Thermal stability, blending poly

Tsuji, H. and Fukui, I. (2003) Enhanced thermal stability of poly(lactide)s in the melt by enantiomeric polymer blending. Polymer, 44, 2891-2896. 

Some polymers have both polar and nonpolar groups in the polymer chain. Thermal stability behavior of blends of some such polymers with PVC have also been studied. McNeill and coworkers [149] have studied the degradation of blends of PVC with poly (tetramethyl-ene sebacate) (PTMS). The structure of PTMS is given in Eq. (40). 

Poly(hydroxyphenyl maleimide)-b-PBA was added to thermosetting phenol resin to improve heat resistance [63]. PVC blended with poly(vinyl copolymer having cyclohexyl maleimide group)-b-PVC showed improved heat resistance and tensile strength with thermal stability during processing [64]. 

On the other hand, silicones are used in organic composites. The application of alloys composed of the fully cured silicone rubber particles in a continuous thermoplastic phase, called thermoplastic silicone vulcanizate, which offers high-performance materials, has been reported.506,507 Functionalized POSS was not only co-polymerized, but also blended with poly(methylmethacrylate) to study the effect of silsesquioxanes on the thermal stability of thermoplastics.508... 

One of the first examples of this type of blend was composed of SPEEK or SPES as the acidic component and diaminated PES, poly(4-vinylpyridine) (P4VP), poly(benzimidazole) (PBl), or poly(ethyleneimine) (PEI) as the basic component. " For blend lEC values of 1.0 meq/g, conductivity values were reported to be good, as was H2/O2 EC performance. Thermal stabilities for these blends was also demonstrated to be high (>270°C). Other examples of acid-base PEMs include blends of SPPO and PBI, sulfonated poly(phthalazinone ether ketone) and aminated SPES, SPIs and aminated Pls, and SPEEK with PES bearing benzimidazole side groups, ° as well as an unusual example in which the blend is composed of sulfonated, hyper-branched polyether and pyridine-functionalized polysulfone. ... 

Blends of poly(ether sulfone) 300 with the poly(hydroxyether) of bisphenol A proved to be quite homogenous and had better thermal stability, though phase separations occurred at higher temperatures <2003PLM867>. As a... 

Blends of polystyrene and poly(2,6-dimethyl-1,4-phenylene oxide) (PPO) can be mixed in the melt as both polymers have reasonable thermal stability. There has however been much discussion as to whether the blends are truly one phase. Some techniques suggest homogeneity while others suggest a heterogeneous structure. On balance it appears that the two polymers are in fact thermodynamically miscible in all proportions but completely efficient mixing is difficult to achieve... 

An HDS additive, zinc/copper hydroxy stearate, was melt-blended with low density poly(ethylene). X-ray diffraction analysis of the composite materials was similar to that found with copper hydroxy dodecyl sulfate combined with poly(vinyl ester), where nanocomposite formation was observed, but additional work is necessary for full characterization of the dispersion. The (nano) composites were found to have better thermal stability via TGA and improvement in PHRR in cone calorimetry. However, smoke production was observed to increase. The 5% loading had better overall performance than 10% in terms of thermal stability and most fire properties. 

Effects of maleated ethylene-propylene diene rubber (EPDM) on the thermal stability of pure polyamides, and polyamide/EPDM and polyamide/poly (ethylene terephthalate) blends kinetic parameters and reaction mechanism/Zl. Vieira, V.L. Severgnini, D.J. Maasra MS. Soldi, E.A Pinheiro, AT.N. Pires and V. ScAAilPolymer degradation and stability (2001), 74 1 151-157. 

Somewhat similar results were obtained with cellulose graft/blend systems with PMA, PMMA and poly(2-hydroxyethyl methacrylate) [Nishioka and Yoshida, 1992] and could be correlated with the degree of compatibility. In one case the thermal stability of blends containing grafted cellulose was 100°C less than those without grafted product [Nishioka et al., 1993]. 

PEEK showed extreme thermal stability, but when blended with a liquid crystalline poly(hydroxybenzoic/naphthoic acid) copolymer, LCP, there is a measurable reduction in this property [Mehta and Isayev, 1991]. 

As we said earlier, the introduction of aromatic units into the main chain results in polymers with better thermal stability than their aliphatic analogs. One such polymer is poly(phenylene oxide), PPO, which has many attractive properties, including high-impact strength, resistance to attack by mineral and organic acids, and low water absorption. It is used, usually blended with high-impact polystyrene (HIPS), to ease processability in the manufacture of machined parts and business machine enclosures. 

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