Market HDT A (@ 1.82
Market HDT A (@ 1.82 MPa) 1 % 5 % HDT B [°C] 72 — 71 — 70 — 69 — 68 — 67 — 66 — Neat PLA HTP1c HTPultra5c NTT05 Fig. 6: Heat Distortion Temperature (HDT A 1.82 MPa (according to ISO 75) of PLA modified with different loadings of micronized talc. Specimens were annealed 3h@110°C before testing Stiffness 1 % 5 % Flexural Modulus [Mpa] 4900 — 4700 — 5400 — 4300 — 4100 — 3900 — 3700 — Impact notched 1 % 5 % Charpy notched @ 23 °C [kj/m 2 ] 8 — 7 — 6 — 5 — 4 — 3 — Neat PLA HTP1c HTPultra5c NTT05 Fig. 5: Charpy noched (according to ISO 179/1eA) of PLA modified with different loadings of micronized talc. Specimens were annealed 3h@110°C before testing Neat PLA HTP1c HTPultra5c NTT05 Fig. 4: Flexural modulus (according to ISO 178) of PLA modified with different loadings of micronized talc. Specimens were annealed 3h @110°C before testing By: Piergiovanni Ercoli Malacari Product and application development IMI Fabi, Milan, Italy For nucleation process the type of talc plays a minor role, while for both mechanical and thermal performances the situation is different and the three considered talc grades gave peculiar set of properties. In order to have comparable data, all specimens were injected by holding the mould at 30°C, to quench the molten polymer. In such condition, the crystallization didn’t take place in the mould. Specimens were annealed in oven at 110°C per 3 hours to post crystallize PLA. In terms of stiffness, the flexural modulus behaviour is shown in Fig. 4. The modification with 1% of talc didn’t affect PLA rigidity, while 5% talc loading recorded a visible improvement, up to 15% for talc NTT05 modification. Thanks to its platy structure, talc is able to improve PLA rigidity. Stiffness enhancement is generally linear with talc loading, but higher loading rates than 5% have not been investigated in this experimental work. The presence of a nucleator let the impact resistance improve versus the neat resin, because of better organized polymer structure. All the samples containing talc gave higher impact resistance than reference (Fig. 5). 1% talc loading is enough to record a significant improving in impact resistance. Ultrafine talc sample (HTPultra5c) shows better results thanks to its very tight particle size distribution. Concerning the evaluation of the service temperature, Heat Distortion Temperature (HDT) has been considered. HDT is the temperature at which a specimen, under a three point bending experiment at a specific load conditions, records a deflection of 0.25mm; it gives an easy indication about the service temperature. In Figure 6, HDT A (@ 1.82 MPa) data are listed. 1% talc modification doesn’t improve HDT of PLA, while the 5% talc modification offers a visible variation in service temperature. The modification with a high performing talc such as NTT05 allows to record a significant variation in HDT temperature versus the same loading of a highly micronized talc as HTP1c. Conclusions To allow PLA utilization in applications where service temperature plays the major role, the addition of highly micronized talc represents a good methodology for improving its thermal and mechanical properties, making such composites more interesting for technical applications. The incorporation of talc significantly accelerates the crystallization of PLA. From the experimental evidences, it appears that a small amount of talc (1%) is enough to achieve crystallization during molten PLA cooling process. In order to record a better kinetic in crystallization process, a higher talc amount has to be considered (5% loading), in combination with a relatively high mould temperature. The modification of PLA with talc allows to achieve higher rigidity (without compromising the impact resistance) and, thanks to the nucleation, better service temperature. In order to achieve reliable results in PLA modification, it is necessary to use micronized talc characterized by high degree in purity, by tight particle size distribution and by high lamellarity such as the three talc products examined in this experimental work. In particular, the right selection of talc becomes very important when relatively high talc loadings are considered (i.e. 5%) and the other mechanical properties can be significantly affected by the type of talc. To summarize, for a cost-effective PLA modification, talc HTP1 offers the most attractive set of properties, while for outstanding final mechanical properties, talc NTT05 can record the best-in-class properties still remaining, in terms of costs, as an extender for PLA. 26 bioplastics MAGAZINE [03/14] Vol. 9
Materials New high heat resistance grade After BIOPLAST 500, their first resin for film applications reaching 51% of biobased carbon according to ASTM D6866, BIOTEC GmbH & Co. KG (Emmerich, Germany) is now achieving new performances with the launch of BIOPLAST 900. Biotec launched the new injection moulding and thermoforming grade at interpack, Düsseldorf in early May 2014. “Products made of BIOPLAST 900 can, unlike some other bioplastics, withstand boiling temperatures without losing their shape, functionality and efficiency. Even at high filling temperatures, the taste of liquids/food is not affected.” says Harald Schmidt, Director of Innovation & New Technology of Biotec. This makes Bioplast 900 perfectly suitable for numerous food applications: coffee capsules, cups for cold as well as for hot drinks or the hot-filling of yoghurt or pudding products. Heat resistance combined with biodegradability - Bioplast 900 shows undisputable environmental advantages, e.g. organic recyclability. For instance, used coffee capsules or other products made of Bioplast 900 are perfectly suitable for industrial composting. The GMO-free product is 69% biobased (potato starch, PLA and other ingredients) High definition moulding and short cycle times “Bioplast 900 processability allows moulding of extremely precise and complicated shapes. This innovative bioplastic resin exhibits moulding properties similar to conventional plastics, such as PP and PS.” adds Harald Schmidt. For example “With a cycle time of 5 seconds for the coffee capsule application, Bioplast 900 meets the challenging cycle time of conventional plastics” states Peter Brunk, Managing Director of Biotec. Technical data Bioplast 900 is designed for the following applications: injection moulded articles (e.g. cutlery, medical devices, clips, cups for hot and cold drinks) semi-finished products thermoformed products (e.g. food trays) blend partner in combination with other Bioplast materials (e.g. BIOPLAST GF 106/02) Products made of Bioplast 900 are applicable for hot filling (e.g. beverages) are biodegradable according to EN 13432 are recyclable are printable by flexographic and offset printing without pretreatment can be coloured with masterbatches are sealable (hot, RF, ultra sonic) www.biotec.de interpack - review bioplastics MAGAZINE [03/14] Vol. 9 27
