Wax Content Research Articles

Mitigating paraffin wax deposition by dispersants and crystal modifiers in flow testing

Functional molecules such as dispersants and crystal modifiers can be effective in mitigating wax deposition from crude oils and gas condensates. Both chemicals reduce the average wax particle size to sub-micron and change the crystal morphology. Water has a further significant effect on size reduction in dispersants. This work focuses on the effectiveness of these two additives in flow condition in a stainless-steel capillary tube. Unlike conventional flow loop systems, a simple open flow system is used to ensure constant wax content to avoid large fluid volume handling. Capillary tubes of 1- and 2-ft long are used to investigate effectiveness of dispersants and crystal modifiers in the laminar flow regime for a light shale oil with saturate content of 80 wt%. The effect of flow rate, concentration of the chemical additives (dispersant, crystal modifier), tube length, and brine on wax deposition are studied.An optimum concentration of chemical additives is found in flow tests, above which the effectiveness of additive decreases. Without aqueous phase, the crystal modifier is more effective than the dispersant. However, with 4% volume brine (of 5 wt% NaCl), the dispersant becomes more effective than the crystal modifier. Both additives are more effective at a higher flow rate; the influence of flow rate is more pronounced in the crystal modifier system than the dispersant. Wettability alteration to hydrophilic state is induced by adsorption of the dispersant backbone chains onto the stainless-steel (and wax molecules). Our results reveal that water improves dispersant effectiveness even in small amounts. A major observation in this work is pronounced pressure fluctuations in dispersants which relate to adhesion.

Influencing Behavior Study of Natural Almond Shell Filler on the Tensile, Thermal, and Free Vibrational Properties of Flax Fiber Intertwined Vinyl Ester Composites

ABSTRACT The structural porosity weakness of a natural flax fiber-layered polymer laminate was reduced by the spatial rearrangement of natural almond shell filler occupying preferentially porous sites between the stacking layers, improving the properties of the polymer laminate. The present work investigates the mechanical, thermal, and free vibrational behavior of composites, including surface modification and the effect of almond shell filler loading in the flax fiber intertwined composites. Alkaline treatment of natural flax fiber and almond shell filler effectively reduced the hydrophilic contents of hemicellulose, lignin, and wax without altering the cellulose nature, as confirmed by FTIR analysis. Tensile strength was 35% higher for the alkaline-treated 10% almond shell-filled composite than the untreated filler composite. However, the tensile strength decreased beyond 10% of filler loading because of the poor dispersion of fillers in the matrix. As evident in the 10% filled almond shell composite, due to stronger interaction, polymer-mixed almond fillers act as a thermal insulating layer between the flax stacks, increasing thermal stability. Alkali treatment with an almond shell of 10 wt% filled flax fiber composite exhibited a higher natural frequency (185 Hz) and damping value (0.042) due to total internal dissipation of dynamic forces.

Cement mortars with ceramic molds shells and paraffin waxes wastes: Physical and mechanical behavior

Foundry industry produces millions of tons of wastes discarded in landfills. Many studies have focused on foundry sands, however other wastes are generated during the casting process and no reuse solutions are known. The main objective of this study was the incorporation of paraffin waxes and ceramic mold shells in cement mortars, evaluating the influence of different paraffin wax contents in the mortars physical and mechanical properties. The obtained results showed a decrease in the workability, water absorption, flexural and compressive strengths of the mortars. However, the mortars presented a satisfactory physical and mechanical behavior, evidencing a possible practical application.

Stratification Properties of Peninsular-Malaysian Peat

Peat is known for its importance as carbon storage. Peatlands in Malaysia especially forest reserve areas are generally lack of natural resources due to poor soil nutrients. Hence, many of peatlands in Malaysia have been converted to plantations and industrialized area. Peninsular-Malaysian peat properties are less studied in terms of its physical and chemical properties. A total of 38 peat samples from 5 depths (surface, 50cm, 100cm, 150cm and 200cm) from 10 locations around Peninsular-Malaysia were characterized for its physicochemical properties: moisture, organic matter, pH, carbon, hydrogen, nitrogen, humic acid content and its FTIR properties. Results showed that moisture content ranges from 60.92% to 94.22% and moisture increases with increasing depth. Organic matter percentage was very high, having an average of 95% (range 74-99%) with most samples having organic matter more than 90%. Peninsular Malaysian peat is quite acidic, with pH average of 3.56 owing to its humic and fulvic acid contents. The min % humic acid (HA) is 32.06% and the highest is 62.44%. There is a slight increase in HA content as the depth increases. C:N ratio increasing with depth, indicating very slow decomposition rate. FTIR results indicated the presence of polysaccharides, fat, wax, lipids and lignins content which increases as the depth increases, especially the aromatics such as humic acids and lignins. These distinct characteristics are described to provide a better understanding of the significance of sustaining peat swamp forest for long-term management.

Extraction and Characterization of Natural Cellulosic Erythrina variegata Fiber for Biocomposites

ABSTRACT This paper presents a study on extraction and characterization of the cellulose fiber from the bark of Erythrina variegate (EV) plant. Several tests were carried out on Erythrina variegata fibers (EVFs) to determine their properties. These included thermogravimetric analysis (TGA)/difference thermogravimetric (DTG), X-ray diffraction (XRD) analysis, Fourier transform infrared spectroscopy (FTIR) as well as morphological analysis, using scanning electron microscopy (SEM) and atomic force microscopy (AFM). From the results obtained, chemical composition of EVFs, such as cellulose, lignin, ash, and wax content of 70.60, 12.70, 8.60, and 0.24 wt.%, respectively, were recorded through standard chemical analysis. The maximum and average tensile strength of the EVFs were found as 6.06 ± 0.02MPa and 2.80 MPa, respectively. The thermogravimetric analysis on the fiber showed excellent stability with a char residue of 19.23% and a maximum degradation temperature of 349°C. The crystallinity index (CI) of 37.5% and crystalline size of 36.93 nm of EVFs were calculated through X-ray diffraction analysis. The morphological study established that EVFs possessed rough surface even in raw form. The density of EVF was obtained at 1412 kg/m3, which was higher than that of Grewia damine of 1378 kg/m3 and lower than that of jute of 1460 kg/m3.

Effect of polyethylene pipe on wax deposition under different temperature and flow rate conditions

AbstractWax deposition is an important but troublesome boulder in petroleum industry that has always plagued pipeline engineering operators. In this study, wax deposition in the polyethylene pipes has different behaviors comparing wax deposition in stainless steel pipes such as smaller weight of wax deposits and lower wax content. After wax deposition experiments, some important parameters, including diffusivity and temperature gradient, were measured and calculated to explore the differences between two material pipes. Moreover, those factors can make a significant impact on radial mass flux. A series of results in polyethylene pipes suggests that higher diffusivity enhances diffusion flux of wax in the radial direction. But it was found that radial concentration gradient accounted for a larger proportion. These factors are the relationship of competition and cooperation and the combination of them results in different performances of wax deposition between polyethylene and stainless steel pipes.

Time-Dependent Properties of Multimodal Polyoxymethylene based binder for Powder Injection Molding

Powder injection molding (PIM) is one of the most versatile methods for the manufacturing of small complex shaped components from metal, ceramic or cemented carbide powders for the use in many applications. PIM consists of mixing the powder and a polymeric binder, injecting this mixture in a mold, debinding and then sintering. Catalytic debinding of polyoxymethylene (POM) is attractive since it shows high debinding rates and low risk of cracking. This work examines the possibility of using bimodal POM as the main component of the binding agent by studying its time-dependent and thermal properties and comparing them to monomodal POM. Furthermore, possible optimization of the binder formulation was investigated by the addition of short molecular weight polymeric chains (wax) to bimodal POM, as to create a multimodal material. It was observed that the magnitude of the complex viscosity for the commercial bimodal material was more than 2 times lower than for the chemically identical monomodal POM within the investigated frequency range. Viscosity values were observed to drop as the content of wax was increased, without compromising thebinders mechanical properties in solid state. A new formulation of bimodal POM plus 8 wt.% of added wax provided the most appropriate results from investigated combinations. This work has shown how the addition of short polymeric chains in POM influences its time-dependent properties in solid and molten state, which can be an important tool for the optimization of binders designed to be used in PIM technology.

Chemical Composition of Cuticle and Barrier Properties to Transpiration in the Fruit of Clausena lansium (Lour.) Skeels.

The plant cuticle, as a lipid membrane covering aerial plant surfaces, functions primarily against uncontrolled water loss. Herein, the cuticle chemical composition and the transpiration of wampee fruit (Clausena lansium (Lour.) Skeels) at the green, turning, and yellow stages in cultivars of “Jixin” and “Tianhuangpi” were comprehensively studied. The coverage of wax and cutin monomers per unit of fruit surface area at the green stage was lower in “Jixin” than in “Tianhuangpi” and increased gradually during development. Cutin monomers accumulated ranging from 22.5 μg cm−2 (green) to 52.5 μg cm−2 (turning) in “Jixin” and from 36.5 μg cm−2 (green) to 81.7 μg cm−2 (yellow) in “Tianhuangpi.” The total composition of waxes ranged between 6.0 μg cm−2 (green) and 11.1 μg cm−2 (turning) in “Jixin,” while they increased from 7.4 μg cm−2 (green) to 16.7 μg cm−2 (yellow) in “Tianhuangpi.” Cutin monomers were dominated by ω-, mid-dihydroxy fatty acids (over 40%), followed by multiple monomers of α,ω-dicarboxylic acids with or without added groups, α-monocarboxylic acids with or without ω- or mid-chain hydroxy or mid-epoxy groups, primary alcohols, and phenolics. The very-long-chain (VLC) aliphatic pattern of cuticular waxes was prominently composed of n-alkanes (ranging from 21.4% to 39.3% of total wax content), fatty acids, primary alcohols, and aldehydes. The cyclic waxes were dominated by triterpenoids (between 23.9 and 51.2%), sterols, and phenolics. Water loss in wampee fruit exhibited linear changes over time, indicating an overall monofunctional barrier to transpiration. Permeance for water in wampee fruit was higher at the green stage than at the yellow stage in both “Jixin” and “Tianhuangpi,” which showed a negative correlation with the changes of VLC n-alkanes. The results showed the cuticular chemicals, including cutin monomers and waxes, in wampee fruit and further indicated the potential contributions of the cuticular chemical composition to the physiological functions in fruits.

Comprehensive Characterization of New Natural Fiber Extracted from the Stem of Grewia flavescens Plant

ABSTRACT The physical, chemical, mechanical, thermal, and morphological characteristics of Grewia flavescens are reported in this article. The G. Flavescens fiber is found to have a satisfactory cellulose content and can be useful for lightweight applications due to its lower density. The fiber was analyzed using X-Ray diffraction (XRD) analysis, thermogravimetric analysis, Fourier transform infrared spectroscopy, scanning electron microscopic test, and atomic force microscopy. While XRD analysis confirms a comparable crystallinity index for this natural fiber, the thermal characteristics confirm the fiber’s stability behavior when subjected to temperatures up to 165°C. Results of the morphological study of the fiber with a rough surface suggest its suitability for use in making composites. The comparatively less amount of wax and moisture content observed are again advantageous as the fiber bonding with the matrix will be improved in the composites. It is recommended that the present G. flavescens fiber can be efficiently utilized for making biocomposites.

Investigation on Physicochemical, Thermal and Mechanical Properties of New Cellulosic Fiber Obtained from the Stem of Tecoma Stans

ABSTRACT The objective of this study is to investigate chemical, physical, mechanical and thermal properties of novel cellulosic fiber extracted from the bark of Tecoma stans tree. Tests such as chemical, X-ray diffraction, Fourier transform infrared spectroscopy, thermogravimetric analysis and differential scanning calorimetry were carried on TS fibers. Higher cellulose and lower wax content in TSF make them stronger and establish better interfacial adhesion. X-ray diffraction analysis revealed the crystallinity index and crystallite size of TSF as 31.24% and 2.2 nm respectively. From thermogravimetric analysis, TSF was found to withstand up to 334°C and exhibit activation energy 72.03 kJ/mol. Tensile strength (330–543 MPa) and Young’s modulus (9.60–16.28 GPa) of TSF were found to be comparatively higher than other natural fibers. The morphology of TS fiber surface examined through FESEM revealed the existence of cellular structure with some serrations which makes the surface rougher and results in better adherence with polymer matrix.

Two-functional phase-change pressure-sensitive adhesives based on polyisobutylene matrix filled with paraffin wax

Paraffin wax was used to impart the function of heat accumulation to pressure sensitive adhesives based on polyisobutylene (PIB) and simultaneously to suppress their cold flow. Laser microinterferometry showed 6% solubility of paraffin wax in PIB at 25 °C with achieving complete miscibility of PIB and wax at temperatures above 46 °C. The thermophysical and rheological properties of mixtures containing from 10% to 60% paraffin wax were investigated. According to calorimetry data, wax reduces the glass transition temperature of PIB, which in turn affects the apparent degree of wax crystallinity, shifting it in different directions. Paraffin wax significantly reduces the effective viscosity of the PIB melt and lowers the values of its storage and loss moduli. This simplifies the processing of adhesives and allows them to be used as easily flowable liquids. Nevertheless, the wax crystallizes during cooling, which leads to a multiple increase in the viscosity of adhesives to a level comparable or even greater than the viscosity of filler-free PIB. In this process, the heat is released in relatively larger quantities than during crystallization of pure wax, as additional heat is produced owing to the loss of solubility of wax in the PIB matrix. With an increase in the wax content, the durability of adhesive joints with steel firstly passes through a minimum, which is associated with the plasticizing effect of paraffin wax. However, the addition of 60% paraffin wax makes it possible to increase the durability of adhesive joints by 20 times, simultaneously reducing the melt viscosity of the adhesive by 4 decimal orders of magnitude. A key fact is that the resulting easy-to-process adhesive allows storing heat, i.e. to play two roles at the same time – a reinforced pressure-sensitive adhesive and a phase-change material.

Self-healable hydrophobic films fabricated by incorporating natural wax into cellulose matrix

Biodegradable cellulose films have high mechanical strength, excellent flexibility, and good transparency, which are potential candidate materials to replace petroleum-based packaging materials and disposable products. However, the poor hydrophobicity of cellulose films seriously limits their practical application. Herein, self-healing hydrophobic films were fabricated by incorporating natural wax into cellulose matrix. The effects of types of natural waxes, wax content, and annealing temperature on the performances of films were systematically investigated. The resultant films exhibited good hydrophobicity (water contact angle: ∼120°), and high tensile strength (>120 MPa), which could be completely biodegraded in natural soil (within 81 days). Importantly, the self-healing of hydrophobic films could be achieved by releasing wax from inside to surface of cellulose matrix during the annealing process. This work demonstrated a facile strategy for designing and developing hydrophobic and self-healable cellulose-based materials for packaging materials to replace petrochemical plastics, which is conducive to alleviate environmental problems caused by nondegradable plastic pollution.

Processability and physico‐mechanical properties of ultrahigh‐molecular‐weight polyethylene using low‐molecular‐weight olefin wax

AbstractThe influence of molecular weight of olefin wax as a plasticizer on the processability and properties of ultrahigh‐molecular‐weight polyethylene (UHMWPE) was thoroughly investigated in this study. Two different grades of olefin wax (H5 and 210P) were used separately to plasticize UHMWPE. Comparative results were analyzed based on mixing torque, mechanical, thermal, thermo‐mechanical, and morphological aspects. The Gaussian mathematical model was applied to the internal thermo‐shear batch mixing torque data to predict processability and plasticization of the resulting compounds. A decrease in the peak torque value with increase in wax content revealed the plasticization effect. Across both types of wax (H5 and 210P) at 4, 8, and 10 phr content, the 10 phr H5 wax plasticized UHMWPE batch showed a minimum peak torque of 4.5 Nm with a broad mixing temperature window (∆T) of 32.4°C. The relatively low‐molecular‐weight wax (H5) seemed to be more efficient at uncoiling the entanglements among the amorphous phase of UHMWPE, perhaps because of its smooth interpenetration between ties. The lowest degree of crystallinity range (34%–40%) and the highest nucleation rate (0.9 min−1) were found with 10 phr H5 wax plasticized UHMWPE. The tensile strength of 30.5 MPa and elastic modulus of 127 MPa, achieved by the addition of H5 wax at 10 phr loading, confirmed the optimum effect of plasticization. The plasticization effect was also established from the loss moduli and Cole–Cole plots (log loss modulus vs. log storage modulus). A smaller number of multiple stress‐induced overshoots and the inclining approach toward the viscous dominant regime with temperature sweep were observed in the case of 10 phr H5 wax composition. Scanning electron microscopy (SEM) analysis revealed disappearance of interfacial crazing and interparticle boundaries progressively with the increase in H5 wax content. Overall, plasticized UHMWPE with 10 phr content of H5 wax showed the optimum processability and properties.

Separation of wax fraction in asphalt binder by an improved method and determination of its molecular structure

The crystalline wax in asphalt binder has obvious influence on the low temperature performance of the asphalt pavement, and it is essential to adopt an accurate and efficient method to separate crystalline wax from asphalt binder. In this paper, the optimum eluted solvents used for the separation of the wax fraction are determined by the solubility parameters, and the reduced pressure column chromatography method is developed through the improvement of existing methods. It was discovered that the efficiency and accuracy of the experiment had been greatly improved with the higher repeatability and recovery of the saturates and aromatics. On this basis, the average molecular structures of the saturate and aromatic wax fraction were determined by the gas chromatography-mass spectrometry (GC–MS), gas chromatography-flame ionization detector (GC-FID), nuclear magnetic resonance (NMR) and Fourier-transform infrared (FTIR) spectroscopy methods. The smaller degree of the branch chain of the wax fraction would attribute to the larger content of the crystalline wax in asphalt binder, which could provide a compositional mechanism explanation for the physical hardening (thermoreversible ageing) of the asphalt binder at the low temperature.

Experimental study on wax removal and viscosity reduction of waxy crude oil by Ochrobactrumintermedium

To investigate the influence of microbial wax removal and viscosity reduction technologies on the fluidity of waxy crude oil, this study took the waxy crude oil from China's Daqing Oilfield as the experimental object for microbial wax removal and viscosity reduction experiment. First, utilizing standard strain screening and culture protocols, a high-efficiency microbial strain H-1 (Ochrobactrum intermedium) was proposed from in situ soil. The single factor experiment and multi-factor response surface analysis were then utilized to optimize the temperature, initial pH value of the medium, and NaCl mass concentration needed for the strain's growth. Oil displaced activity and emulsification tests were used to evaluate the biosurfactants produced by the metabolism of strain H-1, and Fourier transform infrared spectroscopy was used to identify the types of biosurfactants. Finally, the application effect of strain H-1 on wax removal and viscosity reduction of waxy crude oil were clarified through the wax crystal morphology, wax content, and viscosity of waxy crude oil. The research findings indicated that strain H-1 produced best at a temperature of 38.5 °C, pH value was 7.1 and the mass fraction of NaCl was 0.64%. The lipopeptide biosurfactant produced by strain H-1 can displace oil. Additionally, strain H-1 has a high emulsifying capacity, with a 61.25% emulsifying coefficient. After 7 days of treatment with the strain H-1, the wax crystal morphology of the waxy crude oil changed from a large-sized aggregated to a small-sized sparse condition, and the wax content of the waxy crude oil fell by 38.67%. The viscosity reduction rate of strain H-1 to waxy crude oil was consistently greater than 30% over the temperature range of 30–42 °C, with the greatest rate of 42.38% at 39 °C. The preceding results demonstrate that strain H-1 can degrade the wax components of waxy crude oil, lower the crude oil's low temperature viscosity, and then improve the crude oil's low-temperature fluidity.

Effects of residual wax content on the thermal, rheological, and mechanical properties of high‐density polyethylene

AbstractThe influence of residual wax content on the thermal, rheological, and mechanical behavior of two high‐density polyethylene (HDPE) samples from different lots of the same supplier was characterized. HDPE with a low wax content presented a higher melting temperature and a wider melting endotherm. A decrease in the degree of crystallinity and thermal stability of HDPE with a higher wax content was observed. Thermograms obtained by DSC indicated a small additional exothermic transition associated with the exclusion of residual wax. A higher wax content in HDPE produces a decrease in its viscosity due to a lubricating effect, which allows the sliding of HDPE chains of high molecular weight. In contrast, HDPE with lower wax content achieves greater elongational viscosity and melt strength. The mechanical testing results show that HDPE with higher wax content presented lower Young's modulus, tensile strength, elongation at break, and Izod impact strength than HDPE with lower wax content. The results obtained show that a relatively slight difference in wax content significantly affects HDPE properties.

Blueberry water loss is related to both cuticular wax composition and stem scar size

The contributions of the cuticle and stem scar to blueberry water loss were evaluated in four cultivars. Among the cultivars, 55–69% of the water loss occurred through the cuticle, indicating the key role of the cuticle and cuticular waxes in restricting water loss. Cuticular wax content at harvest ranged from 38.12 to 67.00 μg cm−2 across the four cultivars and increased during four-week postharvest storage by an average of 49.5%. Oleanolic and ursolic acid were the most abundant wax compounds. The amount and proportion of oleanolic acid were negatively related to water loss. Wax esters were at low levels in all cultivars, but their content and proportion were directly related to water loss. The stem scar size was directly related to water loss, but only within a given cultivar and not across cultivars. This study provided new knowledge on the role of the cuticular waxes and stem scar in determining water loss in blueberries.

Assessing the performance of analytical methods for propolis – A collaborative trial by the international honey commission

Propolis is a resinous beehive product with extraordinary bioactivity and chemical richness, linked with the botanical sources of the resin. The potential of this product keeps captivating the scientific community, conducting to continuous and growing research on plant sources, composition, or applications in agriculture, cosmetics, pharmacy, odontology, etc. In all cases, the quality assessment is a requirement and relies on methods to extract the bioactive substances from the raw propolis and quantify different components. Unfortunately, besides the absence of international quality requirements, there is also a lack of standardized analytical procedures, despite the presence of several methodologies with unknown reliability, often not comparable. To overcome the current status, the International Honey Commission established an inter-laboratory study, with propolis samples from around the globe, to harmonize analytical methods and evaluate their accuracy. A common set of protocols was matched between twelve laboratories from nine countries, for quantification of ash, wax, and balsamic content in raw propolis, and spectrophotometric evaluation of total phenolics, flavone/flavonol, and flavanone/dihydroflavonol in the extract. A total of 3428 results (97% valid data), were used to assess the methods’ accuracy following ISO-5725 guidelines. The within-laboratory precision, revealed good agreement levels for the majority of the methods, with relative variance below 5%. As expected, the between-laboratory variance increased, but, with exception of the flavanone method that revealed a clear lack of consistency, all the others maintained acceptable variability levels, below 30%. Because the performance of ultrasounds procedures was low, they cannot be recommended until further improvements are made.

Evaluation of rheological behavior of asphalt binder modified by recycled polyethylene wax and crumb rubber

As in recent years the disposal of waste tire rubbers in landfills are increased because of increase in population, the environmental population are increased. The recycle and reuse of these material to modify bitumen can be environmentally and economically beneficial. In current research the polyethylene wax and Crumb Rubber are used to modify original binder. Several bitumen tests were used to evaluate the rheological properties of binder such as; Multiple Stress and Creep Recovery (MSCR) and Linear Amplitude Sweep (LAS), dynamic shear rheometer (DSR), bending beam rheometer (BBR), rotational viscosity. Results revealed that samples modified by 18% crumb rubber and 5% polyethylene wax have better performance to save energy and reduce air pollution. Results indicated that addition of polyethylene wax led to decrease in the performance of binder in low temperature, while CR enhance it. Fatigue test results indicated that addition of CR increased the fatigue life of binder, while as the polyethylene wax content increased, the fatigue lives decreased. MSCR test results indicated that CR improves the recovery potential of binder which lead to enhance the rutting properties of binder. Based on results in 15% CR modified binders, addition of 3% polyethylene wax improves the resistance against permanent deformation while addition of 5% and 7% polyethylene wax reduces the rutting resistance of binder. While in binder modified by 18% and 21% CR, addition of 3% and 5% polyethylene wax enhance the permanent deformation resistance of binder and addition of 7% polyethylene wax decreases the rutting performance.

Profiling of Few of the Tea Accessions on Physiological Growth and Stress Tolerance

Tea [Camellia sinensis(L) O Kuntz] is one of the oldest, most widely consumed and least expensive natural beverages, known to the world over for its heritage brew with various flavor and antioxidant properties. The productivity of tea in world as well as in India has been raised by developing high yielding clones and seed stocks but the genetic base of the existing diversity of the crop is rapidly narrowing down. In present scenario, apart from yield and quality, physiological parameters and abiotic stress tolerance are also raising up to be the most important environmental indicator impacting on sustainability and productivity of tea. In the published research work, an effort was made to characterize and estimate the variation of 20 tea germplasm named as THT1 to THT20, growing in the Experimental Garden for Plantation Crops, AAU, Jorhat on the basis of growth parameters and abiotic stress tolerance capability of tea.
 In the experiment all the germplasm showed highly significant difference amongst them regarding growth parameters, pigment content and on abiotic stress tolerance. THT 1, THT 10, THT 3 contained higher total chlorophyll and THT 4, THT 10, THT 20 showed high carotene content. In case of growth parameters THT 11, THT 7, THT5 showed higher plucking point density whereas THT 11, THT 17, THT 7 showed good abiotic stress tolerance with high value of proline content, relative turgidity, water saturation deficit and epicuticular wax content.
 When clustering was done based on abiotic stress tolerance, pigment and growth parameters respectively, THT11 and THT 17 are found to form a discriminated cluster in the dendogram. The parameters taken especially for abiotic stress tolerance study may be subjected to environmental factors for which more elaborated field trial may be required for these clones to assess their yield and quality parameters.