Mixed composition PIBS

To initiate the scheme, cells in culture are simultaneously infected with a wild type virus and the recombinant, polyhedrin deficient virus. Inside the cell nucleus, an infection is established by both virus types. The recombinant is as replication proficient as the wild type, except for its inability to produce PIBs. This function is carried out by the wild type. The PIBs that form in the nucleus occlude nucleocapsids of both the wild type and the recombinant virus, as they are indistinguishable at this point. We refer to such PIBs as mixed-composition PIBs (MC-PIB). 

Probable range of the phase inversion is an important characteristic for mixed biodegradable composites. This allows from a practical point of view to establish the minimum concentration of PHB (at which a continuous phase is formed) for intensive biodegradation as microorganisms must be able to penetrate deep into the mixed composite. When compared with the atomic force microscopy of samples with different proportions of the components was found that in investigated materials continuous matrix formation occurs when PHB content in the mixture of about 40-50 per cent by weight. The results of atomic force microscopy for the composition ratio of PHB-PIB 50 50 shown in Figure 2.2. 

Structure of mixed compositions of PHB-PIB investigated by atomic force microscopy confirmed the formation of a heterogeneous two-phase structure. PHB forms a continuous elongated... 

However, in addition to their thermoplasticity, representatives of PHAs have optical activity, increase induction period of oxidation, exhibit the piezoelectric effect and, what is most important, they are characterized as being biodegradable and biocompatible. At the same time, the PHAs have disadvantages (high cost, brittleness), which can be partially or completely compensated by using composite materials based on blends with other polymers, with dispersed fillers or plasticizers. Taking into account all the above, we have suggested to create a mixed polymer composite based on poly-3-hydroxybutyrate (PHB) and polyisobutylene (PIB). 

Properties of mixed polymer compositions are determined by many factors, among which in the first place should be allocated phase sfructure (ratio and the size of the phase domains). Therefore, at the first stage of the research attention has been paid to study the stmcture of formed compositions. In the investigation of samples with a low content of PHB (10-30% by weight) has been found that it forms a discontinuous phase, i. e., distributed in a continuous matrix PIB as separate inclusions of the order of 1-2 pm. The results of atomic force microscopy for the composition ratio of PHB-PIB 20 80 were shown in Figure 2.1. 

Polypropylene and the PIB-grafted silicas were mixed in DSM Xploreminicompouder Mixer volume 15 cm, +210°C, 6 minutes. The compositions of the three PP-PIB-silica compounds are summarized in Table 1. 

Silica-PIB aggregates remained visible in the polypropylene composites prepared by melt mixing. The observed silica-PIB aggregate size in the composite corresponds roughly to the native fumed silica aggregate size. 

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