Spatial Heterogeneity of Thermo‐Oxidative Degradation in Impact Poly(propylene) Copolymers

Abstract

The spatial degradation in impact PP copolymers with different ethylene contents is studied by FTIR microscopy and layer‐by‐layer milling of the sample surfaces, followed by ATR‐FTIR, SEC, and CRYSTAF analysis. FTIR allows for tracking of the rate of degradation, providing information on the depth profiling of the degradation. Results show that samples with lower ethylene content degrade faster at all depths than those with higher ethylene content. The latter show a more uniform degradation from the surface to the bulk of the material at longer degradation times. This is ascribed to the higher amorphous content which results in a larger oxygen diffusion to the centre of the material while its slower rate of degradation is ascribed to the lower tertiary carbon content.

Advanced Separation Techniques for Polyolefins

“…Recently, the use of a graphitic stationary phase (Hypercarb) for the separation of PP according to tacticity was reported [38]. This technique enables the generation of 2D characterization data for virtually any polyolefin over a wide compositional range regardless of crystallinity [46][47][48][49]. The fast and efficient separation of polyolefins and olefin copolymers with respect to chemical composition in a short time can only be achieved by the above method [39][40][41][42][43][44].…”

“…With a total polyolefin market of more than 120 million tons, LLDPE has a market share of more than 17 %, with an increasing tendency to replace LDPE [47]. EO copolymers constitute a significant share of the total market of LLDPE.…”

“…FTIR microscopy and a conventional technique involving layer-by-layer milling followed by SEC, FTIR and CRYSTAF analyses were used to study the spatial heterogeneity within the copolymers 3V and 4V [99]. The most important factors that determine the degradation behaviour are the amount and distribution of ethylene in the four components of IPC.…”

Exploring the Compositional Heterogeneity of Vis‐Broken Impact Poly(propylene) Copolymers by Advanced Fractionation Methods

“…Numerous studies have shown that the vis‐breaking process can be applied to IPCs to decrease the average molar mass and to reduce the molar mass dispersity. Longer polymer chains are broken down to shorter chains with the help of peroxides . The vis‐broken IPC materials have higher MFRs, hence, e.g., filling of the narrow cavity molds in injection molding applications is facilitated …”

Recent Advances in High-Temperature Fractionation of Polyolefins

“…These include the SEC-FTIR analysis of ethylene/vinyl acetate copolymers [117], ethylene/ methyl methacrylate copolymers [118,119], ethylene/styrene copolymers [120], HDPE and PP [121]. A number of studies used SEC-FTIR for monitoring the thermo-oxidative degradation of polyolefins [122][123][124][125][126] and a combination of TREF and SEC-FTIR to investigate the complex structure of olefin copolymers [127,128].…”