A natural frequency approach to study the blown film helicoidal stability of HDPE bimodal resins and its relation to their rheological behavior

Abstract

A quantitative study of the helicoidal bubble stability (HBS) of five different HDPE bimodal resins processed under the same conditions was conducted to determine their natural frequencies and how these are related to molecular weight distribution features and typical viscoelastic data. The natural frequency x n , of each resin was obtained by representing the HBS phenomenon as an undamped system under the influence of a harmonic force, whose solution required force balance and Fourier series analyses of video-recorded oscillations of the bubbles. It was found that x n was directly related to the stability grading on these bimodal resins established by experimental technicians running the blown film line. The same trends were observed when comparing with the entanglement index, Mw B /Me, the characteristic retardation time t 67% obtained from recovery compliance data, and the cross-over point frequency (COP). These trends were not linear, indicating perhaps the existence of a percolation threshold for x n with respect to the entanglement index and to the mentioned rheological parameters.

Flash DSC crystallization study for blown film grade bimodal HDPE resins. I. Isothermal kinetics and its application of the blown film modeling

“… Dimensionless temperature profile for blown film simulations of resin HDPE‐11 using the model and DSC data from Treviño‐Quintanilla …”

“…A previous study, 10 using Cao and Campbel ls approach with a modified Phan-Thien-Tanner model, 9,11 included the crystallization constants obtained by normal DSC at different crystallization rates. This study showed that the DSC data are insufficient to simulate the blown film temperature profile for bimodal HDPE resins.…”

“…Measured isothermal heat flow for different crystallization temperatures for HDPE-11 from Treviño-Quintanilla(14).…”

Recent developments in bio-based polyethylene: Degradation studies, waste management and recycling

“…PE is one of the most widely used thermoplastics and the highest-volume polymer in production and consumption. Its high toughness, ductility, excellent chemical resistance, low permeability and electrical conductivity, semicrystalline and ease of process make PE an attractive choice for various products and applications [ [1] , [2] , [3] , [4] ].…”