Academic literature on the topic 'Dipentene'

The work is aimed at experimental substantiation of dipentene (dl-limonene) extraction from pyrolysis liquid obtained by pyrolysis in the lead melt of tires of different brands. Pyrolysis liquid was isolated under conditions that reduce the sulfur content and increase the proportion of dipentene in the direct-contact reactor in the lead melt and in the temperature range of 400-470 °C. A method for extracting dipentene from pyrolytic liquid by distillation at normal pressure, in vacuum, and two-stage distillation (first with water vapor, then vacuum distillation) to obtain fractions enriched with dipentene was tested. The results obtained demonstrate that at this stage of the study the chemically unstable fraction of polyene hydrocarbons in the pyrolysis liquid is actively polymerized during distillation. The chromatographic analysis of the initial samples and distillation fractions was carried out, which showed that the feedstock contains more than 100 chemicals with a dipentene content of not more than 17%. Based on the evaluation of the obtained quantitative characteristics, distillation parameters providing the maximum yield of dipentene were determined. Under the proposed conditions, the enrichment of individual fractions with dipentene by ~4-6 times compared to its initial content in pyrolysis liquid was achieved. During distillation in vacuum, a fraction with a yield of 19.6% with a content of dipentene up to 40.8% was isolated, a narrow fraction with an yield of 4.8% with a maximum content of dipentene of 49.9% was isolated. During distillation with steam and subsequent vacuum distillation with a total yield of 17%, fractions with a dipentene content of 24-36 % were isolated. Further concentration of dipentene will obviously require more complex chemical synthesis and fractionation operations. The data obtained may be of interest in the development of a new process of pyrolysis of tires in the melt of heavy metals (lead), improving its efficiency by identifying economically important components for the production of commercial products.

Tire wear particles (TWPs) are generated by friction between the road and the tire. TWPs are one of the major microplastics found in environmental samples, such as road dust, particulate matter (PM), and sediment. TWP contents in environmental samples are generally analyzed using the pyrolysis technique. Tire tread compounds of heavy vehicles are usually composed of natural rubber (NR). Isoprene and dipentene are the principal pyrolysis products of NR, and dipentene is employed as the key marker for the determination of the TWP contents. In this study, an NR abrasion specimen was thermally aged, and an abrasion test was performed to obtain the wear particles. The influence of the wear particle size and thermal aging on the pyrolysis behavior of NR was investigated. The isoprene/dipentene ratio exponentially increased as the wear particle size decreased, and it was also increased by the thermal aging of the abrasion specimen. The increased isoprene/dipentene ratio by thermal aging was explained by increasing the crosslink density. Using the relationship between the wear particle size and the isoprene/dipentene ratio, it is possible to estimate the isoprene/dipentene ratio for very small TWP such as PM. The experimental results concluded that the wear particle size and thermal aging affect the formation of the key pyrogenic products, and the influencing factors should be considered for the quantification of TWP contents in the environmental samples.

In this paper, we prepared Dipentene Hydrogenation Catalyst by impregnating, with activated alumina as catalyst carrier and nickel nitrate solution as soaking liquid. The objective of this study was to investigate the influences of the amount of nickel loading, calcination temperature and hydrogen reduction temperature on catalyst activity. The results show that the optimum parameters are: 21% of nickel loading, the calcination temperature of 550-650 °C, the hydrogen reduction temperature of 325-350 °C. The purity of p-menthane prepared under the conditions was more than 97 %, reaching special class standards.

The need to regulate the non-exhaust particulate matter (PM) emissions from vehicles has been discussed worldwide due to the bad environmental impact and the toxicity to the human body. In-depth studies have been precisely conducted on the analysis of the non-exhaust particulate matters, in particular, the amount of tire, brake and road wear particles and their proportion in the atmosphere. In this study, the influence of tire and road wear particles (TRWP) on PM in the atmosphere was investigated with tire and PM samples. The PM samples suspended in the atmosphere were collected with a high-volume sampler equipped with a quartz filter. Additionally, polycyclic aromatic hydrocarbons (PAHs) and metal components in tire rubber were analyzed as markers by pyrolysis–gas chromatography/mass spectrometry (pyrolysis–GC/MS), GC/MS, and inductively coupled plasma/mass spectrometry (ICP/MS). More vinylcyclohexene was detected than dipentene in the markers measured in the samples of tires equipped with vehicles driving on the road, while more dipentene was measured in total suspended particles (TSP) samples. Among the PAHs in tire samples, pyrene exhibited the highest concentration. Benzo(b)fluoranthene showed the highest concentration in the TSP samples. Among the metals, the highest concentration was zinc in all tire samples and calcium in TSP samples.

Radiolabelled free radicals were formed by the addition of muonium-a radioactive hydrogen atom with a positive muon as its nucleus-to α-pinene, β-pinene, dihydrocarvone, dihydrocarveol and dipentene, each as adsorbed in porous carbon. The radicals were identified using transverse-field muon spin rotation (TF-MuSR) and the activation parameters associated with their reorientational motion were measured using longitudinal-field muon spin relaxation (LF-MuSRx). Two distinct adsorbed fractions were detected in each sample, characterised by activation energies in the range 2-6 kJ/mol and 12-16 J/mol respectively.

Questa tesi ha affrontato due macro-temi riguardanti lo sviluppo sostenibile. La parte I “Additivi innovativi come modificatori di viscosità per lubrificanti a risparmio energetico" ha riguardato la progettazione e lo sviluppo di nuovi additivi modificatori di viscosità (VM). Essi sono fondamentali per regolare la dipendenza viscosità/temperatura negli oli lubrificanti consentendo loro di prevenire perdite di energia dovute all’attrito che determinano un incremento del consumo di carburante e delle relative emissioni. Sono state sintetizzate delle nuove strutture polimeriche ben definite a stella e a pettine con braccia di copolimeri stirene-b-isoprene. Braccia con bassa polidispersità sono state sintetizzate da polimerizzazione anionica, le strutture a stella sono state prodotte con il metodo arm-first e le strutture a pettine mediante il metodo grafting onto. I polimeri stellari a 4 e 6 braccia sono stati preparati aggiungendo dei nuclei di cloro alchilsilano alle braccia polimeriche viventi. I polimeri a pettine sono stati sintetizzati aggiungendo un nuovo scheletro polimerico fatto di poli(t-butil-6-5-norbornene-eso-2,3-dicarbossiimidoesanoato) come terminatore delle braccia polimeriche viventi. Sono stati ottenuti copolimeri a pettine aventi fino a 16 braccia. Le unità di isoprene sono state idrogenate per renderli stabili alle sollecitazioni ossidative e meccaniche. Dopo l'idrogenazione, i copolimeri stellari a 6 braccia hanno mostrato un buon comportamento a bassa temperatura e un'eccellente compatibilità con il pour point depressant e una stabilità al taglio migliore della maggior parte delle VM commerciali. Inoltre, si prevede che dopo l'idrogenazione i nuovi copolimeri a pettine avranno un'efficienza di ispessimento superiore a quella dei copolimeri stellari idrogenati per il loro gran numero di braccia. La Parte II " Polimeri ricchi di zolfo" ha previsto il riutilizzo del disolfuro di carbonio (CS2) (Parte II A) e dello zolfo elementare (Parte II B), come materia prima per la produzione di polimeri, al fine di aiutare a superare "il problema dello zolfo in eccesso" e produrre materiali di alto valore. Nella parte II A, per la prima volta è stata studiata la copolimerizzazione tra CS2 e cicloesene solfuro con catalizzatori di cromo tipo salen e salphen e sali di PPNX a 25 e 50 °C. Entrambi i sistemi catalitici hanno prodotto sia materiale polimerico che ciclico. I catalizzatori di tipo salphen, rispetto a quelli di tipo salen, hanno mostrato una maggiore produttività e selettività per il polimero. Sono stati ottenuti politritiocarbonati ad alto peso molecolare fino a 18 kg/mol. A 50°C con (salphen)CrCl, il valore massimo di selettività per i copolimeri è stato ottenuto a 3 h. I poli(tritiocicloesene carbonati) hanno alto indice di rifrazione (n > 1.72) e proprietà antimicrobiche che con i valori di Tg di 80 °C rendono questi materiali adatti per applicazioni interessanti diverse da quelle dei poli(tritiopropilenecarbonati). Nella parte II B, il dipentene, una miscela di monoterpeni sostenibile e rinnovabile, è stato usato per la prima volta in combinazione con zolfo elementare, per produrre polisolfuri green ed economici alternativi a quelli prodotti dal limonene. Poli(S-dipenteni) con alto contenuto di zolfo (> 50 %) sono stati sintetizzati mediante polimerizzazione inversa catalitica in presenza di acceleratori a base di zinco. Gli acceleratori hanno permesso di ridurre il tempo di miscelazione tra dipentene e zolfo. Sono stati ottenuti ter-polisolfuri stabili, aggiungendo il 10 % di un crosslinker naturale come garlic oil, mircene e disolfuro di diallile. I ter-polisolfuri prodotti sono solidi morbidi con valori di Tg tra -1 e 4 °C. Sono state preparate delle miscele di ter-polisolfuro e polistirene che mantengono la forma, processabili e in grado di rimuovere gli ioni ferrici da soluzione acquosa.
This thesis addresses two macro themes concerning the sustainable development which implies reduction of petroleum dependence and minimization of carbon footprint. The Part I “Innovative additives as viscosity modifiers for energy saving lubricants” concerns the design and development of new viscosity modifier additives (VMs), which are fundamental to regulate the viscosity/temperature dependence in lubricant oils enabling them to prevent energy loss due to friction phenomena which determines an increment in fuel consumption and consequently the associated emission. New controlled star and comb polymer architectures with styrene-b-isoprene copolymer arms were synthesized. Arms with very low molecular weight dispersion were obtained by anionic polymerization. Star like structures were produced by arm-first method and new comb-copolymers were achieved through “grafting onto” method. Four- and six-arm star polymer structures were prepared by adding chloro alkylsilane cores to living polymeric arms. Comb polymers were synthesized by adding a new polymeric skeleton made of poly(t-butyl-6-5-norbornene-exo-2,3-dicarboxyimidohexanoate) as terminal agent during the arm polymerization. Comb copolymers with up 16-arms were obtained. The isoprene units of styrene-diene copolymers were hydrogenated to make their structure stable to oxidative and mechanical stress. After hydrogenation, the six-arm star copolymers exhibited a good low temperature behaviour, showing excellent compatibility with the pour point depressant and mechanical shear stability slightly better than most commercial VMs. Moreover, it is expected that after hydrogenation the new comb copolymers will have thickening efficiency superior to that of the hydrogenated star copolymers for their large number of arms. The Part II “Sulfur-rich polymers” regards the reuse of carbon disulfide (CS2) (Part II A) and elemental sulfur (Part II B), as feedstocks for polymer production, to help to overcome “excess sulfur problem” and to produce high value products without depleting natural resources. In part II A, for the first time an investigation of the copolymerization of CS2 and cyclohexene sulfide (CHS) catalysed by salen and salphen chromium complexes and PPNX salt as cocatalyst was performed at different times and temperatures. Both catalytic systems produce both polymer and cyclic products. Salphen based catalysts, in comparison with salen based ones, show higher productivity and selectivity for polymers with high molecular weight up to 18 kg/mol when the reaction is carried out at 25 °C. At higher temperature with (salphen)CrCl, the maximum value of selectivity for copolymers (72 %) was obtained at short reaction time (3 h). It was found that poly(trithiocyclohexylcarbonate)s possess high refractive index (n > 1.72), and antimicrobial proprieties against E. Coli and S. Aureus which along with the Tg values of 80 °C make these materials suitable for interesting applications different from those of poly(trithiopropylencarbonate)s. In part II B, dipentene, a bio-based sustainable feedstock, was used for first time in combination with elemental sulfur, to produce green-polysulfides alternative to those produced from enantiomeric limonene. Poly(S-dipentene)s with high sulfur content (> 50 %) were synthesized by catalytic inverse polymerization in presence of zinc-based accelerators at 140 °C. Accelerators allowed to reduce mixing time between dipentene and sulfur. Stable ter-polysulfides with depressed depolymerization reactions were achieved, by adding 10 % of natural crosslinker such as garlic oil, myrcene and diallyl disulfide. Ter-polysulfides produced are soft solids with Tg values between -1 and 4 °C. Shape persistent blend of ter-polysulfide and commercial polystyrene was prepared. The polysulfide-polystyrene blend resulted processable, mouldable and able to remove ferric ions from aqueous solution.

碩士
國立成功大學
化學工程學系
89
The goal of this research is to synthesize a new “DP-type novolac” from acid-catalyzed reaction of 2,6-dimethylphenol and dipentene(DP). DP-type novolac with aliphatic terpene structure should provide excellent hydrophobicity and low dielectric properties. The DP-type novolac is epoxidized to “DP-type epoxy” which is advanced with phosphorus or bromine containing diphenol to the flam retardant epoxy resins, and is also converted to DP-type cyanate ester as a curing agent. In the first part, DP-epoxy was cured with 4 kinds of diamine as curing agent and compared with BPA-type epoxy (DEGBA). The cured DP-type epoxy resins show better properties in glass transition temperature, water absorption, dielectric property than BGEBA epoxy resin. In the other part, the bromine or phosphorus-containing flame retardant DP-type advanced epoxy was cured with DP-type cyanate ester and compared with epoxy-cyanate resin of BPA-type. Althought the incorporation of flame retardant element (P,Br) into epoxy has lowered glass transition temperature and thermal decomposition temperature at 5 wt% (Td-5%), however, the hydrophobicity and dielectric properties were not affected.In addition , the DP-type epoxy-cyanate resins exhibited better thermal stability, dielectric property and less water absorption than BPA-type. From LOI and UL-94 analysis, the epoxy-cyanate resins of DP-type which contained 1.1 wt% of P-element have exhibited the same flame retardancy as the one which contained 21wt% of Br-element. As a whole, DP-type epoxy resin and epoxy-cyanate resin , DP-type can provide better physical and electrical properties than BPA-type.