Glass-transition temperature enhancement

Lin, C. T., Kuo, S. W, and Chang, F. C. 2010. Glass transition temperature enhancement of PMMA through copolymerization with PMAAM and PTCM mediated by hydrogen bonding. Polymer 51 883-889. 

As mentioned above, it seems reasonable that p should not exceed unity if crystal field coordination parameters do not underestimate metal-ligand bonding in the amorphous phase. This restriction on p allows one to identify the minimum value of A(LFSE) for complexes with arbitrary geometry and coordination number. Based solely on experimental data and the proposed concentration dependence of glass transition temperature enhancement. 

Tackifying resins enhance the adhesion of non-polar elastomers by improving wettability, increasing polarity and altering the viscoelastic properties. Dahlquist [31 ] established the first evidence of the modification of the viscoelastic properties of an elastomer by adding resins, and demonstrated that the performance of pressure-sensitive adhesives was related to the creep compliance. Later, Aubrey and Sherriff [32] demonstrated that a relationship between peel strength and viscoelasticity in natural rubber-low molecular resins blends existed. Class and Chu [33] used the dynamic mechanical measurements to demonstrate that compatible resins with an elastomer produced a decrease in the elastic modulus at room temperature and an increase in the tan <5 peak (which indicated the glass transition temperature of the resin-elastomer blend). Resins which are incompatible with an elastomer caused an increase in the elastic modulus at room temperature and showed two distinct maxima in the tan <5 curve. 

The presence of ether linkages in the polymer molecule imparts chain flexibility, lowers glass transition temperature, and enhances solubility while maintaining the desired high temperature characteristics [192]. Recently, polyether imines were prepared by the reaction of different diamines with 4,4 -[l,4-phenylene bis(oxy)] bisbenzaldehyde [184]. The polymers synthesized by the solution method were yellow to white in color and had inherent viscosities up to 0.59 dl/g in concentrated H2SO4. Some of these polyimines can be considered as... 

Fluorinated poly(arylene edier)s are of special interest because of their low surface energy, remarkably low water absorption, and low dielectric constants. The bulk—CF3 group also serves to increase the free volume of the polymer, thereby improving various properties of polymers, including gas permeabilities and electrical insulating properties. The 6F group in the polymer backbone enhances polymer solubility (commonly referred to as the fluorine effect ) without forfeiture of die thermal stability. It also increases die glass transition temperature with concomitant decrease of crystallinity. 

In another smdy, the introduction of an adamantyl group to the poly(etherimide) structure caused polymer glass transition temperature, Tg, and solubility enhancements in some solvents like chloroform and other aprotic solvents [92]. 

The flow of liquid hydrocarbons can be enhanced by introducing into the stream a nonagglomerating suspension of ultra-high molecular weight polyethylene [490,1647] in water with small amounts of surfactant. The finely divided polyethylene is prepared by polymerization and then cryogrinded below the glass-transition temperature. 

Replacement of isopropylidene units in polymer backbones by units of hexafluoroisopropylidene is known to enhance solubility, water and oil repellency, thermal stability, and glass transition temperature (Tg) and to decrease crystallinity and water absorption.1... 

---