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Studies undergone using polyglycolide-made sutures have shown that the material loses half of its strength after two weeks and 100% after four weeks. The polymer is completely resorbed by the organism in a time frame of four to six months. [2] Degradation is faster in vivo than in vitro, this phenomenon thought to be due to cellular enzymatic ...
A wide range of stabilizers is therefore needed. The market for antioxidant stabilisers alone was estimated at US$1.69 billion for 2017, [3] with the total market for all polymer stabilizers expected to reach US$6.5 billion by 2033. In 2023, almost half of all polymer stabilizers sold worldwide were based on calcium, followed by lead (25.1 % ...
In polymer science, dispersion polymerization is a heterogeneous polymerization process carried out in the presence of a polymeric stabilizer in the reaction medium. . Dispersion polymerization is a type of precipitation polymerization, meaning the solvent selected as the reaction medium is a good solvent for the monomer and the initiator, but is a non-solvent for the po
Hindered amine light stabilizers (HALS) are chemical compounds containing an amine functional group that are used as stabilizers in plastics and polymers. [1] These compounds are typically derivatives of tetramethylpiperidine and are primarily used to protect the polymers from the effects of photo-oxidation; as opposed to other forms of polymer degradation such as ozonolysis.
The polymer is manufactured in multiple viscosities, from a thin pourable liquid (when n is very low), to a thick rubbery semi-solid (when n is very high). PDMS molecules have quite flexible polymer backbones (or chains) due to their siloxane linkages, which are analogous to the ether linkages used to impart rubberiness to polyurethanes .
The polymer beads that result can range in size from 100 nm to 5 mm. The size is controlled by the stirring speed, the volume fraction of monomer, the concentration and identity of the stabilizers used, and the viscosities of the different components. The following equation derived empirically summarizes some of these interactions:
Polyetherimide (PEI; branded as Ultem [1]) is an amorphous, amber-to-transparent thermoplastic with characteristics similar to the related plastic PEEK.When comparing PEI to PEEK, the former is cheaper but has lower impact strength and a tighter temperature range.
Certain strains of Bacillus subtilis bacteria can be used to produce polyhydroxyalkanoates. To induce PHA production in a laboratory setting, a culture of a micro-organism such as Cupriavidus necator can be placed in a suitable medium and fed appropriate nutrients so that it multiplies rapidly.