Resin Yield Research Articles

Preparation and Application of Coumarone-Indene-Carbazole Resin as a Modifier of Road Petroleum Bitumen. 1. Influence of Carbazole:Raw Materials Ratio

The possibility of effectively using carbazole as an improver of coumarone-indene resin for use as a modifier of petroleum bitumens is studied. All starting materials for the production of coumarone-indene-carbazole resin (CICR) were obtained from various products of the coal coking process. The influence of raw material composition (amount of carbazole added to an industrial indene-coumarone fraction) on resin yield and its modifying properties was studied. The optimal amounts of carbazole in the raw material were established, and it is recommended to use CICR as an adhesive additive to bitumen.

Improving the extraction of guayulins from guayule stems (Parthenium argentatum A. Gray)

Guayule (Parthenium argentatum A. Gray) exploitation has so far been focused on the production of rubber, but until now was unable to compete commercially, as other guayule co-products have not been equally considered for exploitation. However, to successfully exploit one of these co-products, the guayulins, it will be necessary to establish a robust resin extraction method that maximizes the yield of guayulin compounds for downstream purification. For this purpose, different resin extraction conditions (solvent, temperature, number and time of cycles, and plant material:solvent ratio) were evaluated to select those that produced a resin with a higher guayulins yield. First, accelerated solvent extraction (ASE) was performed using three solvents (ethanol, acetonitrile, and acetone) at three different temperatures (40, 56, and 80 °C) and two cycle times (5 and 20 min) to narrow down the conditions. Then, an industrial scale process was simulated with warm solvent extraction (WSE) using acetone and acetonitrile only at five different cycle times (30, 45, 60, 120, and 180 min). Finally, WSE performance was optimized using four different plant material:solvent ratios (1:20, 1:10, 1:5, and 1:3), and three consecutive extraction cycles. Results from the ASE studies revealed, as expected, that solvent choice had the greatest influence on resin and guayulins yield and allowed to discard ethanol as a suitable extraction solvent while acetonitrile performed best for guayulin extraction. No tangible differences in resin yield were observed in WSE studies between the different process parameters, but they were differences in guayulin extraction. Short cycle times worked best with both solvents, and again, acetonitrile was more selectively extracted guayulins, especially for the polar guayulins C and D. Finally, WSE optimization showed that a 1:5 plant material:solvent ratio and two extraction cycles were the best compromise in terms of guayulins yield and time/cost effectiveness.

Prediction and Comparisons of Turpentine Content in Slash Pine at Different Slope Positions Using Near-Infrared Spectroscopy.

Pine resin is one of the best known and most exploited non-wood products. Resin is a complex mixture of terpenes produced by specialized cells that are dedicated to tree defense. Chemical defenses are plastic properties, and concentrations of chemical defenses can be adjusted based on environmental factors, such as resource availability. The slope orientation (south/sunny or north/shady) and the altitude of the plantation site have significant effects on the soil nutrient and the plant performance, whereas little is known about how the slope affects the pine resin yield and its components. In total, 1180 slash pines in 18 plots at different slope positions were established to determine the effects on the α- and β-pinene content and resin production of the slash pine. The near-infrared spectroscopy (NIR) technique was developed to rapidly and economically predict the turpentine content for each sample. The results showed that the best partial least squares regression (PLS) models for α- and β-pinene content prediction were established via the combined treatment of multiplicative scatter correction–significant multivariate correlation (MSC–sMC). The prediction models based on sMC spectra for α- and β-pinene content have an R2 of 0.82 and 0.85 and an RMSE of 0.96 and 0.82, respectively, and they were successfully implemented in turpentine prediction in this research. The results also showed that a barren slope position (especially mid-slope) could improve the α-pinene and β-pinene content and resin productivity of slash pine, and the β-pinene content in the resin had more variances in this research.

Investigation on a novel preparation process of B-COPNA resin from catalytic cracking diesel

As one of main products in fluid catalytic cracking unit, catalytic cracking diesel (light cycle oil, LCO) has inferior combustion performance, improper to be used as vehicle diesel. Condensed polynuclear aromatic resin of moderate condensation degree (B-COPNA) has a wide range of application prospects, but is seriously limited by the manufacturing cost. A novel process was proposed to convert polycyclic aromatic hydrocarbons in LCO into B-COPNA resin using PXG and PTS as crosslinking agent and catalyst, respectively. The composition of LCO was analyzed first, and the effects of operating conditions such as reaction temperature, reaction time, crosslinking agent and catalysts content on the viscosity and yield of B-COPNA resin were investigated to optimize the process. The molecular structure of B-COPNA resin is characterized by FT-IR spectra, NMR spectra, TOF-MS and elemental analysis. The combustion performance of LCO and the heat resistance of B-COPNA were evaluated and compared. The result shows that LCO is rich in aromatic hydrocarbons with 2-3 rings, making it an ideal raw material for COPNA resin. The optimized conditions of preparation experiments were 240 °C, 5 h, 1:1.8 (PXG:LCO) and 3 wt% of catalyst content with a B-COPNA resin yield of 67.2%. After the crosslinking reaction, the heat resistance temperature of B-COPNA resin product was up to 417 °C, while the cetane value of LCO increased to 43.6, an increase of 42.95%. Hence, it was confirmed that the current process can achieve a high value-added utilization of LCO by converting into B-COPNA resin, which has a superior combustion to bring extra high economic value to petrochemical industry.

Estimation of direct-seeded guayule cover, crop coefficient, and yield using UAS-based multispectral and RGB data

Guayule (Parthenium argentatum, A. Gray), a perennial desert shrub, produces high-quality natural rubber and is targeted as a domestic natural rubber source in the U.S. While commercialization efforts for guayule are on-going, crop management requires plant growth monitoring, irrigation requirement assessment, and final yield estimation. Such assistance for guayule management could be provided with remote sensing (RS) data. In this study, field and RS data, collected via drones, from a 2-year guayule irrigation experiment conducted at Maricopa, Arizona were evaluated. In-season field measurements included fractional canopy cover (fc), basal (Kcb) and single (Kc) crop coefficients, and final yields of dry biomass (DB), rubber (RY), and resin (ReY). The objectives of this paper were to compare vegetations indices from MS data (NDVI) and RGB data (triangular greenness index, TGI); and derive linear prediction models for estimating fc, Kcb, Kc, and yield as functions of the MS and RGB indices. The NDVI and TGI showed similar seasonal trends and were correlated at a coefficient of determination (r2) of 0.52 and a root mean square error (RMSE) of 0.11. The prediction of measured fc as a linear function of NDVI (r2 = 0.90) was better than by TGI (r2 = 0.50). In contrast to TGI, the measured fc was highly correlated with estimated fc based on RGB image evaluation (r2 = 0.96). Linear models of Kcb and Kc, developed over the two years of guayule growth, had similar r2 values vs NDVI (r2 = 0.46 and 0.41, respectively) and vs TGI (r2 = 0.48 and 0.40, respectively). Final DB, RY, and ReY were predicted by both NDVI (r2 = 0.75, 0.53, and 0.70, respectively) and TGI (r2 = 0.72, 0.48, and 0.65, respectively). The RS-based models enable estimation of irrigation requirements and yields in guayule production fields in the U.S.

К МЕТОДИКЕ УСТАНОВЛЕНИЯ ИНТЕНСИВНОСТИ ВЫДЕЛЕНИЯ ТЕРПЕНТИНА ПРИ ЕГО ЗАГОТОВКЕ В ОСУШАЕМЫХ СОСНЯКАХ

An experimental open-type tapping was carried out in pine stands located in the Sokolsky district of the Vologda region. The objects of study are represented by plantations located on the sites, passed in 1972 by hydrotechnical reclamation, as well as similar forests after continuous thinning. The dominant species in the tree layer is pine, the share of spruce and birch does not reach 10%. The release of turpentine was studied in pine forests on a mesotrophic peat deposit. The tapping was carried out using the ascending method of applying the substrates. The main attention was paid to improving the method for determining the resin productivity of Scots pine. In the course of the study, the following tasks were solved: 1) four permanent test plots were laid in drained pine plantations, in addition, continuous thinning was performed on two sites; 2) for research purposes, an experimental double-sided harvesting of pine turpentine was carried out on each trial plot; 3) the influence of hydrotechnical reclamation and thinning on the amount of released pine turpentine has been determined; 4) specifying coefficients have been developed for the mathematical calculation (forecast) of turpentine yield with a 50% trunk load with tapping cuts. Based on the results of the study, a number of correction factors have been proposed to determine the resin productivity of pines, taking into account their taxation diameter, since the mathematical calculation of the turpentine yield under a trunk load with tapping cuts of 50% carr is often overestimated. The positive effect of hydrotechnical reclamation on the increase in the breast height diameter of pine was confirmed. The average yield of pine resin is about 22% higher, relative to the stand without silvicultural care, in a drained pine forest after silvicultural maintenance

Traumatic ducts size varies genetically and is positively associated to resin yield of Pinus oocarpa open-pollinated progenies

Abstract Mexico ranks 5th in worldwide resin production. Pinus oocarpa is the most widely tapped pine tree in Mexico. Michoacán (central-western Mexico) is the first nationwide state producer of resin. Despite the P. oocarpa relevance, there is no genetic improvement program in the country for resin production. We evaluated the degree of genetic control for growth, anatomical traits, resin yield, and the correlation among them at an early age (five-years-old for growth, six for resin, and anatomical traits) in a P. oocarpa half-sib progeny trial. Families were originated from selected mother trees, based on their resin yield. We found significant genetic variation among families for stem volume (h 2 i = 0.12, h 2 f = 0.35), traumatic ducts (diameter: h 2 i = 0.63, h 2 f = 0.51; area: h 2 f = 0.81), and resin yield (individual and family narrow-sense heritability: h 2 i = 0.20, h 2 f = 0.52), and a positive correlation between diameter and area of traumatic ducts with resin yield (Pearson correlation: r= 0.73, p= 0.04; r= 0.71, p= 0.0497; respectively). Results suggest that the early selection (six-years-old) of superior P. oocarpa families, based on resin yield (estimated by microchipping technique), and/or based on larger diameter and area of traumatic ducts, appears to be a feasible strategy to develop seed orchards able to provide genetically improved seeds for intensive resin tree plantations. That would be an important alternative for a state as Michoacán, Mexico, where natural P. oocarpa stands are being replaced for avocado orchards for exportation.

OPTIMASI PROSES EKSTRAKSI MINYAK DAN RESIN NYAMPUNG DENGAN PELARUT BINER MENGGUNAKAN RESPONSE SURFACE METHOD

Calophyllum seeds are potential to be used as raw material for vegetable oil production due to their high oil content. In addition, Calophyllum seeds contain resin consisting of beneficial phenolic compounds for health. The objective of this research was to optimize the oil and resin extraction from Calophyllum seeds on a pilot scale using binary solvent. The analyses of temperature, extraction time and stirring speed effects on the oil and resin yields were carried out using the central composite design, and the variables were optimized using the response surface method. The result of oil yield optimization showed that the best model was the quadratic model. The optimum oil yield (59%) was obtained at temperature of 49.4 oC, extraction time of 5.3 h, and stirring speed of 385 rpm. The result of resin yield optimization showed that the best model was the mean model with average value of 15% for all extraction conditions tested. Model validation at this extraction condition resulted actual oil (60%) and resin (13%) yields conformed passably to their prediction. In addition, the oil and resin obtained from this model validation had good characteristics, and matched the predicted results. Keywords: binary extraction, Calophyllum, oil, optimization, resin, response surface method

Techno-economic, life cycle, and environmental cost assessment of biojet fuel obtained from Pinus pinaster by turpentine hydrogenation

Production of biojet fuel from turpentine shows a reduction of 93% of CO2 eq. emissions. Manual harvesting and resin yield strongly influence the final cost. Cost-competitive for productivities higher than 6 kg of resin per pine per year.

Irrigation effects on seasonal growth and rubber production of direct-seeded guayule

Understanding guayule’s response to environmental factors, such as location, soil type, drought stress, and seasonal growth variation is critical for irrigation management to maximize and estimate rubber and resin accumulation throughout the growing seasons. A study was conducted at two sites with different soil types (sandy loam soil at Maricopa, AZ and a clay soil at Eloy, AZ) to compare plant growth and rubber accumulation among different irrigation treatments during a two-year growing season. The above- and below-ground biomass, biomass growth, rubber/resin content, and rubber/resin accumulation were measured every other month from establishment to final harvest in well-watered treatments, which received 100% replacement of crop evapotranspiration (ETc) and irrigated with subsurface drip and furrow (denoted as D100 and F100, respectively), and compared to reduced irrigation treatments (D50 and F50), which received 50% replacement of ETc. Drip irrigation with high water input (D100) decreased root mass partition, but leaf, stem, and flower partitions were not significantly affected by irrigation treatment. Biomass yield was higher in the well-watered treatments as expected, while rubber and resin content were lower, indicating rubber and resin dilution by higher biomass. For all treatments, rubber and resin yield increased linearly over the two-year growing season. However, the rates of increase were different among the irrigation treatments. The D100 treatment had a higher rubber yield increase rate compared to F100 and D50 in sandy loam soil at Maricopa, while the D100 treatment had the lowest increase rate compared to the F100, F50, and D50 treatments in clay soil at Eloy. Top branches of guayule plants in the D100 treatment at Eloy lodged in the second year and likely contributed to lower rubber content and rubber yield in the treatment. The drip irrigation treatments D50 and D100 had higher water productivity for rubber yield at Maricopa. However, the D50 and F50 treatment had the highest water productivity for guayule rubber yield, while the D100 treatment had the lowest due to lower rubber content at Eloy. Root rubber content was 31–39% lower than stem at the two locations. This study indicates that rubber biosynthesis occurred in guayule year-round and that it is possible in clay soils to reduce irrigation without a significant loss in rubber yield.

Control of clay mineral properties on hydrocarbon generation of organo-clay complexes: Evidence from high-temperature pyrolysis experiments

In clay-rich mudstones, organic matter (OM) is intimately associated with clay minerals to form organo-clay complexes, which play crucial roles in affecting hydrocarbon generation of OM. Different clay minerals show diverse nature and evolution paths, which would affect clay-OM interactions and further the hydrocarbon generation processes and mechanisms. In this way, smectite-octadecanoic acid complex (Sm-OA) and illite-octadecanoic acid complex (I-OA) were prepared for confined pyrolysis experiments to analyze the co-evolution of mineralogy and pyrolytic behaviors. According to the clay-OM interaction, hydrocarbon generation process was divided into three stages. During smectite illitization, the collapse of interlayer space induces the desorption of OA, which contributes to the yield of resin. The Brønsted and Lewis acid sites of clay minerals are considered to promote the hydrogenation and decarboxylation of desorbed OA, respectively, which enables the transformation of resin into saturates and gaseous hydrocarbons. Therefore, the hydrocarbon generation in Sm-OA is a process that OM desorbs from clay minerals and transforms into saturates and then into gaseous hydrocarbons. For I-OA, the quantitative calculation of hydrogen reveals that the lack of inorganic hydrogen supplied by clay minerals compels OM to evolve along the opposite path, generating high-molecular-weight asphaltene and releasing organic hydrogen to ensure the proceeding of cracking reaction. In this case, the desorbed OM converts into asphaltene and then to gaseous hydrocarbons. Conclusions are obtained that the differences in clay and bulk mineralogies determine the different contributions of desorption, hydrogenation, and decarboxylation to hydrocarbon generation in Sm-OA and I-OA, leading to variations in composition of pyrolytic products. Sm-OA is beneficial to the formation of liquid hydrocarbons, while I-OA is conducive to formation of gaseous hydrocarbons. In other words, the differences of mineral properties control the hydrocarbon generation processes and mechanisms.

Optimal analysis of the effects of process conditions on the yield of alkyd resins from castor and soybean seed oils using response surface methodology

This research studied the optimization of the production of alkyd resin from dehydrated castor oil (Ricinus communis) and soybean oil (Glycine max) respectively. The natural content of iodine in soybean oil was sufficient for producing drying alkyd resin while refined castor oil has low iodine content; hence it was severely dehydrated at high temperature to increase its iodine value from 83 to 130, which made it suitable for alkyd resin production. Nine different samples of medium oil alkyd resins of 50% oil length were synthesized from each oil at different reaction conditions using monoglyceride method, which involved mixing of appropriate amount of each oil with glycerol via alcoholysis, followed by the addition of phthalic anhydride via esterification. The acid value was observed to decrease with time during the esterification process and this decrease was a measure of alkyd resin production. The outcomes of the standardization of the soybean and castor oil modified resins through coating analyses revealed that both have desirable commercial attributes in terms of chemical resistance, set to touch, solubility in solvent media and drying time though at any given similar production conditions, soybean oil modified resins have better qualities due to their lower acid values. The kinetic studies carried out indicated that only first order and second order kinetics fitted into the experiment data. Time, temperature and phthalic anhydride dosage were the three independent factors studied and optimized using Composite Rotatable Design (CCRD) of Response Surface Methodology (RSM) while the response was percentage conversion. The suggested model and the process variables were significant as depicted by their p-values. The model validation showed that the optimal conversions, 87.3% and 76.7%, obtained for soybean and castor oil modified resins respectively, at a reaction temperature of 247.5 °C, reaction time of 155.3mins and 46.2 g of phthalic anhydride conformed wholly with the actual conversions, 84.7% and 75.2%, obtained respectively at the same conditions. Therefore, it can be deduced that soybean oil modified resins have better yield and offered more desirable features.

Management of Needle-Eating Caterpillars Associated with Pinus massoniana and P. merkusii in Vietnam

Pine tussock moth (Dasychira axutha Collenette (Lymantriidae)) and masson pine caterpillar (Dendrolimus punctatus Walker (Lasiocampidae)) cause serious damage to Pinus massoniana and P. merkusii plantations in Vietnam. An integrated pest management (IPM) program is required to control these pests. Therefore, this study was undertaken to identify damage thresholds and to evaluate control options for implementing IPM in the Northeast and North Central regions of Vietnam. Three damage thresholds were considered: <25%, 25%–50% and >50% loss of leaf area. Control options were manual collection of eggs and pupae and the use of light traps and biological agents. An initial IPM model was developed for each pest and these gave control efficacies of 82.4% (Da. axutha on P. massoniana) and 77.8% (De. punctatus on P. merkusii). Six extended IPM models were undertaken by forest companies giving pest control efficacies of 79.2%–85.9%. The collection of pine resin provides an important source of income to local communities and the resin yield in the IPM models increased by 20.9%–22.7% compared to untreated control plots. The IPM protocols would help in developing policies that promote a more sustainable management of forest pests in Vietnam, thus reducing dependence on the use of insecticides of environmental and public health concerns.

Trials of frankincense harvesting using organic stimulants

Generally, frankincense resin is used as a raw material of the cosmetic and pharmacy industry and is often used as traditional rituals related to mystical things. However, the information related to the stimulant application on frankincense tapping is lacking even not available yet. This article aims to provide the initial information on frankincense tapping technic using three organic stimulants. The trials were conducted in one of the community forests in Dolog Sanggul, North Sumatera. The trees sampled were 40 with an average diameter of 17.07 cm that adjusted with the variable used. Organic stimulants used in this study were wood vinegar, galangal, and lime. The result showed a) the organic stimulant was potential to be applied in frankincense harvesting based on the productivity of produced resin; b) the application of three organic stimulants in frankincense harvesting affected the resin production compared to the control (without stimulant), and c) the resin yield varied between 0.177-1.051 gr with a harvesting period of one month. As an illustration, the resin yield of one frankincense tree averagely 0.1-0.5 kg per year with a harvesting period of 3-4 months without stimulant. The innovation of frankincense harvesting is necessary to improve the efficiency and effectiveness of the stem wounding process and stimulant application.

TMT-based comparative proteomic analysis reveals regulatory pathways and protein targets associated with resin biosynthesis in Pinus massoniana

Oleoresin is a natural product widely used in industry and plays an important role in the conifer defense system as a natural anti-insect and anti-pathogen substance. As an important resin resource tree species, masson pine (Pinus massoniana) has high commercial value. Resin yield is an important economic trait of masson pine and varies in different clones. In order to evaluate the biosynthesis mechanism of oleoresin in masson pine, a Tandem Mass Tag (TMT)-based quantitative proteomics analysis was applied to observe the proteome profile changes in masson pine secondary xylem with high (H), medium (M), and low (L) resin-yielding capacities (RYCs). A total of 3,745 proteins were identified and quantified in three groups, 507 of which were differentially expressed proteins (DEPs). Most up-regulated proteins were enriched in H vs. L and H vs. M. KEGG enrichment analysis showed that these DEPs were involved in multiple biological pathways, with a particular enrichment of those participating in biosynthesis of secondary metabolism, metabolic pathways, ABC transporter, plant-pathogen interaction, and brassinosteroid (BR) biosynthesis. Using the integrated proteome and transcriptome data to elucidate proteomic profile changes in masson pines, we identified a series of DEPs related to resin biosynthesis, including cytochrome P450, Leucine-rich repeat (LRR) protein, pathogenesis-related (PR) protein, ABC transporter, and chitinase. Our study provides a comprehensive proteomic analysis to aid in understanding the molecular mechanisms involved in resin generation, representing a potential tool for genetic improvement of masson pine.

Short Communication: Timing of resin-tapping operations in maritime pine forests in Northern Spain

Aim of study: To optimize the timing of resin-tapping activities for maximizing the economic efficiency of resin tapping in Atlantic maritime pine forests. Area of study: Northern Spain. Material and methods: We conducted three small experiments in a mature maritime pine forest aimed to test: i) the impact of groove frequency on resin production, ii) the effect of previous grooves as a driver of temporal patterns of resin production along the seasons and iii) the impact of previous tapping on resin production in the following campaign. Main results: The resin produced decreased as groove frequency decreased, but the reduction was low. Considering that the number of trees that a worker can tap increases with more spaced grooves, higher tapping efficiency can be achieved with monthly grooves. Previous tapping increased resin yield during the following campaign but resin production was not affected by the previous grooves during the current tapping campaign. Research highlights: Responses to wounding seem to require time to be effective and temporal patterns of resin production appear to be driven by weather conditions alone. Keywords: resin yield; Pinus pinaster; seasonality; induced responses; wounding.

The synthesis and characterization of phenolic resin with a high content of dimethylene ether bridges

Phenolic resins were synthesized using sodium montmorillonite (MMT) as a catalyst at a concentration of 3%, 5%, and 10%, the reaction time was 24 and 48 h, respectively. The phenolic resin yield was up to 69%. The chemical structure of the resins was determined by NMR, the thermal properties were determined by DSC and TGA, and molar masses were determined by SEC. The resins could not be easily classified as resol or novolac because the most common type of bonding between the aromatic rings was dimethylene ether (DME) bridges. Due to near neutral pH (6.7–7.1), some methylol groups were also present in the structure. Increasing the MMT concentration increased the molar mass of the resin; however, no influence of reaction time was observed. Increased MMT concentration, as well as longer reaction time, decreased the glass transition temperatures, which were very low, in the range of 8–24 °C. Increased content of DME increased the thermal stability of the resins.

Pyrolysis mechanism of phenylboronic acid modified phenolic resin

Phenylboronic acid (PBA) modified phenolic resin (PBPR) is one of the most important phenolic resins (PR) due to its good processability and high char yield. However, the pyrolysis mechanisms of PR and PBPR still remain poorly understood, which imposes limits on the synthesis, development and application of these materials. In this work, the pyrolysis process of PBPR has been studied through novolac resin (NR) and PBA crosslinked NR (PBNR) at high temperatures, and the reasons for the high char yield of PBPR were explored, as well. According to the results, the pyrolysis of NR begins with the cleavage reaction of the covalent single bonds in the molecular backbone. The release of volatile organic compounds (VOCs) such as monophenols and bisphenols formed by the cleavage of C—C single bonds is the major cause of the decreased char yield of NR at elevated temperatures. Meanwhile, increasing NR molecular weight and crosslinking NR could reduce the formation probability of VOCs, which is beneficial to obtaining the high char yield resin. In PBPR, the boronic ester linkages make the formation of VOCs more difficult and contribute to the high char yield of resin. The present work provides guiding significance for deeply understanding the pyrolysis mechanism of PR and PBPR to ensure their high thermal stability and char yield at high temperatures.

Growth, water use, and crop coefficients of direct-seeded guayule with furrow and subsurface drip irrigation in Arizona

Crop establishment costs of guayule (Parthenium argentatum A. Gray), a perennial desert shrub that produces natural rubber, can be significantly reduced using direct seeding rather than the traditional practice of transplanting greenhouse-grown seedlings. However, information regarding the irrigation application, crop evapotranspiration (ETc), and crop coefficients (Kc) for managing direct-seeded guayule crops has not been provided. In this study, guayule was direct-seeded in Apr. 2018 in fields at two location in Arizona; Maricopa, on a sandy loam soil and Eloy, on a clay soil, and harvested 23–24 months later in 2020. At each location, five irrigation rates were applied with subsurface drip irrigation (SDI) ranging from 50 to 150 % replacement of ETc (denoted as D50 to D150 treatments), respectively. A 6th treatment using furrow irrigation at 100 % ETc replacement (F100) was included. Treatments were replicated three times. The ETc was estimated for the first 74–84 days of crop establishment and thereafter, actual ETc (ETc act) was determined weekly-biweekly for the D100 and F100 treatments using a soil water balance. The objectives were to evaluate the responses in dry biomass (DB), rubber yield (RY), and resin (ReY) yield to water application rate, develop irrigation management criteria for the two soil types, and determine the ETc and crop coefficients for the 100 % treatments.The total irrigation applied to treatments ranged from 1830−1910 mm to 5090–5470 and averaged 3590 and 3320 mm for the 100 % SDI (D100) and furrow (F100) treatments at Maricopa and Eloy, respectively. The summed estimated ETc plus ETc act for the D100 and F100 treatments were 3663 and 3506 mm at Maricopa, respectively and 3428 and 3320 at Eloy, respectively. Average measured mid-season Kc in the 1st year varied from 1.20 to 1.26. Average measured mid-season Kc in the 2nd year were higher for D100 (≈1.30) than for F100 (≈1.23). Adjusted to the standard climate proposed in FAO56, mid-season Kc are 1.24 for D100 and 1.17 for F100 in the 2nd year. Average DB at Eloy (28.6 Mg ha−1) was not significantly higher than at Maricopa (24.0 Mg ha−1). However, RY and ReY were both significantly higher at Maricopa. At each location, rubber content was significantly higher for the F100 and the two lowest SDI rates than for other treatments. The highest mean RY and ReY were achieved with D100 at Maricopa and D75 at Eloy. These two also had significantly greater water productivity (WP; DB, RY, and ReY per unit of total water applied) than those at higher SDI rates and the F100 treatments. RY and ReY and their WP were generally higher for D100 than F100 in the sandy loam but not in the clay soil. For direct-seeded guayule in clay soils, furrow irrigation should be considered due to the lower rubber content and higher costs associated with SDI.

Correlation between the emulsion oligomerization parameters for C9 fraction and the characteristics of hydrocarbon resins

This paper investigates the production of hydrocarbon resins by emulsion oligomerization of the С9 fraction hydrocarbons in liquid by-products of oil refining. Such oligomers have a wide range of applications as film-forming agents in paints and anti-color coatings. Emulsion oligomerization was carried out using emulsifiers of the first and second kind. The study was performed at different values of the reaction temperature of the reaction duration, the intensity of agitation; concentrations of the emulsifier; С9:water fraction ratio. The resulting products were estimated according to the following indicators: the yield, unsaturation degree, softening temperature, mean molecular weight, color. Statistical analysis was carried out, the correlation of parameters of emulsion oligomerization and the yield and characteristics of oligomers was established. Given that, it would be possible to establish the optimal conditions for emulsion oligomerization and predict the properties of the products obtained. Specifically, it was established that the yield of hydrocarbon resins does not correlate with the reaction temperature (0.15 and 0.30) and the concentration of emulsifiers (0.08 and 0.03). It was proven that in the intervals studied the variable yield of oligomers depends on the duration of the reaction (correlation 0.88 and 0.81). In the case of oligomerization in the reverse emulsion, a significant correlation with the yield is also demonstrated by agitation intensity (0.51) and a С9:water fraction ratio (0.51). That has made it possible to derive an equation of the yield multiple linear regression dependent on the most significant process parameters. The high values of the yield and bromine number correlation (0.94 and 0.93) give grounds to argue about the progress of oligomerization reaction. The relationship among the characteristics of oligomers has been confirmed. This indicates the possibility of directed adjustment of certain characteristics of hydrocarbon resins.