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The main objective of packaging material is to protect the contents. Glass, paper, cardboard and plastic have become very important packaging materials. From the 1970s, the plastic packaging sector began to grow. Due to the large amount of plastic waste in the environment, consumers demanded the development of environmentally friendly packaging materials. Polylactic acid (PLA) is one of the bio-based and biodegradable alternatives. Besides good processing properties, PLA also has some drawbacks. The most pronounced one for use in the packaging sector is brittleness. To avoid this drawback, nanocrystalline cellulose (NCC) can be incorporated into the PLA matrix. To prevent the agglomeration of NCC and improve the surface interaction between NCC and PLA, the surface modification of NCC is the most researched topic. For packaging material, price is also an extremely important issue. Surface modification of NCC is an additional processing step that also involves chemicals and is not always environmentally friendly. An alternative to surface modification of NCC is the use of a suitable compatibilizer to improve the surface interactions between NCC and the thermoplastic matrix and to allow uniform dispersion and distribution of NCC in the thermoplastic matrix. Three different concentrations of surface unmodified NCC (1 wt.%, 2 wt.%, and 5 wt.%) in PLA-based blends were prepared. A PLA-based blend without NCC was used as a reference. Two compounding cycles were performed to investigate the effect of shearing during processing on the properties of the nanocomposites and the distribution of NCC in the thermoplastic matrix. The addition of NCC increases the stiffness, strength and elongation at break. The glass transition temperatures are not affected by the addition of NCC. Moreover, the NCC prevents the crystallization of the PLA matrix upon cooling and postpones the cold crystallization of the PLA matrix upon heating to higher temperatures. The toughness was improved in the nanocomposites with NCC. The results show that the toughness of the PLA blend was improved by the addition of NCC, although NCC was used without surface modification. Modification with a suitable compatibilizer during compounding is the environmentally friendly alternative for the production of nanocomposites for the packaging industry.

High brittleness of polylactic acid (PLA) is the main drawback for the use of this material in the packaging sector. To overcome this drawback, there are many PLA blends with other thermoplastic tough materials. To maintain the biodegradable properties of PLA blends, the preparation of blends with other biodegradable materials is preferred. The most commonly used are poly(3-hydroxybutyrate) (PHB) and polybutylene adipate terephthalate (PBAT). The disadvantage of PHB is its high price, and the disadvantage of PBAT is the incompatibility of PLA and PBAT. For PLA-PBAT blends, multifunctional reactive polymers are used as reactive compatibilizers. For packaging applications, epoxy oligomers can be used as reactive compatibilizers. To reduce the price of PLA blend, biomass can be added as filler. In the present work, the PLA matrix was mixed with 15 wt.% and 20 wt.% PBAT in the presence of a multifunctional reactive polymer with epoxy groups. As biomass, 5 wt.% and 10 wt.% of hops were added along with compatibilizer. The mechanical, thermal and impact properties were tested and evaluated. The presence of hops keeps the thermal properties of biocomposites at the level of pure PLA. The addition of PBAT lowers the stiffness and strength, but dramatically increases the toughness of the biocomposites. In biocomposites, cold crystallization of PLA occurs at lower temperatures compared to neat PLA. From the results, we can conclude that hops increases the stiffness and decreases the glass transition temperature, while the addition of PBAT decreases the stiffness and glass transition temperatures, but both together act as nucleating agents for the crystallization of PLA matrix. Reactive compatibilization was successful as the biocomposite exhibited over 200 % higher impact strength and over 240 % higher elongation at break compared to the neat PLA matrix. The biocomposites are cheaper alternative and can be used in the packaging sector due to their good stiffness, strength, toughness and low price compared to the petroleum-based materials currently used in the packaging sector. Another advantage is that biomass can be used as a filler in biocomposites without the need for surface treatment as a suitable compatibilizer is used.

Due to low density, high stiffness, moderate strength and low price, biocomposites with polyethylene (PE) as matrix and biomass as reinforcement are also gaining the attention of researchers in the field of packaging. The interfacial bonding between the nonpolar PE matrix and the polar biomass determines the properties of the biocomposites. The interfacial bonding can be improved by surface treatment of the biomass or by the addition of a suitable compatibilizer. The compatibilizer, in the present case maleic anhydride grafted onto the PE main chain, can also facilitate the dispersion of the biomass in the PE matrix. In addition, the nature of the compatibilizer can also be used to increase the surface tension of the biocomposite. This triple compatibilization function was tested with the PE -HD matrix and the addition of 2 wt.%, 3 wt.%, 4. wt.%, and 5 wt.% PE -g- MA compatibilizer. Either 30 wt.% waste paper or miscanthus fibers were used as reinforcement. Adhesion was tested using IML technology during injection molding. The mechanical and thermal properties of the biocomposites were determined using bending and tensile tests, DMA, DSC, TGA and impact tests. An improvement in adhesion was obtained with increasing amount of compatibilizer. Stiffness decreased with increasing amount of compatibilizer while strength increased. Impact strength was increased with the amount of compatibilizer. The results indicate that the compatibilizer can successfully replace the surface treatment of biomass while promoting adhesion on the surface without additional surface treatment such as corona treatment. The results are promising for the use of this approach for the formulation of biocomposites for the packaging sector, as two additional steps are avoided, thus reducing the price of the final product.

Interest in the peel properties of thin polymer films for sealed packaging has increased dramatically over the past year due to increasing demand, particularly in food preservation and medical applications. For customer convenience in all packaging applications and to ensure sterility in medical device packaging, seals should be as easy to peel as possible without compromising functionality. To achieve the desired peel effect, 6 modified blends of PE and PP were prepared using 3 different commercially available modifiers at 2 different concentrations. The first modifier was an ethylene-based α-olefin copolymer, the other two were ethylene-based octene-1 plastomers and were added at 10% and 20%. The percentage of PE was set at 30 %, and the percentage of PP was 50% or 60%, depending on the modifier content. The prepared blends were extruded and granulated using a twin screw extruder. The granules were pressed into thin films, which were analyzed for their tensile properties by standard tensile tests and dynamic mechanical analysis (DMA), heat sealing and peeled on an universal testing machine, for their chemical structure by Fourier transformation infrared spectroscopy (FT -IR), and for their thermal properties by differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA).

One of the basic problems in the development and production process of moulds for injection moulding is the control of the temperature conditions in the mould. Nowadays, the temperature is controlled through a mould cooling system,which is composed of cooling channels, where the cooling fluid transports the needed heat to and from the mould. Such systems control the heat-exchange process throughout the entire mould, which is insufficient in many cases. For this reason it is necessary to develop a new system that will allow fast and precisely located temperature changes in defined mould locations. A precise study of the thermodynamic processes in moulds showed that heat exchange can be manipulated by thermoelectrical means. Such a systemupgrades conventional cooling systems within the mould or can be a stand-alone application for the heat manipulation within it. The upgraded system comprises the temperature-detection unit, the thermo-control unit and the final controlling element (thermo-element module as a heat pump), while the stand-alone unit needs an additional heat exchanger. These units form an adaptive closed loop. In this paper we present the results of a research project that was carried out in three phases, and its results are included in the A686\2006 patent. The testing stage, the prototype stage and the industrialisation phase will be presented. The main results of the project were the total and rapid online thermo-control of the mould over the cycle time and the overall influence on the quality of the plastic product, with an emphasis on deformation control. This system represents a milestone in the field of mould-temperature and product-quality control during the injection-moulding process. Obvladovanje temperaturnih razmer v orodjih za brizganje plastike je eden izmed pomembnejših dejavnikov pri razvoju in izdelavi orodij. Trenutno nadzor nad temperaturami temelji na sistemu hladilnih kanalov v orodjih, po katerih hladilno sredstvo dovaja ali odvaja potrebno toploto prek celotnega orodja. Zmogljivosti opisanega sistema so zaradi narave tehnologije v veliko primerih nezadostne potrebam v industriji, ki narekujejo hitre in locirane spremembe temperatur v orodjih. Obsežna studija termodinamičnih pojavov je pokazala, da toplotni tok v orodjih lahko poteka termoelektrično. Predstavljeni sistem nadgrajuje običajne hladilne sisteme, lahko pa deluje tudi kot neodvisen sistem. V prvem primeru sestoji iz enote za merjenje temperatur v orodjih, krmilne enote in termoelektričnih elementov kot izvršilnih elementov. Samostojen sistem potrebuje dodaten prenosnik toplote. Vse enote sestavljajo sklenjeno krmilno zanko. V predstavljenem delu pisci predstavljajo rezultate raziskovalnega dela, ki sestoji iz treh delov, rezultati pa so patentno zaščiteni v A686\2006. Poglavitni rezultati tako testnega, prototipnega kakor tudi industrijskega sklopa se izrazajo v hitri in popolnoma obvladljivem krmiljenju temperature preko celotnega delovnega kroga in vplivih le-te na kakovost plastičnih izdelkov s poudarkom na obvladovanju deformacij. Predstavljena tehnologija in uporaba sta pomemben mejnik na področju obvladovanja temperaturnih razmer in kakovosti končnih izdelkov pri postopku brizganja plastike.

Mould design for injection moulding of thermoplastics is becoming a more complex and complicated task, where even experienced mould designers could have problems. One of the most important phase of mould design is conceptual mould design, thus the mould designer must pay special attention to this phase. The approach to this mould design phase is usually based on the designer's experience, which can lead to some raw mould design errors. One of the possible solutions for this problem is the application of decision diagrams which can guide to the solution for certain partial mould functions. Decision diagrams are especially important for young and less experienced mould designers, because with their application mould design errors can be avoided in an early phase of mould development.