Impact of gamma irradiation on virgin styrene butadiene rubber blended with ultrasonically devulcanized waste rubber

Basi

Islam

et al. 2020

Development of polyurethanes (PU) has come a long way from their origin in 1937 and has unique applications in a diverse set of fields. Recent PU developments are focusing more on the naturally‐derived diols in the synthesis process in an effort to make them more environmentally friendly. In this study, three different diisocyanates (aliphatic, cycloaliphatic, and aromatic diisocyanates) were combined with laccol, which extracted from Vietnamese lacquer sap (Toxicodendron succedanea) to synthesize novel PUs. Influence of the different diisocyanates in novel PUs, hydrogen bonding capability, and crosslinking ability were investigated to provide a broader characteristic scope for future developments. Resulting materials illustrated good thermal stability after exposed to higher temperatures and the hydrogen bonding regions corresponding to NH (3326 cm−1) and CO (1652 cm−1) groups were shifted to higher wavenumber according to Fourier transform infra‐red spectroscopy analysis. Further curing occurred with temperature treatment and improved the overall quality of novel PUs. Powder X‐ray analysis, micro hardness, and swelling analysis were utilized to identify molecular packing and crosslinking effects. Higher crosslink density observed for cycloaliphatic and aromatic diisocyanate incorporated novel polyurethanes compared to aliphatic diisocyanate incorporated polyurethane.

Section: Resultsmentioning

confidence: 93%

Section: Swelling Analysismentioning

confidence: 99%

Synthesis and characterization of novel laccol based polyurethanes

Basi

Islam

et al. 2020

“…The swelling properties depend on many factors such as polymer network density, nature of the solvent and polymer–solvent interactions . Swelling analysis was conducted in toluene solvent to identify the crosslinking nature of the synthesized limonene:laccol copolymers . Percent weight gain of copolymers was calculated before and after gamma radiation treatment as illustrated in Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The weight of the swollen polymer ( M II ) was determined immediately afterward. Percent weight gain was calculated as follows incorporating Eq 1 .

Weight gain (() %) = ((), \frac{M_{II}}{M_{normalI}} - 1) 100, M_{II} \geq M_{I}

…”

Section: Methodsmentioning

confidence: 99%

Environmentally Friendly Radiation Hardd‐Limonene and Laccol Copolymers Synthesized via Cationic Copolymerization

Patel

Basi

et al. 2019

In the modern world, petroleum‐based synthetic polymers have a great number of applications in fields ranging from food packaging to space travel. However, the processing of petroleum products and the resulting depletion of fossil fuels are major environmental concerns in today's society. As a result, the development of sustainable polymers which are made up of renewable resources and waste products is an immerging area of research. Considering the world food production, citrus fruit is most abundant and its contribution to waste generation is immense. Therefore, this study focuses on offering an alternative to the use of petroleum‐based polymers and also providing a regulatory pathway to manage citrus waste by developing novel copolymers of laccol and limonene. Two environmentally friendly compounds, laccol, derived from the sap of Toxicodendron succedaneum tree and limonene, extracted from orange peels, were copolymerized via cationic polymerization to generate d‐limonene:laccol copolymers with radiation hardening capabilities which is relevant in fields such as nuclear energy generation, medicinal sterilization, commercial irradiation, and space exploration. Formation of these copolymers was verified with infrared and nuclear magnetic resonance analysis. The synthesized copolymers were characterized using different methods and exposed to Co‐60 gamma radiation to identify alterations to their properties. POLYM. ENG. SCI., 60:607–618, 2020. © 2019 Society of Plastics Engineers

“…The possible mechanisms for these processes are illustrated in Schemes and . The synthesized polymer and copolymers were exposed to gamma radiation and investigated the characteristic properties resulted from radiation treatment.…”

Section: Introductionmentioning

confidence: 99%

Synthesizing radiation‐hard polymer and copolymers usinglaccolmonomers extracted from lacquer treetoxicodendron succedaneavia cationic polymerization

Patel

Harmon

2019

In recent years, lacquer chemistry stimulated more attention from the scientific community due to its environmental friendly applications. Additionally, the “laccol” possesses promising radiation resistance due to its highly crosslinked polymer network. In nature, lacquer polymerization is induced via enzymatic radical initiation. Herein, as a novel approach, lacquer polymer was synthesized via cationic polymerization with aluminum chloride‐ethyl acetate coinitiator. This approach was further improved by polymerizing copolymers of laccol and styrene designed for use in radiation‐hard materials. The infrared spectroscopic data clearly provide evidence for reactions with trans conjugated double bonds present in long side chain (988 and 966 cm−1 are bending vibrations of conjugated alkenes) of laccol monomer accompanying polymerization. This was further verified with proton nuclear magnetic resonance analysis. An increase in hardness was observed for all the compositions: remarkably for neat laccol polymer, and 90% and 70% laccol‐styrene copolymers after the gamma irradiation using Co‐60 gamma irradiator. Properties such as thermal stability and hardness were improved after irradiation due to the increase in physical and small amounts of chemical crosslinking. Therefore, the developed materials are suitable candidates to produce radiation‐hard polymer and copolymer coatings for aerospace operations, nuclear reactors, and medicinal and automobile sectors. POLYM. ENG. SCI., 59:1611–1623 2019. © 2019 Society of Plastics Engineers