Preparation and characterization of an epoxy resin modified by a combination of MDI-based polyurethane and montmorillonite

Biopolymer Compositions Based on Poly(3-hydroxybutyrate) and Linear Polyurethanes with Aromatic Rings-Preparation and Properties Evaluation

Polymer biocompositions of poly(3-hydroxybutyrate) (P3HB) and linear polyurethanes (PU) with aromatic rings were produced by melt-blending at different P3HB/PU weight ratios (100/0, 95/5, 90/10, and 85/15). Polyurethanes have been prepared with 4,4'-diphenylmethane diisocyanate and polyethylene glycols with molar masses of 400 g/mol (PU400), 1000g/mol (PU1000), and 1500 g/mol (PU1500). The compatibility and morphology of the obtained polymer blends were determined by infrared spectroscopy (FTIR), scanning electron microscopy (SEM), and differential scanning calorimetry (DSC). The effect of the polyurethane content in the biocompositions on their thermal stability and mechanical properties was investigated and compared with those of the native P3HB. It was shown that increasing the PU content in P3HB-PU compositions to 10 wt.% leads to an improvement in the mentioned properties. The obtained results demonstrated that the thermal stability and mechanical properties of P3HB were improved, particularly in terms of increasing the degradation temperature, reducing hardness, and increasing impact strength. The best thermal and mechanical properties were shown by the P3HB-PU polymer compositions containing 10 wt.% of polyurethane modifiers, especially PU1000, which was also confirmed by the morphology analysis of these biocompositions. The presence of polyurethanes in the resulting polymer biocomposites decreases their glass transition temperatures, i.e., makes the materials more flexible. The resulting polymer biocompositions have suitable mechanical properties and thermal properties within the processing conditions for the predicted application as biodegradable, short-lived products for agriculture.

Thermoset Polymer Matrix Composites of Epoxy, Unsaturated Polyester, and Novolac Resin Embedding Construction and Demolition Wastes powder: A Comparative Study

Composite materials that consisted of a polymer resin as matrix (PMCs), filled using construction and demolition (C&D) wastes powder of different grain sizing in micro-scale were manufactured and studied. Three different kinds of resins were used as the matrix for the purposes of this study. More specifically, composites made of epoxy and unsaturated polyester resins purchased from the market and phenolic resin (novolac) laboratory synthesized, were produced. The morphological and elemental analysis of these materials was performed through scanning electron microscopy (SEM), energy dispersive X-ray spectroscopy (EDX), and X-ray diffraction (XRD). Additionally, mechanical performance and thermal insulating efficiency of these materials were examined through bending and shear strength tests according to the three-point method and via determination of the thermal conductivity coefficient λ. C&D wastes have undergone the appropriate processing in order to prepare filling products of the required granular size in pulverized form. In this research study, construction and demolition waste-based thermosetting polymer composites were produced with flexural strength in the range 20-60 MPa, shear strength in between 1-8 MPa, and thermal conductivity coefficients in the range of 0.27-1.20 W/ m K. The developed materials embedded 30-50% w/w C&D wastes, depending on the resin used as the matrix.

Study on the adhesive properties of reactive liquid rubber toughened epoxy-clay hybrid nanocomposites

The present work investigates the adhesive properties and morphology of diglycidyl ether of bisphenol A nanocomposites modified with reactive butadiene acrylonitrile copolymers having different amine equivalent weight. Tensile adhesive strength and shear adhesive strength of epoxy resin were significantly increased due to reactive rubbers and nanoparticles (ZW1) incorporation to the epoxy matrix. Hybrid composites based on 1 wt% ZW1 and 10 wt% ATBN-16, 1 wt% ZW1 and 15 wt% ATBN-21 exhibited maximum adhesive strength in comparison with neat epoxy resin as well as epoxy nanocomposite containing 1% ZW1. Tensile adhesive strength of hybrid composites containing 1% ZW1 and 10% ATBN-16 as well as 1% ZW1 and 15% ATBN-21 was maximally enhanced. The fracture surfaces of epoxy hybrid composites showed significant plastic yielding together with delaminated and stratified structures, explaining thus the increase of the adhesive strength of tested composites. This finding was confirmed by FTIR spectra in terms of chemical reactions occurrence between the reactive rubbers and epoxy matrix.

Preparation and characterization of reactive liquid rubbers toughened epoxy-clay hybrid nanocomposites

The present work investigates the effect of organomodified nanoclay (ZW1) and butadiene-acrylonitrile copolymer terminated with different amine groups (amine-terminated butadiene-acrylonitrile, ATBN) on the properties and morphology of epoxy resin. The morphologies of the nanocomposites were analyzed by X-ray diffraction (XRD) analysis, transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The nanocomposites structure was confirmed by Fourier transform infrared (FTIR) spectroscopy, XRD and TEM. The properties evaluation showed that the polymeric modifier and nanoclays strongly influence the fracture toughness and flexural properties of the nanocomposites. Hybrid epoxy composites containing 1% ZW1 and ATBN rubbers showed improved fracture toughness and flexural properties in comparison with unmodified epoxy resin. FTIR spectra showed an increase in the hydroxyl peak height peak height of 3360 cm-1 due to reactive rubber incorporation. SEM micrographs of hybrid epoxy resin nanocomposites showed significant plastic yielding of the polymer matrix with stratified structures and more cavitations, explaining thus the enhancement of fracture toughness and flexural strength of the nanocomposites.