Thermal properties, hyperbranched

In 1996, Hawker and Frechet83 discussed a comparison between linear hyperbranched and dendritic macromolecules (Fig. 5.17) obtained with the same monomeric structure, 3,5-dihydroxybenzoic. The thermal properties (glass transition and thermal decomposition) were not affected by the architecture. 

Ferrocene-based Branched Polymers (Dendrimers). One of the topics in macromolecular chemistry is constituted by dendrimers, or hyperbranched macromolecules of tridimensional globular structure, the surface of which is characterized by a large number of functional groups, Scheme 4. Such functionalities impart to the molecules solubility, viscosity and thermal properties different from those of the common linear polymers.38c,d 44... 

Aminopolysaccharides 9 and 10 can be expected to have unusual properties because of the hyperbranched structure. The thermal properties of 9 and 10 were examined (Figure 2) by thermogravimetric analysis (TGA). The TGA curve of 9 shows that decomposition of the tosyl group started at 166°C and showed a 45% weight loss up to 337°C. The residual material exhibited thermal resistance above 337°C, but a second weight loss occurred at... 

Interesting comparisons have been made 17 between dendritic and the hyperbranched structures the thermal properties (glass transition temperature and thermogravimetric analysis) were independent of architecture and their solubilities were comparable, but greater than that shown for linear counterparts. 

The hyperbranched polymers are carbon-rich macromolecules and show excellent thermal stabilities. The thermal properties of the hb-PAs are described below as an example. Their thermal stabilities were evaluated by TGA. Figure 3 shows TGA thermograms of some hb-PAs and Table 4 lists their thermal analysis data. The hb-FAs were thermally very stable for instance, hb-P66 lost merely 5% of its weight at a temperature as high as 595 °C. All the polymers, except for hb-F(44-Vl) and hb-F(59-Vl), carbonized in > 50% yields on pyrolysis at 800 °C, with hb-P(45-V) graphitized in a yield as high as 86% (Table 4, no. 3). The thermal stabilities of the hb-PAs are similar to that of Unear pol-yarylenes such as PPP but different from those of Unear polyacetylenes such as PH and PPA. The dramatic difference in the thermal stability is mainly due to the structural difference PPP is composed of thermally stable aromatic rings (Td 550 °C) [108-112], whereas PPA and PH are comprised of labile polyene chains, which start to decompose at temperatures as low as 220 and 150 °C, respectively [113]. The excellent thermal stabilities of the hb-FAs... 

Zagar E, Huskic M, Grdadolnik J, Zigrai M, Zupancic-Valant A (2005) Effect of annealing on the theological and thermal properties of aliphatic hyperbranched polyester based on 2,2-bis (methylol)propionic acid. Macromolecules 38 3933-3942... 

Jin Jin, F.-L., Park, S.-J. Thermal properties and toughness performance of hyperbranched-polyi-mide-modified epoxy resins. J. Polym. Sci. Part B Polym. Phys. 44 (2006) 3348-3356. 

Explain the thermal properties of vegetable oil-based hyperbranched polymers. 

H. Deka and N. Karak, Bio-based hyperbranched polyurethane/clay nanocomposites Adhesive, mechanical and thermal properties , Po/ym Adv Technol 2011, 22, 973-80. 

H. Chen, J. Yin, Synthesis and characterization of hyperbranched polyimides with good orga-nosolubility and thermal properties based on a new triamine and conventional dianhydrides, J. Polym. Sci. Part A Polym. Chem., 40, 3804—3814 (2002). 

Kou et al., reported using a hyperbranched acrylated aromatic polyester as a modifier in UV eurable epoxyacrylate resin. The material is compatible with the epoxy-acrylate resins. They found that the photopolymerization rate of the resin is promoted by this modifier. Also, the shrinkage of the resin was redueed. At the same time, the tensile, flexmal, compressive strength, and thermal properties of the ultraviolet light eured films are greatly improved. 

The incorporation of 5 % organically modified sepiolite, which is a microcrystalline-hydrated magnesium silicate, in a bisphenol A-based epoxy resin has no significant effect over the thermal stability of the epoxy resin, due to the poor dispersion of the clay and poor diffusion of the resin between fibres [69]. The effect of attapulgite (magnesium aluminium phyllosilicate) over the thermal properties of hyperbranched polyimides was studied. The presence of this silicate in the nanocomposites significantly improved the thermal stability of the neat polyimide [70]. 

Hyperbranched poly(phenylene germolenes) Characterisation, optical and thermal properties [53]... 

Allara, D. L., Swalen, J. D. (1982), An infiared reflection spectroscopy study of oriented cadmium arachidate monolayer films on evaporated silver. J. Phys. Chem., 86,2700-4. Asif,A., Shi, W., Shen, X.,Nie, K. (2005), Physical and thermal properties of UV curable waterborne polyurethane dispersions incorporating hyperbranched aliphatic polyester of varying generation number, Po/ywier, 46,11066-78. 

Baek JB, Tan LS (2003) Linear-hyperbranched copolymerization as a tool to modulate thermal properties and crystallinity of a para-poly(ether-ketone). Polymer 44 3451-3459... 

Possum E, Tan LS (2005) Geometrical influence of AB monomer structure on the thermal properties of linear-hyperbranched ether-ketone copolymers prepared via an AB + AB route. Polymer 46 9686-9693... 

A comparison of the physical properties of hyperbranched and dendritic macromolecules with linear polymers and the linear analogs of these 3-dimensional polymers is presented. It is found that thermal properties, such as glass transition temperature and degradation, are the same regardless of the macromolecular architecture but are very sensitive to the number and nature of chain end functional groups. However, other properties, such as solubility, melt viscosity, chemicd reactivity, intrinsic viscosity were found to be very dependent on the macromolecular architecture. 

Abstract This chapter describes the apphcation of hyperbranched polymer-based electrolyte membranes for high temperature fuel cells. Hyperbranched polymers with a sulfonic acid group or a phosphonic acid one as a proton source were synthesized and the proton conductivity, thermal property and fuel cell performance of their polymers and crosslinked membranes were investigated. The concept of the proton conduction coupled with the polymer chain motion was proposed for high temperature fuel cells. 

In order to compare general properties of hyperbranched polymers and dendrimers, Wooley et al. examined a model hyperbranched polyester and corresponding dendrimer. Pol)miers prepared from 3-hydroxy-5-( eri-butyldi-methylsiloxy)benzoic acid, as branching point, showed that thermal properties, such as Tg and those shown by thermogravimetic analysis (TGA), were independent of pol)mier architecture. However, the dendritic and hyperbranched materials demonstrated comparative solubilities that were much greater than that found for the linear polymer [99]. Their conclusions on the thermal properties may contradict some other findings. For examples, the of hyper-... 

Hyperbranched polyurethanes are constmcted using phenol-blocked trifunctional monomers in combination with 4-methylbenzyl alcohol for end capping (11). Polyurethane interpenetrating polymer networks (IPNs) are mixtures of two cross-linked polymer networks, prepared by latex blending, sequential polymerization, or simultaneous polymerization. IPNs have improved mechanical properties, as weU as thermal stabiHties, compared to the single cross-linked polymers. In pseudo-IPNs, only one of the involved polymers is cross-linked. Numerous polymers are involved in the formation of polyurethane-derived IPNs (12). 

Aliphatic hyperbranched polyesters, 56 Aliphatic isocyanate adducts, 202 Aliphatic isocyanates, 210, 225 Aliphatic polyamides, 138 Aliphatic polyesteramides, 56 Aliphatic polyesters, 18, 20, 29, 32, 87 degradable, 85 hyperbranched, 114-116 melting points of, 33, 36 structure and properties of, 40-44 syntheses of, 95-101 thermal degradation of, 38 unsubstituted and methyl-substituted, 36-38... 

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