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

Abstract

The dynamic mechanical behavior of modified deproteinized natural rubber (DPNR) prepared by graft copolymerization with various styrene contents was investigated at a wide range of temperatures. Graft copolymerization of styrene onto DPNR was performed in latex stage using tert-butyl hydroperoxide (TBHPO) and tetraethylene pentamine (TEPA) as redox initiator. The mechanical properties were measured by tensile test and the viscoelastic properties of the resulting graft copolymers at wide range of temperature and frequency were investigated. It was found that the tensile strength depends on the grafted polystyrene; meanwhile the dynamic mechanical properties of the modification of DPNR meaningfully improved with the increasing of both homopolystyrene and grafted polystyrene compared to DPNR. The dynamic mechanical properties of graft copolymer over a large time scale were studied by constructing the master curves. The value of bT has been used to prove the energetic and entropic elasticity of the graft copolymer.

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

“…Figure 9 shows the loss modulus (G ″ ) in the plateau region versus the frequency for DPNR and DPNR-graft-PMMA samples. The loss modulus value of DPNR was 10 4 Pa. We can readily demonstrate that this value is typical for conventional uncross-linked rubber and is similar to the G ″ of NR previously reported [29,40]. In addition, the loss modulus decreases as the frequency increases [41].…”

Improvement of thermal properties of Vietnam deproteinized natural rubber via graft copolymerization with styrene/acrylonitrile and diimide transfer hydrogenation

“…Due to increasing relevance of environmental issues in recent times, the development of biogenic sustainable materials, such as NR, has been receiving more attention. Furthermore, NR possesses outstanding properties, such as excellent elasticity, high strength, good tear resistance, and good dynamic properties 2,3 . However, due to the presence of carbon‐carbon (CC) double bonds in the isoprene backbone, NR is prone to thermal, oxidative, and radiation‐induced degradation when exposed to oxygen, long‐term heating, ozone, and sunlight 4,5 .…”

“…These drawbacks limit the application of NR, and therefore, reduce the value of the rubber tree. To overcome the limitation, many types of chemical modifications have been applied on NR, demonstrating their high efficiency toward the improvement of NR's properties 2,6‐11 …”

Dynamic mechanical properties of crosslinked natural rubber composites reinforced with cellulosic nanoparticles

“…The storage modulus measures the stiffness and stored energy; representing the elastic region of viscoelastic materials [6]. -CB NR-BNC NR-CHNC NR-CLNC NR 100 100 100 100 100 Zinc oxide 5 5 5 5 5 Stearic acid 2 2 2 2 2 Reinforcing filler -25 25 25 25 TMQ 1 1 1 1 1 MBTS 2 2 2 2 2 Sulphur 3 3 3 3 3 NR = natural rubber, TMQ = trimethylquinolone, MBTS = mercaptobenzothiazoledisulfide, NR-CB = natural rubber-carbon black, NR-BNC = natural rubber-bamboo cellulosic particles, NR-CHNC = natural rubber-coconut husk cellulosic particles, NR-CLNC = natural rubber-cotton lint cellulosic particles.…”

“…The principle of DMA measurement is such that, a sinusoidal stress is applied and the corresponding strain in the material is evaluated, allowing one to determine the storage modulus, loss modulus and loss tangent or damping Factor. By studying the dependence of these parameters on temperature or frequency, it is possible to show the dynamic mechanical properties (such as thermodynamic transitions and other molecular relaxation) of the materials and their applications [5,6]. The vulcanization of natural rubber inserts three dimensional crosslink network structures into rubber matrix that will lead to decrease in its chain mobility and conformational entropy [7][8].…”