Glass transition temperatures terpolymers

Copolymers with acrylates (vinyl acrylics) or other vinyl esters are also commonly produced, mostly as aqueous dispersions. They are, independent of the nature of the comonomer, often referred to as copolymers or terpolymers . The presence of comonomers of course heavily influences a number of physical properties like the glass transition temperature and melting point, water solubility or flexibility, to name just a few. 

The relative initial ratio of acrylonitrile to butadiene and degree of conversion of nitrile to amidoxime are directly related to the resultant film s solubility parameter and glass transition temperature. Ideally, the concentration of amidoxime functional groups would be maximized while the coating s solubility parameter is matched to the vapor to be detected and the glass transition temperature is kept below room temperature. In practice, the conversion limitations are set by the reaction conditions of limited polymer solubility, reaction temperature and time. Three terpolymers of varying butadiene, acrylonitrile and amidoxime compositions were prepared as indicated in Table 1. 

The infrared spectra of the butadiene-acrylonitrile copolymer and butadiene-acrylonitrile-acrylamidoxime terpolymers are presented in Figure 2. The amidoxime specific bands appear at 3480 and 3380 cm-l (NH2 stretching) and at 1660 cm"l (C =N stretching) (1 2 ). The glass transition temperatures and solubility parameters of the corresponding polymers are also presented in Table 1. As the aerylamidoxime content increases from 3 to 7 to 45 mole percent, the... 

Fig. 5 MSF and DMMP Vapor Concentration Dependence of SAW Device Coated with 3,7 and 45% Acrylamidoxime Terpolymers and Correlation with Terpolymer Glass Transition Temperature and Solubility Parameter.

Fig. 17 Effect of compatibilization via SBM triblock terpolymers on the glass transition temperature of PPE/SAN blends, in absence and in presence of carbon dioxide (as predicted by [75] and [76, 77])...

For miscible blend phases, these parameters need to be described as a function of the blend composition. In a first approach to describe the behavior of the present PPE/PS and SAN/PMMA phases, these phases will be regarded as ideal, homogeneously mixed blends. It appears reasonable to assume that the heat capacity, the molar mass of the repeat unit, as well as the weight content of carbon dioxide scale linearly with the weight content of the respective blend phase. Moreover, a constant value of the lattice coordination number for PPE/PS and for SAN/PMMA can be anticipated. Thus, the glass transition temperature of the gas-saturated PPE/SAN/SBM blend can be predicted as a function of the blend composition (Fig. 17). Obviously, both the compatibilization by SBM triblock terpolymers and the plasticizing effect of the absorbed carbon dioxide help to reduce the difference in glass transition temperature between PPE and SAN. 

Different materials for the hydrophobic membrane in which the receptor is incorporated, have been investigated. Polysiloxanes that have the required glass transition temperature and dielectric constant provide a stable chemical system that transduces the complexation of cationic species into electronic signals. The material properties can be optimized by copolymerization of three building blocks viz. dimethyl-, (3-cyanopropyl)methyl-, and methacryloxypropylmethyl siloxane. CHEMFETs made with this terpolymer have fast response times (<. 1 sec.). With valinomycin and hemispherands (2) and (3) linear responses to changing K+ concentrations are obtained in the range 10"5 - 1.0M (55-58 mV/decade) in a solution of 0.1M NaCl. Similar devices specific for Na+ and Ca2+ have been obtained with other ionophores. 

Figure 12.1 A typical 129Xe NMR spectrum of a polymer at a temperature above the glass transition temperature (T ) (here ethylene-propylene diene terpolymer (EPDM)) in a ca. 1,000,000 Pa Xe atmosphere. The signal of the free gas is used as an internal...

Internal plasticizers are synthesized by copolymerization of suitable monomers. Polymeric non-extractable plasticizers, mostly copolymers having substantially lower glass transition temperatures due to the presence of plasticizing ( soft ) segments such as poly(ethylene-co-vinyl acetate) with approximately 45 % vinylacetate content, ethylene-vinyl acetate-carbon monooxide terpolymer, or chlorinated PE, are available for rather special applications in medicinal articles (Meier, 1990). In this case, the performance of the internally plasticized polymers is the principal advantage. However, copolymerization may account for worse mechanical properties. A combination with external plasticizers may provide an optimal balance of properties. For example, food contact products made from poly(vinylidene chloride) should have at most a citrate or sebacate ester based plasticizers content of 5 % and at most 10 % polymeric plasticizers. 

Table 7.2. Theoretical (T h) and experimental (T ) values of glass transition temperatures of terpolymers of various weight compositions prepared at complete conversion p = 1 (x[° is weight fraction of units Mj in terpolymer) [310, 201]...

As previously mentioned, the properties of olefm-CO copolymers depend strongly on the nature of the olefin employed. The glass transition temperature of 1-olefin-CO copolymers decreases from room temperature to nearly -60 °C upon increasing the chain length of the 1-olefin from propylene to 1-dodecene [33]. By contrast to polar ethylene-CO copolymers, copolymers with higher l-olefins display a hydrophobic character. For 1-olefin copolymerization, catalysts with entirely alkyl-substituted diphosphine hgands R2P-(CH2) -PR2 (R=alkyl, by comparison to R=Ph in dppp) such as 3 are particularly well-suited [48]. Efhylene-l-olefin-CO terpolymers and 1-olefin-CO copolymers can be prepared in aqueous polymerizations [43, 47, 48]. In the aforementioned copolymerization reactions, the polyketone was reported to precipitate during the reaction as a sohd [45, 47, 48, 50]. However, in the presence of an emulsifier such as sodium dodecyl sulfate (SDS) and under otherwise suitable conditions, stable polymer latexes can be obtained. 

Figure I. Effect of maleic anhydride content on distortion temperature under load (DTUL) and on glass transition temperature (Tg). Key o, Si MA copolymer and a. Si MAI MM terpolymer (ca. 6% MM).

One of the most important bulk property variables of polymers is the glass transition temperature 7g, which must be well below the use temperature to allow the interdiffusion and entanglement of polymer chains when the particles get in contact, once the aqueous phase has been evaporated. Thus, the monomer(s) used have to be selected such that the desired is obtained. Useful tables showing Tg and other physical and chemical properties of homopolymers are available in the literature [66-68]. The well-known Fox equation [69] can be used to estimate the Tg of a copolymer as a function of monomer composition and TgS of the component monomers. It is important to take into account that polar polymers tend to hydroplasticize, reducing the in the film formation process [70]. Several commercial latexes are terpolymers that contain two of the monomers present in major amounts to grossly obtain the basic desired properties, with the third monomer present in a minor amount for fine tuning of a special property [71-73]. 

Poly(vinyl acetate) dispersions form lightfast, dry, hard, brittle films. Plasticizers therefore have to be used (external plasticization), which are, however, volatile and lead to embrittlement of the films after a relatively short time. Internally plasticized dispersions of copolymers of vinyl acetate with vinyl laurate, butyl maleate, Versatic Acid esters, or ethylene form permanently flexible, nonaging films that are not, however, always sufficiently resistant to hydrolysis. Terpolymer (vinyl acetate-ethylene-vinyl chloride) dispersions form films that are more resistant to hydrolysis than homopolymer and copolymer dispersions. The films also have a higher mechanical strength and lower flammability. The glass transition temperature of the terpolymer can be varied within wide limits and properties can be matched to requirements by using a suitable choice of comonomers. The same is true of vinyl propionate copolymer dispersions. 

Chen, J. K., Kuo, S. W., Kao, H. C., and Chang, R C. 2005. Thermal properties, specific interactions, and surface energies of PMMA terpolymers having high glass transition temperatures and low moisture absorptions. Polymer 46 2354-2364. 

Considerable quantities of styrene are used in producing copolymerisates and blends, as, for example, in the production of copolymers with acrylonitrile (SAN), terpolymers from styrene/acrylonitrile/butadiene (ABS polymers) or acrylonitrile/styrene/acrylic ester (ASA), etc. The glass transition temperature of poly (styrene), 100 C, can be increased by copolymerization with a-methyl styrene. What are known as high impact poly (styrenes) are incompatible blends with poly(butadiene) or EPDM, which are consequently not transparent, but translucent. For this reason, pure poly (styrenes) are occasionally called crystal poly (styrenes). 

Terpolymers of tetrafluoroethylene, perfluoromethyl vinyl ether, and small amounts of a cross-linking termonomer, such as, for example, perfluoro(4-cyanobutyl vinyl ether), are free radically copolymerized in emulsion. Vulcanization occurs by cyclotrimerization of the cyano groups to s-triazine rings. The elastomer has a glass transition temperature of —12 C and a brittle temperature of —39° C. It is very resistant to weathering and possesses a good low-temperature flexibility. 

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