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Polycarbonates ester exchange

By reaction of polyhydroxy compounds with a carbonic acid derivative, a series of related polymers may be produced with carbonate (—0 C0 0—) linkages, the polymers being referred to as polycarbonates. Carbonic acid, C0(0H)2, itself does not exist in the free state but by means of ester exchange Figure 20.1) (1) and phosgenation techniques (II) it is possible to produce useful products. [Pg.556]

Thus PET has been prepared by reaction of DMT and diacetoxyethane. Similarly, polycarbonates have been made from the bis(alkyl carbonates) or bis(aryl carbonates) of bisphenols. No important kinetic studies have been made of the esterolysis (or double ester-exchange) reaction. [Pg.518]

Ester-exchange reactions in polyesters (and analogous amide reactions in nylons) that result in a new block copolymer. An example is the formation of a blend between polycarbonate and poly(butylene terephthalate) in which the compatibilizer is formed by a transesterification reaction at elevated temperatures (350 °C), but, when processed at lower temperatures, the systems are not compatible. [Pg.124]

This technique is less frequently used in the condensation polymerisation process as the removal of by-products is difficult, as is controlling the reaction. The problems mentioned previously in condensation polymerisation produce polymers with a low molecular weight. The process is therefore only used for the preparation of some resins and polycarbonates by an ester exchange process. [Pg.15]

Polycarbonate (PC) and polyesters blends are phase separated and are obtained without ester exchange reaction. So, the crystallinity of polyester is maintained. These blends combine the characteristics of both polymers. Catalysts could be added to promote ester exchange reaction and yielding to the disappearance of the PET crystallinity. [Pg.121]

Figure 4.4 Ester exchange reaction in polycarbonate leading to healing [20]. Figure 4.4 Ester exchange reaction in polycarbonate leading to healing [20].
Polycarbonate - Polycarbonates are thermoplastics prepared by either phosgenation of dihydric phenols such as bisphenol A or by ester exchange between diaryl carbonate, usually diphenyl carbonate, and dihydric phenol. They are characterized by the presence of repeating carbonyldioxy groups in the backbone, but classified by some as polyesters. They have very good mechanical prop-... [Pg.626]

The synthesis and characteristics of poly(ester-ester) multiblock copolymers from DMT, alkyl glycols (C2-C10), and pivalolactone have also been described [36,37]. More details about the exchange of units between chains or segments in polymer systems, i.e., the type of the sequential order in condensation copolymers, were given by Fakirov and Denchev [185]. Roslaniec et al described the synthesis and physical properties of PEE containing aliphatic polycarbonate soft segments [38,40,41]. Multiblock copolyesters can also be obtained by an... [Pg.90]


See other pages where Polycarbonates ester exchange is mentioned: [Pg.144]    [Pg.144]    [Pg.23]    [Pg.146]    [Pg.39]    [Pg.537]    [Pg.655]    [Pg.23]    [Pg.423]    [Pg.256]    [Pg.122]    [Pg.21]    [Pg.585]    [Pg.275]    [Pg.101]    [Pg.92]    [Pg.147]    [Pg.162]    [Pg.394]    [Pg.18]    [Pg.247]    [Pg.369]   


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