 requires ≤2 ppm for food-contact grades. Always request food-contact grade documentation from your resin supplier.

### Why does apparent density matter for PVC processing?

Apparent density affects how efficiently the resin fills the extruder hopper and feeds into the screw. Low apparent density (<400 g/L) resins can cause hopper bridging, uneven feed, and extruder surging  -  all of which produce dimensional inconsistency in the finished product.

        
---

        

By NBT Technical Desk · Updated 2026-07-04

        

[Run a related diagnosis](/defect-doctor) · [Review standards](/standards) · [Browse materials](/products)

        

[Technical Editorial & Evidence Policy](/editorial-policy)