Compatibilization Efficiency Research Articles

Compatibilization of poly(ethylene‐co‐vinyl alcohol) (EVOH) and EVOH–HDPE blends: Structure and properties

Hydrogenated and maleated S-B-S block copolymer (SEBS-g-MA) was applied as a compatibilizer in melt-mixed binary blends with poly(ethylene-co-vinyl alcohol) (EVOH) and in ternaries containing high-density polyethylene (HDPE) as the major component. The techniques applied were dynamic, mechanical, and tensile testing; differential thermal analysis; Fourier transform infrared spectroscopy; and optical and electron microscopy (SEM). Small and large deformation behavior under dynamic and static mode, coupled with other physical characterization data, as well as morphological evidence, demonstrated that SEBS-g-MA is an efficient compatibilizer in the binary and ternary blends. In the latter, its function is the coupling of EVOH with the HDPE matrix, thus reducing the moisture sensitivity of the former and the improvement of performance-to-cost ratio of the final product. After leaching out EVOH from the ternaries, morphology examination of the cross section of films, showed a laminar EVOH phase distribution, a feature desirable in barrier materials applications. © 1998 John Wiley & Sons, Inc. J Appl Polym Sci 68: 589–596, 1998

Reactive compatibilization of polymer blends of poly(butylene terephthalate) and polyamide 6,6: 2. Morphological and mechanical properties

Bisphenol-A type solid epoxy resin has been demonstrated as a low cost and efficient compatibilizer for the immiscible and incompatible blends of polyamide 6,6 (PA66) and poly(butylene terephthalate) (PBT). The phase domains of the compatibilized blends have been reduced, while their mechanical properties substantially improved. A fraction of this difunctional epoxy resin is able to form in situ the PBT- co-Epoxy- co-PA66 mixed copolymer at the interface. This mixed copolymer with both segments structurally identical to both base polymers will anchor along the interface, and functions as an effective compatibilizer for the PA66/PBT blends. The mechanism of the mixed copolymer formation has been discussed in detail. The mechanical property improvement of the PA66-rich blends is more significant than of the PBT-rich blends after compatibilization. The nature of the reactive compatibilization tends to leave a greater fraction of the compatibilizer in the PBT phase than in the PA66 phase. Therefore, the intrinsic properties of the PBT matrix have been reduced after compatibilization. This is why the improvement in properties of the PBT-rich blends are not as great as expected. Different types of core-shell elastomers have also been employed to toughen the PA66/PBT blends.

Reactive compatibilization of PET and PPE blends by epoxy couplers

A commercially available tetrafunctional epoxy monomer was demonstrated to be an effective reactive compatibilizer for blends of poly(ethylene terephthalate) (PET) and polyphenylene ether (PPE). It requires about 10–20% by weight of a conventional reactive compatibilizer to achieve the same level of compatibilization in terms of domain size reduction and mechanical property improvement. This epoxy monomer is able to contact and react with PET and PPE simultaneously during high shear extruder blending to form the desirable PET–epoxy–PPE mixed copolymer. This mixed copolymer contains PET and PPE segments that tend to anchor at the interface to act as an efficient compatibilizer of the PET and PPE blends. © 1997 John Wiley & Sons, Inc. J Appl Polym Sci 65: 739–753, 1997

Polymer blends of PA6 and PPE compatibilized by phenolic novolac epoxy coupler

A commercially available multi-functional epoxy monomer, phenolic novolac epoxy (PNE) resin, has demonstrated to be an effective reactive compatibilizer for the blends of polyamide-6 (PA6) and poly(2,6-dimethyl-1,4-phenylene ether) (PPE). It requires about 1/10 by weight relative to a typical conventional reactive compatibilizer to achieve same level of compatibilization in terms of mechanical property improvements. By acting as a coupler, this multi-functional epoxy can react with PA6 and PPE during melt blending and produces the desirable PA6-co-PNE-co-PPE mixed copolymers at the interface. This in situ-formed copolymer containing PA6 and PPE segments tends to reside at the interface between PA6 and PPE domains to reduce melt interfacial tension and enhance interface adhesion as an efficient compatibilizer of the PA6/PPE blends.

Compatibilizing effect of poly(hydrogenated butadiene-methyl methacrylate) copolymer for PVC/LLDPE blends

The mechanical properties of incompatible polymer pairs, and so blend compatibility, may be improved by the addition of well-chosen copolymers which can act as efficient compatibilizers. Poly(butadiene-b-methyl methacrylate) copolymer (PBD-b-PMMA) with a 1,4-PBD block (more than 80%) has been synthesized by anionic polymerization. Hydrogenation of the PBD chain produces a (HPBD-b-PMMA) copolymer which is a good compatibilizer for blends of poly(vinyl chloride) and linear low density polyethylene (PVC/LLDPE). Results of the Charpy impact strength and the tensile mechanical behaviour demonstrate that the copolymers can significantly enhance the compatibility of the blends. Nevertheless, the compatibilizing efficiency depends on a combination of the molecular weight, the copolymer concentration and the composition of blends.

Designing Compatibilizers To Reduce Interfacial Tension in Polymer Blends

We use self-consistent mean field methods and analytical theory to determine the behavior of AB copolymers at the interface between two incompatible homopolymers, A and B. We calculate the reduction in interfacial tension, γ, resulting from the copolymers localizing at the A/B interface. We examine the effects of chain length, composition, and molecular architecture on the efficiency of the copolymers. In particular, we compare the interfacial behavior of different linear copolymers (random, alternating, and diblock) and various branched copolymers (stars and combs). At fixed molecular weight, the diblock copolymers are the most efficient at reducing γ. However, when we compare random and comb copolymers with diblocks at different molecular weights, we observe that the longer random or comb copolymers are more efficient than short diblocks. These studies allow us to predict the reduction in interfacial tension produced by a wide variety of copolymers and, thereby, permit a rational design of cost-effective and efficient compatibilizers.

Random copolymers as effective compatibilizing agents.

We introduce a mean field model that allows us to determine the interfacial behavior of AB random copolymers. Through this model, we calculate the reduction in interfacial tension \ensuremath{\gamma} that occurs when the random copolymers localize at the interface between immiscible homopolymers A and B. We also isolate the conditions under which the random copolymers are most efficient at reducing \ensuremath{\gamma} and therefore act as efficient compatibilizers. The calculations are useful in designing low-cost copolymer additives that significantly improve the properties of polymer blends.

Compatibilization and toughening of PPE—PP blends with hydrogenated, styrene—diene block copolymers

AbstractSimple blends of poly(2,6 dimethyl 1,4‐phenylene ether) (PPE) and polypropylene (PP) are highly incompatible and consequently quite brittle regardless of the molecular weights and ductility of the individual components. Hydrogenated, styrene‐diene block copolymers, viz. S‐EB‐S triblock and S–EP diblock copolymers, can be used to compatibilize and toughen the blends. The ductility and impact toughness of the PPE–PP blends depend not only upon the nature of styrene block copolymers but also on the nature of PPE and PP used. It was found that lower‐molecular‐weight PPE was actually better in achieving a blend with desired combination of high‐impact toughness and high heat distortion temperature. Compatibilization efficiency and morphological considerations influencing the blend's properties are discussed. © 1992 John Wiley & Sons, Inc.

Modifiers and processing aids

Micropowder of poly(tetrafluoroethylene) (PTFE) can be used in base oils to improve the tribological properties significantly, if oil molecules are covalently linked to primary PTFE particles in the dispersion. Enhanced properties are not only determined by the amount of PTFE micropowder added to the oil but as well by the surface charge, radical concentration, and the size and distribution of PTFE particles in the oil phase.The chemical compatibilization (=cc) between PTFE micropowder and ester oil by the use of two types of PTFE micropowder, which differ in radical concentration and the amount of functional groups is shown. The concentration of PTFE micropowder in the dispersions was varied from 5 to 20 wt%. Both the pure PTFE micropowder and the oil-PTFE-cc dispersions were characterized by ESR and FTIR spectroscopy as well as by zeta potential measurements. Rheological and tribological tests were performed on the ester oil and the oil-PTFE-cc dispersions. Qualitative differences are discussed in terms of particle interactions, dispersion stability, chemical compatibilization efficiency and the amount of functional groups.A correlation between flow properties and surface charge of the PTFE particles within the dispersions was obtained. The influence on tribological properties is discussed as well.