Synthesis and characterization of block copolymers based on natural rubber and polypropylene oxide

Abstract

Segmented block copolymers from different grades of hydroxyl terminated liquid natural rubber (HTNR) (Mn 3000, 8800, 10,000, and 17,000) and polypropylene oxide (PPO) (Mn 1000, 2000, 3000, and 4000) have been synthesized and characterized by spectral analysis, thermal analysis, scanning electron microscopy (SEM), and mechanical testing. The glass transition temperature of NR block was found to be at about −64°C, which is independent of the PPO whose transition is around 15°C. The thermogravimetric analysis (TGA) shows that the thermal degradation of the samples proceeded in two steps characteristic of the immiscible components. The inability of PPO segments to provide physical crosslinking and the subsequent formation of hard domains is reflected in the low tensile properties and tear properties. The amorphous nature of the PPO phase and its immiscibility with NR phase are evidenced by the SEM studies. The effect of molecular weight of PPO as well as HTNR on the properties of the block copolymers has also been discussed. © 2006 Wiley Periodicals, Inc. JAppl Polym Sci 103: 909–916, 2007

Bio‐based diblock copolymers prepared from poly(lactic acid) and natural rubber

“…NR has been chemically modified to obtain a hydroxyl terminated liquid rubber (a hydroxyl telechelic natural rubber, HTNR). Only two publications have reported the synthesis of HTNR‐based diblock copolymers, i.e., HTNR‐poly(butyl acrylate) and HTNR‐poly(propylene oxide) diblock copolymers …”

PAA-g-PPO Amphiphilic Graft Copolymer: Synthesis and Diverse Micellar Morphologies

“…Moreover, PPO homopolymer prepared by anionic polymerization contains one or two hydroxyl end functionalities, and this kind of commercially available functional PPO homopolymer is in favor of almost unlimited chemical modification. PPO-based block copolymers (PEO was usually selected as another block) − have been extensively studied due to their convenient syntheses, and only a few examples touched on PPO-based graft copolymers. − Most of these graft copolymers were synthesized from PPO-based macromonomers containing (meth)acrylate end groups using living or traditional radical polymerization, and ester linkages were employed to connect PPO side chains with the hydrophobic backbone in these “graft” copolymers, implying PPO segments would be detached after the hydrolysis of ester connections. − PPO-based graft copolymers can also be obtained via other types of PPO-based macromonomers by the condensation polymerization or catalyzed coupling polymerization. , Moreover, nucleophilic substitution reactions , were also applied to synthesize the graft copolymers containing PPO side chains, whose backbone and side chains were prepared independently; however, the grafting densities of these graft copolymers were not clear or very low (60/1230 = 4.88%), and they possessed broad molecular weight distributions, , this indicating that these graft copolymers might not be well-defined. The pendant hydroxyls of ethylene−vinyl alcohol copolymer were also employed to initiate anionic graft polymerization of propylene oxide to afford the densely grafted polymers containing PPO side chains .…”

“…Moreover, PPO homopolymer prepared by anionic polymerization contains one or two hydroxyl end functionalities, and this kind of commercially available functional PPO homopolymer is in favor of almost unlimited chemical modification. PPO-based block copolymers (PEO was usually selected as another block) [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19] have been extensively studied due to their convenient syntheses, and only a few examples touched on PPObased graft copolymers. [20][21][22][23][24][25][26][27][28] Most of these graft copolymers were synthesized from PPO-based macromonomers containing (meth)acrylate end groups using living or traditional radical polymerization, and ester linkages were employed to connect PPO side chains with the hydrophobic backbone in these "graft" copolymers, implying PPO segments would be detached after the hydrolysis of ester connections.…”

Penggunaan enzim protease pada pengolahan lateks pekat DPNR sebagai bahan pembuatan sphygmomanometer Use of protease on the processing of concentrated latex DPNR as material for sphygmomanometer manufacturing

“…Penurunan kadar protein dan N total tersebut dapat difahami karena protein dalam lateks pekat DPNR terurai oleh aktivitas enzim proteolitik dan hasil pemecahannya terbuang bersama-sama dengan serum ketika lateks disentrifugasi. antioksidan (Nair, 2006). Namun, terurainya protein dari BM tinggi menjadi BM yang lebih rendah menyebabkan produk yang dihasilkan sedikit lengket (sticky).…”