A phase field model for dynamic simulations of reactive blending of polymers

A facile way to generate compatibilized blends of immiscible polymers is through reactive blending of end-functionalized homopolymers. The reaction may be reversible or irreversible depending on the end-groups and is...

Thermochemical compatibilization of reclaimed tire rubber/ poly(ethylene-co-vinyl acetate) blend using electron beam irradiation and amine-based chemical

Waste tire rubber is commonly recycled by blending with other polymers. However, the mechanical properties of these blends were poor due to lack of adhesion between the matrix and the waste tire rubber. In this research, the use of electron beam irradiation and (3-Aminopropyl)triethoxy silane (APTES) on enhancing the performance of 50 wt% reclaimed tire rubber (RTR) blend with 50 wt% poly(ethylene-co-vinyl acetate) (EVA) was investigated. Preparation of RTR/EVA blends were carried out in the internal mixer. The blends were then exposed to electron beam (EB) irradiation at doses ranging from 50 to 200 kGy. APTES loading was varied between 1 to 10 wt%. The processing, morphological, mechanical, and calorimetric properties of the blends were investigated. The stabilization torque and total mixing energy was higher in compatibilized blends. Mechanical properties of RTR/EVA blends were improved due to efficiency of APTES in further reclaiming the RTR and compatibilizing the blends. APTES improved the dispersion of embedded smaller RTR particles in EVA matrix and crosslinking efficiency of the blends. Calorimetric studies showed increased crystallinity in compatibilized blends which corresponds to improved mechanical properties. However, the ductility of the blend was decreased due to increased interaction between EVA and APTES. Presence of APTES increased the efficiency of electron beam irradiation induced crosslinking which was shown through gel content analysis and Charlesby-Pinner equation.

Epoxidized polybutadiene rubber as an effective compatibilizer for acrylonitrile butadiene rubber and polybutadiene rubber blend

In the present study, epoxidized polybutadiene rubber (EBR; 30 mol% epoxidation) was synthesized using commercial-grade cis-polybutadiene rubber (BR). The EBR was successfully utilized as an effective compatibilizer between two incompatible elastomers, namely polar acrylonitrile butadiene rubber (NBR) and non-polar polybutadiene rubber (BR). The NBR and BR were blended in varied formulations and studied for morphological and mechanical properties. The observed properties of the blends containing EBR, as a compatibilizer, were compared with analogous blends without EBR. The optimum loading of EBR in NBR/BR formulations was found to be 5 phr (parts per hundred gram of rubber). The significant improvement in various mechanical properties such as tensile strength, tensile modulus, elongation at break and hardness were observed in presence of optimum loading of EBR in NBR/BR blends. Atomic Force Microscopy (AFM), Differential Scanning Calorimetry (DSC) and Dynamic Mechanical Analyser (DMA) studies revealed that the compatibility between two incompatible rubbers improved in the presence of EBR. The results observed with EBR-compatibilized blends revealed that EBR can be used as an effective compatibilizer between two incompatible rubbers (NBR and BR).

Compatibilization of Poly(Lactic Acid) (PLA)/Plasticized Cellulose Acetate Extruded Blends through the Addition of Reactively Extruded Comb Copolymers

In the perspective of producing a rigid renewable and environmentally friendly rigid packaging material, two comb-like copolymers of cellulose acetate (AC) and oligo(lactic acid) OLA, feeding different percentages of oligo(lactic acid) segments, were prepared by chemical synthesis in solvent or reactive extrusion in the melt, using a diepoxide as the coupling agent and were used as compatibilizers for poly(lactic acid)/plasticized cellulose acetate PLA/pAC blends. The blends were extruded at 230 °C or 197 °C and a similar compatibilizing behavior was observed for the different compatibilizers. The compatibilizer C1 containing 80 wt% of AC and 14 wt% of OLA resulted effective in compatibilization and it was easily obtained by reactive extrusion. Considering these results, different PLAX/pAC(100-X) compounds containing C1 as the compatibilizer were prepared by extrusion at 197 °C and tested in terms of their tensile and impact properties. Reference materials were the uncompatibilized corresponding blend (PLAX/pAC(100-X)) and the blend of PLA, at the same wt%, with C1. Significant increase in Young’s modulus and tensile strength were observed in the compatibilized blends, in dependence of their morphologic features, suggesting the achievement of an improved interfacial adhesion thanks to the occurred compatibilization.

PLA/PHB Blends: Biocompatibilizer Effects

The purpose of this work was to formulate a fully bio-based blend with superior properties, based on two immiscible polymers: polylactic acid (PLA) and poly-hydroxy butyrate (PHB). To improve the miscibility between the polymeric phases, two different kinds of compatibilizers with a different chemical structure were used, namely, an ethylene oxide/propylene oxide block copolymer in the form of flakes and a mixture of two liquid surfactants with a variable lipophilic–hydrophilic index. The morphology of the blends and their thermal, mechanical, and rheological behavior were evaluated, aiming at assessing the influence of the selected compatibilizers on the microstructure and final properties of the systems. Morphological analyses of the compatibilized blends indicated that the liquid surfactant is more effective than the solid copolymer in inducing morphology refinement, as also suggested by results coming from rheological measurements. Furthermore, thermal analyses demonstrated that the presence of both kinds of compatibilizers induced an enhancement of the crystallinity content of blends. Finally, a remarkable increase of the elastic modulus values was obtained for the compatibilized blends as compared to the pure counterparts, with a consequent significant enhancement of the HDT values.

Improvements in the Rheological Properties, Impact Strength, and the Biodegradability of PLA/PCL Blend Compatibilized by Electron-Beam Irradiation in the Presence of a Reactive Agent

In this study, we blended poly(ε-caprolactone) (PCL) into poly(lactic acid) (PLA) and compatibilized these PLA/PCL blends by electron-beam irradiation in the presence of a reactive agent to overcome drawbacks of PLA. To produce compatibilized blends, mixtures of the PLA/PCL/reactive agent were prepared using a twin-screw extruder and exposed to electron-beam radiation at room temperature. Glycidyl methacrylate (GMA) was chosen as the reactive agent to achieve interfacial cross-copolymerization between PLA and PCL phases. Morphological, rheological, and mechanical properties and biodegradabilities of blends were investigated. The morphological study showed significantly improved interfacial adhesion for compatibilized blends, and this was supported by FTIR analysis and a rheological study. Impact strengths, thermal stabilities, and rheological properties of PLA/PCL blends were improved by compatibilization, and the biodegradabilities of compatibilized PLA/PCL blends were greater than that of pure PLA.