Blends copolymer miscibility

Polymeric material, exhibiting macroscopically uniform physical properties throughout its whole volume, that comprises a compatible polymer blend, a miscible polymer blend, or a multiphase copolymer. 

It has been found by Baird and others [74-77] that the presence of LCP may accelerate and presumably direct the crystallization of conventional polymers (PET, etc.). Porter [76] has shown that, by blending biphasic polymers such as the PET-poly HBA copolymers, miscibility may be achieved between the conventional phase of the biphasic polymer with another conventional polymer that component is miscible with, i.e., X7-G/PBT. The latter phenomena may offer direction in the search for useful compatibilizing agents for LCP/conven-tional polymer systems. 

The present review is mainly concerned with the preparation and functionalization of micro compositional materials with cellulosic polysaccharides as the principal component, including four major categories graft copolymers, miscible or compatible polymer blends and networks, polysaccharide/inorganic nanohybrids, and mesomorphic ordered systems. Ultrathin layers of cellulosic... 

Gausepohl et ah [31] investigated the behavior of blends between sPS and random styrene-l,l-diphenylethylene copolymers obtained by anionic synthesis. The blends were miscible for copolymer contents of 1,1-diphenylethylene lower than 15 wt% as indicated by the occurrence of a single Tg (114°C). Tm and crystallization rate were not influenced. 

The PS/PEC blends are not shown. The presence of a single Tg for each blend composition is indicative of the presence of a single amorphous phase (2.3). and on this basis we conclude that i-PS/PEC and PS/PEC blends are miscible for trimethyl compositions in the copolymer from 0 to 20 moleX. The Tg of pure PEC is raised by only 12 °C with respect to PPO by the addition of 20 moleX comonomer, and this does little to raise the blend Tg at intermediate PEC concentrations. 

Morphological study, together with DMTA and DSC results, confirms the expectation of miscibility of the diblock copolymer with each component of the blend. This miscibility occurs at the interphases between the components of blends, allowing enhanced interphase interactions and better stress transfer in the blend system. This is probably due to the anchoring of each sequence of the block with its corresponding component of the blend, which is in good... 

COPO blends with styrene/vinyl phenol copolymers - miscible... 

Approaches to modify acetate include polymer blending. No miscible polymer systems have been identified for aeetate. To improve compatibility, graft copolymer additives and cross-linking prepolymer additives have been investigated, and some potentially useful compatible blends have been identified [101 106]. Extraction of one blend component has provided voids in the aeetate fiber for holding useful additives or for gas extraction in chromatography [107]. Cellulose acetate fiber has been treated to become a substrate for ion exchange and for immobilization of catalyst [108 110]. 

This dependence of the strength of the silanol self-association on the substituents provided an approach for tailor-made miscibility in their binary hydrogen bonded polymer blends. A miscibility window was formed for ST-VPDMS/PBMA blends when the copolymers contained 4 to 34 mol % silanol groups. As a direct result of reduced silanol self-association in ST-VPMPS copolymers, a extended miscibility window was formed when ST-VPMPS copolymers contained 9 to 56 mol % silanol groups. ... 

It is known that PLA forms miscible blends with polymers such as PEG [53]. PLA and PEG are miscible with each other when the PLA fraction is below 50 per cent [53]. The PLA/PEG blend consists of two semi-miscible crystalline phases dispersed in an amorphous PLA matrix. PHB/PLA blends are miscible over the whole range of composition. The elastic modulus, stress at yield, and stress at break decrease, whereas the elongation at break increases, with increasing polyhydroxybutyrate (PHB) content [54]. Both PLA/PGA and PLA/PCL blends give immiscible components [55], the latter being susceptible to compatibilization with P(LA-co-CL) copolymers or other coupling agents. 

The influence of pressure, P, on the miscibility needs a comment. Since pressme reduces the effects of the free volume contributions, for most blends the miscibility increase with P (Walsh and ZoUer 1987 Schwahn 2005). The effects are very sensitive to the monomer structure, as one would expect from free volume considerations, as, for example, in PB/PS blends (Fig. 2.17) In the case of tf-PB/PS blends, the general trend of an increase of the phase boundaries with pressure is observed for all systems (viz., increased binodal and spinodal temperatures with P, due to the reduction of free volume), but the shapes of Ti,i odaAP) and TJiP) are linear for /-PB(l,4)/PS and /-PB(l,4-c )-l,2)/PS blends and are more parabolic for the blend with /-PB(l,2)/PS also the compatibility of PS is best for tf-PB(l,4) and worst for /-PB(l,2), with the d-PB(l,4-co-l,2) copolymer being in between the two, as expected (Fig. 2.17). The P effect generally depends on the magnitude of the heat of mixing For systems with Af/ , < 0, the miscibility is enhanced by compression, whereas for those with Af/ , > 0 it is reduced (Rostami and Walsh, 1984, 1985 Walsh and Rostami 1985). For PS solutions, the pressure gradient of... 

A new polymer modification process has been developed to reduce the cost of the engineering resin. The modification process is blended polymers. A blended polymer is a mixture of at least two polymers or a copolymer. There are three types of blended polymers miscible, immiscible, and compatible polymers. On occasion, blended polymers have properties that exceed those of either of the constituents. For instance, blends of polycarbonates (PC) resin and polyethylene terephthalate (PET) polyester were originally created to improve the chemical resistance of the PC. This is because PC actually had a fatigue resistance and low-temperature impact resistance that was superior to either of the individual polymers. 

Micellar objects and micelle-like domains are induced by low amounts of MAM (5-20 wt%) and presented a core-shell structure, with the core identified as PMMA and the shell as PBA surrounded by PMMA chains of the copolymer miscible with the PMMA matrix. Micelle density seemed to be constant in the solid unfoamed precursors with values of approximately 4-4.5 x 10 " micelles/cm. Moreover, the apparent size of the micelles varies from 20 nm in 95/5 PMMA/MAM blends to 50 nm in 80/20 PMMA/MAM blends, with the core size approximately one-third of the micelle size (Fig. 9.11). This evolution of the nanostructure was noticed as unexpected and related to the processing conditions during the self-assembly of the nanostructuration, probably out of equilibrium. In addition, it was noticed that the injection procedure induces an orientation or even an elongation of the micellar-like domains in the injection direction (Fig. 9.12). On the contrary, 25/75 PMMA/MAM blends showed no influence of the injection process on the orientation of the nanostructure, with poorly defined lamella of 20-30 nm apparent thickness. 

Keywords blends, alloys, miscibility, compatibilization, crystallization, nucleation, polyamide (PA-6, PA-66), polycarbonate (PC), thermoplastic polyesters (PET, PBT), polyoxymethylene (POM), pol3 henylene ether (PPE), ethylenevinylacetate (EVA), grafting with maleic anhydride (MA), grafting with glyddyl methacrylate (GMA), liquid crystal pol)oners (LCP), copolymer compatibilizer. 

Keywords compatibilization, functionalization, reactive processing, blends, copolymer crosslinking, in-situ formed copolymers, low molecular weight compatibilizers, miscibility. 

Intramolecular Repulsive Interactions. Miscible blends can also be achieved in absence of specific interactions, by exploiting the so-called intramolecular repulsive effect. This is observed in mixtures where at least one of the components is a statistical copolymer miscibility is restricted to a miscibility window, that is, it takes place within a well-defined range of copolymer composition. For example, poly(styrene-co-acrylonitrile) (SAN) and poly(methyl methacrylate) form miscible blends for copolymer compositions in the range 9-39% acrylonitrile (26,27). Miscibility in these systems is not a result of specific interactions but it is due to the intramolecular repulsive effect (28) between the two monomer units in the copol5uner such that, by mixing with a third component, these imfavorable contacts are minimized. The same situation is encoimtered in binary mixtures of two copol5uners (29). 

PLA/PVAc blends ediibited a single over the entire a>nqx> itiPVAc copolymer, phase separation was observed. 

Using the repoited data on the experimentally derived values of glass transition temperature, Tg, degree of crystallinity, Vickers indentation microhardness, H, and blend compositions for homopolymers, block copolymers, blends of polyolefins, or of polycondensates, blends of miscible amorphous polymers and copolymers (some of them with rather complex molecular architecture), all of them containing a soft component and/or phase at room temperature, an attempt is undertaken to look for the reasons for the frequently reported drastic deviations of the experimentally derived H values from the calculated ones by means of the additivity law assuming that the contribution of the soft component and/or phase is negligibly small. 

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