Improved melt strength and processability of impact copolymer polypropylene by introducing long‐chain branching via reactive extrusion with “ene” functionalized dendrimer

Abstract

A generation two dendrimer (G2) having eight terminal double bonds has been prepared via esterification reaction from a dendritic precursor having eight hydroxyl end groups (G1). The reactive extrusion of impact co-polymer polypropylene (ICP) with G1 resulted in improved processability while leading to enhanced melt strength in the case of linear low-density polyethylene (LLDPE). G2 being an extension of G1, was melt grafted on ICP using a radical initiator to introduce long-chain branching in the polymer backbone. The prepared samples were analyzed for their molecular weight distribution, thermal, rheological properties, and mechanical properties. Thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) analysis showed higher thermal stability and slightly higher crystallization temperature with grafting of G2 on ICP. The rheological analysis through melt flow index measurements and parallel plate rheometer indicated higher processability, melt strength, complex viscosity, and zero-shear viscosity for ICP grafted with an optimized amount of G2. The presence of long-chain branching was confirmed with an increase in activation energy for ICP modified with G2 as compared to neat ICP. Modified ICP samples retained their bulk mechanical properties as neat ICP.

Dendrimers and Hyperbranched Polymers as Promising and Versatile Additives in Polyolefins

“…54 An improvement in both processability and melt strength was observed with G2 as an additive in the ICP matrix. 55 The schematic structures of G1 and G2 have been shown in Figure 5.…”

“…In the case of LLDPE, G1 enhanced the melt strength while maintaining its processability . An improvement in both processability and melt strength was observed with G2 as an additive in the ICP matrix . The schematic structures of G1 and G2 have been shown in Figure .…”

“…Copyright 2021 American Chemical Society. Reproduced with permission from ref . Copyright 2022 John Wiley & Sons.…”

Organically modified mesoporous silica as a performance additive in tubular quenched polypropylene films

“…In the first step of the post-modification procedure, 3-(trimethoxysilyl) propyl methacrylate was treated with mono-thioglycerol via thiol-ene chemistry using TEMPO as an initiator. [24][25][26][27][28] The reaction mixture was continuously stirred until the disappearance of NMR signals corresponding to vinyl protons. The synthesis of modified silane was confirmed using 1 H NMR, as shown in Figure 1.…”

Reactive Compatibilization of Impact Copolymer Polypropylene and Organically Modified Mesoporous Silica to Prepare Composites Possessing Enhanced Mechanical Properties

“…The reactive compatibilization of prepared mesoporous silica was carried out using Luperox-101 as the radical initiator and maleic anhydride as the coagent. In our earlier work, we utilized a similar approach and evaluated relatively small molecular weight dendrimers with a terminal "hydroxyl" 36 and "ene" 37 functional groups as additives in ICP. ICP composites with control and organically modified mesoporous silica were prepared in loadings of 1, 5, and 10 phr.…”