Copolymer strength values

Likewise, the mechanical properties of the copolymers were nearly identical or even somewhat enhanced towards the polyimide homopolymer in terms of the modulus and tensile strength values [44,47]. For most of the block copolymers, the elongations to break were substantially higher than that of PMDA/ODA polyimide (Table 4). The shape of the polyimide stress-strain curve is similar to that of a work-hardened metal with no distinguishable yield point... 

The nature of the polymer latex is determined by the monomer ratio in the copolymer and this property of the latex affects strength values in manner similar to that obtained with the polymer-cement ratio. The effects of polymer-cement ratio on strength are presented in Table 6.14 [87]. 

Figure 1. Relationship between (normalized) tensile strength and HPL content of injection molded blends with ethylene vinyl acetate copolymer. (Vinyl acetate content of the thermoplastic copolymer is given in parentheses.) (Strength values expressed in percent of unblended copolymer.) (From Ref. 11, with permission by Marcel Dekker, Inc.)...

A closer inspection of the free energy (74) and (75) as a function of Cp allows us to specify the structural properties (aggregation number and size) of the equilibrium micelle as a function of the copolymer composition (values of Nb and Na) and the external parameters that control the strength of interactions in the coronal domain. 

Attempts have been made to use compatibiUsers in reclaiming three-component plastics waste consisting of PE, PP and PS. The PET (bottles) were first separated, and the remaining three polymers were successfiilly compatibilised with a mixture of EPDM rubber and styrene-butadiene block copolymer. Provided that a substituted diamine stabiliser was also added, the recycled mix achieved impact strength values comparable with those of virgin polyolefins. 

Mica products with smallest particle size, PM-325 and C-3000, provide highest flexural strength and Izod impact values. For example, C-3000 and HiMod-270 at 30 wt% loading in the copolymer give flexural strength values of 5570 and 4760 psi, respectively. Izod impact for the C-3000 composite was 3.7 versus 1.9 ft-lb/in for the HiMod-270 composite. 

Javni et al. (2011) studied the possibility of replacing polyol copolymers used in the preparation of flexible PU foams by the incorporation of unmodified and modified montmorillonites. While the addition of the unmodified MMT increased hardness, compression strength, and resilience of the foams, the incorporation of the organically modified MMT resulted in foams with lower modulus, hardness, and compression strength values, a direct result of the higher open-cell contents and poorer cellular structure of the resulting foams, apparently leading to the conclusion that in this specific case the addition of modified MMT led to a counterproductive result. 

Measurement techniques are based on a circuit developed by Sawyer and Tower in 1930 [19]. For PVDF and the VDF TrFE copolymers, typical values of Pj. and are in the region of 5 juCm and SOkVmm" respectively. Furukawa et al [20] have shown that for PVDF, switching times of a few microseconds can be obtained at room temperature with an applied field of a few hundred kVmm Further investigations into VDF TrFE [21] have found that for a 65 35 molar composition at 20 °C, tg decreases from 1 ms to 100 ns as the field strength increases from 80 to 400kVmm . ... 

Content of Ot-Olefin. An increase in the a-olefin content of a copolymer results in a decrease of both crystallinity and density, accompanied by a significant reduction of the polymer mechanical modulus (stiffness). Eor example, the modulus values of ethylene—1-butene copolymers with a nonuniform compositional distribution decrease as shown in Table 2 (6). A similar dependence exists for ethylene—1-octene copolymers with uniform branching distribution (7), even though all such materials are, in general, much more elastic (see Table 2). An increase in the a-olefin content in the copolymers also results in a decrease of their tensile strength but a small increase in the elongation at break (8). These two dependencies, however, are not as pronounced as that for the resin modulus. 

In nonrigid ionomers, such as elastomers in which the Tg is situated below ambient temperature, even greater changes can be produced in tensile properties by increase of ion content. As one example, it has been found that in K-salts of a block copolymer, based on butyl acrylate and sulfonated polystyrene, both the tensile strength and the toughness show a dramatic increase as the ion content is raised to about 6 mol% [10]. Also, in Zn-salts of a butyl acrylate/acrylic acid polymer, the tensile strength as a function of the acrylic acid content was observed to rise from a low value of about 3 MPa for the acid copolymer to a maximum value of about 15 MPa for the ionomer having acrylic acid content of 5 wt% [II]. Other examples of the influence of ion content on mechanical properties of ionomers are cited in a recent review article [7],... 

In most ionomers, it is customary to fully convert to the metal salt form but, in some instances, particularly for ionomers based on a partially crystalline homopolymer, a partial degree of conversion may provide the best mechanical properties. For example, as shown in Fig. 4, a significant increase in modulus occurs with increasing percent conversion for both Na and Ca salts of a poly(-ethylene-co-methacrylic acid) ionomer and in both cases, at a partial conversion of 30-50%, a maximum value, some 5-6 times higher than that of the acid copolymer, is obtained and this is followed by a subsequent decrease in the property [12]. The tensile strength of these ionomers also increases significantly with increasing conversion but values tend to level off at about 60% conversion. 

The mechanical properties of ionomers are generally superior to those of the homopolymer or copolymer from which the ionomer has been synthesized. This is particularly so when the ion content is near to or above the critical value at which the ionic cluster phase becomes dominant over the multiplet-containing matrix phase. The greater strength and stability of such ionomers is a result of efficient ionic-type crosslinking and an enhanced entanglement strand density. 

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