The effect of ultrafiltration (UF) operation on the stability of a sizing agent based on starch has been studied. Hydroxypropyl starch (HPS) has been used as a water soluble modified starch. The investigation was carried out in two categories:
effect of UF time (the concentration of the solution was kept constant by recirculating the permeate), and
raising the concentration by discharging the permeate.
The changes in the HPS solution properties were assessed by investigating the rheological properties (apparent viscosity as a function of filtration time, temperature and activation energy of flow) and molecular properties (Infra‐Red spectroscopy (IR), number of average molecular weight (Mn) and molecular weight distribution). The investigation was carried out on HPS solutions before, after and during the ultra‐filtration process. The results indicated that some degradation takes place during UF process.
The present work was undertaken to achieve two aims
the recoverability of carboxy methyl starch (CMS) from the diluted solutions (desizing solutions) by using the ultra‐filtration (UF) technique,
the extent of changes in the physical and mechanical properties of CMS as sizing agent after the UF recovery.
In order to investigate the effect of UF recovery on CMS properties, the diluted CMS solution was subjected to two UF cycles during the recovery, and the end product of each cycle was intensively examined. The investigations are included: the characteristic UF factors (rejection “R”, and flux of permeate “V”), viscosity, average molecular weights, molecular weight distribution (MWD), and the mechanical properties (adhesive force, weaving properties as abrasion percent AG “dust and fluff”, and clinging factor TK). The obtained results showed that:
The efficiency of the UF recovery of CMS is higher in the second than the first UF cycle.
The viscosity of CMS is:
lower after than before the first UF cycle,
higher after than before the second UF cycle.
The average molecular weight determinations are indicated the occurrence of degradation in CMS molecules.
The MWD are shifted towards unity after the UF recovery.
The changes in the mechanical properties of CMS after the UF recovery are:
Adhesion force decreased.
Abrasion % (dust and fluff) decreased.
Clinging factor TK increased.
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