No abstract

The carboxymethyl starch-based films in a presence of citric acid were prepared by casting technique. The influence of citric acid content on physicochemical properties of obtained hydrophilic films were evaluated (solubility in water, moisture absorption, mechanical and thermal properties). The crosslinking of starch derivative chains has been confirmed by FTIR spectroscopy, however, an excess of citric acid could cause hydrolysis of carboxymethyl starch chains. The best mechanical performance has been noted for the system containing 30 wt% (the highest tensile strength as well Young modulus 160 kPa and 650 kPa, respectively) as well as the highest T g (ca. 58 °C). Additionally for the mentioned system the lowest solubility in water has been determined.

Silicone pressure-sensitive adhesives (Si-PSA) exhibit unique properties, such as high Si-O-Si backbone flexibility, low intermolecular interactions, low surface tension, excellent thermal stability, and high UV transparency, which often explains why silicone PSAs have an impressive performance at high-and lowtemperature extremes, excellent electrical properties, chemical resistance, and outstanding weathering resistance turning them superior compared to organic PSAs. It is well known that due to their unique properties, silicone pressure-sensitive adhesives are materials for special applications. In the present study, we focus on changing the useful properties of the best compositions of silicone pressure-sensitive adhesives in time to verify the impact of aging on them. The influence of time on given silicone pressure-sensitive adhesive tapes and their useful properties is a very important factor for the description of the life-time of potential products based on such compositions. Aging of Si-PSA was carried out for 1 h, 24 h, 7 days, 31 days, and 92 days. The tests did include such properties like adhesion, cohesion (at 20 and 70°C), tack, and yellowness.

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.

The purpose of this work was to obtain single-sided tapes with different concentrations of kaolin and to check its impact on the self-adhesive properties of commercial adhesives. The most important self-adhesive properties were examined, such as tack, peel adhesion, shear strength, shrinkage, and thermal resistance. Tapes based on silicone PSAs with kaolin can be used in many branches of industry to bond elements operating at elevated temperatures, i.e., in aeronautics, aerospace including solar cells for satellites and space stations. There are few reports on one-sided adhesive tapes based on silicones with the addition of kaolin. However, taking into account the number of their potential applications, we did self-adhesive tests and explained how kaolin affects them. In addition, the reactivity of the crosslinking compound and silicone adhesive during the crosslinking process and the thermal effects of this process were also examined. In connection with the various applications of the obtained tapes, also the flammability and heat of combustion were tested, in accordance with applicable standards. As a result of the tests, one-sided self-adhesive tapes with new properties (increased temperature resistance, less shrinkage, and increased resistance to flammability) were obtained.