Morphology and Long Term Behavior of Polymer Cement Concrete

1989 ◽  
Vol 179 ◽  
Author(s):  
K. P. Grosskurth
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Polymeric Materials ◽  
Heterogeneous Material ◽  
Cement Concrete ◽  
Temperature Dependent ◽  
Dependent Behavior ◽  
Long Term Behavior

AbstractPolymer-modified cement concrete represents a heterogeneous material whose properties are influenced more by the properties of the polymers than by the properties of the cement component. Typical of polymeric materials are their temperature dependent behavior. This temperature dependence can be related to the glass transition temperature of the polymer. In cases where the temperature is higher than the glass transition temperature, strength decreases while deformability simultaneously increases. Polymeric films are formed in the dispersed polymer systems as a result of reactions occurring at the glass transition temperature. A styrene/acrylic modified concrete was studied at different polymer loadings. The tensile and compressive strengths of this system were studied as a function of temperature. Increasing deformability temperatures principally at higher polymer loadings near the glass transition temperature and decreasing strength occurred.

scholarly journals Long-Term Physical (In)Stability of Spray-Dried Amorphous Drugs: Relationship with Glass-Forming Ability and Physicochemical Properties

Pharmaceutics ◽  
2019 ◽  
Vol 11 (9) ◽  
pp. 425 ◽  
Author(s):  
Edueng ◽  
Bergström ◽  
Gråsjö ◽  
Mahlin
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Physicochemical Properties ◽  
Physical Stability ◽  
Glass Forming Ability ◽  
Melt Quenching ◽  
Glass Forming ◽  
Spray Dried

This study shows the importance of the chosen method for assessing the glass-forming ability (GFA) and glass stability (GS) of a drug compound. Traditionally, GFA and GS are established using in situ melt-quenching in a differential scanning calorimeter. In this study, we included 26 structurally diverse glass-forming drugs (i) to compare the GFA class when the model drugs were produced by spray-drying with that when melt-quenching was used, (ii) to investigate the long-term physical stability of the resulting amorphous solids, and (iii) to investigate the relationship between physicochemical properties and the GFA of spray-dried solids and their long-term physical stability. The spray-dried solids were exposed to dry (<5% RH) and humid (75% RH) conditions for six months at 25 °C. The crystallization of the spray-dried solids under these conditions was monitored using a combination of solid-state characterization techniques including differential scanning calorimetry, Raman spectroscopy, and powder X-ray diffraction. The GFA/GS class assignment for 85% of the model compounds was method-dependent, with significant differences between spray-drying and melt-quenching methods. The long-term physical stability under dry condition of the compounds was predictable from GFA/GS classification and glass transition and crystallization temperatures. However, the stability upon storage at 75% RH could not be predicted from the same data. There was no strong correlation between the physicochemical properties explored and the GFA class or long-term physical stability. However, there was a slight tendency for compounds with a relatively larger molecular weight, higher glass transition temperature, higher crystallization temperature, higher melting point and higher reduced glass transition temperature to have better GFA and better physical stability. In contrast, a high heat of fusion and entropy of fusion seemed to have a negative impact on the GFA and physical stability of our dataset.

scholarly journals Determination of glass transition temperature using temperature dependent signal from a cryogenic photopyroelectric instrument

2019 ◽  
Vol 676 ◽  
pp. 7-12 ◽  
Author(s):  
Allen Mathew ◽  
Fabrice Goutier ◽  
Benoit Escorne ◽  
Abdelaziz Elass ◽  
Gérard Louis ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Temperature Dependent ◽  
Dependent Signal

Mechanical and thermal properties of glass fiber–vinyl ester resin composite for pipeline repair exposed to hot-wet conditioning

2016 ◽  
Vol 51 (11) ◽  
pp. 1605-1617 ◽  
Author(s):  
Md Shamsuddoha ◽  
Luke P Djukic ◽  
Md Mainul Islam ◽  
Thiru Aravinthan ◽  
Allan Manalo
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Glass Fiber ◽  
Vinyl Ester ◽  
Resin Composite ◽  
Oil And Gas Industry ◽  
Mechanical And Thermal Properties ◽  
Fiber Reinforced

Fiber-reinforced composites are a well-recognized option for repair and rehabilitation of the pipelines for the oil and gas industry. Infilled composite sleeve system provides an effective rehabilitation solution, where the sleeve acts as prime reinforcement without any direct contact with steel. However, the long-term performance of the repair is dependent, in part, on the effect of hygrothermal ageing of the composites. In this publication, glass transition temperature and mechanical properties are compared for glass-fiber reinforced vinyl ester composite, both as-manufactured and after hot-wet conditioning at 80℃. The tensile and shear strength reduced substantially during conditioning, whilst the elastic modulus was relatively stable. The average glass transition temperature of the composite dropped from the as-manufactured value of 110℃ to 97℃ and 101℃, after 1000 and 3000 h of conditioning, respectively, indicating that it is stable and that the composite is suitable for use as a pipeline repair material operating at 80℃. The results indicate that a 1000 h conditioning period, specified as a minimum period in ISO/TS 24817 is suitable for representing long-term properties for stiffness-based designs for the composite material and conditioning temperature investigated.

scholarly journals Review of Recent Developments of Glass Transition in PVC Nanocomposites

Polymers ◽  
2021 ◽  
Vol 13 (24) ◽  
pp. 4336
Author(s):  
Jolanta Tomaszewska ◽  
Tomasz Sterzyński ◽  
Aneta Woźniak-Braszak ◽  
Michał Banaszak
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Thermomechanical Analysis ◽  
Mechanical Analysis ◽  
Temperature Dependent ◽  
Scanning Calorimetry ◽  
Recent Developments ◽  
Dielectric Thermal Analysis ◽  
The Impact

This review addresses the impact of different nanoadditives on the glass transition temperature (Tg) of polyvinyl chloride (PVC), which is a widely used industrial polymer. The relatively high Tg limits its temperature-dependent applications. The objective of the review is to present the state-of-the-art knowledge on the influence of nanofillers of various origins and dimensions on the Tg of the PVC. The Tg variations induced by added nanofillers can be probed mostly by such experimental techniques as thermomechanical analysis (TMA), dynamic mechanical analysis (DMA), differential scanning calorimetry (DSC), and dielectric thermal analysis (DETA). The increase in Tg is commonly associated with the use of mineral and carbonaceous nanofillers. In this case, a rise in the concentration of nanoadditives leads to an increase in the Tg due to a restraint of the PVC macromolecular chain’s mobility. The lowering of Tg may be attributed to the well-known plasticizing effect, which is a consequence of the incorporation of oligomeric silsesquioxanes to the polymeric matrix. It has been well established that the variation in the Tg value depends also on the chemical modification of nanofillers and their incorporation into the PVC matrix. This review may be an inspiration for further investigation of nanofillers’ effect on the PVC glass transition temperature.

Polymeric materials for Solar Sail: The combined effects of polymer thickness, radiation, and temperature

2004 ◽  
Vol 851 ◽  
Author(s):  
David L. Edwards ◽  
Mircea Chipara
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Film Thickness ◽  
Polymeric Materials ◽  
Solar Sail ◽  
Polymeric Films ◽  
Space Environment ◽  
Combined Effects ◽  
Polymer Thickness

ABSTRACTThe feasibility and the performance of solar sail depend critically on the availability of light materials and extremely thin polymeric films. The main requirements imposed on solar sail materials are analyzed in depth. The potential effects of the space environment are discussed in detail, with emphasis on the radiation-temperature-polymeric film thickness relationships. It is shown that the radiation component of the space environment triggers two competing degradation processes (erosion and depolymerization) and that both processes act towards the decrease in the glass transition temperature.

scholarly journals The Scissors Effect in Action: The Fox-Flory Relationship between the Glass Transition Temperature of Crosslinked Poly(Methyl Methacrylate) and Mc in Nanophase Separated Poly(Methyl Methacrylate)-l-Polyisobutylene Conetworks

Materials ◽  
2020 ◽  
Vol 13 (21) ◽  
pp. 4822
Author(s):  
Szabolcs Pásztor ◽  
Bálint Becsei ◽  
Györgyi Szarka ◽  
Yi Thomann ◽  
Ralf Thomann ◽  
...  
Keyword(s):  
Glass Transition ◽  
Transition Temperature ◽  
Glass Transition Temperature ◽  
Methyl Methacrylate ◽  
Single Case ◽  
Average Molecular Weight ◽  
Polymeric Materials ◽  
Poly Methyl Methacrylate ◽  
Margin Of Error ◽  
20 Nm

The glass transition temperature (Tg) is one of the most important properties of polymeric materials. In order to reveal whether the scissors effect, i.e., the Fox–Flory relationship between Tg and the average molecular weight between crosslinking points (Mc), reported only in one case for polymer conetworks so far, is more generally effective or valid only for a single case, a series of poly(methyl methacrylate)-l-polyisobutylene (PMMA-l-PIB) conetworks was prepared and investigated. Two Tgs were found for the conetworks by DSC. Fox–Flory type dependence between Tg and Mc of the PMMA component (Tg = Tg,∞ − K/Mc) was observed. The K constants for the PMMA homopolymer and for the PMMA in the conetworks were the same in the margin of error. AFM images indicated disordered bicontinuous, mutually nanoconfined morphology with average domain sizes of 5–20 nm, but the correlation between Tg and domain sizes was not found. These new results indicate that the macrocrosslinkers act like molecular scissors (scissors effect), and the Tg of PMMA depend exclusively on the Mc in the conetworks. Consequently, these findings mean that the scissors effect is presumably a general phenomenon in nanophase-separated polymer conetworks, and this finding could be utilized in designing, processing, and applications of these novel materials.

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