Physical and mechanical properties of poly(methyl methacrylate)‐grafted natural rubber synthesized by methyl methacrylate photopolymerization initiated by N,N‐diethyldithiocarbamate functions previously created on natural rubber chains

Abstract

Well-defined poly(methyl methacrylate) (PMMA)-grafted natural rubbers (NRs) were prepared to study the structure-property relationships. Syntheses were achieved by the photopolymerization of methyl methacrylate initiated by N,N-diethyldithiocarbamate groups created beforehand in side positions on the NR chains. With this procedure, good control of the graft density and PMMA content could be obtained. Thermal, morphological, and mechanical properties of NR-g-PMMA copolymers were studied as a function of the NR/PMMA composition and graft density. NR-g-PMMAs containing 15-80% grafted PMMA showed characteristics of heterogeneous materials (characterized by two glass-transition temperatures, those of PMMA and NR, in differential scanning calorimetry). Under these conditions, they developed the morphology of thermoplastic elastomers with PMMA nodules dispersed in the rubber matrix when the PMMA content was near 20%; conversely, they developed the morphology of softened thermoplastics with rubber nodules dispersed in PMMA when the PMMA content was near 80%. Graft copolymers containing about 20% PMMA remained essentially rubbery, but they were already different from pure NR. On the other hand, the thermal stability of NR wash improved after the introduction of PMMA grafts onto NR chains.

Improvement of Thermal and Mechanical Properties of Vietnam Deproteinized Natural Rubber via Graft Copolymerization with Methyl Methacrylate

“…There was only one T g observed at -62.5°C, which corresponds to the cis-1,4 polyisoprene structures of the DPNR, which has also been reported in Derouet's study [23]. It can be seen that after graft copolymerization, the T g of graft copolymer slightly shifts to -60.5°C due to the presence of grafted PMMA chain on the NR molecules.…”

“…In addition, different aspects of this modification have been examined recently. Some prominently used vinyl monomers are acrylonitrile (AN) [19], methyl methacrylate (MMA) [20][21][22][23], maleic anhydride (MA) [24], and styrene [2,7,8]. MMA and styrene are the most suitable for grafting with NR because of their high grafting efficiency.…”

Dynamic Mechanical Properties of Vietnam Modified Natural Rubber via Grafting with Styrene

“…The master curves were built following the timetemperature superposition principle. The horizontal shift factor, , and vertical shift factor, , are expressed by the WLF equations (1) and (2), respectively [21,27,[31][32][33].…”

Influence of Reaction Volume on the Properties of Natural Rubber-g-Methyl Methacrylate

“…of PMMA measured by extraction method was calculated based on the conversion and GE compared with initial weight of monomer. On the other hand, the grafting level based on 1 H-NMR technique was determined from the integrated peak area of protons according to Equation (6). It is seen that both the techniques gave decreasing trends of grafted PMMA with increasing reaction volume.…”