Blends of Bio-Based Poly(Limonene Carbonate) with Commodity Polymers

In this study, blends of the bio-based poly(limonene carbonate) (PLimC) with different commodity polymers are investigated in order to explore the potential of PLimC toward generating more sustainable polymer materials by reducing the amount of petro- or food-based polymers. PLimC is employed as minority component in the blends. Next to the morphology and thermal properties of the blends the impact of PLimC on the mechanical properties of the matrix polymers is studied. The interplay of incompatibility and zero-shear melt viscosity contrast determines the blend morphology, leading for all blends to a dispersed droplet morphology for PLimC. Blends with polymers of similar structure to PLimC (i.e., aliphatic/aromatic polyester) show the best performance with respect to mechanical properties, whereas blends with polystyrene or poly(methyl methacrylate) are too brittle and polyamide 12 blends show very low elongations at break. In blends with Ecoflex (poly(butylene adipate-co-terephthalate)) and Arnitel EM400 (copoly(ether ester)) with poly(butylene terephthalate) hard and polytetrahydrofuran soft segments) a threefold increase in E-modulus can be achieved, while keeping the elongation at break at reasonable high values of ≈200%, making these blends highly interesting for applications.     

Fully renewable limonene‐derived polycarbonate as a high‐performance alkyd resin

Limonene‐derived polycarbonate‐based alkyd resins (ARs) have been prepared by copolymerization of limonene dioxide with CO₂, catalysed by a β‐diiminate zinc–bis(trimethylsilyl)amido complex, and subsequent chemical modification with soybean oil fatty acids using triphenylethylphosphonium bromide as the catalyst. This quantitative partial modification was realized via epoxy–carboxylic acid chemistry, affording ARs with higher oil lengths, lower polydispersities and higher glass transition temperatures (T_g) in comparison to a conventional polyester AR based on phthalic acid, multifunctional polyol pentaerythritol and soybean fatty acid. The novel limonene polycarbonate AR and the conventional polyester AR were evaluated as coatings and both the physical drying (without the presence of the oxidative drying accelerator Borchi® Oxy Coat) and chemical curing (with Borchi® Oxy Coat) processes of these coatings were monitored by measuring the König hardness and complex modulus development with time. A better performance was obtained for the alkyd paint containing polycarbonates modified with fatty acids (FA‐PCs), which showed a faster chemical drying, a higher König hardness and a higher T_g in coating evaluation, demonstrating that the fully renewable FA‐PCs are promising resins for alkyd paint applications. © 2019 Society of Chemical Industry     

双氧水环氧化柠檬烯的实验研究与模拟分析

采用PW-Amberlite离子交换树脂为催化剂,以乙腈为溶剂,双氧水与柠檬烯同时进料进行反应制备1,2-环氧柠檬烯。同时考察了反应时间、进料比、反应温度等工艺条件对柠檬烯环氧化生成1,2-环氧柠檬烯选择性的影响。利用化工模拟软件Aspen Plus中的Rbatch模块对整个反应进行模拟。模拟计算值与实验结果吻合良好,表明所建立的Rbatch模型能够很好地描述双氧水环氧化柠檬烯制备1,2-环氧柠檬烯的反应过程。以产品1,2-环氧柠檬烯的收率为考察目标,通过模拟计算并结合实验分析,确定了最佳的工艺参数:反应时间为24h;双氧水与柠檬烯的最佳进料摩尔比是n(双氧水):n(柠檬烯)=2:1;反应温度为33℃。     

壳聚糖-柠檬烯涂膜对鲜切哈密瓜贮藏品质的影响

目的 探究壳聚糖-柠檬烯涂膜对鲜切哈密瓜贮藏品质的影响。方法 以无菌蒸馏水和2%壳聚糖涂膜处理鲜切哈密瓜作为对照组,用2%壳聚糖复配0.1%柠檬烯涂膜处理鲜切哈密瓜作为实验组,在贮藏第0、1、3、5、7 d对鲜切哈密瓜的感官、硬度、呼吸强度、可溶性固形物含量、色差、维生素C含量、多酚氧化酶(polyphenol oxidase, PPO)活性、过氧化物酶(peroxidase, POD)活性、过氧化氢酶(catalase, CAT)活性、超氧化物歧化酶(superoxide dismutase, SOD)活性及菌落总数进行测定。结果 2%壳聚糖复配0.1%柠檬烯涂膜显著(P<0.05)减缓了鲜切哈密瓜果肉软化,可溶性固形物和维生素C含量的下降及色差值L^*、a^*、b^*的改变;抑制了鲜切哈密瓜的呼吸强度、PPO和POD活性,增强了SOD和CAT活性,并抑制了菌落的生长,有利于鲜切哈密瓜感官品质的维持。结论 2%壳聚糖复配0.1%柠檬烯涂膜处理鲜切哈密瓜可以降低鲜切哈密瓜贮藏期间的营养物质损耗,减缓果肉的衰老变质,较好地...     

天然活性单萜--柠檬烯的研究进展

柠檬烯是一种天然的功能单萜，在食品中作为香精香料添加剂被广泛使用。近来研究发现，柠檬烯具有多种生理作用，特别是有很好的抗癌活性。本系统地介绍了柠檬烯的物化性质、生理功效及其在食品、香料、医药中的应用。     

Essential oil yield and composition of Pistacia vera ‘Kerman’ fruits,peduncles and leaves grown in California

BACKGROUND: Pistacia vera ‘Kerman’ is the predominant pistachio nut cultivar in the United States (California), the world's second largest producer. Despite several reports on the essential oil (EO) content in the genus Pistacia, data on ‘Kerman’ are limited. The EO content and volatile organic compound (VOC) emissions of tree nut orchards are of current interest to researchers investigating insect pests and the potential role of EO and VOCs as semiochemicals. To establish a basis for the VOC output of pistachios, the EO content of fruits, peduncles, and leaves was analyzed. RESULTS: Evaluated plant parts contained limonene as the primary EO component, followed by α‐terpinolene. Peduncles were unique in containing relatively high levels of α‐thujene. The results were reproducible between two different geographical locations. In situ solid phase microextraction (SPME) studies demonstrated the volatile emission was representative of the EO composition. CONCLUSION: This is the first report detailing the content and distribution of EO and the unique limonene‐dominant profile for this Pistacia vera cultivar which may influence pistachio insect pest semiochemical research. Copyright © 2010 Society of Chemical Industry     

“柠檬烯提取”教学实验的改进

选取提取柠檬烯的最佳原料、改进微型实验装置及提取方法。选择皇帝柑皮为原料,采用超声辅助提取新技术,并进一步结合微型简易水蒸气蒸馏实验装置提取柠檬烯。该方法不仅试样用量少、提取率高、实验效果明显、装置简单、易于操作、缩短了实验时间;而且使学生实践了超声辅助提取的新技术,渗透了微型化学实验的新理念,提高了学生实验的积极性,主动性。"柠檬烯提取"实验的改进方法值得在有机实验教学中推广。     

Oxidation of d-Limonene in Presence of Low Density Polyethylene

Headspace oxygen contents of sodium citrate-water buffers containing d-limonene with and without low density polyethylene (LDPE) were measured on a weekly basis for 10 wk. d-Limonene was readily sorbed into LDPE. Results indicated first order kinetics for limonene oxidation. GC/MS analyses determined production of limonene oxidation end-products, including d-carvone, carveol, limonene oxide, perrilaldehyde and linalool, as well as α-terpineol, a hydrolysis product. Headspace oxygen contents of the d-limonene/buffer (control) samples were lower thau that of the d-limonene/buffer/LDPE samples, suggesting a higher oxidation rate in the control than in LDPE. Oxidation rate constants and half-lives were 5.9 × 10^-3 log(%O₂) wk^-1, t_1/2= 116 wk for control and 1.2 × 10^-3 log(%O₂) wk^-1, t_1/2= 580 wk for LDPE samples, respectively.