Vicat Softening Temperature Research Articles

Synergistic effects of dual reactive compatibilizers for high-performance fully biodegradable polylactic acid/poly (butyleneadipate-co-terephthalate) composites

The PLA-g-(GMA-co-St) graft copolymer (PGS) was prepared using melt-free radical grafting technology, PGS and ESO were simultaneously employed as compatibilizers for the poly (lactic acid)/poly (butylene adipate-co-terephthalate) (PLA/PBAT) blends. The effects of the type and amount of compatibilizers on the properties of the blends were studied. The results reveal that the epoxy groups in PGS and ESO can interact with the terminal groups of PLA and PBAT. The incorporation of either PGS or ESO separately can improve the compatibility between PLA and PBAT to a considerable degree. However, the introduction of both compatibilizers into the PLA/PBAT blends results in a notable shift of the Tg of the two phases, reduces the size of PBAT particles, and makes their dispersion more uniform. This reveals that the dual reactive compatibilizers can achieve a synergistic effect, significantly reducing the interfacial tension between the two phases and facilitating inter-phase dispersion, ultimately forming a more uniform microstructure. Simultaneously, as the amount of ESO added to the blends gradually increases, the vicat softening temperature and complete decomposition temperature of the blends continue to increase, the notched impact strength and elongation at the break of the blend gradually increase and then decrease. When the ESO amount reaches 4 wt%, the performance of each property increases to 88.9 °C, 447.66 °C, 335.16 %, and 23,359.30 J/m2, respectively. At this point, the fracture surface of the blend samples is accompanied by a large-scale plastic deformation. In conclusion, this work represents the first attempt to accomplish synergistic effects via dual reactive compatibilizers. Under the best formulation and processing circumstances, the PLA/PBAT blends greatly increase their overall performance while maintaining biodegradability, hence broadening their application prospects in packaging, agriculture, and disposable tableware.

Enhancing the Stereocomplex Crystallization of PLLA/PDLA Symmetric Blend by Controlling the Degree of Molecular Chain Entanglement

In order to enhance the content of stereocomplex crystals (SC) in poly L-lactic acid (PLLA)/poly D-lactic acid (PDLA) symmetric blend, thereby improving the defects of low crystallinity and poor heat resistance of polylactic acid (PLA)-based materials, the samples with different entanglement degrees were prepared by freezing extration method. The critical overlap concentration of the blend system was quantitatively obtained using an Ubbelohde viscometer. Based on this concentration, samples with a series of concentration gradient were prepared to control the different degrees of molecular chain entanglement inside. The results indicated that the chain disentanglement could greatly increase the content of SC in the blend, whether in the precipitation crystallization or the melt crystallization process. Especially after the isothermal crystallization for 30min at 130oC, the L/D-0.1 sample with the highest degree of disentanglement almost only formed SC, accounting for 95.2% of the total crystallinity. Samples with lower entanglement degree had more crystal nuclei and faster growth rate of formed spherulites. For completely entangled sample L/D-50, the crystal nucleus of homo-crystalls (HC) could be considered as SC. Besides, the Vicat softening temperature (VST) of L/D-0.1 sample increased from 79.9oC of L/D-50 sample to 103.8oC with an obvious increase of 24.9oC. All these results provide new ideas for improving the performance of PLA-based materials and show promising development prospects of green and sustainable polymers.

Influence of functional group structures in nucleating agents on the crystallization behavior of poly(ethylene terephthalate)

AbstractNucleating agents are crucial for modifying semi‐crystalline polymers, but the impact of different end‐group structures on crystallization behavior remains unclear. This study synthesized succinic dihydrazide nucleating agents with various end groups (methyl, ethyl, and tert‐butyl) for PET composite materials. The tert‐butyl‐terminated nucleating agent showed the best performance, increasing the crystallization peak temperature to 203.8°C, crystallinity to 27.3%, and reducing half‐crystallization time to 2.8 min at 220°C. It also enhanced the impact strength to 47.2 kJ·m−2 and flexural modulus to 2623 MPa, while improving Vicat softening temperature and heat distortion temperature by 41 and 8°C, respectively. The results from FTIR and Raman Spectroscopy indicate that the interactions between the end groups of the nucleating agent and the CH bonds in the PET structure, the π–π interactions between the nucleating agent and the PET molecular structure, as well as the modulation of the PET chain conformation by the nucleating agent, are the primary factors contributing to the enhanced crystallinity of PET. This study provides a new approach for designing efficient nucleating agents for high‐performance materials.

Enhanced rheological, crystallization, mechanical, and heat resistance performance of poly(L‐lactide)/basalt fibers composites via in situ formation of stereocomplex polylactide crystals

AbstractDue to its favorable mechanical strength, transparency, and biocompatibility, polylactic acid (PLA) has considerable potential as a biodegradable material. Nevertheless, developing high‐performance PLA composites through environmentally friendly and cost‐effective methods remains a significant challenge. In this study, the composites comprising poly(L‐lactide) (PLLA), basalt fibers (BFs), and poly(D‐lactide) (PDLA) are prepared through facile melt blending. The in situ formed stereocomplex polylactide (SC‐PLA) crystals improve the crystallization ability and rheological behavior of PLLA/BF/PDLA composites. Upon adding 5 wt% PDLA, BFs are nicely dispersed in PLLA matrix because of increased shear intensity. The synergistic effect of BFs and SC‐PLA crystals enhances the mechanical, thermomechanical, and heat resistance properties of PLLA. In particular, PLLA/BF/10%PDLA composites exhibit a Vicat Softening Temperature (VST) of 155.5°C, increasing by approximately 100°C over neat PLLA. Annealing treatment increases the Young's modulus, thermomechanical properties, and VST of samples while reducing their tensile strength. Interestingly, the tensile strength of the annealed PLLA/BF/10%PDLA composites is 50.2 MPa, twice that of the annealed neat PLLA due to the introduction of SC‐PLA crystals. Simultaneously improving the rheological, mechanical, and heat resistance performance of PLLA opens possibilities for expanding its potential applications in the industrial field.

Highly-toughened PLLA/PVA biodegradable blends: Graft copolymer tailored crystallization and phase morphology

Poly(l-lactic acid) (PLLA), recognized as a promising substitute for petroleum-based polymers, has garnered significant attention for its various advantages. However, the practical application of PLLA is limited by its poor toughness. This study introduces a novel approach, using a graft copolymer, poly(vinyl alcohol)-graft-poly(l-lactic acid) (PVA-g-PLLA), synthesized through a "grafting to" method to enhance the compatibility of PLLA/PVA blends. It is demonstrated that even though the graft copolymer promotes crystallization, the resultant ternary blends, especially with a mass ratio of 7:3:1, exhibited an 88.7 % elongation at break, representing a 1642 % improvement over pure PLLA and a 576 % increase over binary PLLA/PVA blends. In addition, incorporating PVA-g-PLLA significantly enhanced the toughness of the PLLA/PVA blends without sacrificing strength, thermal stability, or transparency. Remarkably, the Vicat softening temperature of the blends with a 7/3/1.5 ratio increased to about 94.4 °C, substantially higher than the 59.9 °C observed in PLLA/PVA blends. These findings suggest that the newly developed copolymer and the ternary blends hold substantial promise for creating biodegradable materials that do not compromise performance. It suggests a promising future for these materials in various applications where enhanced durability, thermal stability, and environmental sustainability are crucial.

Semi‐aromatic poly(m‐xylylene adipamide‐co‐isophthalamide) copolyamides (MXD6/I): Effect of isophthalic acid on the thermal, crystallization, mechanical, and barrier properties

AbstractSemi‐aromatic nylon MXD6 shows superior mechanical strength and gas barrier properties. To improve its toughness and get sight into its excellent properties, a series of poly(m‐xylylene adipamide‐co‐isophthalamide) (MXD6/I) random copolyamides were synthesized using adipic acid, isophthalic acid (IPA) and m‐xylylene diamine as monomers via direct melt polycondensation. The effect of IPA content on the thermal, crystallization, heat resistant, mechanical, and barrier properties of the copolyamides were systematically investigated. The results showed that the increase of IPA content from 0 to 12 mol% resulted in a decrease in the melting point of the copolyamides from 238 to 217°C but the glass transition temperature (Tg) increased from 88 to 105°C. Correspondingly, the Vicat softening temperature decreased from 199.2 to 172.5°C. The crystallization rate of the copolyamides significantly decreased with the increase of the IPA content. The copolyamides had improved elongation and rupture energy and decent oxygen barrier properties with the introduction of IPA. It is expected that this study would guide design of MXD6 macromolecular chain structure to prepare high‐performance MXD6 materials.

Poly(vinyl chloride) composites reinforced with wood flour and calcinated halloysite

ABSTRACT Hybrid poly(vinyl chloride) composites were prepared by adding calcinated halloysite and wood flour to the PVC matrix by mixing in a molten state. The mechanical (DMTA analysis, tensile strength, strain at break, Young’s modulus, hardness and impact strength) and thermal (thermal stability, Vicat softening temperature and heat deflection temperature) properties of the composites were tested. The plastographometric analysis suggests that simultaneous addition of two fillers of different origins to the PVC matrix results in a longer gelation time and higher torque values than those observed for neat PVC. Moreover, the presence of calcinated halloysite in PVC/wood flour composites leads to the rise of weight loss temperature compared to PVC composites with only wood flour. When added to PVC/halloysite composites, wood flour improves their homogeneity by breaking halloysite agglomerates, which ensures approx. 116% better thermal stability (confirmed in the Congo red test) compared to unfilled PVC. The synergistic effect of the fillers used on the mechanical properties is demonstrated by the 14.4% higher stiffness and 22.5% higher tensile strength of the PVC composites containing wood flour and 5 wt% halloysite compared to the material loaded with wood flour only.

Preparation of expandable polystyrene/acrylonitrile-butadiene-styrene by multi-stage initiator dosing with the application of artificial neural networks

By increasing usage of polymers, environmental problems for them increase. The polymers that after usage, contribute to these issues, their preparation process may generate wastage, that affects production. In the production of expandable polystyrene (EPS), several batches on batch were discharged due to disruption in suspension, and the presence of these wastages in the production place can cause problems. This study tries to introduce a new polymer with special features by mixing different percentages of this polymer (10, 20, 30) with ABS polymer. According to the fact that disarray can occur in 60, 63, 66, and 69% of the polymerization, the polymerization continued until those percentages and then mixed with ABS. Different tests (like: Elongation at break, yellow index, Modular melt flow, Impact test, and Vicat softening temperature) was performed for mixed polymer. The results show that in some materials the quality of the mixed polymer may decrease but it is still in an acceptable range. The Multi-Layer Perceptron method of Artificial Neural Networks has been used in order to simulate data that has not been tested.

Biochar as an efficient reinforcing agent for poly(lactic acid)/poly(ε-caprolactone) biodegradable composites with high robustness and thermo-resistance

The brittleness of poly(lactic acid) (PLA) can be effectively mitigated by melt-blending it with poly(ε-caprolactone) (PCL). However, this approach compromises the vital strength and modulus of PLA, while the thermo-resistance remains low. In this regards, biochar (BC) was introduced to reinforce PLA/PCL composites as a modifier to improve mechanical and thermal performances. Herein, the effects of various contents of BC and annealing treatments were investigated on the properties of PLA/PCL composites. Interestingly, BC not only improved the mechanical properties of the composites but also reduced the semi-crystallization time by more than 70 %. Furthermore, annealing treatment increased the tensile strength and tensile modulus of the PLA/PCL/BC composites by 10.1 % and 6.3 %. Notably, Vicat softening temperatures of the composites with PLA to PCL proportions of 70:30 and 60:40 were increased to above 100°C. More importantly, the addition of BC effectively formed physical interaction with PLA, resulting in improvement in mechanical properties. Annealing treatment perfected the PLA crystal into a much more stable α-crystal form, resulting in an increase in thermal properties. This work paves an effective way to prepare PLA based biodegradable composites with high strength and thermo-resistance.

Fabrication of biopolyethylene-based biocomposites with coffee ground waste: Effect of polyethylene-graft-maleic anhydride

The production of plastic products from non-renewable raw materials, such as petroleum, damages the environment. Consequently, biocomposites have aroused interest from industry and researchers due to their ecologically correct characteristics, mainly because they come from renewable sources. Therefore, this study aimed to produce biopolyethylene/coffee ground waste (BioPE/CGW) biocomposites and analyze the impact of CGW and polyethylene-graft-maleic anhydride (PE-g-MA) on BioPE. The biocomposites were prepared in a co-rotational twin-screw extruder equipped with a side feeder to feed the CGW. The materials were subsequently injection molded to produce the impact, tensile, and HDT samples. The temperature profiles used during extrusion and injection were between 170 and 180°C. The BioPE and biocomposites were investigated for the vibrational (Infrared Spectroscopy - FTIR), thermal (differential scanning calorimetry), mechanical (tensile, impact, and hardness), thermomechanical (heat deflection temperature (HDT) and Vicat softening temperature (VST)), and morphological (scanning electron microscopy (SEM)) properties. The compatibilizer improved the interface between phases, promoting mechanical and thermomechanical improvements in the biocomposites. PE-g-MA promoted increments in tensile strength and elastic modulus of up to 38% and 25% in the BioPE/CGW30 and an increase of 44% in the elastic modulus compared to BioPE. The thermomechanical investigations showed that HDT increased by 8.8 and 3.3°C and VST increased by 2.5 and 6.6°C compared to BioPE and the BioPE/CGW30, respectively. Biocomposites from renewable and biodegradable sources align with a sustainable development concept.

One-step facile pathway synthesis of PAPXD/1214-PEA thermoplastic elastomer: Structure and properties

In this study, a novel and facile one-step synthesis route was conducted to prepare semi-aromatic polyamide elastomer (PAPXD/1214-PEA) with p-phenylenediamine, dodecane diamine, dodecanedioic acid and polyether amine (PEA) as monomers. A systematic investigation has been conducted into the effect of hard segment content on the thermal, mechanical and solvent resistance of polymers when semi-aromatic polyamides are used as hard segments. It was found that the melting point of the copolymers gradually increased from 191.2 °C to 231.5 °C with the hard segment content increased from 39 % to 76 %, while the Vicat softening temperature (VST) enhanced from 103.2 °C to 192.2 °C. Compared with the commercial polyamide elastomer Pebax@ (produced by Arkema Inc) with similar hard segment contents, the VST of PAPXD14/1214-PEA were 17.4–66.2 °C higher. The mechanical performance of these elastomers was also largely improved with tensile strength increasing from 15.1 to 40.6 MPa, Young's modulus from 28.2 to 168.7 MPa, toughness from 91.1 to 170.7 MJ/m3. In addition, the solvent resistance properties of PAPXD14/1214-PEA was compared with the commercial polyamide elastomer Pebax@. After soaking in hydrochloric acid for 24 h, the tensile strength of PAPXD/1214-PEA with the hard segment content increased from 50 % to 63 % decreased down to 9.4 and 14.4 MPa, respectively. While the commercial polyamide elastomer Pebax@ (with similar hard segment content) decreased down to 1.5 and 4.3 MPa, indicating the commercial polyamide elastomer products were deteriorated. This suggests the corrosion resistance of the synthesized PAPXD/1214-PEA is much better than that of commercial product, and these semi-aromatic polyamide elastomers can be potentially applied in some harsh service environment especially for high temperature and corrosion sealing.

Impact of aromatic sulfonate derivative on the crystallization, thermal resistance, and hydrolytic properties of poly(lactic acid)

AbstractThe thermal, crystallization kinetics and hydrolysis properties of poly(lactic acid)‐based blends containing different concentrations of 5‐dimethylthioisosulfate salts (LAK) were systematically investigated and compared with those of poly(lactic acid) (PLA). PLA/LAK blends were prepared by melt blending method‐using LAK as a nucleating agent of PLA. During the isothermal crystallization process, the morphology of PLA crystal in the neat PLA and PLA/LAK blends showed spherical crystals. With an increase in the concentration of LAK, the nucleating density of the PLA spherulites increased and the size of the PLA spherulites decreased. Differential scanning calorimetry indicates that after the addition of LAK, both the crystallinity and crystallization rate of PLA have been enhanced. In situ X‐ray diffraction analysis also shows that the sample exhibits the same crystal structure as neat PLA and continues to strengthen, indicating that LAK enhances the crystallization properties of PLA. Moreover, the crystallinity of PLA increased and crystal size of PLA decreased with the increase in the LAK content. The Vicat softening temperatures of PLA/LAK blends increased, so the heat resistance improved. Through hydrolysis testing under identical conditions, the PLA/LAK blends exhibits better hydrolytic stability.

Bio-based poly(lactic acid) foams with enhanced mechanical and heat-resistant properties obtained by facilitating stereocomplex crystallization with addition of D-sorbitol

The preparation of bio-based poly(lactic acid) (PLA) foams with high mechanical properties and heat resistance is of great significance for environmental protection and green sustainable development. In this paper, D-sorbitol (DS) containing six hydroxyl groups was introduced into poly(l-lactide) (PLLA)/poly(d-lactide) (PDLA) blends for first time to promote the formation of stereocomplex (SC) crystals, which could improve the foaming behavior and enhance mechanical properties and heat resistance of PLA foams. The results showed that DS could improve the formation efficiency and crystallinity of SC crystals by enhancing the hydrogen bonding between the enantiomeric molecular chains. Furthermore, the compression modulus and interactions Vicat softening temperature of the PLLA/PDLA/DS blend foam increased about 854% and 16% compared to the pure PLLA foam, respectively. Besides, when the annealing process was introduced, the compression and heat resistance of the PLA foams increased further. This study provided a feasible strategy for the preparation of bio-based and biodegradable PLA foams with outstanding compressive and heat resistance properties.

Preparation of PLA/PBAT blends with high performance via the synergistic effect of high mold temperature and strong shear field

As a bio-based polymer with excellent mechanical properties, good biodegradability and biocompatibility, polylactic acid (PLA) displays considerable potential to replace traditional petrochemical-based polymers for application. However, poor toughness and heat resistance restrict its wide application. In this work, PLA based PLA/PBAT blends with excellent comprehensive performance were prepared through the synergistic effect of high mold temperature as well as strong shear field. SEM, DSC and WAXD were conducted to characterize the crystal and micro-morphology of the samples. The results show that highly oriented shish-kebab and hybrid shish-kebab structures are observed in VIM-H sample. The crystallinity increases dramatically, which can reach 48%. Besides, the toughness, strength and heat resistance of VIM-H all markedly improve. The Vicat softening temperature (VST) reaches up to 149.2 °C, while the tensile strength and impact strength increase to 89.07 MPa and 10.36 kJ/m2, respectively. This study proves the synergistic enhancement of the properties for PLA/PBAT blends by high mold temperature as well as strong shear field, which provides a new method to obtain high-performance PLA materials and is beneficial for the wider application of PLA products.

Waste cotton stalks enhancing the impact and crystallization performances of polylactic acid/polypropylene composite with PP-g-mah compatibilizer

Although polymers based on polylactic acid (PLA) are considered by researchers as prime candidates for replacing traditional plastics, they are confronted with challenges including high production costs, limited thermal stability, and inferior impact resistance. In this study, novel composites with exceptional impact resistance, robust thermal stability, and satisfactory crystalline properties were fabricated by using PLA and polypropylene (PP) as raw materials, PP-g-MAH was employed as a compatibilizer to enhance the compatibility between the individual components. by adjusting the quantity of discarded cotton stalk fibers (CSF). The optimal mass ratio of CSF was determined to be 20%, resulting in a composite that exhibited a moderate increase of 56.31% in impact strength and a remarkable improvement of 23.05% in Vicat softening temperature. While the crystallinity was enhanced and the crystallization temperature (Tc) value decreased, the storage modulus also increased. Furthermore, the observed increase in storage modulus within the temperature range of 80 °C–100 °C was attributed to the influence of polymer cold crystallization. The hydrophobicity of the composite was enhanced. Significantly, this strategy can be extended to the application of other plant fibers, improving the crystalline properties of semi-crystalline polymers such as PLA and exemplifying the true ‘valorization of waste' through the secondary utilization of discarded CSF.

Research on modification of polylactic acid multifunctional composite materials for 3d printing

Polylactic acid is an important 3D printing material, but its further development and application in the field of 3D printing are limited due to its flammability, poor toughness, and lack of high temperature resistance. This article modifies polylactic acid wire for 3D printing by adding flame retardants aluminum hypophosphate, polycarbonate, and chain extender to prepare multifunctional composite flame retardant materials. It was found that with the increase of aluminum hypophosphate addition, the flame retardancy of polylactic acid composite materials gradually improved, while the tensile strength, impact strength, and hardness showed a decreasing trend, and the flowability decreased, but the Vicat softening temperature increased. Through 3D printing testing, when the amount of aluminum hypophosphate added is 15-20 parts, the printing quality is good and the comprehensive performance is the best, which can meet the basic usage requirements.

INFLUENCE OF FLUID UPTAKE ON THE MECHANICAL AND THERMAL PROPERTIES OF PMMA-BASED BONE CEMENT

According to the latest report from the German Arthroplasty Registry, aseptic loosening is the primary cause of implant failure following primary hip arthroplasty. Osteolysis of the proximal femur due to the stress-shielding of the bone by the implant causes loss of fixation of the proximal femoral stem, while the distal stem remains fixed.Removing a fixed stem is a challenging process. Current removal methods rely on manual tools such as chisels, burrs, osteotomes, drills and mills, which pose the risk of bone fracture and cortical perforation. Others such as ultrasound and laser, generate temperatures that could cause thermal injury to the surrounding tissues and bone. It is crucial to develop techniques that preserve the host bone, as its quality after implant removal affects the outcome of a revision surgery.A gentler removal method based on the transcutaneous heating of the implant by induction is proposed. By reaching the glass transition temperature (TG) of the periprosthetic cement, the cement is expected to soften, enabling the implant to be gently pulled out. The in-vivo environment comprises body fluids and elevated temperatures, which deteriorate the inherent mechanical properties of bone cement, including its TG. We aimed to investigate the effect of fluid absorption on the TG (ASTM E2716-09) and Vicat softening temperature (VST) (ISO 306) of Palacos R cement (Heraeus Medical GmbH) when dry and after storage in Ringer's solution for up to 8 weeks.Samples stored in Ringer's solution exhibited lower TG and VST than those stored in air. After 8 weeks, the TG decreased from 95.2°C to 81.5°C in the Ringer's group, while the VST decreased from 104.4°C to 91.9°C. These findings will be useful in the ultimate goal of this project which is to design an induction-based system for implant removal.Acknowledgements: Funded by the Deutsche Forschungsgemeinschaft (DFG, German Research Foundation) – SFB/TRR-298-SIIRI – Project-ID 426335750

Citrus waste fibres for natural cosmetic and bioplastic packaging

In this work new biocomposite materials from wasted citrus peels has been validated for a value-added packaging and novel cosmetic products. Specifically, extracted natural fibres and dehydrated pulp from citrus fruit were combined with polylactic acid and other additives as materials for the production of bio-based packaging jars and cosmetic products. For the composition of the packaging an orange powder (dehydrated wastes) was found to be the best performing, while orange comminute, which results from milling the orange peel, was most suitable for composition of the cosmetic formulations. Polylactic acid was compounded with citrus fibres by up to 25 wt.% by twin screw extrusion and processed via injection moulding, one of the most widespread processing technologies for producing rigid packaging containers. Composites were characterized, defining their mechanical, morphological and thermal properties. Validation of packaging thermostability performance was performed by Heat deflection temperature in compliance to ISO75 and VICAT softening temperature in accordance with ISO306. Compatibility tests of packaging demonstrators with newly formulated cosmetic products has been investigated as well. An accelerated compatibility test of the cosmetic jars with water and oil-based simulants was performed at ambient temperature, -5 °C, and at 45 °C. The results indicated that new cosmetic packaging are not consistent with water-based cosmetic formulations but are compatible with products based on natural oils. While the price of these products is generally higher than those using conventional plastics, they are competitive for premium cosmetic brands.

Fiber treatment impact on toughness and interfacial bonding in epoxidized soya bean oil compatibilized PLA/PBAT bamboo fiber composites

Biodegradable plastics such as Poly(lactic acid) (PLA) and polybutylene adipate terephthalate (PBAT) are commonly used in composite fabrication and applications. However, their inherent properties limit their use. In this study, Epoxidised soyabean oil (ESO) compatibilized PLA/PBAT was filled with modified bamboo fiber (BF). The BF was modified in a two-stage environmentally friendly process involving steam treatment followed by a new approach to hydrophobic natural fiber modification with naturally occurring fatty acid (myristic acid) (MA). Then, the ESO/PLA/PBAT/BF composite was fabricated, and the influence of the new fiber modification method on the toughness and interface bonding of the composite was studied. The composite was characterized using mechanical analysis, scanning electron microscopy (SEM), thermogravimetry analysis (TGA), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction analysis (XRD), water contact angle measurement, and statistical methods. The melting behavior was also studied using Vicat softening and heat deflection temperatures. The ESO compatibilisation improved the compatibility of the PLA/PBAT blend, resulting in a continuous PLA/PBAT phase, as evidenced by the interface modulus, glass transition temperature, and fractured surface. The modification of BF enhanced its dispersion in the matrix and improved interfacial adhesion. Elongation at break and impact toughness were improved by more than double compared to neat PLA. Adding PBAT and modified BF to PLA resulted in a thermally stable composite. The statistical analysis results suggested that BF modification and BF loading significantly influenced the composite strength and toughness (P ≤ 0.05). The tough and flexible composite material can used in flexible/lightweight and impact-resistant applications, consumer goods, and heat shields.

Implications of ageing effects on thermal and mechanical properties of PMMA-based bone cement for THA revision surgery

Loosening and infection are the main reasons for revision surgery in total hip arthroplasty (THA). Removing partially detached cemented implant components during revision surgery remains challenging and poses the risk of periprosthetic bone damage.A promising approach for a gentler removal of partially detached prostheses involves softening the PMMA-based bone cement by heating it above its glass transition temperature (TG), thus loosening the implant-cement bond. It is assumed that the TG of PMMA-based bone cement decreases in-vivo due to the gradual absorption of body fluid. Reliable data on TG are essential to develop a heat-based method for removing cemented implant components during revision surgery.The effect of water absorption was investigated in-vitro by ageing PMMA-based bone cement samples for different periods up to 56 days in both Ringer's solution (37 °C) and air (37 °C and 30% humidity). Subsequently, the TG and Vicat softening temperatures of the samples were determined by differential scanning calorimetry and Vicat tests, respectively, according to prescribed methods.Over the entire ageing period, i.e. comparing one day of ageing in air and 56 days in Ringer's solution, the Vicat softening temperature dropped by 16 °C, while the TG dropped by 10 °C for Palacos® R PMMA-based bone cement. Water absorption over time correlated significantly with the Vicat softening temperature until saturation of the PMMA-based bone cement was reached.Based on the TG and Vicat softening temperature measurements, it can be assumed that in body-aged bone cement, an optimal softening can be achieved within a temperature range of 85 °C–93 °C to loosen the bond between the PMMA-based bone cement mantle and the prosthesis stem. These findings may pave the way for a gentler removal of the implant in revision THA.