Transparent PC/PMMA Blends with Enhanced Mechanical Properties via Reactive Compounding of Functionalized Polymers

Reactive compounding of terminally phenolic OH-functionalized polycarbonate (PC) with epoxy-functionalized polymethylmethacrylate (PMMA) prepared by copolymerization with glycidyl methacrylate was investigated. It was spectroscopically demonstrated that a PC/PMMA copolymer was formed during the melt reaction of the functional groups. Zirconium acetylacetonate could catalytically accelerate this reaction. Correlations of the phenomenological (optical and mechanical) properties with the molecular level and mesoscopic (morphological) structure were discussed. By the investigated reactive compounding process, transparent PC/PMMA blends with two-phase morphologies were obtained in a continuous twin-screw extruder, which, for the first time, combined the high transmission of visible light with excellent mechanical performance (e.g., synergistically improved tensile and flexural strength and high scratch resistance). The transparency strongly depended on (a) the degree of functionalization in both PC and PMMA, (b) the presence of the catalyst, and (c) the residence time of the compounding process. The in-situ-formed PC/PMMA copolymer influenced the observed macroscopic properties by (a) a decrease in the interphase tension, leading to improved and stabilized phase dispersion, (b) the formation of a continuous gradient of the polymer composition and thus of the optical refractive indices in a diffuse mesoscopic interphase layer separating the PC and PMMA phases, and (c) an increase in the phase adhesion between PC and PMMA due to mechanical polymer chain entanglement in this interphase.

Mechanical Properties of Some Epoxy-PMMA Blends

The thermoset polymers and the thermoplastic polymers matrix composites require different forming techniques due to the different properties of two classes of polymers. While the forming technique for thermoset polymer matrix composites does not require the use of special equipment, the thermoplastic polymer matrix composites imposes the rigorous control of temperature and pressure values. Each type of polymer transfers to the composite a set of properties that may be required for a certain application. It is difficult to design a composite with commonly brittle thermoset polymer matrix showing properties of a viscoelastic thermoplastic polymer matrix composite. One solution may consist in mixing a thermoset and a thermoplastic polymer getting a polymer blend that can be used as matrix to form a composite. This study is about using PMMA solutions to obtain thermoset-thermoplastic blends and to mechanically characterize the obtained materials. Three well known organic solvents were used to obtain the PMMA solutions, based on a previous study concerning with the effect of solvents presence into the epoxy structure.

Blend Structure and n-Type Thermoelectric Performance of PA6/SAN and PA6/PMMA Blends Filled with Singlewalled Carbon Nanotubes

The present study investigates how the formation of melt-mixed immiscible blends based on PA6/SAN and PA6/PMMA filled with single walled nanotubes (SWCNTs) affects the thermoelectric (TE) properties. In addition to the detailed investigation of the blend morphology with compositions between 100/0 wt.% and 50/50 wt.%, the thermoelectric properties are investigated on blends with different SWCNT concentrations (0.25–3.0 wt.%). Both PA6 and the blend composites with the used type of SWCNTs showed negative Seebeck coefficients. It was shown that the PA6 matrix polymer, in which the SWCNTs are localized, mainly influenced the thermoelectric properties of blends with high SWCNT contents. By varying the blend composition, an increase in the absolute Seebeck coefficient, power factor (PF), and figure of merit (ZT) was achieved compared to the PA6 composite which is mainly related to the selective localization and enrichment of SWCNTs in the PA6 matrix at constant SWCNT loading. The maximum PFs achieved were 0.22 µW/m·K2 for PA6/SAN/SWCNT 70/30/3 wt.% and 0.13 µW/m·K2 for PA6/PMMA/SWCNT 60/40/3 wt.% compared to 0.09 µW/m·K2 for PA6/3 wt.% SWCNT which represent increases to 244% and 144%, respectively. At higher PMMA or SAN concentration, the change from matrix-droplet to a co-continuous morphology started, which, despite higher SWCNT enrichment in the PA6 matrix, disturbed the electrical conductivity, resulting in reduced PFs with still increasing Seebeck coefficients. At SWCNT contents between 0.5 and 3 wt.% the increase in the absolute Seebeck coefficient was compensated by lower electrical conductivity resulting in lower PF and ZT as compared to the PA6 composites.

On predicting the deformation and fracture properties of ABS / PMMA / Nano-SiO2 composites

The damage mechanism of ABS/PMMA/nano-SiO2 composites was studied by both experiments and finite element analysis in this paper. A microstructure-based the Homogenization theory and the surface-based cohesive method was developed to predict the deformation and fracture behavior of ABS/PMMA/nano-SiO2 composite. The constitutive behavior of the elastoplastic-damage in the matrix, the fracture for the nano-SiO2 reinforement, and the traction-separation for interfaces, were simulated in this model. The validity of the modeling results were validated by the agreement of the experiment and the morphology of fracture section with those predicted by the simulation. The numerical results were used to provide insight into the damage mechamisms of ABS/PMMA/nano-SiO2 composites, and the effects of nano-SiO2 strength on ABS/PMMA blends mechanical properties were also discussed in detail.

Crystallinity and β Phase Fraction of PVDF in Biaxially Stretched PVDF/PMMA Films

Polyvinylidene fluoride (PVDF) and poly(methyl methacrylate) (PMMA) blend films were prepared using biaxial stretching. The effects of PMMA content and stretching ratio on the crystallinity and β phase fraction of PVDF in blend films were investigated. The distributions of crystallinity and β phase fraction on variable locations were also studied. The results of FTIR and XRD showed that β phase appeared in PVDF/PMMA blends after extrusion and casting procedures. Although β phase fraction decreased after preheating, there was still an increasing trend during following biaxial stretching. More importantly, the increase in PMMA content improved β phase fraction, and the highest β phase fraction of 93% was achieved at PMMA content of 30 wt% and stretching ratio of 2×2. Besides, the reduction in PMMA content and the increase in stretching ratio improved the crystallinity of PVDF. The mechanical properties of the stretched films were significantly improved by increasing the stretching ratio as well. The uniform stress distribution on different regions of biaxial stretching films contributed to the uniform distribution of β phase fraction and crystallinity of PVDF with the aid of simulation. This work confirmed that biaxial stretching can be a candidate method to prepare PVDF/PMMA blend films with uniform distributions of comparable β phase and crystallinity of PVDF.

Isothermal and Non-Isothermal Crystallization Kinetics of PVDF and PVDF/PMMA Blends

Background: poly(vinylidene fluoride) PVDF and PVDF/PMMA blends have been investigated with a focus on the crystal structure, immiscibility and mechanical properties. However, few reports were found on the crystallization behaviors of PVDF and PVDF/PMMA blends, especially on crystallization kinetics. The article is to report the research on isothermal and nonisothermal crystallization kinetics for PVDF and PVDF/PMMA blends using differential scanning calorimetry (DSC). Results: Besides crystallization temperature and isothermal crystallization activation energy, the Avrami equation exponent of PVDF in blends decreased compared with pure PVDF. The nonisothermal crystallization kinetics of PVDF and PVDF/PMMA (70:30) blends were investigated by Ozawa equation, Jeziorny method and crystallization rate constant (CRC) in detail. The nonisothermal crystallization energy of pure PVDF and its blends were determined by the Kissinger and Vyazovkin’s method. Conclusion: The nucleation and growth mechanism of PVDF in blends changed compared with pure PVDF. The Ozawa equation is not applicable in nonisothermal crystallization kinetics of PVDF and PVDF/PMMA blends. The decreasing of crystallization ability of PVDF in blends were found and confirmed by CRC and the decline of crystallization rate constant in Jeziorny method. Such is opposite to the results of Kissinger’s and Vyazovkin’s method, chances are that these two methods were not used to calculate the nonisothermal crystallization activation energy where the nucleation process was influenced.

Effects of ABS-g-MAH on morphologies, compatibilities and properties of polycarbonate ternary blends

In this work, ABS-g-MAH was used as the compatibilizer in poly carbonate/acrylonitrile styrene acrylate/poly(methyl methacrylate) blends. The polymer blends were prepared via a two-step method: first, raw PC, ASA, PMMA resins and ABS-g-MAH additives were completely mixed and granulated by extrusion molding, and then the standard PC/ASA/PMMA blends samples were obtained by injection molding. A comprehensive characterizations were performed on the PC/ASA/PMMA blends of their morphologies, mechanical properties and thermal properties. The results showed that the addition of ABS-g-MAH could promote the compatibilities among PC, ASA and PMMA, and ABS-g-MAH would significantly alter the mechanical and thermal properties of blends. In addition, the modified PC/ASA/PMMA was well compatible with natural rubber and cause less cytotoxicity when interacting with cells.