Effects of Coagent Functionalities on Properties of Ultrafine Fully Vulcanized Powdered Natural Rubber Prepared as Toughening Filler in Rigid PVC

Abstract

Ultrafine fully vulcanized powdered natural rubber (UFPNR) has a promising application as a renewable toughening modifier in polymer matrices. In this work, the effects of acrylate coagents, which had different amounts of functional groups, on properties of UFPNR produced by radiation vulcanization and spray-drying was systematically investigated for the first time. Dipropylene glycol diacrylate (DPGDA), trimethylol propane trimethaacrylate (TMPTMA), and ditrimethylol propane tetraacrylate (DTMPTA) were used as coagents with two, three, and four acrylate groups, respectively. The radiation in the range of 250 to 400 kGy and coagent contents of up to 11 phr were used in the production process. Physical, chemical, and thermal properties of the UFPNR were characterized by swelling analysis, scanning electron microscopy, infrared spectroscopy, thermogravimetric analysis, and differential scanning calorimetry. The properties of UFPNR produced by using different type and content of coagents were compared and discussed. The results revealed that UFPNR with the smallest particle size of 3.6 ± 1.1 μm and the highest thermal stability (Td5 = 349 °C) could be obtained by using DTMPTA, which had the highest amount of functional group. It was proposed that the coagent with the greater number of acrylate groups enhanced the crosslinking of natural rubber as it had more reactive groups. Finally, an application of UFPNR as a toughening filler in rigid PVC was demonstrated with 34% improvement of impact strength.

Ultrafine fully vulcanized natural rubber modified by graft-copolymerization with styrene and acrylonitrile monomers

“…In addition, intermolecular forces in grafted copolymers increased due to the introduction of polar nitrile groups in PAN at interface of NR and may cause movement limitation of NR chain. However, the effect of irradiation dose on T g of modified UFPNRs was slightly increased compared with un-irradiated NR, which is about − 64 °C, agreeing with previous work (Lin et al 2021;Taewattana et al 2018;Wongkumchai et al 2021).…”

“…Recently, ultrafine fully vulcanized powdered natural rubbers (UFPNRs) have become an alternative to traditional commodity synthetic rubber powder, due to renewable resources used for their preparation, which are environmentally friendly and reasonably priced (Gupta et al 2016 ; Haile et al 2021 ; Yang et al 2021 ). UFPNRs are illustrated to be suitable toughening fillers in a polymer matrix (Lin et al 2021 ; Wongkumchai et al 2021 ). Ultrafine fully vulcanized powdered rubbers (UFPRs) were prepared by irradiation vulcanization followed by a spray drying process to produce a controllable spherical particle powder (Qiao et al 2002 ).…”

Radiation Graft-Copolymerization of Ultrafine Fully Vulcanized Powdered Natural Rubber: Effects of Styrene and Acrylonitrile Contents on Thermal Stability

“…Furthermore, it was found that the average particle size of the UFPNR-g-PANs was from 7.73 ± 3.29 µm to 6.95 ± 3.33 µm, 6.62 ± 2.90 µm and 6.39 ± 2.71 µm with increasing radiation doses from 50 kGy to 300 kGy, respectively. Regardless, the developed UFPNRs grafted St or AN monomers and subsequently irradiated at 300 kGy showed good dispersion the least aggregation than the UFPNR without grafting and irradiated approximately 350 kGy, however, the similar rubber particle size about 6 µm was obtained [ 1 , 2 ].…”

“…Recently, ultrafine fully vulcanized powdered natural rubbers (UFPNRs) have been developed and demonstrated high potential as a toughening filler in a polymer matrix [ 1 , 2 ] with competitive performance compared to ultrafine fully vulcanized powdered rubbers (UFPRs) based on synthetic rubbers, such as styrene-butadiene (UFPSBR) [ 3 , 4 ], nitrile-butadiene (UFPNBR) [ 5 , 6 ] and polybutadiene rubber (UFPBR) [ 7 ].…”

Ultrafine Fully Vulcanized Natural Rubber Modified by Graft-Copolymerization with Styrene and Acrylonitrile Monomers

“…Recently, ultrafine fully vulcanized powdered natural rubbers (UFPNRs) have become an alternative to traditional commodity synthetic rubber powder, due to renewable resources used for their preparation, which are environmentally friendly and reasonably priced (Gupta et al 2016;Haile et al 2021;Yang et al 2021). UFPNRs are illustrated to be suitable toughening fillers in a polymer matrix (Lin et al 2021;Wongkumchai et al 2021).…”