Cross-linking temperature

The mechanical properties, degradation, and surface characteristics of poly(diol citrates) could be controlled by choosing different diols and by controUing synthesis conditions such as cross-linking temperature and time, vacuum, and initial monomer molar ratio. 

Typical Cross-Linking Temperatures of Cross-Linking Peroxides Based on Their Half-Life... 

FIGURE 9.2 Gas chromatograms of an FT product, original and precolumn hydrogenated. Ampoule samples taken from the gaseous product flow at ca. 200°C. GC conditions Capillary, 100 m dr 0.25 mm df, 0.5 pm methyl silicone cross-linked temperature programm -80 to 270°C carrier gas H2 introducing gas N2 FID. 

The disc is placed onto the hot-stage and the Mylar ring added such that it encircles the deposited sample. Heat the hot-stage at 5°C min to the cross-linking temperature (60°C). 

Once the cross-linking temperature has been attained, add the second KBr disc to the top of the sample and apply pressure to define the sample thickness. If an aligned sample is desired a small, linear, oscillatory shear may be applied at this point (amplitude 5 mm, frequency 1 Hz). 

Chemically cross-linked temperature sensitive poly(N-isopropyl acrylamide) gel beads were prepared from NIPA, methylenebisacrylamide crosslinker (BA), ammonium persulphate initiator (APS), and tetra-... 

The crosslinking temperature of aliphatic poly(isocyanate)s, based on 1,6-hexane diisocyanate, which are blocked with equimolar quantities of diisopropylamine and 1,2,4-triazole is 139°C, without the addition of any catalyst. Aliphatic poly(isocyanate)s, which are bloeked with equimolar quantities of diisopropylamine and malonic acid diethyl ester have a cross-linking temperature of 130°C. °... 

Another challenge in terms of molding and process technique is presented by hard-soft composites pairing thermoplastics with elastomers. Elastomers are superior to the thermoplastics when it comes to dynamic sealing qualities, temperature resistance, and useful life. The injection molds used in this process are cooled in the area of the thermoplastic cavity, whereas the cavities into which the elastomer is injected have to be kept within the cross-linking temperature range of 180-200° C. 

FIGURE 2 Effect of cross-linking temperature on beads catalytic activity. 

Table 4. Deblocking/Cross-linking Temperatures of lEM Derivatives...

The authors successfully prepared chemically cross-linked temperature-responsive electrospun nanofibers by thermal curing [llj. As a member of the NIPAAm family, N-hydroxymethylacrylamide (HMAAm) was copolymerized with NIPAAm by free-radical copolymerization because temperature-responsive HMAAm can be cross-linked by self-condensation at high temperatures (above 110°C). As a result of cross-linking, very stable nanofibers in aqueous solution were obtained and manipulated as a bulk material. By extension of the above-mentioned examples, the authors successfully prepared temperature-responsive electrospun nanofibers by photocuring [12]. The temperature-responsive nanofiber mats were prepared using the copolymers NIPAAm and 2-carboxyisopropylacrylamide conjugated to 4-aminobenzophenone, a photoinitiator. The crosslinked temperature-responsive nanofibers were obtained by UV irradiation for 30 min (Fig. 5.4.3). Chemically cross-linked nanofibers were also reported by... 

The estimations have shown [51], that the introduction MMT in reactionary mixture increases substantially the valne J if for reaction without MMT J =0.027, then at MMT introduction J increases np to 0.175-0.452 and raises at cross-linking temperature increase. A macromolecnlar coil (nucrogel) fractal dimension EP can be determined with the help of the relationship (12) the account made according to the indicated ratio has shown, that the smallest value equal to 1.52, is obtained for cross-linking reaction without MMT and at MMT introduction it increases up to 1.67-2.19. 

A cleavable, temperature-responsive polymeric cross-linker was utilized by Xu and cowoikers [111] to stabilize micelles from PEO-b-PAPMA-b-poly((Af,Af-diisopropylamino)ethyl methacrylate) triblock copolymer. The PNIPAm cross-linker contained activated ester end groups that were reacted with the primary amines on the PAPMA middle block. The trithiocarbonate moiety located at the middle of PNIPAm cross-linker could then be degraded by aminolysis to break the cross-links. Temperature-responsive micelles and vesicles from diblock and triblock copolymers were shell cross-linked via interpolyelectrolyte complexation [108, 112]. The cross-links formed by the electrostatic interactions of oppositely charged polyelectrolytes could be disrupted by the addition of SME. 

Table 11.5 The effect of cross-linking temperature on the percentage of loading content and loading efficiency of BSA for grafted and mixed beads...

Figure 11.8 Effect of variation the cross-linking temperature on the release profiles of BSA of (a] CS- -ALG copolymers and (b) ALG-CS mixed hydrogels. At constant grafting and mixing conditions [0.3% CS, 40°C, 3 h], formulation conditions [3% CaCl2, for 1 h] and release conditions [at 37°C, SPB PH 7.4), using BSA [20% w/w), and wet beads 1 g.

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