Plasma filler, mechanical properties

The results demonstrate the versatility of plasma polymerization of various monomers onto rubber fillers and vulcanization ingredients. The largest effects are seen in blends of different rubbers with unequal polarities. Substantial improvements in mechanical properties are seen in comparison with the use of unmodified fillers and curatives. 

Surface modification of silica, another filler used in the rubber industry, has been reported by Nah et al. [36, 37]. The silica surface was modified by plasma polymerization of acetylene. The modified silica was mixed with SBR to study its performance. They observed an increase in reinforcement with the plasma-modified silica and hence better mechanical properties. They also observed an improvement in the dispersion properties for the plasma-coated silica. The authors explained the observed improvement in properties by a mild crosslinking between plasma-polymerized acetylene and the butadiene part of the SBR matrix. 

Mechanical Properties of Polymer Composites Using Plasma-Modified Mica Filler... 

It is concluded that surface modification of mica, produced by exposing the material to microwave plasmas, can create large positive or negative effects in the mechanical properties of filled polymers and polymer blends. Property enhancement is associated with the production of surface layers on the filler which... 

Young s modulus values of 2.7 GPa. Plasma-enhanced chemical vapour deposition (PECVD) was successfully used to produce a PMMA conformal coating (using methyl methacrylate monomers) on MWNTs. This increased the Young s modulus to 2.85 GPa at 3 wt% which corresponds to dT/dFf of 28.4 GPa. The overall set of mechanical properties indicates that the polymer coating had a significant effect on the mechanical properties at a 1 wt% concentration of tubes, suggesting improved interfacial adhesion between the filler and the matrix material. 

Powders are commonly used as fillers for rubber mixes. The most popular are carbon black, silica, kaolin, or more modem like graphene, fullerenes and carbon nanotubes. The nature of their surface is the main attribute of fillers, as surface energy and specific area determine the compatibility of filler with mbber matrix and the affinity to other c ingredients. One of the major problems is the tendency of fillers to agglomeration - formation of bigger secondary stmctures, associated with lower level of filler dispersion, what is reflected by the decrease of mechanical properties of mbber vulcanizates [1]. Surface modification of powder can improve interaction between mbber matrix and filler. Application of low-temperature plasma treatment for this purpose has been drown increasing attention recently [2, 3]. 

Pictures of NBR-W-REF samples (Fig. 4a, b) present broken needles of wollastonite in the area of fracture, whereas in the case of NBR-W-48 sample (Fig. 4c, d) needles of wollastonite are non-broken but pulled out fi om rubber matrix. This change to morphology, reflected by lower rubber-filler interactions, responsible for worse mechanical properties of rubber vulcanizates (see Section 12.3.3), is undoubtedly the result of an increase of SFE polar component of filler after plasma treatment. The SEM pictures of the vulcanizates, no matter, containing virgin or modifies wollastonite particles, do not reveal any filler agglomeration. 

Morphology of SBR-K-REF and SBR-K-16H samples are presented in Fig. 12.5. Agglomerates of kaolin can be seen in vulcanizate containing reference filler (Fig. 12.6a, b). Modified kaolin does not exhibit tendency to agglomeration (Fig. 12.5c, d). Better filler dispersion suggests on higher mechanical properties of the SBR vulcanizates filled with plasma treated kaolin. 

Mechanical properties of the vulcanizates studied, containing virgin and plasma modified fillers are presented in Figs. 12.6a-12.6f. 

Mechanical properties of wollastonite filled NBR vulcanizates decrease due to plasma modification of the filler (Fig. 12.6c), whereas in case of vulcanizates based on SBR an increase of TS and Eb is observed (Fig. 12.6d) - especially for the most effective 48 min treatment. SEM pictures of the vulcanizates confirm on adequate changes to their morphology. 

The effects of modifying particulate surfaces are illustrated in terms of the mechanical properties of the filled LDPE. In Fig. 30 are given the values of Young s modulus vs CaC03 concentrations (wt%) for different particulate surface treatments. Addition of unmodified filler raises the modulus (Fig. 30, curve 1) as may be expected. Modifications of the acid-base interaction characteristics and of the surface energies yield major changes in the effect of filler on modulus. Treatments in Ar, CH4 and both Ar and CH4 plasma are most effective in increasing the modulus of the compounds (curves 2 and 3, Fig. 30), while the treat-... 

---