Low BN Research Articles

Construction of 3D BN network with high-density thermal conductive paths

Efficient heat dissipation is essential to further improve the integration of high-power electronic packaging devices. Three-dimensional BN networks with high-density thermal conductive paths were designed as the heat transfer skeleton of thermal interface materials. 3D networks with high-density thermal conductive paths inlaid between oriented BN paths were constructed using precursor self-assembly and freeze-drying to improve the thermal conductivity of polymeric materials. The results show that high-density thermally conductive paths have stronger polymer-enhanced thermal conductivity than directional thermal paths and compared with pure TPU, the thermal conductivity of TPU/BN-2 under low BN filling content (10%wt) is increased by 250 % and 286.5 % in the through surface and flat surface respectively. This work provides new ideas for the preparation of polymer composites for thermal interface materials in electronic packaging and integrated circuits with excellent thermal management properties.

Growth of polyaniline nanowire arrays on boron nitride microrods enables high‐efficient thermal transport

AbstractThe rapid development of flexible conductive materials has promoted the research on conductive polymer (CP)‐based materials. However, CPs have relatively low thermal conductivity (TC), which can result in severe heat dissipation problems for device applications. In this work, core–sheath structured polyaniline@boron nitride (BN@PANI) composites were prepared by in‐situ growth strategy, in which PANI nanowire arrays were uniformly anchored to the surface of BN microrods. Thanks to the particular structure, the as‐prepared BN@PANI composite shows excellent thermal management capabilities. Specifically, the TC of the BN@PANI composite is 4.32 W/m·K at low BN loading of 10 wt%, which is almost 17.8 times that of pure PANI. Moreover, the excellent heat dissipation performance is intuitively presented through infrared imaging technology. Impressively, the PANI nanowire arrays are vertically arranged on the BN surface to form a conductive pathway, which results in conductivity comparable to pure PANI. This work broadens the ideas for preparing high‐performance CP‐based composites by using insulating fillers.Highlights Core–sheath structured BN@PANI composites were prepared by an in‐situ growth strategy. The thermal conductivity of composite was 4.32 W/m·K at 10 wt% BN loading. The introduction of BN had little effect on the conductivity of PANI. The BN@PANI composites possessed excellent thermal management capability. This work contributes to understanding heat transport in conductive polymers.

Preparation of strong soy protein composite materials with thermal conductivity and biodegradability by constructing nanophase enhanced organic-inorganic hybrid structure

The development of multifunctional films with high strength, biodegradability, and excellent thermal conductivity has drawn increasing interest. In this study, inspired by the unique hybrid structure of oysters, a nanophase-reinforced organic–inorganic hybrid structure was built using polydopamine modified boron nitride (BN@PDA), soy protein isolate (SPI), dialdehyde cellulose (DAC), and polyethylene glycol (PEG) to develop a strong soy protein film with multifunctionalities. The resultant films displayed excellent thermal diffusion ability and exhibited high tensile strength (24.03 MPa) and thermal conductivity (TC, 2.96 W·m−1·K−1) under low BN load (<0.5%). Meanwhile, the formation of non-covalent cross-linking and organic–inorganic hybrid structure endowed the films with superior flexibility. Importantly, owing to the selection of bio-based materials for preparation, the SPI-based films exhibited good biodegradability. It is believed that this study provides a creative perspective for the development of value-added multifunctional film materials and has good application prospects in advanced bio-based thermal conductive materials.

Vertically Aligned Boron Nitride Nanosheets Films for Superior Electronic Cooling.

Thermally conductive and electrically insulating thermal interface materials (TIMs) are highly desired for electronic cooling. To improve heat transfer efficiency, thermally conductive fillers with a high loading content have been incorporated into the polymer-based TIMs. However, this is usually at the expense of the interfacial thermal resistance reduction and reliability. In this study, vertically aligned boron nitride nanosheet films (VBNFs) have been prepared by a scalable microfluidic spinning process and template-assisted chemical vapor deposition conversion method. A further high-temperature annealing was applied to achieve high crystallinity. VBNFs have been applied as fillers to fabricate TIMs and achieve a superior through-plane thermal conductivity of 6.4 W m-1 K-1 and low modulus of 2.2 MPa at low BN loading of 9.85 vol %, benefitting from the well-aligned vertical sheet structure and high crystallinity. In addition, the fabricated TIMs present high-volume resistivity and breakdown strength, satisfying the electrical insulation demands. The high thermal conductivity and low modulus contribute an outstanding cooling performance to the TIMs in the heat dissipation application for high-power LEDs. This template-assisted conversion technology for the fabrication of orientated BN nanosheets structure and the prepared high-performance TIMs pave the way for efficient thermal management of high-power electronics.

Novel nanoparticles prepared from isothiocyanate derivatives for phototherapy of tumor.

Phototherapy is a new method to treat tumor, including photodynamic therapy (PDT) and photothermal therapy (PTT). However, the GSH in tumor cells could deplete ROS produced by photosensitizers, resulting in inadequate PDT. Isothiocyanate not only is a new type of anti-tumor drug, but also may combine with GSH, increasing the content of intracellular ROS and improving PDT effect. Here we synthesized a kind of water-soluble nanoparticles (BN NPs) parceling BODIPY-I-35 up with mPEG-ITC and lecithin. mPEG-ITC can react with GSH in tumor cells to reduce the consumption of ROS. BN NPs can be used as vectors to deliver drugs to tumor sites. Under 808nm laser irradiation, BN NPs solution increased 13°C within 10min, indicating that BN NPs had superb photothermal performance. In vitro experiments, low dose BN NPs showed satisfactory PDT and PTT effects, and the cell viability of MCF-7 cell was only 13%. In vivo, BN NPs with excellent biocompatibility showed favorable phototherapy effect and tumor was effectively inhibited. Fluorescence imaging could present the long retention effect of BN NPs in tumor locations. In conclusion, the BN NPs showed the effect of enhancing phototherapy and provided a remarkable application prospect in the phototherapy of tumor cells.

Investigating the thermal conductivity and flame-retardant properties of BN/MoS2/PCNF composite film containing low BN and MoS2 nanosheets loading

Cellulose has attracted considerable attention as a potential substitute for plastics. However, the flammability and high thermal insulation properties of cellulose contradict the unique requirements for highly integrated and miniaturized electronics i.e., rapid thermal dissipation and efficient flame retardancy. In this work, cellulose was first phosphorylated to achieve intrinsic flame-retardant properties, and subsequently treated with MoS2 and BN, ensuring efficient dispersion throughout the material. Via chemical crosslinking, a sandwich-like unit was formed, in the order of BN, MoS2, and phosphorylated cellulose nanofibers (PCNF). The sandwich-like units were further self-assembled, layer-by-layer, to successfully create BN/MoS2/PCNF composite films exhibiting excellent thermal conductivity and flame retardancy, and comprised a low MoS2 and BN loading. The thermal conductivity of the BN/MoS2/PCNF composite film containing 5 wt% BN nanosheets was higher than that of neat PCNF film. The combustion characterization of BN/MoS2/PCNF composite films revealed highly desirable properties that were far more superior than the BN/MoS2/TCNF (TCNF, TEMPO-oxidized cellulose nanofibers) composite films. Moreover, the toxic volatiles that escaped from flaming BN/MoS2/PCNF composite films were significantly reduced compared to that of the BN/MoS2/TCNF composite film alternative. The thermal conductivity and flame retardancy of BN/MoS2/PCNF composite films have promising application prospects in highly integrated and eco-friendly electronics.

Evaluation Study on the Use of Non-Contact Prevention and Protection Products in the Context of COVID-19: A Comprehensive Evaluation Method from AHP and Entropy Weight Method.

In the post-epidemic era, there is an endless supply of epidemic prevention products that cover a wide range of public areas. The introduction of such products has eased the tense pattern of virus proliferation in the context of the epidemic, and effectively demonstrated the initiatives implemented by the Chinese people in response to the outbreak. This paper therefore begins with the study of contactless epidemic prevention products, which appear in a form that meets the needs of contemporary society and offers a new mode of living to it. It enriches the measures for epidemic prevention and control. By obtaining satisfaction ratings from the user community, the performance of such products can be understood in time to provide a substantial basis for the subsequent upgrading and optimization or transformation of such products. This study uses the KJ method and questionnaires to construct an index system for contactless epidemic prevention products, grasp users' needs for epidemic prevention products in real time, classify and identify such products, and select such products as epidemic prevention smart security gates, medical delivery robots, infrared handheld thermometers, thermographic body temperature screening, contactless inductive lift buttons, and contactless medical vending machines. The questionnaire was designed with four dimensions: safety, intelligence, aesthetics and economy. A sample size of 262 was collected through the distribution of questionnaires. We used AHP and entropy weighting methods for the comprehensive evaluation; AHP basically tells us how satisfied most users are with this type of product. The use of the entropy weighting method can achieve objectivity in the weighting process. Combining the two approaches helps to improve the scientific nature of the weighting of the evaluation indexes for contactless and epidemic-proof products. It is clear from the AHP analysis that, firstly, there are differences in the perceptions of the performance of this type of product between different age groups. Secondly, the user group rated the perceived performance of the product presented as high (Bn>0.200), which users can subjectively and directly perceive. Next, the perceived future sustainable economic development of this product category is low (Bn≤0.200), and users place low importance on its economic aspects as an objective additional condition. The entropy method of analysis shows that, under reasonable government control of the market for intelligent products, the safety, intelligence and aesthetic effects of these products are significant (Cm≤0.100); further, the economic presentation of these products has yet to be optimized and upgraded (Cm>0.100).

Polyurethane-templated 3D BN network for enhanced thermally conductive property of epoxy composites

Utilizing three-dimensional filler has been deem as a promising approach to improve the thermal conductivity of polymer composites. In this research, we developed a polyurethane sacrificial template technique to fabricate a novel three-dimensional porous carbon bonded BN foam (3D-CBNF), aiming to improve the thermal performance of polymers (epoxy). The as-prepared 3D-CBNF/epoxy composite exhibits a high thermal conductivity (TC) of 2.11 Wm−1K−1 at a relatively low BN loading of 24.7 wt%, corresponding to a TC enhancement (TCE) of 1072% compared with the pure epoxy resin. The analysis of the thermal conductivity mechanism based on EMT and Foygel models and finite element simulation indicated that the high thermal conductivity of composites was due to the efficient heat transfer pathways provided by the 3D interconnected BN network and lower interface thermal resistance in internal of it. In addition, the as-obtained composite possessed a relatively low dielectric constant (below 4.5 at 1 MHz) and a high volume electrical resistivity (beyond 1015 Ω·cm). Overall, a novel and promising method of preparation for 3D construction with thermally conductive filler, which is designed to attain composites with high thermal conductivity, has been proposed in this work.

Design of thermoelectric battery based on BN aerogels and Bi2Te3 composites

The Seebeck coefficient, electrical conductivity and thermal conductivity of thermoelectric materials are related but not independent, so it is difficult to improve the figure of merit value of thermoelectric materials. In the compound with nanometer grain size, a large number of surface interfaces and various defects in the material will increase the phonon scattering, resulting in the decrease of lattice thermal conductivity. Therefore, the nano-structure of the material is expected to increase its thermoelectric performance parameters. This work presents is based on the self-synthesized BN nano-materials, different structure of the thermoelectric cell composed of nanomaterial BN and thermoelectric material bismuth telluride are designed and analyzed, and its output voltage and power are simulated. Low dimensional BN nanomaterials with low thermal conductivity may contribute to reduce the overall thermal conductivity of the battery and improve the output efficiency. The thermoelectric coefficient of the thermoelectric battery is approximately calculated to be 1.22, which will satisfy the power supply requirements of some small power electronic equipment in practical application.

Beneficial effect of low BN additive on densification and mechanical properties of hot-pressed ZrB2–SiC composites

The incorporation of 1 wt% hexagonal BN (hBN) into ZrB2–30 vol% SiC could noticeably better the fracture toughness, hardness, and consolidation behavior of this composite. This research intended to scrutinize the effects of various amounts of hBN (0–5 wt%) on different characteristics of ZrB2–SiC materials. The hot-pressing method under 10 MPa at 1900 °C for 120 min was employed to sinter all designed specimens. Afterward, the as-sintered samples were characterized using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDS), and Vickers technique. The hBN addition up to 1 wt% improved relative density, leading to a near fully dense sample; however, the incorporation of 5 wt% of such an additive led to a composite containing more than 5% remaining porosity. The highest Vickers hardness of 23.8 GPa and fracture toughness of 5.7 MPa.m1/2 were secured for the sample introduced by only 1 wt% hBN. Ultimately, breaking large SiC grains, crack bridging, crack deflection, crack branching, and crack arresting were introduced as the chief toughening mechanisms in the ZrB2–SiC–hBN system.

Microwave‐assisted in situ polymerization of polycaprolactone/boron nitride composites with enhanced thermal conductivity and mechanical properties

AbstractPolycaprolactone/boron nitride (PCL/BN) composites were prepared by microwave‐assisted ring‐opening polymerization of ε‐caprolactone (ε‐CL). In order to improve the dispersibility and interfacial interaction between BN fillers and PCL matrix, hydroxyl functional BN (mBN) was first prepared to be used as a macroinitiator for ε‐CL. Then BN grafted PCL (BN‐g‐PCL) copolymers were obtained via the in situ method, which acted as in situ compatibilizers in the PCL/BN composites. Various techniques were applied to characterize the mBN and PCL/BN composites. The Fourier transform infrared spectroscopy results confirm the structure of the BN‐g‐PCL copolymer. Field emission SEM graphs exhibit that, for the PCL/mBN composites, the mBN presents a homogeneous dispersion in the matrix and interfacial adhesion between the PCL and mBN is improved. These are beneficial for enhancing the thermal conductivity of the PCL/mBN composites. Notably, the PCL/mBN composite with 5 wt% mBN loading achieves the highest thermal conductivity of 0.55 W m−1 K−1, which is 2.75 times higher than that of pure PCL, 0.20 W m−1 K−1. This indicates that the excellent dispersion and interfacial adhesion could lead to the construction of continuous thermal conductive paths at a low BN loading and reduce the heat loss caused by phonon scattering in the interface. Furthermore, mBN could help to improve the mechanical properties of the composite. On adding 5 wt% mBN, the tensile strength and tensile modulus of the composite are 1.58 and 2.05 times higher, respectively, than those of PCL. © 2020 Society of Chemical Industry

Improving gas barrier properties with boron nitride nanosheets in polymer-composites

Abstract Liquid exfoliated, size selected, hexagonal boron nitride (hBN) nanosheets are dispersed in thermoplastic polyurethane (TPU) via solution processing and their properties such as CO2 gas barrier and mechanical properties were evaluated. Aspect ratio and filler loading are important parameters for gas permeation of polymer composites. The range of BN volume in the polymer matrix is 0–1.1%. The aspect ratio ∼331 of BN is estimated with transmission electron microscope. With the inclusion of tiny BN, the permeation reduction levels are considerably enhanced for CO2 in BN-TPU composites. At 0.011 vol% BN, permeability is reduced up to ∼55%, further reducing to 82% (0.054 vol% BN). Further increase of BN concentration (0.5–1.1 vol%) in TPU slightly reduces the gas retention maintaining a permeation level of 76–80% as compared to the base polymer. Theoretical models predict well the experimental results at low BN concentrations with both Neilson and Bhardawaj models which differ for orientation of fillers inside the polymer. The reduction in gas retention at maximum BN loading occurs may be due to the aggregation of filler inside polymer. X-ray diffraction and tensile testing also suggest the aggregation phenomena. The enhancement in CO2 barrier properties and the mechanical robustness may pave a way for utilization of these composites in applications like coating in CO2 gas transmission pipelines and food packaging.

Highly Thermally Conductive Polyimide Composites via Constructing 3D Networks.

Easy and high efficient methods are in great demand to obtain polyimide (PI) composites with high thermal conductivity in the electronic packaging field. In this work, PI/boron nitride (BN) composites with high thermal conductivity are easily fabricated. Tightly connected and well-arranged BN platelets construct effective 3D thermally conductive networks in the PI matrix upon hot pressing, after BN platelets are coated on the surface of PI granules by the help of a kind of PI adhesive. The thermal conductivity of the PI/BN composites reaches as high as 4.47WmK-1 at a low BN loading of 20vol%, showing an enhancement of 2099%, compared to pure PI. Such enhancement of the thermal conductivity is the highest compared with the results in the open literature. Our work is a good example that utilized the sufficient physical connection (aggregates) of thermally conductive fillers to significantly promote the thermal conductivity of polymer composites.

Cross-sectional transmission electron microscopy studies of boron ion implantation in hexagonal boron nitride

We have reported on the implantation of boron ion into hexagonal boron nitride (h-BN) material to aid the nucleation of cubic boron nitride nanocrystals (nc-BN).Single crystal h-BN was implanted with boron ion at 150 keV at fluences of the order of 1015 and 1017 ions/cm2 at room temperature. High Angle Annular Dark-Field Scanning Transmission Electron Microscopy (HAADF-STEM) mapping showed a variation in image contrast in samples irradiated to a fluence of 1 × 1015 ions/cm2. As predicted by Stopping Range and Ions in Materials (SRIM) calculations, the implanted region with the highest damage density appeared to have a bright contrast in HAADF-STEM which represented the high density c-BN symmetry. High Resolution Transmission Electron Microscopy (HRTEM) and electron diffraction measurements showed regions with nc-BN for samples implanted with low fluences and amorphous BN after implantation with high fluences indicating a fluence-related phase transition in BN. Raman spectroscopy showed the emergence of longitudinal optical frequency mode associated with c-BN after implantation.

Hydrogen Bond-Regulated Boron Nitride Network Structures for Improved Thermal Conductive Property of Polyamide-imide Composites.

Highly thermal conductive polymer composites with minimized content of fillers are desirable for handling the issue in thermal management in modern electronics. However, the difficulty of filler dispersion restricts the heat dissipation performance of thermoplastic composites and the intermolecular interaction is another crucial factor in this problem. In the present study, the hydrogen bond was used to regulate the formation of the three-dimensional boron nitride (3D BN) interconnected network to act as a high thermal conductive network in thermoplastic polyamide-imide (PAI) materials. The prepared electrical insulated PAI/3D-BN composites have a thermal conductivity (TC) of 1.17 W·m-1·K-1 at a low BN loading of 4 wt %/2 vol % and exhibit a thermal conductivity enhancement of 409%. We attribute the increased TC to the construction of 3D BN interconnected network and the hydrogen bond regulated between hydroxylated BN and polyvinyl alcohol, in which an effective thermal conductive network is constructed. This study provides a guided hydrogen bond strategy for thermally conductive polymer composites with good mechanical and electrical insulation properties in thermal management and other applications.

Surface Insulation Breakdown Behaviors in Liquid Nitrogen Environment of Epoxy/BN Composite

Epoxy resin as an insulating material is widely used in superconducting motors because it has excellent insulation properties under extremely low temperature. The insulation properties could be damaged by surface discharge. Our previous studies were focused on surface insulation breakdown behaviors in the room temperature condition, and the results showed that the accumulated heat at the discharge area was the main reason to cause insulation breakdown. The performance of surface discharge erosion resistance in a liquid nitrogen environment was not clear. In this paper, surface insulation breakdown behaviors in liquid nitrogen were studied to clarify the effects of extremely low temperature and BN particles on tracking performance. A digital camera and an infrared camera were used to measure the breakdown process. The camera was used to record the time to breakdown and observe the whole insulation breakdown process, while the thermal accumulation and decay process was measured by the infrared camera. Obtained results indicated that insulation breakdown performance was affected by BN fillers and low temperature significantly. In the liquid nitrogen environment, the time to tracking failure is much longer than that in air. It is concluded that the extremely low temperature in liquid nitrogen could produce an inhibitory effect on surface insulation breakdown.

Uterine leiomyomas with bizarre nuclei: a clinicopathologic study of 59 cases.

Leiomyoma with bizarre nuclei (LM-BN) is an uncommon tumor with histologic features (mononucleated or multinucleated bizarre cells that may have a diffuse distribution, prominent nucleoli, and karyorrhectic nuclei that may mimic atypical mitoses) that often causes confusion with leiomyosarcoma. Fifty-nine LM-BNs were collected from our consultation files over the years 2000 to 2011. Features recorded included patient age, therapy, tumor size, border, gross appearance, density and distribution of BN, mitotic count, karyorrhectic nuclei, prominent nucleoli, cells with conspicuous dense eosinophilic cytoplasm (rhabdoid-like), vascular changes and type of vasculature, and presence of necrosis and its nature. Follow-up information was obtained for all patients. Patients ranged in age from 25 to 75 (average 45) years (11 patients between 25 and 35 y, 20 between 36 and 45 y, 22 between 46 and 55 y, and 6 between 56 and 75 y). Forty-two underwent hysterectomy and 17 myomectomy. For 51 tumors gross findings were known. Forty (78%) had a solid white and whorled cut surface and 11 (22%) a yellow appearance. Five (10%) neoplasms showed prominent cystic degeneration, and hemorrhage and/or necrosis was seen in 9 (18%). Forty-five LM-BNs had a pushing margin with the surrounding myometrium, whereas 1 showed irregular borders. Margins could not be ascertained in the slides available in 13 cases. Twenty-eight (48%), 19 (32%), and 12 (20%) LM-BN showed low, intermediate, and high BN density. Eighteen (30%) tumors showed diffuse, 26 (44%) showed multifocal, and 15 (26%) had focal BN distribution. Mitotic counts ranged from 0 to 7/10 high-power fields (HPF) (average 1 to 2/10 HPF). Thirty-seven (63%) had <2/10 HPF, 19 (32%) had 2 to 5 mitoses/10 HPF, and in 3 tumors (5%) mitotic counts were 6, 7, and 7/10 HPF (2 with focal and 1 with diffuse BN). All but 4 LM-BNs showed karyorrhectic nuclei, striking in 12 neoplasms, mimicking atypical mitoses. Nineteen (32%) LMs had prominent eosinophilic nucleoli surrounded by a clear halo. Ischemic necrosis was detected in 21 (36%) LM-BN. Rhabdoid-like cells were noted in 24 (41%) tumors. All patients had no evidence of recurrence, ranging from 1 to 13 years (overall average 6 y; in patients with myomectomy 6.3 y with a range of 2.6 to 11 y). Our results corroborate that LM-BN is associated with a favorable outcome even in those patients only treated by myomectomy and highlights that a conservative approach can be undertaken in these patients, as many of them are of reproductive age. Because of the favorable outcome, the term LM-BN is preferable to alternative terminology including "atypical leiomyoma."

Direct assessment of the mechanical modulus of graphene co-doped with low concentrations of boron-nitrogen by a non-contact approach.

Boron and nitrogen co-doping has been shown to be an effective way to induce a band gap in graphene for electrical applications but only a few theoretical studies have been done to understand the elastic and mechanical properties of the modified graphene. Until now, no experimental assessment of the mechanical modulus of boron-nitrogen-doped graphene (BNG) has been reported in the literature. Here, we demonstrate a novel non-contact approach to determine the in-plane stiffness of BNG at low BN concentrations. The in-plane stiffness of BNG with 2 at% BN concentration was estimated to be about 309 N m(-1), which is lower than that of pristine graphene, in good agreement with some theoretical studies. Moreover, we correlated the conductivity of BNG with induced strain and found the BNG to be more sensitive than pristine graphene in response to externally applied strain. This result indicates that BNG is a more suitable material than graphene for strain sensor applications.

Band Gap Engineering of Chemical Vapor Deposited Graphene byin SituBN Doping

Band gap opening and engineering is one of the high priority goals in the development of graphene electronics. Here, we report on the opening and scaling of band gap in BN doped graphene (BNG) films grown by low-pressure chemical vapor deposition method. High resolution transmission electron microscopy is employed to resolve the graphene and h-BN domain formation in great detail. X-ray photoelectron, micro-Raman, and UV-vis spectroscopy studies revealed a distinct structural and phase evolution in BNG films at low BN concentration. Synchrotron radiation based XAS-XES measurements concluded a gap opening in BNG films, which is also confirmed by field effect transistor measurements. For the first time, a significant band gap as high as 600 meV is observed for low BN concentrations and is attributed to the opening of the π-π* band gap of graphene due to isoelectronic BN doping. As-grown films exhibit structural evolution from homogeneously dispersed small BN clusters to large sized BN domains with embedded diminutive graphene domains. The evolution is described in terms of competitive growth among h-BN and graphene domains with increasing BN concentration. The present results pave way for the development of band gap engineered BN doped graphene-based devices.

Screening of Greek wheat landraces for their yield responses under arid conditions

The present study was a part of a long time screening experiment that included a high number of wheat landraces (Triticum aestivum L.) cultivated in Greece, and focused on the agronomic point of view and the drought adaptation for some of these landraces. One of the most acceptable ways for the assessment of drought resistance is the examination of yield and yield components in different water regimes. Therefore, in our two-years experiments parameters of plants water relations and yield components such as grain yield, total biomass, number of kernels per spike and mean grain weight were recorded for the several cultivars. The data obtained during the two experimental seasons clearly pointed out the differential behavior of wheat landraces under water stress conditions. The populations that exhibited the greater adaptability (low bN) were Grinias Zakinthou (biomass, grain yield) and Skilopetra Ptolemaidas (harvest index, kernels per spike) and they could be used in breeding programs in Greece and other arid regions.