Sharkskin (melt fracture) affects polymer extrusion quality and efficiency. Learn its causes, traditional solutions, and why fluorine and PFAS-free polymer processing aids like SILIKE SILIMER Polymer Processing Aids are the sustainable alternative.
What is sharkskin or surface melt fracture during the extrusion of polymers?
Sharkskin (also known as surface melt fracture) is a surface defect observed during the extrusion of polymer melts, where the extrudate develops a rough, wavy, or rippled appearance resembling the texture of shark skin. especially in processes like film blowing, extrusion molding, and wire coating.
It is characterized by:
A rough, matte, or ridged surface on the extrudate (the polymer melt as it exits the die).
It looks somewhat like the texture of shark skin, which is where the name comes from.
Causes of sharkskin in polymer extrusion
Sharkskin is a form of melt fracture, caused by instabilities at the polymer–die wall interface. When the polymer melt exits the die, it experiences a sudden drop in pressure and a large increase in velocity.
If the melt sticks strongly to the die wall (high wall shear stress), the surface layer gets stretched too much.This leads to periodic rupturing and tearing of the polymer melt surface, which creates the sharkskin pattern.
Typical Conditions for Sharkskin
Shear stress above a critical limit (often ~0.1–0.3 MPa, depending on the polymer).
High extrusion speed / shear rate.
High-viscosity or high-molecular-weight polymers are more susceptible, occurring more frequently in PP and linear polymers (e.g., LLDPE，mLLDPE) than in branched polymers.
Consequences for Manufacturers
Poor surface quality of films, sheets, or coatings.
Reduced mechanical properties (because defects can be stress concentrators).
Problems with optical clarity and aesthetics.
How to Solve Sharkskin and cracking of polymer melt extrudates?
Traditional Polymer Additives Solutions & Limitations
Fluoropolymer PPAs have been used since the 1960s to reduce sharkskin. They work by migrating to the die surface during extrusion, lowering surface energy and facilitating polymer slip. While effective, these PPAs are PFAS-based, raising environmental and health concerns:
• Persistence in soil and water
• Bioaccumulation and potential endocrine disruption
• Regulatory scrutiny worldwide
The Rise of PFAS-Free Polymer Processing Aids: The Future of Sustainable Extrusion Solutions
SILIKE SILIMER PFAS-Free PPA Solutions for Smarter, Greener Extrusion
The SILIMER Series includes a comprehensive range of PFAS-free polymer processing aids (PPAs) designed for modern manufacturing needs:
• Pure fluorine-free PPAs
• PTFE-free additives
These solutions are engineered to boost processing efficiency while eliminating the risks associated with PFAS.
SILIKE SILIMER PFAS-free PPAs are compatible with a wide variety of polymers and extrusion processes, enhance processing in:
• Polyolefins and recycled polyolefin resins
• Blown, cast, and multilayer films
• Fiber and monofilament extrusion
• Cable and pipe extrusion
• Masterbatch and compounding applications
Whether producing films, pipes, cables, or fibers, SILIMER PPAs help manufacturers achieve smoother processing, better surfaces, and improved throughput.
Do you know which PFAS-free PPA is preferred by polymer manufacturers?
SILIKE SILIMER 9100- PFAS-free polymer processing aid for Polyolefins and recycled polyolefin resins
SILIKE SILIMER 9200 –Fluorine-free plastic processing additive for compounding
SILIKE SILIMER 9300 – Cost-effective PFAS-free PPA for film, pipe, and wire & cable extrusion
SILIKE SILIMER 9400 – Fluorine-free processing additive with broad regulatory compliance
….
Why Choose SILIKE’s PFAS-Free Polymer Processing Aids?
Like traditional fluoropolymer-based additives, SILIMER PFAS-Free functional additives eliminate fluorine, deliver high performance—without the environmental risks:
• Enhanced Lubricity – Improved internal/external lubricity for smoother processing
• Increased Extrusion Speed – Higher throughput with less die buildup
• Defect-Free Surfaces – Eliminate melt fractures (sharkskin) and improve surface quality
• Reduced Downtime – Longer cleaning cycles, shorter line interruptions
• Environmental Safety – PFAS-free, compliant with REACH, EPA, PPWR and global sustainability standards
From film and fiber to wire and pipe extrusion, sharkskin defects no longer need to compromise efficiency, quality, or compliance. With SILIKE SILIMER PFAS-free polymer processing aids, manufacturers can achieve smoother extrusion, higher productivity, and sustainable operations.
If you are looking for ways to:
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Use PFAS-free polymer additives for pipe and cable extrusion,
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Apply sustainable PPAs for film and fiber extrusion,
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Utilize fluorine-free polymer processing aids,
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Improve extrusion throughput, or reduce die buildup and surface defects in polymer extrusion
contact Amy Wang (amy.wang@silike.cn) or visit www.siliketech.com to get your PFAS-free solution for extrusion processes or eco-friendly polymer extrusion additives.
Post time: Aug-18-2025
