Compatibility of liquid deproteinized natural rubber having epoxy group (LEDPNR)/poly (L‐lactide) blend

Abstract

Reaction after mixing of liquid epoxidized natural rubber/poly(L-lactide) blend was performed to enhance the compatibility of the blend. The liquid epoxidized natural rubber was prepared by epoxidation of deproteinized natural rubber with peracetic acid in latex stage followed by depolymerization with peroxide and propanal. The resulting liquid deproteinized natural rubber having epoxy group (LEDPNR) was mixed with poly(L-lactide) (PLLA) to investigate the compatibility of the blend through differential scanning calorimetry, optical light microscopy, and NMR spectroscopy. After heating the blend at 473 K for 20 min, glass transition temperature (T g ) of LEDPNR in LEDPNR/PLLA blend increased from 251 to 259 K, while T g and melting temperature (T m ) of PLLA decreased from 337 to 332 K and 450 to 445 K, respectively, suggesting that the compatibility of LEDPNR/ PLLA blend was enhanced by a reaction between the epoxy group of LEDPNR and the ester group of PLLA. The reaction was proved by high-resolution solid-state 13 C NMR spectroscopy.

Poly(Lactic Acid) Blends

“…A more recent objective has been to increase the bio-based content of these polymer blends. Among the main polymer families that have been blended with PLA, polyolefins [3][4][5][6][7], vinyl and vinylidene polymers [8,9] and copolymers [23][24][25], and elastomers and rubbers [10][11][12]26] can be extensively found in the research literature. 1 …”

“…proposed that epoxidized natural rubber (ENR), having higher reactivity and better mechanical properties than NR, could be a good candidate to toughen PLLA since compatibility between the polymer pairs could be generated via interaction of the epoxy group from the ENR and the ester group from PLLA [26]. However, the naturally occurring proteins of ENR may prohibit formation of ester linkages between epoxy and ester groups.…”

“…However, the naturally occurring proteins of ENR may prohibit formation of ester linkages between epoxy and ester groups. Therefore, NR-high ammonia NR latex-was modified by deproteinization, epoxidization with peracetic acid, and depolymerization to produce liquid deproteinized natural rubber with epoxy groups (LEDPNR) [26]. For comparison, liquid natural rubber having epoxy groups (LENR) was prepared following the LEDPNR modification method except for the deproteinization.…”

“…The slight changes in T g 's of the blends (an increase in LEDPNR or LENR's T g and a decrease of PLLA's T g ) and a small reduction in the PLLA's T m were more obvious with LEDPNR/PLLA blends than with LENR/blends. 13 C nuclear magnetic resonance (NMR) spectra revealed the existence of an ester linkage peak only when the LEDPNR/PLLA blend underwent a heat treatment of 200 C for 20 min after mixing [26].…”

Development of Biobased Poly(Lactic Acid)/Epoxidized Natural Rubber Blends Processed by Electrospinning: Morphological, Structural and Thermal Properties

“…As NR is an unsaturated polymer with a large number of double bonds in the backbones that are reactive, epoxidized natural rubber (ENR) can be prepared in latex stage by reacting natural rubber with peroxide [26] [27] forming epoxy groups of ENR that would improve the polarity of rubber and hence promoting compatibility with PLA. Nghia et al [28] investigated the compatibility of the ENR/PLA solution blend; they concluded that the reaction occurred between the epoxy groups of ENR and the ester groups of PLA. In this way, a new biomaterial based on PLA/ENR electrospun blends was obtained by electrospinning approach and the effect of ENR content on the blends was studied with the help of characterization techniques such as scanning electronic microscopy (SEM), Fourier transform infrared spectroscopy (FTIR), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) and dynamic mechanical analysis (DMA).…”