High‐temperature SEC coupled with MALLS detector for evaluating the end‐use performance of LDPE

Abstract

SYNOPSISLow-density polyethylene (LDPE) is the most widely used plastic material in the filmpackaging industry. To improve its tensile strength and elongation, it is blended with linear LDPE. Three commercial samples of LDPE, which were found to give different performances in the sealing strength of films prepared from their blends, have been evaluated for their molecular weight (MW) , molecular weight distribution (MWD) , and long-chain branching by high-temperature size exclusion chromatography (SEC) and SEC coupled with a multiangle laser light-scattering (MALLS) detector. It has been shown that the differences in MW and MWD that remain unnoticed by conventional SEC are detected by SEC/MALLS. Wide MWD and a low weight-average MW of the resin has been found to favor film-sealing strength.

Mechanism and molecular weight model for thermal oxidation of linear ethylene–butene copolymer

“…No large difference exists between the reported molecular weights obtained through the two methods just described. This type of behavior has already been described for polymers with low polydispersity [18]. We show in Fig.…”

Single-Chain Conformation of Poly(α-olefins) in Dilute Solutions at the Crossover between Linear and Bottlebrush Architectures

“…The branching indices defined in eqs and are very useful parameters commonly used to determine the degree of branching in polyolefins. ,− The definitions of these parameters are based on the fact that branched polymers have a more compact conformation than analogous linear chains, at any given molecular weight. Therefore, both R g and R h (and consequently, [η]) take lower values as the degree of branching increases. , The only requirement to determine g ′ and g is knowing the Mark–Houwink parameters for the linear polymer of the same chemistry.…”

Size Exclusion Chromatography

“…The unperturbed dimensions were estimated by an extrapolation technique using the measured dependence of the radius of gyration on molecular weight. Dayal and Mehta (G8,G9) used MALLS and high-temperature SEC to characterize molecular weight and branching in polyethylene. Pille and Solomon (G10) used MALLS to study the formation of microgel during the crosslinking of living poly(4-tert-butylstyrene) by 1,4-divinylbenzene.…”