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Summary: Blends of high molecular weight poly(R‐3‐hydroxybutyrate) (PHB) ($\overline M _{\rm w}$ = 352 000 g · mol−1), comprising of either low molecular weight poly(R‐3‐hydroxybutyrate) (D‐PHB) ($\overline M _{\rm w}$ = 3 900 g · mol−1) or poly[(R‐3‐hydroxybutyrate)‐co‐(R‐3‐hydroxyvalerate)] (PHBV) ($\overline M _{\rm w}$ = 238 000 g · mol−1) with 12 mol‐% hydroxyvalerate (HV) content as a second constituent, were investigated along with the thermal properties and morphologies. After isothermal crystallization, a lowering of the melting temperature of PHB can be observed with increasing content of the second component in the blends. This behavior points towards miscibility of the constituents both in the liquid and the solid state. Crystallization kinetics was studied under isothermal and non‐isothermal conditions. The overall kinetics of isothermal crystallization was analyzed in terms of the Avrami equation. Only one crystallization peak is observed in all cases for the PHB/D‐PHB and PHB/PHBV blends under the conditions studied. This demonstrates co‐crystallization of the constituents. The addition of D‐PHB or PHBV to PHB reduces the rate of crystallization of the blends compared to that of neat PHB. The corresponding activation energies of crystallization also decrease with an increasing concentration of the second constituent. Non‐isothermal crystallization, carried out with different cooling rates held constant, is discussed in terms of a quasi‐isothermal approach. The corresponding rate constants as functions of reciprocal undercooling show Arrhenius‐like behavior in a certain range of temperatures. At sufficiently high undercooling, the rate constants of crystallization for the isothermal process exceed those reflecting non‐isothermal conditions, whereas in the limit of low undercoolings, the rate constants become similar. Ring‐banded morphologies are observed when PHB is in excess. When the respective second component is the major component, fibrous textures of the spherulites develop.Polarized micrograph of PHB/PHBV 90/10.magnified imagePolarized micrograph of PHB/PHBV 90/10.

We present a basic principle and good practices of the rheology of polymers, particularly for teachers or lecturers at colleges or universities for educational purposes, as well as for beginner researchers who may refer to this article as their self-learning resources. Basic consideration of the experimental methods using parallel-plate oscillatory rheometer and step-by-step guidelines for the estimation of the power law dependence of storage, G′ and loss, G″ modulus as well as the estimation of the relaxation time at f    cross   G ′ − G ′′ ${f}_{\,\mathrm{cross}}^{\,{G}^{\prime }-{G}^{\prime \prime }}$ at terminal zone using various approaches such as commercial graphical software, manual graphical approach and commercial rheometer software are highlighted. Good practices for data interpretation using different approaches are described and compared where the outcomes revealed the manual graphical approach or commercial graphical software yield comparable results with the commercial rheometer software. In order to have better insight, several examples and exercises which are applicable for teaching and self-learning activities are also provided.

Solid solutions of blends of poly(ethylene oxide) (PEO) and epoxidized natural rubber (ENR) comprising 12 wt % of LiClO 4 were studied. Two glass transition temperatures, corresponding to the T g s of the constituents, confirm immiscibility of the polymers over the entire composition range. It turns out that the T g s of both polymers slightly increase after addition of salt to the blends. This shift is approximately constant over the whole range of blend composition. Accordingly, T g measurements reveal that the salt dissolves to approximately equal relative amounts in the two phases. The degree of crystallinity of PEO in blends with ENR descends only to a minor extent with ENR content. However, addition of salt leads first to decreasing crystallinity and second this decrease becomes more pronounced with the addition of ENR. It shows that under these experimental conditions the salt content in PEO increases as compared to ENR. As one expects, the rate of isothermal crystallization does not change in blends as long as PEO is in excess. The situation changes again when salt is added. The rate decreases in a certain range of crystallization temperatures when ENR is added, demonstrating that salt is favorably dissolved in PEO. Conductivity was measured in polymers comprising different salt concentrations. A power-law dependence of conductivity on salt concentration was found. It results that the mobility of charge carriers in PEO exceeds that of ENR by five orders of magnitude. Therefore, the conductivity in blends is primarily governed by PEO as long as PEO is in excess. Conductivity measurements reveal again that salt is preferably dissolved in PEO. The distribution coefficient is estimated.

The influence of epoxidation level of natural rubber (i.e., ENR25, ENR50) on the dielectric and oxygen gas barrier properties of thermally reduced graphene oxide (GR) and graphite (GT) (with 2%·w/w) filled nanocomposites are investigated here. GR, GT filled epoxidized natural rubber (ENR) nanocomposites were fabricated by mechanical mixing using environment friendly two‐roll mill mixing method. Raman spectroscopy and Fourier transform infrared spectroscopy studies were carried out to investigate the extent of chemical interactions between GR and ENR. Morphological studies were done using transmission electron microscopy to evaluate the distribution of GR and GT in the ENR. The improved gas barrier and dielectric properties of GT‐ENR and GR–ENR composites synthesized by a novel green ecofriendly method is correlated with the chemical interactions among GT, GR, and ENR. POLYM. ENG. SCI., 55:2439–2447, 2015. © 2015 Society of Plastics Engineers