Daosheng Yuan

Dynamically Vulcanized Biobased Polylactide/Natural Rubber Blend Material with Continuous Cross-Linked Rubber Phase

We prepared a biobased material, dynamically vulcanized polylactide (PLA)/natural rubber (NR) blend in which the cross-linked NR phase owned a continuous network-like dispersion. This finding breaks the traditional concept of a sea-island morphology formed after dynamic vulcanization of the blends. The scan electron microscopy and dissolution/swell experiments provided the direct proof of the continuous cross-linked NR phase. This new biobased PLA/NR blend material with the novel structure is reported for the first time in the field of dynamic vulcanization and shows promise for development for various functional applications.

Crosslinked bicontinuous biobased PLA/NR blends via dynamic vulcanization using different curing systems

In this study, blends of entirely biosourced polymers, namely polylactide (PLA) and natural rubber (NR), were prepared through dynamic vulcanization using dicumyl peroxide (DCP), sulphur (S) and phenolic resin (2402) as curing agents, respectively. The crosslinked NR phase was found to be a continuous structure in all the prepared blends. The molecular weight changes of PLA were studied by gel permeation chromatography. Interfacial compatibilization between PLA and NR was investigated using Fourier transform infrared spectroscopy and scanning electron microscopy. The thermal properties of blends were evaluated by differential scanning calorimetry and thermogravimetric analysis instrument. It was found that the molecular weight of PLA and interfacial compatibilizaion between PLA and NR showed a significant influence on the mechanical and thermal properties of blends. The PLA/NR blend (60/40 w/w) by DCP-induced dynamic vulcanization owned the finest mechanical properties and thermal stability.

Green method to reinforce natural rubber with tunicate cellulose nanocrystals via one-pot reaction

Tunicate cellulose nanocrystals (t-CNs) isolated from marine biomass were mixed with natural rubber (NR) via two different approaches. The first approach was the green one-pot route, NR latex was first mixed with t-CNs suspension, followed by epoxidization of the mixture. Meanwhile, a two-step method, referring to the way that NR latex was first epoxidized and then mixed with t-CNs suspension, was also carried out for comparison. The interfacial interaction, thermal performance, morphology, mechanical properties and water swelling behavior were investigated. Hydrogen bonds formed in the both nanocomposites and mechanical properties improved with increasing t-CNs content. Moreover, better dispersion and enhanced interfacial interaction were achieved for one-pot method, which was ascribed to the etching effect of hydrogen peroxide on the t-CNs surface and the possible grafting reaction during one-pot process. Therefore, compared with two-step method, 20% increase in tensile strength and 50% increase in tensile modulus were achieved for one-pot method at 10 phr t-CNs content.

Phenolic Resin-Induced Dynamically Vulcanized Polylactide/Natural Rubber Blends

ABSTRACT Blends based on polylactide (PLA) and natural rubber (NR) were prepared through phenolic resin-induced dynamic vulcanization. The cross-linked NR had a continuous phase structure in PLA. The incorporation of NR sacrificed the tensile strength but only had a limited increase in the impact strength of PLA. The viscoelasticities of the PLA melts were largely improved by the cross-linked NR phase, however, the crystallization of the PLA phase was restricted by the continuous NR phase. The initial decomposition temperature of the blends was lowered by the incorporation of NR. GRAPHICAL ABSTRACT