Crosslinking reactions of polymers

Many miscellaneous crosslinking reactions of polymeric materials are reported in the literature. For instance, poly(acryloyl chloride) can be crosslinked with diamines  

In a similar manner, polymers with pendant chlorosulfonate groups crosslink when reacted with diamines or with glycols.  

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One of the earliest approaches to studying the crosslinking reactions of polymer networks is based on a simple statistical analysis of the polymer system (23,24). This work included three important assumptions 1) all functional groups of the same type are equally reactive, 2) all functional groups react independently of one another, and 3) no intramolecular reactions occur. More elaborate approaches consider the reactivity differences for various sites on the monomers and changes in reactivity of a site as the reaction proceeds (25-29). 

Loan, L. D. (1972). Peroxide crosslinking reactions of polymers. Pure Appl. Chem,... 

As discussed briefly in the previous section, gelation can generally be discussed within the framework of critical phenomena [7] by having the gel point and critical point correspond. Stauffer applied the percolation theory often used for the general theory of critical phenomena to the crosslinking reaction of polymers [8, 9],... 

BMI was also used as a crosslinking agent for poly(iminoethylene). The Michael addition takes place with the nucleophilic nitrogen of the imino group and the double bonds of the electrophilic BMI. The Michael addition of BMI is now adopted as a crosslinking reaction for polymers with amino end groups [2]. 

A. Crosslinking reactions of two polymer chains of different types. 

Interfacial adhesion and, thereby, compatibility can be enhanced by the selective crosslinking reaction in polymer blends. Inoue and Suzuki [26] reported the properties of blends dynamically crosslinked PP-EPDM blends. The crosslinking agent was yV,N -/w-phenylene-bismaleimide - poly(2,2,4 - trimethyl - 1,2-dihydroquino -line) system. Increase in interfacial adhesion leads to... 

The purpose of the second dwell is to allow crosslinking of the matrix to take place. It is during the second dwell when the strength and related mechanical properties of the composite are developed. To characterize the exothermic crosslinking reaction of a thermosetting polymer matrix, a thermal cure monitor technique such as Differential Scanning Calorimetry... 

There are several mechanisms which are essentially different in chemomechanical reactions of polymer molecular level structure changes, polymer conformational change, change of polymer-polymer interactions and the change of crosslinked structure in polymer gels. 

As can be seen from all of these works, sequential IPNs have been extensively used with silicone with various crosslinking reactions and polymers. As a result, attention must be paid to the influence of processing conditions, of the chemical nature of components (silicone and the other polymer), of the evolution of the material at each step of the IPN synthesis etc. Depending on the mastering of these parameters, reactivity, morphology and entanglement can be controlled and consequently targeted properties can be reached. 

Different methods have been used to follow crosslinking reactions. When polymers were irradiated by U. V. light in dilute THF solution above 200 nm (Method A) or 300 nm (Method B), the insolubilization reaction was followed by measuring the solution ultra violet absorbance versus time. Likewise the course of disappearance of cinnamic structure was measured on polymers films placed on quartz at 9cm of the lamp and irradiated above 200 nm (Method C). Lamp used for methods A and C was a PCQ 9 G-1 which emits in the U.V. region at 253.7 (2.5 W), 312.5, 365 nm, the other rays being in visible. A Pyrex filter was placed beetween 450 W Hanovia lamp and solution when only higher wave lenghts were expected. Lamps powers were controled before and after irradiation with a Black-Ray Ultra-Violet Intensity Meter. 

CD polymers can be synthesized (1) by radical polymerization of monofunctional CD monomers, (2) by polymer-analogous reaction of polymers with CDs, and (3) by partial crosslinking of CDs, as exemplified below. 

When the crosslinking reactions of Chapter 6 are driven far beyond the gel point, nearly all species are attached to the gel in a single macroscopic network polymer. Such networks, with either chemical or strong physical bonds, are important soft solids. If the glass transition and melting temperatures are below room temperature, the material is a rubber. Rubbers... 

There are two further possibilities for preventing segregation in complex immiscible mixtures. The first one Implies crosslinking reaction of the dispersed phase, associated with interfacial bonding and leads to the well-known dynamic vulcanisation (17). The second one results from mechanical interlocking of the phases which are created in interpenetrated polymer networks (IPN). 

Coupling or crosslinking Reaction of a polymer with a Viscosity building for nylon-6,6 ... 

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