Agriculture Reference
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Figure 14. TEM images of ENR/PVA blends crosslinked with maleic acid (MA).
Figure 15. Tensile strength of semi-IPN based on ENR/PVA with maleic acid contents.
The polarity of ENR was improved by blending with polyethylene glycol (PEG) and St,
which was then crosslinked with isophorene diisocyanate. The results showed that the tensile
strength of the ENR/PEG blend increased with the starch (St) content and then decreased as a
function of the St as shown in Figure 16. The highest tensile strength of the ENR/PEG blend
was found to be at 20% St. This is due to a good chemical interaction between the polymers
in the blends.
With an increase of the St content in the blend, the swelling ratio of the ENR/PEG blend
crosslinked with isophorene diisocyanate dramatically decreased because of the chemical
interaction between the polymer blends (Figure 17). The crosslinking density of the samples
was estimated by the swelling ratio both in water and hot water. The swelling ratio of the
maleic acid crosslinked blend, based on the ENR/PVA/starch blend having different maleic
acid and starch contents, all cured at 120ºC for 60 min., was studied in water after keeping the
samples immersed in solvents for 5 days. The blends, based on the ENR and PVA, in both the
presence and absence of starch had a lower swelling ratio after being cured with maleic acid
as shown in Figure 18. This result indicated that a chemical reaction occurred between the
PVA or starch network with maleic acid.
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