Carboxymethyl starch with high degree of substitution: synthesis, properties and application **) Summary -Highly substituted (degree of substitution, DS about 0.9) carboxymethyl starch (CMS) was prepared in isopropanol/water suspension. The influence of etherification reaction parameters on DS, reaction efficiency, number average molar mass as well as the viscosity of 2 wt. % aqueous solution was determined. Using laser scanning microscopy, X-ray diffraction and infrared spectroscopy techniques allowed to evaluate the morphological changes of modified starch granules when compared to native starch ones. An attempt to apply CMS (of high and medium DS: 0.94 and 0.39, respectively) for flocculation or dispergation tests of selected aqueous suspensions [iron(II) sulphate, iron(III) oxide, iron(III) laurate and aluminosilicates: kaolinite and calcium montmorillonite] has been performed. In case of iron(II) sulphate and iron(III) oxide high substituted CMS exhibited effective flocculating properties. Moreover, it worked as a good dispersing agent for mineral aluminosilicate suspensions.

The carboxymethylated derivatives of starch (CMS) and cellulose (CMC) were used for film preparation. The infrared spectroscopy revealed that crosslinking via ester bridges with citric acid occurred between the two polysaccharide derivatives. The effect of polysaccharide derivatives ratio on physicochemical properties of prepared films was evaluated. Generally, the values of tested parameters (moisture absorption, surface roughness, and mechanical and thermal properties) were between the values noted for neat CMS or CMC-based films. However, the physicochemical properties of the system with equal CMS/CMC weight ratio diverged from this trend, i.e., the highest tensile strength, the highest Young’s modulus (ca. 3.4 MPa and ca. 4.9 MPa, respectively), with simultaneously the lowest moisture absorption (18.5% after 72 h) have been noted. Such systems could potentially find application in agriculture or pharmacy.

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A new fabrication method for thin (120 µm) thermally curable structural self-adhesive tapes (SATs) was demonstrated by utilizing a series of acrylic syrups (ASs) modified using Bisphenol A-based liquid epoxy resin. The acrylic syrups containing poly(butyl acrylate-co-butyl methacrylate-co-glycidyl methacrylate-co-2-hydroxyetyl acrylate-co-4-acryloyloxy benzophenone) were synthesized via free-radical bulk-photopolymerization (FRBP) process. Influence of different type I radical photoinitiators (PIs), i.e., α-hydroxyalkylphenones (HPs), acylphosphine oxides (APOs) and its mixtures (HPs/APOs and APO/APO) on selected physico-chemical features of obtained ASs was studied. It turned out that APO-type PIs are more effective in the FRBP process (NMR studies). Self-adhesive tests of SATs revealed that the monomers’ conversion in ASs have a significant influence on adhesion and tack. Moreover, the polymer structures formed at the UV cross-linking stage of SATs significantly affect the cross-linking degree of SATs during thermal curing (differential scanning calorimetry method). The highest values of overlap shear strength were achieved by SATs based on ASs with monomers’ conversion on the level 50–60%.

Starch graft copolymers have been obtained via grafting of acrylic monomers i.e. acrylamide (AAm) and acrylic acid (AA) during the reactive extrusion processes. 2,2'-azobis (2-methylpropionamidine) dihydrochloride (AAPH) was used as a radical initiator and N'N-methylenebisacrylamide (MBA), mixture of pentaerythritol triacrylate and pentaerythritol tetraacrylate (trade name PETIA) and alkoxylated pentaerithritol acrylate (trade name Ebecryl 40) were applied as acrylic crosslinkers. The obtained materials were characterized by FTIR and their water sorption properties investigated using swelling (vol. %) and sorption (wt. %) tests. Sorption of water into these graft copolymer samples reached values of ca. 6 -13 g of water per g of dry materials. It was also found that water sorption values were dependent on ratio of AAm and AA as well as on a type of the applied crosslinking agent.