Chemistry Reference
In-Depth Information
of polymer blends determined by the properties of the polymer matrix, so
the properties of melts are generally defined by PHB. Lower viscosity of
the melt blend composition (due to the formation of a continuous matrix
PHB) in this case will significantly simplify the processing of the investi-
gated materials. Also, the data in Fig. 4.6 are consistent with the position
that the greater the difference in viscosity of mixed polymers, the earlier
the formation of a continuous matrix less viscous component.
Previous studies [7] revealed that the main physical and mechanical
characteristics (tensile strength, tensile modulus, elongation at break)
PHB-PIB composition containing 30-50% by weight of PHB, not inferior
to traditional polymers used in the production of packaging (polyethylenes
of different brands). But the undeniable advantage of the compositions
PHB-PIB is the possibility of biodegradation. It has been found that mix-
tures containing 40-60% PHB stepwise lose mass when exposed to soil. In
the first stage (100 days) intensive degradation of phase PHB occurs under
the action of microorganisms. The result of the first stage of this scenario
is PIB samples with very high surface area. In the second step (after 100
days), mass loss is stabilized and is much slower.
TABLE 4.1
The Average Molecular Weight of PIB Samples
The average mo-
lecular weight
PIB samples
The intrinsic viscosity
The original sample
0.68
185-000
The sample after 200 days of exposure
in the soil (0% PHB)
0.65
175-000
The sample after 200 days of exposure
in the soil (60% PHB)
0.49
115-000
As can be seen from Table 4.1, the average molecular weight PIB
sample (previously containing PHB) much less compared to the original
molecular weight PIB and PIB after exposure to soil. Significant impact
of PHB phase on the ability of PIB to degradation in soil was found by
research of the molecular weight of the elastomer. Destruction of the origi-
nal structure PIB can occur due to physical factors (large specific surface
films), chemical factors (interaction of the products of biodegradation of
PHB with PIB phase, and initiation of the degradation of the elastomer)
