Branch Content Research Articles

Small‐Angle Scattering From Branched Polymers

AbstractThe single‐polymer form factor is determined for branched polymers using a scaling argument in order to recover the low‐Q Porod exponent characteristic of the overall structure. The high‐Q Porod exponent characterizes the local branching structure. An alternative approach based on a high‐Q expansion contains information about functionality, branch length and branch content. The specific case of a starburst dendrimer for which the form factor is known is discussed. The model predictions are compared to small‐angle neutron scattering data from a dilute solution of dendrimer in D2O.magnified image

What drives the ultraviolet colours of passive galaxies?

We present and analyse optical and ultraviolet (UV) colours for passive and optically‐red Coma cluster galaxies for which we have spectroscopic age and element abundance estimates. Our sample of 150 objects covers a wide range in mass, from giant ellipticals down to the bright end of the dwarf‐galaxy regime. Galaxies with ongoing star formation have been removed using strict Hα emission‐line criteria. We focus on the colours FUV−i, NUV−i, FUV−NUV, u*−g and g−i. We find that all of these colours are correlated with both luminosity and velocity dispersion at the >5σ level, with FUV−i and FUV−NUV becoming bluer with increasing ‘mass’ while the other colours become redder. We perform a purely empirical analysis to assess what fraction of the variation in each colour can be accounted for by variations in the average stellar populations, as traced by the optical spectra. For the optical colours, u*−g and g−i, most of the observed scatter (∼80 per cent after allowing for measurement errors and for systematic errors in u*−g) is attributable to stellar population variations, with colours becoming redder with increasing age and metallicity (Mg/H). The FUV−i colour becomes bluer with increasing age and with increasing Mg/H, favouring the ‘metal‐rich single‐star’ origin for the UV upturn. However, correlations with the optically‐dominant stellar populations account for only about half of the large observed scatter. We propose that the excess scatter in FUV−i may be due to a varying proportion of ancient stars in galaxies with younger [simple stellar population (SSP) equivalent] average ages. The NUV−i colour is sensitive to SSP‐equivalent age and Mg/H (in the same sense as optical colours), but also exhibits excess scatter that can be attributed to ‘leakage’ of the far‐UV‐dominant (FUV‐dominant) old hot population. After applying a correction based on the FUV−i colour, the much of the remaining variance in NUV−i is attributable to variations in the spectroscopic parameters, similar to the results for optical colours. Finally, the FUV−NUV colour is surprisingly well behaved, showing strong correlations with age and metallicity, and little residual scatter. Interpreting this colour is complicated, however, since it mixes the effects of the main‐sequence turn‐off, in the near‐UV, with the variation in the hot post‐red giant branch content dominating the FUV.

Ligand Steric and Electronic Effects on β-Ketiminato Neutral Nickel(II) Olefin Polymerization Catalysts

A series of novel neutral nickel complexes 3a-g and 4a-d bearing the beta-ketiminato ligands [(2,6-(Pr2C6H3)-Pr-i)N=CHCHC(R)O]Ni(R')(L) (for 3a-g, R' = Me, L = Py, and R = Bu-t (3a), Ph (3b), 1-naphthyl (3c), 9-anthryl (3d), PhNMe2(p) (3e), PhOMe(p) (3f), PhCF3(p) (3g); for 4a-d, R' = Ph, L = PPh3, and Bu-t (4a), Ph (4b), 1-naphthyl (4c), 9-anthryl (4d)) have been synthesized and characterized. The molecular structures of 3b-d,f,g and 4a,c were further confirmed by X-ray crystallographic analysis. These complexes were employed in ethylene polymerization to systematically investigate ligand steric and electronic effects on the catalytic properties, including activity, molecular weight (MW), and branching number of the polyethylene obtained. The complexes bearing more bulky ligands showed higher activities and produced more branched polyethylene. Electron-deficient ligands were found to increase the catalytic activity, decrease the MW, and enhance the branching content of the polyethylene. In addition, phosphine Ni-II-Ph complexes 4a-d proved to be more active than the corresponding pyridine Ni-II-Me complexes 3a-d, probably due to the easier dissociation of PPh3 relative to a pyridine from a nickel center.

Copolymerization of ethylene with α‐olefins over supported titanium–magnesium catalysts. II. Comonomer as a chain transfer agent

AbstractThe data on the effect of comonomer (propylene and 1‐hexene) on molecular weight (Mw), molecular weight distribution (MWD), and content of terminal double bonds were obtained for ethylene/α‐olefin copolymers produced over a supported titanium–magnesium catalyst (TMC) upon polymerization in the absence of hydrogen. The experimental data on the effect of comonomer concentration on Mw of polymers were used to calculate the ratios between the effective rate constants of chain transfer with monomer and the propagation rate constant. It was shown that the effective rate constant of chain transfer with monomers increases in the row of monomers: ethylene < 1‐hexene < propylene. Meanwhile, the data on the effect of copolymers on content of terminal double bonds of various types demonstrate that different reactions of chain transfer with comonomer may simultaneously occur during copolymerization. It results in simultaneous formation of terminal vinylidene and trans‐vinylene bonds. Therefore, the calculated rate constants of chain transfer with comonomer are complex values, which include the rate constants of chain transfer with comonomer occurring via different mechanisms. The data on MWD, short chain branching (SCB) and terminal double bonds content of different types were obtained by molecular weight fractionation of copolymers followed by the analysis of narrow fractions. The analysis of the data on MWDs of SCB and terminal double bonds shows that active sites of the TMC are considerably heterogeneous with respect to the rates of different chain transfer reactions with monomers. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Copolymerization of ethylene with α‐olefins over supported titanium–magnesium catalysts. I. Effect of polymerization duration on comonomer content and the molecular weight distribution of copolymers

AbstractThe data on the effect of polymerization duration on molecular weight (MW), molecular weight distribution (MWD), and content of α‐olefin were obtained for ethylene/1‐hexene copolymers produced on a supported titanium–magnesium catalyst (TMC) upon polymerization in the absence and presence of hydrogen. An increase in MW, narrowing of the MWD, and a decrease in 1‐hexene content in the copolymer takes place with increasing polymerization duration. It was shown by molecular weight fractionation of copolymers obtained at different polymerization duration followed by analysis of narrow fractions to determine the butyl branching content that the decrease comonomer content in copolymers with increasing polymerization duration is accounted for by the decrease in the share of low molecular weight fractions with an increased butyl branch content. These data, in combination with the data concerning the narrowing of the MWD of copolymers and the decrease in activity with polymerization duration allow arriving at conclusion that active sites producing low molecular weight polymer with an increased butyl branching content is predominantly deactivated with polymerization. Active sites producing high molecular weight polymer has a low ability to copolymerize ethylene with α‐olefins; however, these sites show higher stability during copolymerization. © 2012 Wiley Periodicals, Inc. J Appl Polym Sci, 2012

Quantification of Branching in Model Three-Arm Star Polyethylene

The versatility of a novel scaling approach in quantifying the structure of model well-defined 3-arm star polyethylene molecules is presented. Many commercial polyethylenes have long side branches, and the nature and quantity of these branches varies widely among the various forms. For instance, low-density polyethylene (LDPE) is typically a highly branched structure with broad distributions in branch content, branch lengths and branch generation (in hyperbranched structures). This makes it difficult to accurately quantify the structure and the inherent structure–property relationships. To overcome this drawback, model well-defined hydrogenated polybutadiene (HPB) structures have been synthesized via anionic polymerization and hydrogenation to serve as model analogues to long-chain branched polyethylene. In this article, model 3-arm star polyethylene molecules are quantified using the scaling approach. Along with the long-chain branch content in polyethylene, the approach also provides unique measurements...

Basic density and moisture content of coniferous branches and wood in Northern Norway

With the increasing demand for fuel the use of biomass from other tree components like branches and tops has increased rapidly. Norway has abundant raw material resources which can be use for bioenergy. Sitka spruce and Norway spruce are becoming more interesting due to their potential energy for heating. The study consisted of 2 site locations in Nordland - 1 stand of Sitka spruce in Steigen area, and 1 stand of Sitka spruce, 1 stand of Norway spruce, and 1 stand of Lutz spruce in Somna area. Bark thickness differed between the sites within decreasing pattern along the stem. Significant differences of bark density between sites, tree species and tree height levels with decreasing trend towards the top were found. Branches density decreased along the crown level and had about 15-20% higher density than wood density. Wood density varied significantly with sites and height of tree - highest pattern on the tree base, decreasing to 20% of height, and again increasing to the top. The moisture content of branches, wood and bark increased from the base of tree to the top. Bark moisture was about 20-25% higher as wood moisture content. Sitka spruce in Northland may be highly considered as a valuable bioenergy source.

Identification and Evaluation of Drought Resistance in Different Peanut Varie- ties Widely Grown in Northern China

It is necessary to systematically identify and evaluate drought-resistant varieties for stable development of peanut pro- duction in arid and semi-arid regions in northern China. To establish drought resistance index of peanut varieties, we determined 13 morphological and biochemical indices including plant height, number of branch, biomass, leaf water content and photosyn- thetic pigment content in the pot experiment at pod setting and pod filling stages with 29 peanut varieties (lines) widely grown in north China under artificial water stress condition. Drought resistances of varieties were scored with drought coefficient method and subordinate function value under water stresses. The results showed that the same index of drought resistance characterized in different peanut varieties achieved different results, and 29 peanut varieties were divided into four grads: high tolerant, moderate tolerant, weaker tolerant, and drought susceptible. In the 29 varieties (lines), we screened out the high drought tolerant varieties consisting of Tangke 8, Jihua 2, Jihua 4, Huayu 25, Huayu 17, Huayu 22, Datangyou, and Huayu 21. The varieties (lines) of Huayu 20, Huayu 24, Weihua 6, Huayu 27, Luhua 11, Fuhua 11, Fuhua 13, Tangyou 4, Fenghua 1, and G2 had moderate drought resistance. The varieties (lines) with weaker drought resistance were 16-8, Fuhua 10, M5, Huayu 16, and Luhua 14. At pod setting and pod filling stages Huayu 19, Huayu 23, Fenghua 6, Weihua 8, M7, and TE-2 were all drought susceptible. From seedling to pod setting stages under water stress, all morphological and biochemical indices but the number of branch and carotenoid content and their comprehensive D-values could be taken as evaluation criteria. From seedling to pod filling stages under water stress, there only existed significanct correlation between leaf area and drought resistance. Either at pod setting or pod filling stages un- der water stress, comprehensive D-value of the indices had significant correlation with drought resistance, which could be used to identify peanuts drought resistance.

Effects of Polymerization and Crosslinking Technologies on the Crystallization Behaviors and Gel Network of Crosslinked Polyethylene

In the present study, we investigated the influences of polymerization and crosslinking technologies on the branched-chain structures, crystallization behaviors, and gel networks of two types of low-density polyethylenes, LDPE1 and LDPE2, polymerized under different polymerization conditions in commercial large-capacity production lines. High temperature 13C NMR analysis suggests that the molar contents of both long-chain branches and short-chain branches of LDPE2 were markedly higher than those of LDPE1 due to a higher polymerization temperature for LDPE2. The high content of chain branches of LDPE2 leads to its relatively higher storage modulus, entanglement density, and gel content, as indicated by dynamic mechanical analysis. In addition, when the crosslinking temperature reached 180°C, the LDPE2 crosslinked with 2 wt% dicumylperoxide (XLPE2-D2) displayed a relatively wider processing time window and a faster crosslinking rate than XLPE1-D2. Successive self-nucleation and annealing fractionation indicated that increasing the concentration of dicumylperoxide can improve the crosslinking degree, but resulted in lower crystallinity and thinner lamellar crystals.

신규 채소작물용 번행초의 토성 및 염도에 대한 생육 반응

This research was conducted to investigate potential use of New Zealand spinach (Tetragonia tetragonoides) as a new vegetable crop which will be cultivating in salt-affected soils including reclaimed land. Traditionally New Zealand spinach has been studied to explore functional compound or salt removing potential. To cultivate the crop species in the salt-affected soil widely, it is essential to obtain salt and soil texture responses under the controlled environment. Fifty nine New Zealand spinach ecotypes native to Korean peninsula first collected over seashore areas, and primitive habitat soil environment was evaluated by analyzing soil chemical properties from 32 locations. Different textures of sandy, silt loam, and sandy loam soils were prepared from nearby sources of sea shore, upland and paddy soils, respectively. Target salinity levels of 16.0 dS/m, 27.5 dS/m, 39.9 dS/m, and 52.4 dS/m in electrical conductivity (ECw) were achieved by diluting of 25, 50, 75, 100% (v/v) sea water to tap water (control, 0.6 dS/m), respectively. Various measurements responding to soil texture and irrigation salinity included plant height, root length, fresh weight (FW), dry weight (DW), leaf parameters (leaf number, leaf length, leaf width), lateral branching, and inorganic ion content. was found to adapt to diverse habitats ranging various soil chemical properties including soil pH, organic matter, exchangeable bases, EC, and cation exchange capacity (CEC) in Korea. Responding to soil texture, New Zealand spinach grew better in silt loam and sandy loam soil than in sandy soil. Higher yield (FW and DW) seemed to be associated with branch number (r=0.99 and 0.99, respectively), followed by plant height (r=0.94 and 0.97, respectively) and leaf number (r=0.89 and 0.84, respectively). Plant height, FW, and DW of the New Zealand spinach accessions were decreased with increasing irrigation salinity, while root length was not significantly different compared to control. Based on previous report, more narrow spectrum of salinity range (up to 16 dS/m) needs to be further studied in order to obtain more accurate salinity responses of the plant. As expected, leaf Na content was increased significantly with increasing salinity, while K and Ca contents decreased. Growth responses to soil texture and irrigation salinity implied the potential use of New Zealand spinach as a leafy vegetable in salt-affected soil constructed with silt loam or sandy loam soils.

A thermal method for quantitatively determinating the content of short chain branching in ethylene/α-olefin copolymers

Abstract A quantitative method including peak-fitting for determination of the content of short chain branching (SCB) in ethylene/α-olefin copolymers based on differential scanning calorimetry is described. After stepwise isothermal crystallization, the fractions with similar SCB and lamellar thickness are sorted into groups. The content of each group is determined using the peak-fitting area. The statistical terms, the arithmetic mean SCB content , the weighted mean SCB content and the branching broadness index are calculated. Through comparing with the SCB contents measured by 13CNMR analysis, the results show that this method can quantitatively characterize the content of SCB in ethylene/α-olefin copolymers with a high degree of accuracy.

Impacts of Wenchuan Earthquake-induced landslides on soil physical properties and tree growth

How earthquake-induced landslides impact the growth of existing trees remains unknown worldwide. Therefore, we established an experiment with two tree species ( Cupressus funebris, Cryptomeria fortunei) and two landslide conditions (non-impacted and impacted stands) near the northern section of the fault belt one year after the Wenchuan Earthquake (8.0 M s) that occurred in China in 2008. At site I, two plots of each species were located in non-impacted stands. At site II, three plots of Cu. funebris were established in non-impacted stands, and three plots were established in impacted stands. At site III, three plots of Cr. fortunei were placed in non-impacted stands, while two plots were placed in impacted stands. All plots were 20 m × 20 m in size. At each plot, we measured the diameter at breast height and the height of each tree and used their mean values to select five trees representing average growth. Two to three small fine roots (≤2.0 mm in diameter, >20 cm long) were sampled in just three of the five selected trees to investigate root parameters. Leaf, branch and root water contents of the sampled trees were also examined. Soil samples were collected from 0 to 10, 10 to 20 and 20 to 40 cm depths at the center and near the four corners of each plot to analyze soil physical properties. The study revealed that saturated water content, capillary moisture capacity, field water capacity, total porosity and capillary porosity were lower in the impacted stands than in the non-impacted stands. Conversely, bulk density was higher in the impacted stands, indicating that the soils in the impacted stands had become compacted and dry. Soil water content, saturated water content, capillary moisture capacity, field water capacity, total porosity, capillary porosity and non-capillary porosity were greater in Cr. fortunei stands than in Cu. funebris stands, while bulk density was lower, indicating that impacted stands of Cu. funebris were more compacted and dry than those of Cr. fortunei. In impacted Cu. funebris stands, mean tip length/length and mean tip length/biomass decreased, while plant organ water contents did not change. In impacted Cr. fortunei stands, in contrast, these root parameters as well as specific root area, specific root length and leaf water content increased. These patterns suggest Cr. funebris experiences a much higher root growth than Cu. funebris in landslide impacted stands. Survival and recovery may be more difficult for Cu. funebris than for Cr. fortunei.

Thermal Analyses of Blends of Hyperbranched Linear Low-density Polyethylene (LLDPE) with High-density Polyethylene and LLDPE Prepared by Dissolving Method

Blends of high-density polyethylene (HDPE), moderate and hyper-branched LLDPEs (LLDPE and HbPE, respectively) have attained widespread commercial applications, though the understanding of the mechanical and melt-flow properties of such blends has been handicapped by the absence of a consensus concerning the degrees of mixing of the components. Moreover, usually the blends are obtained by melt blending, which may not ensure the initial homogeneity of the components. In our work the mixtures were prepared by dissolving the conventional LLDPE having branching content 7.2 wt% with HbPE with comonomer content 17.8 wt% in xylene at 130 °C and stirring for 2 hours. The same procedure was applied for the blending of HDPE with HbPE. After dissolving the mixtures were cooled in liquid nitrogen and after that freeze dried in vacuum line. The ratio of components in the blends was varied. Differential scanning calorimetry has been used to investigate the miscibility and thermal behavior of the blends. For this purpose isothermal and non-isothermal treatment of prepared blends were conducted. By preliminary study the double melting peaks in non-isothermal endotherms have been observed in all the studied blends. The presence of two peaks in DSC scan can be attributed to the formation of separated crystals from both the high density/linear low density and highly branched components. However, certain limited degree of co-crystallization is detected in all the LLDPE/HbPE blends and HDPE/HbPE blend rich in HbPE component.http://dx.doi.org/10.5755/j01.ms.17.3.589

The study on the effect of irrigation levels and mulch application on growth indices and essential oil content of peppermint (Mentha piperita L.)

In order to study the effects of different irrigation regime and mulch types on growth indices and, essential oil content of peppermint (Mentha piperita L.) in 2010 in research field of Agricultural college of Ferdowsi University of Mashhad as factorial randomized complete block design was performed in four replicates. Irrigation treatments included three levels (100, 80 and 60 percent of water requirements calculated by evaporation pan class A and two types of mulch (black plastic and wood chips) and the uncoated control. Traits include inter-node distance, number of flowers/plant, branch number/plant, plant height, fresh weight, dry weight, chlorophyll content, leaf relative water content, leaf area, essential oil percentage and yield were evaluated during full flowering. The results showed that the effect of irrigation on fresh weight, dry weight, leaf relative water content and leaf area was significant (at 0.05 level). The effect of mulch on fresh weight, dry weight, leaf area, inter-node distance, number of branch and leaf relative water content was significant (at 0.05 level). Interaction between irrigation and mulch on inter-node distance, number of branches, fresh weight, dry weight, relative water content of leaves and leaf area and height were significant (at a 0.05 level). The effect of irrigation, mulch and interaction effects on traits such as flower number, chlorophyll content, percentage essential oil (at 0.05 level) was not significant.

Thermorheological behavior of polyethylene: a sensitive probe to molecular structure

Recent investigations have shown that different topographies in polyethylene (PE) lead to either thermorheological simplicity (linear and short-chain branched PE) or two different types of thermorheologically complex behavior. Low-density polyethylene (LDPE) has a thermorheological complexity, which can be eliminated by a modulus shift, while long-chain branched metallocene PE (LCB-mPE) has a temperature dependent shape of the spectrum and thus a total failure of the time-temperature superposition principle. The reason for that behavior lies in the different relaxation times of linear and long-chain branched chains, present in LCB-mPE. The origin of the thermorheological complexity of LDPE might be the temperature dependence of the miscibility of the different molar mass fractions that differ in their content of short chain branches.

Ethylene polymerization using novel titanium catalytic precursors bearing N,N‐dialkylcarbamato ligands

AbstractPolymerization catalysts based on N,N‐dialkylcarbamato complexes of titanium(IV) appear particularly interesting, because these novel catalytic precursors are rather cheap and easy to synthesize and handle. This contribution reports ethylene polymerization behavior of titanium(IV) complexes of general formula Ti(O2CNR2)4 R = Me (I) and Et (II) and TiCl2(O2CNMe2)2 (III). These precursors in conjunction with methylaluminoxane resulted active catalysts for the polymerization of ethylene, affording high‐density polyethylene with limited branch content. The influence of the polymerization parameters was studied with particular reference to the type of catalyst components, solvent, temperature, monomer concentration, and Al/Ti ratio. The nature of the solvent appears crucial for catalytic performances: when toluene was replaced by chlorobenzene, a significant increase of the productivity was ascertained. The obtained polymers were characterized by DSC, size exclusion chromatography, FTIR, and NMR techniques. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

Branch length distribution in TREF fractionated polyethylene

Commercial polyethylene is typically heterogeneous in molecular weight as well as in molecular topology due to variability in catalyst systems and catalyst activity. Further, processing of polyethylene after polymerization may also result in changes to the structure. While quantification of molecular weight is routine using gel permeation chromatography (GPC); quantification of the heterogeneity in molecular topology and microstructure is more difficult. In this paper, a novel method is used to examine the structure and branch content of a linear low-density polyethylene (LLDPE). The method uses a scaling model to analyze small-angle neutron scattering (SANS) data from dilute solutions of a series of LLDPE fractions. The scaling approach quantifies short-chain and long-chain branch content in polymers concurrently, thereby illustrating the distribution of these branches in the polyethylene fractions. Additionally, new quantities such as the average long-chain branch length and hyperbranch content are measured to provide further insight into the structure of these polymers. LLDPE used in this study is fractionated using temperature rising elution fractionation (TREF). Results from the analysis of these fractions show evidence of long-chain branching in commercial LLDPE which could be partly attributed to post-synthesis processing conditions.

Impact of branching on the UV degradation of metallocene LLDPE

The effect of UV degradation on metallocene linear low density polyethylenes (LLDPEs) of different branching characteristics was studied. The samples were exposed to natural weather condition. The extent of the degradation on these LLDPEs was measured by Mechanical, FTIR and GPC testings. This paper addressed the structural modifications due to UV degradation of metallocene LLDPE (m-LLDPE). The results suggested that Z-N HDPE is very stable. Carbonyl absorbance and degradation of mechanical properties of m-LLDPEs increased with increasing branch content of the polymers. For short exposure times, the results suggested increase in the degree of cross-linking of m-PEs with the increase in BC leading to brittle behavior. However, at high exposure times chain scission dominates and it is branch content dependent. Most of the mechanical properties show a sharp rate of drop at branch contents less than 20 branches/1000 C followed by a slow drop rate. The results of the mechanical properties correlate very well with the carbonyl absorbance. GPC results confirmed that chain scission leading to a broader MWD is dominant at high exposure times and for LLDPEs with high branch contents. Branch type did not show any influence on mechanical properties.

Synthesis and characterization of materials prepared via the copolymerization of ethylene with 1-octadecene and norbornene using a [(π-cyano-nacnac)Cp] zirconium complex

[3-Cyano-2-(2,6-diisopropylphenyl)aminopent-2-en-4-(phenylimine)tris (pentafluorophenyl)borate](η5-C5H5)ZrCl2, [(B(C6F5)3- NC-nacnac)CpZrCl2], precatalyst (2) can be treated with low concentrations of methylaluminoxane (MAO) to generate active sites capable of copolymerizing ethylene with 1-octadecene or norbornene under mild conditions. A series of poly(ethylene-co-octadecene) and poly(ethylene-co-norbornene) copolymers were prepared, and their properties were characterized by NMR, differential scanning calorimetry, and mechanical analysis. The results show that this system produced poly(ethylene-co-octadecene) copolymers with a branching content of about 8 mol %. However, upon increasing the comonomer concentration, a drastic reduction in the Mn of the product is observed concomitant with an increase in comonomer incorporation. This leads to a gradual decrease in Young's modulus and stress at break, indicating an increase in the “softness” of the copolymer. In the case of copolymerizations of ethylene and norbornene, the catalytic system (2/MAO) shows a substantial decrease in reactivity in the presence of norbornene and generates copolymer chains in which 5–10 mol % norbornene is in blocks. We also observe that ethylene norbornene copolymers exhibit a high degree of alternating insertions (close to 50%), as determined by NMR spectroscopy. © 2011 Wiley Periodicals, Inc. J Polym Sci Part A: Polym Chem, 2011

A three-phase microstructural model to explain the mechanical relaxations of branched polyethylene: a DSC, WAXD and DMTA combined study

The thermal transitions of well-characterised single-site catalysed polyethylenes having various degrees of short chain branching have been studied by differential scanning calorimetry, X-ray diffraction and dynamic mechanical thermal analysis. A critical discussion based on the results obtained by means of the different techniques is presented. The results suggest that the γ transition is independent of the branching content and degree of crystallinity, pointing towards a sub-glass local relaxation mechanism related to both amorphous and crystalline fractions. The temperature of the β transition, T β from dynamic mechanical measurements, is in agreement with the glass transition temperature obtained by calorimetry, T g. Moreover, T γ, and also T β are directly related to a change in the thermal expansion coefficient of the amorphous phase observed by X-ray scattering. It is found that the corresponding scattering distance of the amorphous halo depends on crystallinity. In addition, the calorimetric heat capacity values at T β do not account for the total amorphous fraction determined for each material. The relaxation motions assigned to the amorphous phase glass transition seems to parallel the subsequent melting of the crystalline structure, suggesting a hierarchical motion of different structures as temperature increases. Dynamic mechanical thermal analysis supports these observations, showing a broad transition in the phase angle involving first the relaxation of amorphous phase, then the (presumable) more rigid intermediate phase, and finally the crystalline phase, as the temperature increases.