How do dendritic internal and external lubricants for polyester improve melt flowability and molding stability in PET systems through their highly branched structure?
Publish Time: 2026-06-17
During the processing of PET and related polyester systems, due to the high rigidity of molecular chains, rapid crystallization speed, and high melt viscosity, problems such as difficulty in mold filling, uneven flow, and surface defects often occur during injection molding, extrusion, or thermoforming, especially in thin-walled products and complex structure molding. Dendritic internal and external lubricants for polyester, as additives with a highly branched structure and multifunctional groups, can simultaneously provide internal and external lubrication at the molecular level, thereby significantly improving the processing flowability and molding stability of the system.1. Highly branched structure reduces molecular chain entanglementDendritic lubricants have a multi-level branched structure and high-density end-group structure. Compared to linear molecules, their spatial configuration is more compact and has a stronger steric hindrance effect. In the PET melt system, this structure can effectively interfere with the tight arrangement and entanglement of polymer molecular chains, reducing interchain interaction forces, thereby reducing overall melt viscosity and improving flowability.2. Enhanced Interfacial Lubrication and External LubricationThe multifunctional groups in the dendritic structure easily migrate to the interface region between the melt and the processing equipment during processing, forming a uniform lubricating layer on the mold wall and screw surface, thereby reducing the coefficient of friction between the melt and the metal surface. This external lubrication significantly reduces flow resistance, making the PET melt flow more smoothly during conveying and mold filling, while also reducing shear heat accumulation and improving the stability of the processing.3. Improved Melt Rheological Behavior and Mold Filling CapacityUnder high shear conditions, the PET system is prone to uneven flow or localized stagnation. Dendritic lubricants, through their spatial structure, regulate the melt rheological behavior, giving the system superior shear-thinning properties, thus maintaining good fluidity even under high-speed processing conditions. This regulating effect helps improve mold filling integrity, reduce defects such as short shots and weld lines, and improve molding quality.4. Improved Filler Dispersion and System UniformityIn filler-containing or modified PET systems, the multi-functional structure of dendritic lubricants improves the interfacial compatibility between the resin and filler, resulting in more uniform filler dispersion in the matrix and preventing agglomeration. This not only helps improve processing fluidity but also enhances the structural uniformity of the product, making it more stable during molding and reducing localized stress concentration.5. Improved Overall Processing Stability and Product QualityDendritic internal and external lubricants for polyester reduce intermolecular resistance through internal lubrication, reduce interfacial friction through external lubrication, and improve rheological behavior. These dendritic polyester lubricants form a synergistic mechanism in PET systems, significantly improving processing stability. In practical applications, this improvement is not only reflected in enhanced fluidity but also in smoother product surfaces, higher dimensional stability, and a significant reduction in defects. As polyester processing technology continues to advance towards higher speeds and precision, these dendritic lubricants will play an increasingly important role in improving processing performance and product quality.
