Trommsdorff

Deooia P L, Hoohstrasser R M and Trommsdorff H P 1980 Vibrationai reiaxation in moieouiar orystais by four-wave mixing naphthaiene Chem. Phys. Lett. 72 1-4... 

The rate process for termination is hindered through the Trommsdorff effect. 

Trometh amine Trommels Trommel screens Trommsdorff effect Trona... 

Bulk Polymerization. This is the method of choice for the manufacture of poly(methyl methacrylate) sheets, rods, and tubes, and molding and extmsion compounds. In methyl methacrylate bulk polymerization, an auto acceleration is observed beginning at 20—50% conversion. At this point, there is also a corresponding increase in the molecular weight of the polymer formed. This acceleration, which continues up to high conversion, is known as the Trommsdorff effect, and is attributed to the increase in viscosity of the mixture to such an extent that the diffusion rate, and therefore the termination reaction of the growing radicals, is reduced. This reduced termination rate ultimately results in a polymerization rate that is limited only by the diffusion rate of the monomer. Detailed kinetic data on the bulk polymerization of methyl methacrylate can be found in Reference 42. 

Studies of the copolymerization of VDC with methyl acrylate (MA) over a composition range of 0—16 wt % showed that near the intermediate composition (8 wt %), the polymerization rates nearly followed normal solution polymerization kinetics (49). However, at the two extremes (0 and 16 wt % MA), copolymerization showed significant auto acceleration. The observations are important because they show the significant complexities in these copolymerizations. The auto acceleration for the homopolymerization, ie, 0 wt % MA, is probably the result of a surface polymerization phenomenon. On the other hand, the auto acceleration for the 16 wt % MA copolymerization could be the result of Trommsdorff and Norrish-Smith effects. 

Chain transfer to polymer is reported as a major complication and is thought to be unavoidable in the polymerization of alkyl acrylates.200 202 The mechanism is believed to involve abstraction of a tertiary backbone hydrogen (Scheme 6.32). It has been proposed that this process and the consequent formation of branches may contribute to the early onset of the gel or Norrish-Trommsdorff effect in the polymerization of these monomers. At high temperatures the radicals formed may undergo fragmentation. 

The chain termination rate varies inversely with the viscosity of the polymerization medium because of the Trommsdorff Effect (i.e., the reduction of the macroradical mobility with increasing reaction viscosity). This effect significantly influences reaction rate[ ,2, 10]. 

Autoacceleration, Glass and Zutty (S) and Burnett and Melville 9) reported an increase in the rate and average degree of polymerization with increasing solution viscosity, heterogeneous conditions and chain coiling for free radical, vinyl polymerizations. Autoacceleration is also called Trommsdorff. (10) effect. 

A kinetic study for the polymerization of styrene, initiated with n BuLi, was designed to explore the Trommsdorff effect on rate constants of initiation and propagation and polystyryl anion association. Initiator association, initiation rate and propagation rates are essentially independent of solution viscosity, Polystyryl anion association is dependent on media viscosity. Temperature dependency correlates as an Arrhenius relationship. Observations were restricted to viscosities less than 200 centipoise. Population density distribution analysis indicates that rate constants are also independent of degree of polymerization, which is consistent with Flory s principle of equal reactivity. 

Digimed (Hormosan) Digimed (Trommsdorff) Digimerck (Merck) Digipural (Schaper ... 

Neobiphyllin-Clys (Trommsdorff)-comb. Perasthman (Polypharm) Pulmidur (pharma-stern) Pulmo-Timelets (Temmler) Solosin (Hoechst) theo (ct-Arzneimittel) Theolair (3M Medica) Theophyllard (OPW) Theophyllin (Heumann Stada)... 

Theophyllin retard ratiopharm (ratiopharm) Tromphyllin (Trommsdorff)... 

The desorption and termination constants were calculated for a copolymer from the corresponding homopolymer constants as discussed in Nomura and Fujita (12.) The homopolymer desorption coefficients were calculated from the appropriate chain transfer constants and radical diffusivities in the aqueous and polymer phases using an extension of the desorption theory developed by Nomura and Fujita (12.). The homopolymer termination constants were corrected for the Trommsdorff effect by using the Friis and Hamielec (12) correlation. 

E. TrommsdorfP, Colloquium on High Polymers (Freiburg, 1944) E. Trommsdorff, H. Kohle, and P. Lagally, MakromoL Chem., 1, 169... 

Although the basic mechanisms are generally agreed on, the difficult part of the model development is to provide the model with the rate constants, physical properties and other model parameters needed for computation. For copolymerizations, there is only meager data available, particularly for cross-termination rate constants and Trommsdorff effects. In the development of our computer model, the considerable data available on relative homopolymerization rates of various monomers, relative propagation rates in copolymerization, and decomposition rates of many initiators were used. They were combined with various assumptions regarding Trommsdorff effects, cross termination constants and initiator efficiencies, to come up with a computer model flexible enough to treat quantitatively the polymerization processes of interest to us. 

Consistent with the preceeding acid work, when TMPTA is added to the monomer solutions containing either lithium salt or urea, synergistic effects are observed for the radiation grafting of styrene to polypropylene (Table IV). Again the maximum increase in yield occurs in the monomer solution corresponding to the Trommsdorff peak. 

---