Scheme 1 shows a one-pot method of preparing the TN hydrogels by in situ chemical crosslinking
, freezing/thawing, and soaking in multivalent cation salt solution.
The chemical crosslinking
using the grafted poly(IA) chains increased the shape recovery of the IA series, but the CIA series did not receive the crosslinking effect because of the lack of grafted poly(IA) chains.
Composition and chemical crosslinking
can be followed by the changes in the respective peak height between 2500 [cm.sup.-1] and 3800 [cm.sup.-1].
Figure 2b shows the probable chemical crosslinking
reaction between the epoxy-functionalized xanthan and chitosan .
Based on the unsaturated bond on EPDM side chain, a kind of weak chemical crosslinking
may be introduced into strong chemical crosslink network.
Other toxic residual components associated with chemical crosslinking
such as initiators, chains transfer agents, and stabilizers may also present in PVA.
There are two main methods for crosslinking of EVA at present: high-energy irradiation ([.sup.60]Co [gamma]-rays or electron beam) crosslinking [6, 7] and chemical crosslinking
(peroxide and silane crosslinking) [8-11].
In this work a strength control procedure, based on the use of two chemical crosslinking
agents PK and TG, has been assessed.
A molten polymer undergoing a chemical crosslinking
process is converted from a viscoelastic liquid into a viscoelastic solid.
Modification of poly(vinyl chloride) by chemical crosslinking
has aroused wide interest because of the improvements of the elevated temperature properties of PVC.
Figures 14b-d show that a chemical crosslinking
reaction might have taken place between the two phases at the interface.
The dark coloration and brittleness in the films cured 300 [degrees] C in air and at 400 [degrees] C in nitrogen suggest that chemical crosslinking
is taking place.