The Use of Ethylene/Propylene Copolymers as Compatibilizers for Recycled Polyolefin Blends

Compatibilizing effects of ethylene/propylene (EPR) diblock copolymers on the morphology and mechanical properties of immiscible blends produced from recycled low‐density polyethylene (PE‐LD) and high‐density polyethylene (PE‐HD) with 20 wt.‐% of recycled poly(propylene) (PP) were investigated. Two different EPR block copolymers which differ in ethylene monomer unit content were applied to act as interfacial agents. The morphology of the studied blends was observed by scanning‐ (SEM) and transmission electron microscopy (TEM). It was found that both EPR copolymers were efficient in reducing the size of the dispersed phase and improving adhesion between PE and PP phases. Addition of 10 wt.‐% of EPR caused the formation of the interfacial layer surrounding dispersed PP particles with the occurrence of PE‐LD lamellae interpenetration into the layer. Tensile properties (elongation at yield, yield stress, elongation at break, Young's modulus) and notched impact strength were measured as a function of blend composition and chemical structure of EPR. It was found that the EPR with a higher content of ethylene monomer units was a more efficient compatibilizer, especially for the modification of PE‐LD/PP 80/20 blend. Notched impact strength and ductility were greatly improved due to the morphological changes and increased interfacial adhesion as a result of the EPR localization between the phases. No significant improvements of mechanical properties for recycled PE‐HD/PP 80/20 blend were observed by the addition of selected block copolymers.     

Use of Monomethyl Itaconate Grafted Poly(propylene) (PP) and Ethylene Propylene Rubber (EPR) as Compatibilizers for PP/EPR Blends

The use of grafted poly(propylene) (PP) and a random copolymer of ethylene and propylene (EPR) with an itaconic acid derivative, monomethyl itaconate (MMI), as compatibilizer for PP/EPR blends was analyzed. The grafting reaction was performed at 190 °C in a Brabender Plasticorder. 2,5‐Dimethyl‐2,5‐bis(tert‐butylperoxy) hexane was the radical initiator for the functionalization of PP; dicumyl peroxide was used as the radical initiator for the modification of EPR. The obtained degree of grafting was 1.5% by weight for PP and 1.2% by weight for EPR. The compatibilizing effect of modified polymers on the processability, morphology, and mechanical and thermal properties of the blends was of interest. Compatibilization substantially improved the toughness and deformation with little effect on the tensile modulus and strength. Moreover, this effect was particularly evident when both polymeric phases were grafted. Regarding compatibilization, the viscosity of the blends increased due to the high interfacial adhesion. Morphological studies showed that the particle size of the rubbery phase was reduced and the dispersion in the matrix improved by compatibilization. The grafted polymers behaved as nucleating agents, accelerating the PP crystallization.

Change in complex viscosity with angular frequency at 180 °C for unmodified and MMI‐functionalized PP/EPR (70/30) blends.     

Compatibilization of PE/PS and PE/PP blends. I. Effect of processing conditions and formulation

The objective of this work was to study the effectiveness of low‐cost commercial compatibilizers and several processes (internal mixer, single‐ and twin‐screw extruders) for two types of plastic blends: high‐density polyethylene/polypropylene and high‐density polyethylene/polystyrene blends, to gain insight into the recycling of wastes from those frequently encountered mixed plastics. Blends going from a pure A to a pure B component, with and without a compatibilizer, were prepared using an internal mixer, a corotating twin‐screw extruder, as well as a single‐screw extruder to follow an industrial‐convenient process. In both cases, the analyses of blend morphologies highlighted the poor adherence between the two phases in the uncompatibilized blends. Compatibilized blends display better adherence between phases and the ability to process blends made from both single‐ and twin‐screw extruders. When adding a compatibilizer, the viscosity of each blend (PE/PP or PE/PS) increased due to a better adhesion of the phases. Charpy impact tests showed that the presence of the compatibilizer in PE/PS blends increased their impact properties. Indeed, the improvement of the adhesion between the two phases enabled stress transfer at the interface. A single‐screw extruder seems to be efficient as a processing method on an industrial scale when a compatibilizer is used. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2475–2484, 2003     

Use of Functionalized Metallocene Copolymers from Ethylene and Polar Olefins as Compatibilizers for Low‐Density‐Polyethylene/Starch and Low‐Density‐Polyethylene/Dextran Blends

Summary: Functionalized metallocene copolymers synthesized from ethylene with 5‐hexen‐1‐ol and ethylene with 10‐undecen‐1‐ol were used as compatibilizers in LDPE/starch and LDPE/dextran blends in order to improve the interfacial adhesion between hydrophobic LDPE and hydrophilic natural polymers. An increase in tensile modulus and a slight decrease in tensile strength was observed when poly[ethylene‐co‐(10‐undecen‐1‐ol)] was added to a 70:30 wt.‐% LDPE/dextran blend, whereas the addition of poly[ethylene‐co‐(5‐hexen‐1‐ol)] as compatibilizer resulted in obtaining a more rigid material with a slightly higher modulus. Scanning electron microscopy of modified dextran blends containing 3 wt.‐% of both compatibilizers showed some degree of phase cocontinuity. Enhanced interfacial adhesion and decrease in particle size of starch was observed when 5 wt.‐% of poly [ethylene‐co‐(5‐hexen‐1‐ol)] copolymer was used as the compatibilizer in starch blends. The crystallization temperature of LDPE, determined by DSC, was shifted to a slightly higher temperature as a consequence of the addition of the compatibilizers. The existence of phase segregation was also revealed by thermal analysis when 5 wt.‐% of the copolymers were used as blend modifiers.

SEM micrograph of 70:30 wt.‐% LDPE/dextran blend with added poly[ethylene‐co‐(5‐hexen‐1‐ol)] compatibilizer.     

Influence of the Recycling Process on the Fire‐Retardant Properties of PP/EPR Blends

The fire‐retardant properties of a recycled poly(propylene)‐based material were investigated and compared to the non‐recycled formulation. An intrinsic intumescent system and zinc borate were used to flame‐retard these polymers. By mass loss calorimetry, the best results were obtained with 20 wt.‐% of additives. Synergisms between AP765 and ZB were observed in the non‐recycled blends but not in the recycled ones. Solid‐state NMR showed that chemical reactions during the decomposition process were leading to the formation of borophosphates, reinforcing the efficiency of the intumescent char. From a ‘physical’ point of view, it was shown that the fire retardant properties of the materials are related to the formation speed of the intumescent structure and not on the char thickness.

     

Partial replacement of EPR by GTR in highly flowable PP/EPR blends: Effects on morphology and mechanical properties

This research analyzes the effect of ground tire rubber (GTR) and a novel metallocene‐based ethylene–propylene copolymer (EPR), with high propylene content, on the morphology and mechanical behavior of ternary polymer blends based on a highly flowable polypropylene homopolymer (PP). The PP/EPR blends morphology, with very small domains of EPR dispersed in the PP matrix, indicates a good compatibility among these materials, which leads to a significant improvement on elongation at break and impact strength. The incorporation of EPR on the rubber phase of thermoplastic elastomeric blends (TPE) based on GTR and PP (TPE^GTR) has a positive effect on their mechanical performance, attributed to the toughness enhancement of the PP matrix and to the establishment of shell‐core morphology between the rubber phases. The mechanical properties of the ternary blends reveal that TPE^GTR blends allow the upcycling of this GTR material by injection molding technologies. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015 , 132, 42011.     

Compatibilization of PP/PE blends and scraps with Royalene: Mechanical properties,SAXS, and WAXS

PP/PE 93/7 model virgin blends and recycled scraps were compatibilized with Royalene (EPDM/PE 65/35 blend) and mechanically tested. No differences in impact and tensile properties between them were found. However, the tensile-impact strength increased almost twice with 10%-compatibilized sample in comparison with uncompatibilized ones. The yield stress of blends containing 10% Royalene decreased to 75–80% of the original value. This effect is in agreement with microhardness measurements; the increase in the compatibilizer content causes softening of the blend. The elongation at break and elongation at yield do not depend on the compatibilizer concentration. The compatibilizer does not influence the degree of crystallinity (WAXS data) of the blends either. Vickers microhardness is in good agreement with Tabor's relationship. The differences between long periods of HDPE in Royalene and LDPE in PP/PE blends (SAXS) proved PE/EPDM interaction. The interaction plays a key role in the toughening of PP/PE blends. © 2008 Wiley Periodicals, Inc. J Appl Polym Sci, 2008     

Evaluation of the Effectiveness of New Compatibilizers Based on EBAGMA‐LDPE and EBAGMA‐PET Masterbatches for LDPE/PET Blends

The present paper is aimed to evaluate the efficiency of two masterbatches, i.e., EBAGMA/LDPE (MB1) and EBAGMA/PET (MB2) with 50/50 w/w composition, prepared by melt mixing and used as new compatibilizers for blends of LDPE/PET. The morphology, the mechanical and the thermal properties of LDPE/PET/MB1 and LDPE/PET/MB2 ternary blends have been investigated. Morphological investigation by SEM of LDPE/PET/MB1 ternary blends showed a finer dispersion of PET in LDPE matrix with a better interfacial adhesion compared to those of both LDPE/PET/MB2 and binary LDPE/PET blends. The results also indicated a substantial improvement in both elongation at break and impact strength, while the Young's modulus decreased. Moreover, the thermal properties showed a decrease of the crystallization phenomena of PET in LDPE/PET/MB1 blend, thus confirming the good dispersion of PET particles into the continuous phase of LDPE matrix, leading to the conclusion that MB1 could be an efficient compatibilizer for LDPE/PET system.

     

Viable utilization of polycarbonate as a phosgene equivalent illustrated by reactions with alkanedithiols,mercaptoethanol, aminoethanethiol,and aminoethanol: A solution for the issue of carbon resource conservation

Methods for the chemical recycling of polycarbonate (PC) wastes in the forms of bisphenol A (BPA) and cyclic heterocarbonates, such as 1,3‐dithiolan‐2‐one (DTO), 1,3‐dithiane‐2‐one (DTA), and cyclic unsymmetric heterocarbonates, were investigated to prove that PC can be utilized as a phosgene equivalent for industrial purposes. Treatment of PC pellets or waste PC compact discs with 1,2‐ethanedithiol and a catalytic amount of base (e.g., 1.5 mol % NaOH) in dioxane for a short period at 40°C produced DTO and BPA, both in nearly quantitative yields. The reaction could also be carried out in DTO, which saved the use of conventional solvents. Other cyclic heterocarbonates, that is, DTA, 1,3‐oxathiolan‐2‐one, 1,3‐thiazolidine‐2‐one, and N‐methyl‐1,3‐oxazolidine‐2‐one, were prepared in high yields under analogous conditions. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 90: 2959–2968, 2003     

Use of EPDMSDD as compatibilizer agent for EPDM/EPDMR blends: Rheologic,mechanical, and morphologic properties

Around the world, concern is growing about the amount of waste rubber going into landfills. Policymakers are encouraging researchers to find innovative ways to recycle this waste. In this study, as part of an effort to recycle waste rubber (EPDMR) as filler in compositions of EPDM, we prepare a terpolymer of ethylene–propylene–diene with 1‐dodecanethiol (EPDMSDD). We use it as a compatibilizing agent to improve adhesion and incorporation of the residue (EPDMR) in EPDM/EPDMR blends. We synthesize and characterize EPDMSDD through ¹³C‐NMR and FTIR spectroscopy. We evaluate the effect of the compatibilizer EPDMSDD using vulcanization parameters, such as optimum cure time, scorch time, and torque. To evaluate its effect on the interaction between EPDMSDD/EPDMR, we carried out mechanical tests of samples with and without EPDMSDD. Our findings show that the tensile strength and elongation increased with the addition of EPDMSDD, indicating a better interaction between EPDMR/EPDM. Tear strength also increased with the presence of EPDMSDD, particularly for the amount of 70 and 80 phr of EPDMR. This suggests a good adhesion between the phases in high amounts of waste. The micrographs of the mixtures revealed that the addition of EPDMSDD improved the dispersion of the EPDMR in the EPDM phase. © 2011 Wiley Periodicals, Inc. J Appl Polym Sci, 2011.     

Numerical and experimental approach to testing the adhesive properties of modified polymer blend based on EVA/PMMA as coatings for optical fibers

The adhesive properties of polymer blends based on poly(ethylene-co-vinyl acetate) (EVA) and poly(methyl methacrylate) (PMMA) were studied. Two samples were prepared, whereby one kind was a physically mixed blend of commercial polymers in a solution of toluene and the other was a blend with EVA-g-PMMA polymer in a toluene solution, produced via in situ free radical polymerization using redox system initiators. A scanning electron microscopy (SEM) revealed the improved microstructure that was achieved blending with graft polymer that could also be seen by FTIR spectral analysis. Optical fibers were glued together using both of the solutions and subjected to a micro mechanical testing machine. The adhesion test showed that the graft copolymer had enhanced mechanical properties as an adhesive than the physical polymer blend. Optical microscopy of the samples after the adhesion test enabled the determination of the type of adhesive failure. Image analysis of the SEM micrographs was used to determine an area of the contact surface, and characterization microstructure. These results were then implemented in a numerical simulation that demonstrated the influence of microstructure on the adhesive properties showing the stress distribution for both samples. The main aim of obtaining an adhesive with uniform structure, great miscibility of the polymers, and good mechanical and adhesive properties was achieved and a numerical model was established that can be used in selecting the adhesive.     

Controlled Reversible Anchoring of η6‐Arene/TsDPEN‐ Ruthenium(II) Complex onto Magnetic Nanoparticles: A New Strategy for Catalyst Separation and Recycling

A new catalyst separation and recycling protocol combining magnetic nanoparticles and host‐guest assembly was developed. The catalyst, (η⁶‐arene)[N‐(para‐toluenesulfonyl)‐1,2‐diphenylethylenediamine]ruthenium trifluoromethanesulfonate [Ru(OTf)(TsDPEN)(η⁶‐arene)] bearing a dialkylammonium salt tag, was easily separated from the reaction mixtures by magnet‐assisted decantation, on basis of the formation of a pseudorotaxane complex by using dibenzo[24]crown‐8‐modified Fe₃O₄ nanoparticles. The ruthenium catalyst has been successfully reused at least 5 times with the retention of enantioselectivity but at the expense of relatively low catalytic activities in the asymmetric hydrogenation of 2‐methylquinoline.     

Use of a sodium ionomer as a compatibilizer in polypropylene/high‐barrier ethylene–vinyl alcohol copolymer blends: The processability of the blends and their physical properties

The effect of a sodium ionomer (ion.Na⁺) on the compatibility of polypropylene (PP)/high‐barrier ethylene–vinyl alcohol copolymer (EVOH) blends was studied in terms of the thermal, mechanical, and optical properties and morphology. The rheological behavior, tensile tests, and morphology of the binary blends showed that the miscibility of EVOH with PP was very poor. The miscibility of the polymers improved with the ionomer addition. In general, the ion.Na⁺ concentration did not alter the thermal behavior of the blends, but it did improve the ductility of the injection‐molded specimens. Scanning electron micrographs displayed better adhesion between the PP and EVOH phases in the samples with the ionomer. The mechanical improvement was better in the film samples than in the injection‐molded samples. A 90/10 (w/w) PP/EVOH film with 5% ion.Na⁺ and an 80/20 (w/w) PP/EVOH film with 10% ion.Na⁺ presented better global properties than the other blends studied. © 2004 Wiley Periodicals, Inc. J Appl Polym Sci 94: 1763–1770, 2004     

A Chemometric Approach to Assess the Frying Stability of Cottonseed Oil Blends During Deep-Frying Process: I. Polar and Polymeric Compound Analyses

The main goal of the present study was (i) to determine the formation of degradation products in cottonseed oil (CSO) blends during deep frying process by adsorption and high performance size exclusion chromatography techniques and (ii) to evaluate the impacts of food additives on total polar (TPC) and polymeric compound (PTAG) formation using a chemometric approach. In order to prepare the frying CSO blends; ascorbic palmitate, mixed tocopherols, dimethylpolysiloxane, lecithin and sesame oils were used as additives. To determine the real impacts of additives, a quarter-fraction factorial experimental design with two levels and five factors was used. The changes in TPC and PTAG data were carefully evaluated during 10 h of frying at 170 ± 5 °C with normal distribution (ND) graphs and analyzed using a one-way analysis of variance (ANOVA), followed by Tukey’s Post-hoc test (α = 0.05). The results indicated that the increasing values for TPC and PTAG during the frying processes for all blends, TPC and PTAG contents reached maximum levels of 16.37 and 6.01 % respectively, which are below the limit values stated by official authorities for the quality assessment of frying oils. The ANOVA test results were in good agreement with ND graphs and data indicated that the impact of mixed tocopherols was significant for TPC formation, meanwhile the impact of lecithin and ascorbic palmitate × dimethylpolysiloxane were significant for PTAG formation. Thus, the present study should be considered to be a very useful guide for developing new frying oil formulations based on CSO by using food additives.     

Relation of glass transition temperature to the hydrogen bonding degree and energy in poly(N-vinyl pyrrolidone) blends with hydroxyl-containing plasticizers: 3. Analysis of two glass transition temperatures featured for PVP solutions in liquid poly(ethylene glycol)

The phase behaviour of poly(N-vinyl pyrrolidone)-poly(ethylene glycol) (PVP-PEG) blends has been examined in the entire composition range using Temperature Modulated Differential Scanning Calorimetry (TM-DSC) and conventional DSC techniques. Despite the unlimited solubility of PVP in oligomers of ethylene glycol, the PVP-PEG system under consideration demonstrates two distinct and mutually consistent glass transition temperatures (T_g) within a certain concentration region. The dissolution of PVP in oligomeric PEG has been shown earlier (by FTIR spectroscopy) to be due to hydrogen bonding between carbonyl groups in PVP repeat units and complementary hydroxyl end-groups of PEG chains. Forming two H-bonds through both terminal OH-groups, PEG acts as a reversible crosslinker of PVP macromolecules. To characterise the hydrogen bonded complex formation between PVP (M_w=10⁶) and PEG (M_w=400) we employed an approach described in the first two papers of this series that is based on the modified Fox equation. We evaluated the fraction of crosslinked PVP units and PEG chains participating to the complex formation, the H-bonded network density, the equilibrium constant of complex formation, etc. Based on the established molecular details of self-organisation in PVP-PEG solutions, we propose a three-stage mechanism of PVP-PEG H-bonded complex formation/breakdown with increase of PEG content. The two observed T_gs are assigned to a coexisting PVP-PEG network (formed via multiple hydrogen bonding between a PEG and PVP) and a homogeneous PVP-PEG blend (involving a single hydrogen bond formation only). Based on the strong influence of coexisting regions on each other and the absence of signs of phase separation (evidenced by Optical Wedge Microinterferometry) we conclude that the PVP-PEG blend is fully miscible on a molecular scale.     

Design and Validation of a Sensitive Multisteroid LC-MS/MS Assay for the Routine Clinical Use: One-Step Sample Preparation with Phospholipid Removal and Comparison to Immunoassays

Steroid analysis in clinical laboratories is dominated by immunoassays (IAs) that have a high sample turnover but are inherently limited in trueness, precision, and sensitivity. Liquid chromatography coupled to mass spectrometry (LC-MS/MS) has proved to be a far more capable tool, delivering better sensitivity, specificity, and the possibility of parallel analysis of multiple steroids and metabolites, providing the endocrinologist with more reliable and comprehensive diagnostic information. An LC-MS/MS assay with gradient elution over less than eight minutes and a one-step sample preparation combining protein precipitation with phospholipid removal of off-line solid-phase extraction was developed and validated. It allowed the quantification of 11-deoxycorticosterone (11-DOC), 11-deoxycortisol (11-DF), 17-OH-progesterone (17P), 21-deoxycortisol (21-DF), androstenedione (ANDRO), aldosterone (ALDO), corticosterone (CC), cortisol (CL), cortisone (CN), dehydroepiandrosterone (DHEA), dehydroepiandrosterone sulfate (DHEAS), dihydrotestosterone (DHT), estradiol (E2), progesterone (PROG), and testosterone (TES) in human serum. Interday imprecision was generally better than 15%, trueness was proven by recovery experiments with ISO 17034-certified reference materials, proficiency testing (UK NEQAS), and measuring serum reference standards. In-house comparison against IVD-CE-certified immunoassays (IA) for 17P, ANDRO, CL, DHEAS, E2, PROG, and TES was conducted by assessing leftover routine patient samples and purpose-built patient serum pools. None of the compared routine IAs were meeting the standards of the LC-MS/MS. Insufficient overall comparability was found for ANDRO and 17P (mean bias > +65%). Accuracy limitations at lower concentrations were present in IAs for PROG, E2, and TES.     

Evaluation of titanium dioxide and cerium oxide as anodes for the electrooxidation of toluene: A theoretical approach of the electrode process

Cerium oxide and titanium dioxide were prepared by thermal decomposition of the precursor salts and thermal treatment of titanium plates. In aqueous medium, the metal oxides show a well-defined electrochemical reaction; a solid state redox process takes place in the cathodic range of potentials and only water discharge reaction occurs in the anodic region. At the experimental conditions, the prepared materials were not totally active for the electrooxidation of toluene. The theoretical modeling suggests that the lack of activity is due to the weak interaction between toluene and the metal oxide surface.