But what is titanium dioxide, exactly? Here's what you need to know about this popular food additive — including what products it's used in and whether it's safe to consume.
Zhu et al. were the first to provide evidence that TiO2 NPs (21 nm) can transfer from daphnia to zebrafish by dietary exposure. Hence, dietary intake could be a major route of exposure to NPs for high trophic level aquatic organisms. Ecological research should therefore focus, not only on the concentration of NPs in the environment, but also on its bioconcentration, bioaccumulation and biomagnification. In addition it has been shown that TiO2 NPs can increase accumulation of other environmental toxicants: enhanced accumulation of cadmium (Cd) and arsenic (As) was found in carp in the presence of TiO2 NPs. The strong adsorption capacity for Cd and As was explained by the large specific surface area and strong electrostatic attraction of TiO2 NPs that contribute to facilitated transport into different organs.
Polyvinyl Butyral Resin (PVB) is a solvent Resin synthesized by the acetal reaction of Polyvinyl Alcohol (PVA) and butyraldehyde in contact with coal.
Because Pvb Resin itself contains a lot of hydroxyl groups, it can bridge with some thermosetting resins to improve the properties of chemicals and film hardness.
Because PVB resin has the above excellent characteristics, it is widely used in adhesive safety glass intermediate film of automobile and building, rust cutting primer, baking paint, wood paint, printing ink, adhesive of electronic ceramics and printed circuit board, adhesive between metal and metal, between metal and plastic, modifier of hot-melt adhesive, iron dimension waterproof processing of textile, etc. A variety of new industrial applications are also continuously developed and applied.
The general characteristics of PVB are as follows:
The appearance of polyvinyl butyral (PVB) resin is white spherical porous particles or powder, and its specific gravity is 1:1; However, the filling density is only 0.20 ~ 0.35g/ml.
Thermal properties
The glass transfer temperature (TG) of polyvinyl butyral (PVB) resin ranges from 50 ℃ of low degree of recombination to 90 ℃ of high degree of recombination; The glass transfer temperature can also be adjusted by adding an appropriate amount of Plasticizer to reduce it below 10 ℃.
Mechanical properties
The coating of polyvinyl butyral (PVB) resin has good water resistance, water resistance and oil resistance (it is resistant to aliphatic, mineral, animal and vegetable oils, but not to sesame oil). PVB is widely used in printing inks and coatings because it contains high hydroxyl groups and has good dispersibility to pigments.
In addition, its chemical structure contains both hydrophobic acetal and acetic ACID groups and hydrophilic hydroxyl groups, so PVB has good adhesion to glass, metal, plastic, leather and wood.
Chemical reaction
Any chemical that can react with secondary alcohol will also react with PVB. Therefore, in many applications of PVB, it is often used with thermosetting resin to bridge and harden with the hydroxyl group of PVB, so as to achieve the characteristics of chemical resistance, solvent resistance and water resistance.
Of course, films with different characteristics (such as hardness, toughness, impact resistance, etc.) can be prepared according to different types of thermosetting resin and different mixing ratio with PVB.
Safety properties
