Search results
Results from the WOW.Com Content Network
The melting point of polypropylene occurs in a range, so the melting point is determined by finding the highest temperature of a differential scanning calorimetry chart. Perfectly isotactic PP has a melting point of 171 °C (340 °F). Commercial isotactic PP has a melting point that ranges from 160 to 166 °C (320 to 331 °F), depending on ...
Dipole bonding is not as strong as hydrogen bonding, so a polyester's melting point and strength are lower than Kevlar's , but polyesters have greater flexibility. Polymers with non-polar units such as polyethylene interact only through weak Van der Waals forces. As a result, they typically have lower melting temperatures than other polymers.
Compared to other fluoropolymers, it has an easier melt process because of its relatively low melting point of around 177 °C. Processed materials are typically in the non-piezoelectric alpha phase. The material must either be stretched or annealed to obtain the piezoelectric beta phase.
Liquid crystallinity in polymers may occur either by dissolving a polymer in a solvent (lyotropic liquid-crystal polymers) or by heating a polymer above its glass or melting transition point (thermotropic liquid-crystal polymers). [6] Liquid-crystal polymers are present in melted/liquid or solid form. [7]
The diamines in PPAs are aliphatic.PA6T homopolymer melts at 371 °C, [5] which renders it intractable. To make usable polymers, it is necessary to lower the melting point, which can be achieved practically using either a longer diamine (with 9-12 carbon atoms) or by copolymerizing 6I.
HDPE is known for its high strength-to-density ratio. [4] The density of HDPE ranges from 930 to 970 kg/m 3. [5] Although the density of HDPE is only marginally higher than that of low-density polyethylene, HDPE has little branching, giving it stronger intermolecular forces and tensile strength (38 MPa versus 21 MPa) than LDPE. [6]
Therefore, flexible elements must be incorporated into the chains, this is done in the form of ether groups. Ether groups allow a free rotation of the polymer chains. This leads to a significantly reduced melting point and also improves the mechanical properties by an increased impact strength. [7]
MFI Measuring device. The Melt Flow Index (MFI) is a measure of the ease of flow of the melt of a thermoplastic polymer.It is defined as the mass of polymer, in grams, flowing in ten minutes through a capillary of a specific diameter and length by a pressure applied via prescribed alternative gravimetric weights for alternative prescribed temperatures.