Grafting, viii

Similar studies were undertaken as a comparison in the styrenic systems, although in these systems we also were able to compare the graft systems to diblock systems of similar composition. DSC also shows a depression of the high temperature Tg for all of the styrenes for the IK graft systems. The 5K systems showed a smaller depression but still a slight lowering of the Tg (Table VIII). Clearly, the t-butylstyrene system is most influenced, as anticipated. 

Table VIII. Dependence of Architecture and Molecular Weight of Styrenic-Siloxane Block and Graft Copolymers on Tg (Copolymers 20 wt.% PSX)...

Table VIII. Synergistic Effect of Multifunctional Acrylates with Inorganic Salts (L) in Grafting Styrene to Polypropy- lene Initiated by UVa ...

TABLE VIII. Effect of Acid in Methanol to in the Radiation Grafting of Styrene Polyethylene using Open Tubes.a ... 

Table VIII. Synthesis Data and Physical Characteristics of Graft Terpolyraer...

Reaction 22 has an RC>2H/Fe2+ mole ratio of 160 but has about the same yield as an uncontaminated reaction, 17 and 21. Reaction 19 has an RC>2H/Fe2+ mole ratio of 13.3 but again shows no change in yield from that of an uncontaminated reaction. Sample 20 has a 1.35 mole ratio of RO2H to Fe2+ and shows a sharp decrease in reaction yield and grafting. Here, the approximately 1 1 mole ratio of peroxide to iron should produce a high concentration of hydroxide radicals and extensive polymerization if these radicals are part of the polymerization process. Instead of a high yield, however, the reaction yield was less than one third of that obtained in the absence of iron. Therefore, a Fenton s initiation mechanism for this reaction is inconsistent with the data and probably does not occur. Elemental analysis data of Table VIII showed that product composition is proximate to, but not equal to, reaction mixture composition. 

It is thus possible to investigate the conditions under which common intermediates may exist in both grafting and homopolymerisation processes. The results in the following Tables I -VIII thus concern acid effects in the radiation homopolymerisation of styrene in dioxan. 

Tables VII and VIII and Figure 11 show the effect of reaction time on the percent grafting, grafting efficiency, and molecular weight of the grafted chains for BPO and AIBN systems.

Table VIII. Effect of Reaction Time on Grafting Reaction with AIBN as Initiator...

In the absence of benzoyl peroxide, no discernible conversion of acrylic esters has been observed under the conditions used for AFR polymerization. At levels of 0.1-0.3 gram of peroxide and 0.5-5.0 ml. of dimethylaminoethyl methacrylate, conversion to graft polymers was observed at 70 °C. for 16 hours with an active polypropylene slurry, as shown in Table VIII. 

Table VIII. Graft Copolymer Containing 8% Ethylene—Vinyl Acetate Copolymer (45% VAc) and 92% PVC°...

Tables VIII and IX show the essential data of the most important graft copolymers regarding application.

Table VIII. Effect of Formic Acid in UV Grafting of Ethyl Acrylate (EA) in Methanol to Cellulose Using Styrene Comonomer Technique0...

Table VIII lists the parts of graft per 100 parts of rubber for some laboratory runs as well as the latex particle size and tensile impact. The correlation of the degree of grafting to tensile impact still holds—i.e., within each latex system the higher the degree of grafting, the greater the impact. This condition however does not hold from latex to latex. A higher level of graft in one latex does not necessarily produce a higher...

Table VIII. Quantitative Measurement of Degree of Grafting and Its Correlation with Tensile Impact...

Inclusion of DVB into the copolymer also minimised the degradation effect during sulfonation and the resins produced were more stable (Table VII). However the migration of ions in and out of the grafted resins were slower when DVB was included (Table VIII). The results indicate that the DVB resins are structurally... 

Table VIII. Effect of DVB on Rates of Exchange of Sulfonated Styrene-Polypropylene Graft Copol3mier Ion Exchange Resins...

The presence of stabilizer has little effect on poly (vinyl chloride) carboxylation (Table VIII). Since the other polymers were also subjected to the carboxylation process without removing commercial additives such as antioxidants, UV and thermal stabilizers, antiblocking agents, etc.—the additives inhibit neither the polymerization of the styrene-maleic anhydride complex nor the grafting reaction. 

Using various silica-supported group VIII host metals (Ru, Rh, Ni, Pd, Pt) in the reduced state and SnIU as organometallic compounds, similar grafted species were obtained by reactions at temperatures close to 300 K under hydrogen (or with the surface of the host metals, covered by chemisorbed hydrogen). 

A.S. Singha, and B.S. Kaith, "Modification of natural polymers-VIII Graft copolymerisation of methylmethacrylate onto cellulose" International Congress of Chemistry and Environment, 2001. 

Lithium salts when used as additives also increase the grafting yields for the same reaction, lithium perchlorate being more efficient that lithium nitrate (Table VII ). A comparison of the effectiveness of acid versus lithium perchlorate in the same grafting reaction Is shown in Table VIII, the salt being more effective than acid only at the lower monomer concentrations l.e. 25%. 

Table VIII. Synergistic Effect of Acid and Polyfunctional Monomers as Additives for Enhancing UV and Ionizing Radiation Grafting of Styrene in Methanol to Polyethylene Film...

In a unique application of RRC, the present authors are preserving timber and leather artefacts from Henry VIII s warship. The Mary Rose, which sunk in the Solent and was recently recovered after 438 years on the seabed. The fact that, using the additives outlined in this paper, grafting may be Increased during these RRC treatments is very Important, since the enhancement effect may well improve the physical properties of the material and thus should assist the longevity of the final product of the preservation process. 

Phenyl diisocyanate (VIII) was used as a grafting molecule following the same strategy discussed above in the case of the double anhydride in [14—17]. As expected, the FTIR spectrum of the modified wood surface, after extraction of the unreacted VIH, displayed a strong peak at 2 250cm, characteristic of the presence of isocyanate functions (see Fig. 20.5). These modified wood samples were treated with the biocides IV and V, which provided an excellent resistance to fungi [18]. 

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