Effect of a poly(dimethylsiloxane) modified polyolefin additive on the processing and surface properties of LLDPE

Abstract

A polydimethylsiloxane (PDMS) modified polyolefin (obtained by reacting an ethylene-ethyl acrylate-maleic anhydride (EEAMA) copolymer with an amine terminated PDMS in the melt phase) was used as a processing aid to facilitate the extrusion of linear low density polyethylene (LLDPE). In blends of LLDPE and PDMS modified polyolefin (PMPO), apparent viscosity and shear stress at the die wall are reduced in comparison to pure LLDPE, and extrusion instabilities are delayed as evidenced by the fact that extrudate surface roughness only occurs at higher shear rates when the additive is present. A higher PDMS content in the PMPO leads to a more pronounced delay of extrusion instabilities. Single-screw extrusion of LLDPE compounds with a PMPO results in nearly doubled throughput per unit input energy. The reduction of viscosity and improvements in extrudate quality are attributed to the decreasing surface free energy of the PMPO with an increasing PDMS content, as determined by contact angle measurements. Chemical composition analysis of the extrudate surface and cross-section reveals silicon enrichment at the surface. The friction coefficients of pure PMPO and PMPO/LLDPE blends are measured and found to decrease as a result of the presence of

Mechanical reprocessing of polyolefin waste: A review

“…Polyolefins, mainly low‐density polyethylene (LDPE), high‐density polyethylene (HDPE), and polypropylene (PP), are major types of thermoplastics used throughout the world in a wide variety of applications, such as grocery bags , toys, containers , pipes , industrial wrappings and film , automotive parts , electrical components , etc. In Australia, a total of 0.8 million tonnes of polyolefins were consumed in 2013, which is 53% of the total plastics consumption in Australia.…”

Modification of Thermoplastics with Reactive Silanes and Siloxanes

“…A positive effect of a poly(dimethylsiloxane) modified polyolefin additive on the processing and surface properties of linear low density polyethylene (LLDPE) was observed (Zhu et al, 2007). A polydimethylsiloxane (PDMS) modified polyolefin , o b t a i n e d b y r e a c t i n g a n ethylene-ethyl acrylate-maleic anhydride (EEAMA) copolymer with an amine terminated PDMS in the melt phase, was used as a processing aid to facilitate the extrusion of LLDPE.…”

Facile synthesis and applications of polypropylene/polydimethylsiloxane graft copolymer

“…The unique dual nature of its repeating units makes polysiloxane possess many distinguished and attractive physicochemical properties, such as high thermal stability, low surface energy, high electrical resistance, and excellent biocompatibility. Polyolefin graft polysiloxane, which covalently bonds polyolefin and polysiloxane segments, can retain the favorable characteristics of both parent polymers and, thus, finds various potential real‐world applications, such as compatibilizers, processing aids, and surface modifiers …”

“…Polyolefin graft polysiloxane, which covalently bonds polyolefin and polysiloxane segments, can retain the favorable characteristics of both parent polymers and, thus, finds various potential real-world applications, such as compatibilizers, processing aids, and surface modifiers. 4,5 Grafting other polymers onto the backbone of polyolefin is by far the most convenient and also economic approach for synthesizing polyolefin-based graft copolymer since many maleic anhydride-grafted polyolefins are commercially available and maleic anhydride group is highly reactive towards some organic groups (ie, -NH 2 and -OH).…”

“…Further study showed that the prepared PDMS-grafted polyolefin, when applied as a processing aid of linear low-density polyethylene (LLDPE), could migrate to the die wall/melt interface forming a thin lubricating layer, which consequently postpone the shear rate at which LLDPE melt flow instability and extrudate defects occur. 4 As for PP/polysiloxane graft copolymers, although some patents claimed the successful preparation of PP graft polydimethylsiloxane (PP-g-PDMS) via melt mixing maleic anhydride-grafted polypropylene (MA-PP) with aminoterminated PDMS, 5,8 the detailed process has never described in nonpatent literatures. Meanwhile, as far as we know, no spectral and chromatographical data are available concerning PP-g-PDMS.…”