Effect of PEW and CS on the Thermal, Mechanical, and Shape Memory Properties of UHMWPE

Abstract

Modified ultra-high-molecular-weight polyethylene (UHMWPE) with calcium stearate (CS) and polyethylene wax (PEW) is a feasible method to improve the fluidity of materials because of the tense entanglement network formed by the extremely long molecular chains of UHMWPE, and a modified UHMWPE sheet was fabricated by compression molding technology. A Fourier-transform infrared spectroscopy test found that a new chemical bond was generated at 1097 cm−1 in the materials. Besides, further tests on the thermal, thermomechanical, mechanical, and shape memory properties of the samples were also conducted, which indicates that all properties are affected by the dimension and distribution of crystal regions. Moreover, the experimental results indicate that the addition of PEW and CS can effectively improve the mechanical properties. Additionally, the best comprehensive performance of the samples was obtained at the PEW content of 5 wt % and the CS content of 1 wt %. In addition, the effect of temperature on the shape memory properties of the samples was investigated, and the results indicate that the shape fixity ratio (Rf) and the shape recovery ratio (Rr) can reach 100% at 115 °C and 79% at 100 °C, respectively, which can contribute to the development of UHMWPE-based shape memory polymers.

Qualifying the contribution of fiber diameter on the acrylate-based electrospun shape memory polymer nano/microfiber properties

“…To ensure the repeatability, at least three individual samples are tested. The temporary shape fixity ratio ( R f ) and shape recovery ratio ( R r ) equations are given as 54 …”

The in situ synthesis of weakly entangled ultrahigh‐molecular‐weight polyethylene/polyethylene wax blends and its synergetic disentanglement effect on LLDPE reinforcement

“…This illustrates that the molecular chains of polyethylene wax did not just act as the coating layers on the UHMWPE particle surfaces, but also gradually creep into the nano or mesopores of UHMWPE particles. The strong motion ability of the PE wax chains might influence the crystallization behavior and entanglement state of the growing polyethylene chains, which will be explained in the following section 25–27 . Besides, the particle size distribution index (PDI, ~2.0, see Table 2) of UHPE‐X% samples exhibit nearly no changes with PE wax addition, illustrating the similar coating effect on the particles of different sizes.…”

“…The strong motion ability of the PE wax chains might influence the crystallization behavior and entanglement state of the growing polyethylene chains, which will be explained in the following section. [25][26][27] Besides, the particle size distribution index (PDI, $2.0, see Table 2) of UHPE-X% samples exhibit nearly no changes with PE wax addition, illustrating the similar coating effect on the particles of different sizes. UHPE-X% sample with 30 min of polymerization time (i.e., UHPE-20%-30 min in Table 1) was also synthesized for comparison of the average particle size.…”

Analysis of thermal‐active bending and cyclic tensile shape memory mechanism of UHMWPE/CNT composite

“…Furthermore, the bending shape memory property is related with the flexural modulus. [ 38 ] In general, the larger the flexural modulus, the greater the maximum theoretical bending recovery stress [ 37 ] and the higher the shape recovery ratio, and hence it is one of the reasons why the UHMWPE/CNT composite exhibits much higher RB r . As observed in Figure 5C, experimental research shows that UHMWPE/CNT composite can almost accomplish entire shape recovery within 120 s, and there is little or no shape recovery beyond 120 s.…”

“…UHMWPE molecular chains have excellent flexibility, and therefore its shape memory behavior is mainly affected by the physical entanglement network and crystalline region. [35,37] The physical entanglement of molecular chains and the crystalline region act as "soft phase" and "hard phase," respectively. As shown in Figure 5A, the RB f value of C00 can reach 100% at 115 C due to the ubiquitous physical entanglement and the flexibility of molecular chains.…”