Thermoplastic Dynamic Vulcanizates with In Situ Synthesized Segmented Polyurethane Matrix

Abstract

The aim of this paper was the detailed investigation of the properties of one-shot bulk polymerized thermoplastic polyurethanes (TPUs) produced with different processing temperatures and the properties of thermoplastic dynamic vulcanizates (TDVs) made by utilizing such in situ synthetized TPUs as their matrix polymer. We combined TPUs and conventional crosslinked rubbers in order to create TDVs by dynamic vulcanization in an internal mixer. The rubber phase was based on three different rubber types: acrylonitrile butadiene rubber (NBR), carboxylated acrylonitrile butadiene rubber (XNBR), and epoxidized natural rubber (ENR). Our goal was to investigate the effect of different processing conditions and material combinations on the properties of the resulting TDVs with the opportunity of improving the interfacial connection between the two phases by chemically bonding the crosslinked rubber phase to the TPU matrix. Therefore, the matrix TPU was synthesized in situ during compounding from diisocyanate, diol, and polyol in parallel with the dynamic vulcanization of the rubber mixture. The mechanical properties were examined by tensile and dynamical mechanical analysis (DMTA) tests. The morphology of the resulting TDVs was studied by atomic force microscopy (AFM) and scanning electron microscopy (SEM) and the thermal properties by differential scanning calorimetry (DSC). Based on these results, the initial temperature of 125 °C is the most suitable for the production of TDVs. Based on the atomic force micrographs, it can be assumed that phase separation occurred in the TPU matrix and we managed to evenly distribute the rubber phase in the TDVs. However, based on the SEM images, these dispersed rubber particles tended to agglomerate and form a quasi-continuous secondary phase where rubber particles were held together by secondary forces (dipole–dipole and hydrogen bonding) and can be broken up reversibly by heat and/or shear. In terms of mechanical properties, the TDVs we produced are on a par with commercially available TDVs with similar hardness.

Sustainable and greener coatings produced from accelerator‐ and sulfur‐free polyurethane dispersion/carboxylated nitrile butadiene latex blends

“…Ning et al 26 and Kohári et al 27 produced sulfur‐free blends by using dicumyl peroxide as a crosslinker agent. Ning et al 26 produced a thermoplastic polyurethane (TPU) and XNBR blend and observed that the blending compatibility was reduced as the TPU content in the blend was more than 20%.…”

“…Ning et al 26 produced a thermoplastic polyurethane (TPU) and XNBR blend and observed that the blending compatibility was reduced as the TPU content in the blend was more than 20%. Kohári et al 27 used in‐situ synthesized TPU and crosslinked XNBR to create thermoplastic dynamic vulcanizates. The finished blend contained 50% TPU and 50% XNBR.…”

Development of thermoplastic vulcanizates based on in situ synthesized thermoplastic polyurethane and acrylonitrile-butadiene rubber: the influence of the curing system

“…This can be improved by various compatibilization methods [30]. A new method aims to improve this relationship; here, the enclosing thermoplastic matrix is also processed with a reactive technology, i.e., the matrix itself is formed in situ from its constituents during the preparation of the blend [31,32].…”

Functional Polyurethanes—In Memory of Prof. József Karger-Kocsis

“…They demonstrated that introducing 1H,1H,10H,10H-perfluor-1,10-decanediol chain extender enhances the rigidity of the PU films by forming hydrogen bonds between the fluorinated moieties and the NH of the urethane bonds. In another paper, an intriguing approach to producing thermoplastic dynamic vulcanizates (TDVs) based on PUs is presented by A. Kohári et al [19]. The authors dispersed rubbers such as NBR, XNBR, and ENR in "in situ"-generated thermoplastic PUs to obtain PU based TDVs.…”